SYNTHESIS, SPECTROSCOPIC AND BIOLOGICAL STUDIES OF 3d TRANSITION METAL COMPLEXES WITH VARIOUS ANILINE BASED SCHIFF BASES
Submitted By HABIB HUSSAIN (2008-Ph.D Chemistry-02)
Supervisor Prof. Dr. Syeda Rubina Gilani
DEPARTMENT OF CHEMISTRY University of Engineering and Technology, LAHORE-PAKISTAN (2015)
Synthesis, Spectroscopic and Biological Studies of 3d Transition Metal Complexes with Various Aniline Based Schiff Bases
HABIB HUSSAIN (2008-Ph.D Chemistry-02)
Department of Chemistry
University of Engineering and Technology, Lahore
Supervisor: Prof. Dr. Syeda Rubina Gilani
A dissertation submitted to the
University of Engineering & Technology Lahore
in accordance with the requirements of the degree of Ph. D in the Faculty of Science.
(2015) II
Synthesis, Spectroscopic and Biological Studies of 3d Transition Metal Complexes with Various Aniline Based Schiff Bases
This Research Thesis Is Submitted To the Department of Chemistry, University of Engineering & Technology Lahore for the Fulfillments for the Degree of
DOCTOR OF PHILOSOPHY
In
CHEMISTRY
Approved on ______
Internal Examiner: Signature: ______
(Supervisor) Name: Prof. Dr. Syeda Rubina Gilani
External Examiner: Signature: ______Name: ______
Chairperson of the Department: Signature: ______Name: Prof. Dr. Syeda Rubina Gilani
DEPARTMENT OF CHEMISTRY
UNIVERSITY OF ENGINEERING & TECHNOLOGY LAHORE
III
FORM FOR THE RELEASE OF RESEARCH THESIS FOR EXAMINATION
Declaration by the Candidate
I “HABIB HUSSAIN” declare that the thesis titled; “Synthesis, Spectroscopic and Biological Studies of 3d Transition Metal
Complexes with Various Aniline Based Schiff Bases” is my own work and has not been submitted previously in whole or in part in respect of any other academic award.
______
Signature of Candidate Date
I approved that the above thesis can be submitted for examination.
______
Signature of Supervisor Date (Prof. Dr. Syeda Rubina Gilani)
IV
IN THE NAME OF ALLAH
The Most Gracious
The Most Merciful
V
Dedicated To My
Beloved Parents
Brother and Sister
Family and Beloved Wife
VI
ACKNOWLEDGEMENTS
I am very thankful to Almighty Allah; the entire source of knowledge and wisdom; and His Prophet Muhammad (peace be upon him) who enabled me to complete this work. I would like to take this opportunity to thank all the people who helped and supported me throughout the past years.
Firstly, I would like to thank Prof. Dr. Syeda Rubina Gilani for giving me the opportunity to work within her group and for the supervision, guidance and education that she provided along the way. It has been a great pleasure for me to work with many wonderful people in this research group: thank you to everyone for providing a great atmosphere in which to work and develop my chemistry skills. I have learnt a great deal during my PhD and I know that my experiences will stay with me long after leaving University of Engineering & Technology Lahore.
I am thankful to Prof. Dr. Fazeelat Tahira, Dean of Sciences and Humanities, University of Engineering and Technology, Lahore for providing me this precious opportunity. I am also thankful to all worthy Professors of Chemistry Department, U.E.T Lahore for providing me guidance time to time when needed.
Prof. Dr. Varinder Aggarwal, Dr. Jack Chen, Dr. Helen Scott and the staff of the NMR, Mass Spectroscopy and X-ray crystallography departments, University of Bristol, U.K and University of Malaysia deserve a mention for their efforts in analyzing the complexes in this thesis and their willingness to answer my questions.
Determination of antibacterial activities of ligands and complexes was a part of my work so I am highly thankful to Dr.
VII
Farkhanda Jabeen, Department of Botany, University of Punjab Lahore who provided me lab, memorable working environment and facilities for the investigation of bacterial activities.
I am also thankful to Dr. Tayyeba (S.O), Shahid Rehman (S.O) and uncle Imam din PCSIR Lahore for her guidance in spectroscopic analysis and Mr. Atif, Mr. Anwar Nadeem, Mr. Tanveer Ahmed, Mr. Dilshad, Mr. M. Anwar and Mr. Niamat laboratory staff University of Engineering & Technology Lahore for their help and memorable cooperation throughout in my project.
I am very grateful to Zulfiqar Ali, Hajira Rehman, Imdad Hussain, Dr. Amin Abid, Dr. Faiz Rabbani, Dr. Asif Ali, Amir Khan, Mehmood Baig, Nabeel-ur- Rehman, Mudassar Khalil, Mudassir Abbasi, Anum Saleem, Sarah Rahman, M. Imran Pasha, Hafiz Yousaf and all the management of Superior Group of Colleges especially Prof. Dr. Abdul Rehman (CEO) for their skilled guidance and encouraging attitude throughout my research work.
Here I remember Higher Education Commission of Pakistan and say special thanks for providing me research funds.
Finally, I have to thank my Father, Mother, Brother Zaheer Hussain Bubak, Sister Narjis Khatoon Bubak, Wife Humaira Perveen and Love for their support over the years. I know that you have no idea what most of this thesis means but it still couldn’t have been written without you.
Habib Hussain (2008-Ph.D Chemistry-02)
VIII
Author’s Declaration
I declare that the work in this dissertation was carried out in accordance with the regulations of the University of Engineering and Technology Lahore. This work is original, except where indicated by special reference in the text. And no part of the dissertation has been submitted for any other academic award.
All views expressed in the dissertation are those of the author and in no way represent those of the University of Engineering and Technology.
The dissertation has not been presented to any other University for examination in Pakistan or overseas.
Signed: …………………… Date: …………………….
IX
Table of Contents
Chapter 1
INTRODUCTION...... ……………………………………………………………1-25 1.1 Studies of Metal Chelates------02 1.2 Schiff Bases------02 1.3 Importance of Schiff Bases------03 1.4 Biological Importance of Schiff Bases------05 1.5 Types of Ligands------06 1.5.1 Mono-dentate Ligands------06 1.5.2 Bi-dentate Ligands------06 1.6 Chelate Formation------07 1.7 Stability of Schiff Bases------08 1.8 Methods for Preparation of Imines------08 1.9 Synthesis of Imines------09 1.10 Synthesis of Imine Metal Complexes------10 1.11 Applications of Imine Metal Complexes------12 1.11.1 Imine Metal Complexes used as Catalysts------12 1.11.2 Use of Imine Metal Complexes in Oxidation Reactions------12 1.11.3 Use of Imine Metal Complexes in Hydrogenation Reactions------13 1.11.4 Use of Imine Metal Complexes in Epoxidation Reactions------14 1.11.5 Use of Imine Metal Complexes in Polymerization Reactions------16 1.12 Biological Activities of Imine Metal Complexes ------16 1.12.1 Antimicrobial Activities------16 1.12.2 Antifungal Activities------17 1.12.3 Antitumor and Cytotoxic Activities------17 1.13 Photochromism and Thermochromism in Schiff Bases------17 1.14 Stability of Metal Complexes------18 1.15 Reactions of Transition Metal Complexes------19
X
1.15.1 Substitution Reactions ------19 1.15.1.1 Substitution Reactions in Aqueous Solvent------19 1.15.1.2 Substitution Reactions in Non-Polar Solvents------19 1.15.1.3 Substitution Reactions in absence of Solvent------19 1.15.1.4 Substitution Reactions without Metal-Ligand Bond Cleavage------20 1.15.2 Thermal Dissociation of Solid Complexes------20 1.15.3 Oxidation-Reduction Reactions ------20 1.15.4 Catalysis ------20 1.15.4.1 Heterogeneous Catalysis ------21 1.15.4.2 Homogeneous Catalysis ------21 1.16 Transition Metals used for Synthesis of Complexes------21 1.16.1 Copper------21 1.16.2 Zinc------22 1.16.3 Nickel ------23 1.16.4 Cobalt ------24
Chapter 2
INSTRUMENTATION…………………………………………………………26-36 2.1 Melting/Decomposition Points------27 2.2 UV-Visible spectrophotometry------27 2.3 Infra-red (IR) Spectroscopy------28 2.3.1 Preparation of Samples------29 2.3.2 Method for Analyzing a Sample------30 2.4 Atomic Absorption Spectrophotometry (AAS) ------31 2.5 Thermal gravimetric Analysis (TGA) ------31 2.6 Powdered X-ray Diffraction (PXRD) ------32 2.7 Nuclear Magnetic Spectroscopy (NMR)------33 2.8 Electron Spray Ionization-Mass Spectroscopy (ESI-MS) ------34 2.9 Vibrating Sample Magnetometer (VSM) ------35
XI
Chapter 3
EXPERIMENTAL WORK..……………………………………………………37-55
3.1 Chemicals and Reagents------38 3.2 Synthesis of 3-acetyl-2H-chromen-2-one------38 3.3 Synthesis of Schiff Bases ------38 3.3.1 General Procedure------38 3.3.2 Synthesis of (E)-3-(1-(p-tolylimino)ethyl)-2 H-chromen-2-one ------39 3.3.3 Synthesis of (E)-3-(1-((4-chlorophenyl)imino)ethyl)- 2H-chromen-2-one ------39 3.3.4 Synthesis of (E)-3-(1-((2-nitrophenyl)imino)ethyl)-2H- chromen-2-one------40 3.3.5 List of Prepared Ligands------41 3.4 Synthesis of Imine Metal Complexes------41 3.4.1 General Procedure------41 3.4.2 Mechanism of Reaction------42 3.4.3 Synthesis of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) – 2 H – chromen – 2 – one ]Nickel( II)------43 3.4.4 Synthesis of Bis[(E) - 3 -( 1- (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Nickel( II)------43 3.4.5 Synthesis of Bis[(E) – 3 - ( 1 - (( 2 – nitrophenyl ) imino ) ethyl ) – 2 H – chromen – 2 – one ]Nickel(II)------43 3.4.6 Synthesis of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) – 2 H - chromen – 2 - one ]Cobalt( II)------43 3.4.7 Synthesis of Bis[(E) – 3 - ( 1 - (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Cobalt(II)------44 3.4.8 Synthesis of Bis[(E) – 3 - ( 1 - (( 2- nitrophenyl ) imino ) ethyl ) – 2 H – chromen - 2 – one ]Cobalt(II)------44 3.4.9 Synthesis of Bis[(E) - 3 - ( 1 - ( p - tolylimino ) ethyl) - 2 H – chromen - 2 - one ]Copper( II)------44 3.4.10 Synthesis of Bis[(E )- 3 - ( 1- (( 4 – chlorophenyl ) imino) XII
ethyl ) -2 H - chromen- 2 – one ]Copper(II)------45 3.4.11 Synthesis of Bis[(E) - 3 - ( 1 - (( 2 - nitrophenyl ) imino ) ethyl ) – 2 H – chromen - 2 –one ]Copper(II)------45 3.4.12 Synthesis of Bis[(E) - 3 - ( 1 -( p - tolylimino) ethyl ) - 2 H - chromen – 2 – one ]Zinc( II)------45 3.4.13 Synthesis of Bis[(E) - 3- ( 1- (( 4- chlorophenyl) imino ) ethyl ) - 2 H- chromen - 2 – one ]Zinc(II)------45 3.4.14 Synthesis of Bis[(E)- 3 -( 1- (( 2 – nitrophenyl ) imino ) ethyl) -2 H – chromen - 2 – one ]Zinc(II)------46 3.5 Methods for Purification and Recrystallization ------46 3.5.1 By Slow Evaporation------46 3.5.2 By Cooling at Low Temperature------46 3.5.3 List of Synthesized metal Complexes------47 3.6 Techniques used for Characterization of Ligands and Complexes ------48 3.6.1 UV-Visible Spectroscopy (UV-VIS) ------48 3.6.2 Infra-red (IR) Spectroscopy------48 3.6.3 Atomic Absorption Spectrophotometry (AAS) ------48 3.6.4 Thermo gravimetric analysis (TGA)------49 3.6.5 Powdered X-ray Diffraction (PXRD)------50 3.6.6 Nuclear Magnetic Resonance (NMR) Spectroscopy ------50 3.6.7 Electron Spray Ionization-Mass spectroscopy (ESI-MS)------50 3.7 Antibacterial Activity of Metal Imine Complexes------51 3.7.1 Materials ------51 3.7.2 Preparation of LB Agar Plates ------51 3.7.3 Obtaining Single Colony of Bacterial Strain------52 3.7.4 Streaking of Plates------52 3.7.5 Spreading diluted Stock Culture to obtain Single Colony ------53 3.7.6 Preparation of Antibacterial Solution------54 3.7.6.1 Antibacterial Activity assay Procedure------54 3.7.6.2 Concentrations of Test Ligands/Complexes------55
XIII
Chapter 4
ANTIBACTERIAL ACTIVITY….………………………….…………………56-67 4.1 Introduction------57 4.2 Mode of Action------58 4.3 Test Cultures------58 4.4 Classification of Bacteria------59 4.4.1 Methicillin-Resistant Staphylococcus Aureus (MRSA) ------59 4.4.2 Bacillus Subtilis: Family (Bacillaceae) ------61 4.4.3 Staphylococcus aureus: Family (micrococcaceae)------62 4.4.4 Escherichia coli: Family (Enterobacteriaceae) ------63 4.4.5 Pseudomonas aeruginosa------64 4.4.6 Salmonella Typhi (S. Typhi) ------65 4.5 Evaluation Techniques------67
Chapter 5
RESULTS AND DISCUSSION….……………………………………………68-183 5.1 Results and Discussion------69 5.2 Proposed Structures of Ligand/Complexes and Abbreviations------69 5.3 Physical Properties ------72 5.4 Solubilities of Imine Ligands and Metal Complexes------74 5.5 Elemental Analysis------75 5.6 Characterization of Ligands/Complexes------77 5.6.1 Characterization of 3–acetyl-2H–chromen-2–one ------77 5.6.1.1 IR Study of 3–acetyl-2H–chromen-2–one ------77 5.6.1.2 NMR Spectroscopic Study of 3–acetyl-2H –chromen-2–one------78 5.6.2 Characterization of Imine Ligands------78 5.6.2.1 Characterization of (E) – 3 - ( 1 - ( p – tolylimino )
ethyl ) -2 H- chromen- 2 - one [4CH3I2C]------79 XIV
5.6.2.1.1 IR study of 4CH3I2C------79
5.6.2.1.2 NMR-Studies of 4CH3I2C ------80
5.6.2.1.3 ESI Mass Spectrum of 4CH3I2C ------82 5.6.2.2 Characterization of (E) – 3 - ( 1 - (( 4 – chlorophenyl ) imino ) ethyl) - 2 H – chromen - 2 – one [4ClI2C]------83 5.6.2.2.1 IR Studies of 4ClI2C------84 5.6.2.2.2 NMR Studies of 4ClI2C ------84 5.6.2.2.3 ESI Mass Spectrum of 4ClI2C------85 5.6.2.3 Characterization of (E) – 3 - ( 1 - (( 2 – nitrophenyl )
imino ) ethyl ) - 2 H - chromen – 2 – one [2NO2I2C]------86
5.6.2.3.1 IR Studies of 2NO2I2C------86
5.6.2.3.2 NMR Studies of 2NO2I2C ------86
5.6.2.3.3 ESI Mass Spectrum of 2NO2I2C------87 5.6.3 Characterization of Imine Metal Complexes ------88 5.6.3.1 Characterization of Ni-Imine Complexes ------88 5.6.3.1.1 Determination of Stability of Ni-Imine Complexes ------88 5.6.3.1.2 Characterization of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl )
– 2 H – chromen – 2 – one ]Nickel( II): [Bis4CH3I2CNi] ----89
5.6.3.1.2.1 Infra-red Spectral Studies of Bis4CH3I2CNi ------89
5.6.3.1.2.2 Estimation of λmax for Bis4CH3I2CNi ------92
5.6.3.1.2.3 Estimation of Metal Ion in Bis4CH3I2CNi------94 5.6.3.1.2.4 Determination of Metal to Ligands Ratio by AAS------95
5.6.3.1.2.5 Powder X-ray Diffraction Analysis of Bis4CH3I2CNi------97
5.6.3.1.2.6 Thermal Gravimetric Analysis of Bis4CH3I2CNi------100 5.6.3.1.3 Characterization of Bis[(E) - 3 -( 1- (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Nickel( II): [Bis4ClI2CNi]------101 5.6.3.1.3.1 Infra-red Spectral Studies of Bis4ClI2CNi------101
5.6.3.1.3.2 Estimation of λmax for Ni Complex Bis4ClI2CNi------101 5.6.3.1.3.3 Estimation of Metal Ions in Bis4ClI2CNi------103 5.6.3.1.3.4 Determination of Metal to Ligands Ratio by AAS------103 5.6.3.1.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CNi------104 5.6.3.1.3.6 Thermal Gravimetric Analysis of Bis4ClI2CNi------108 XV
5.6.3.1.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)
-2H-chromen-2-one]Nickel(II) [Bis2NO2I2CNi]------109
5.6.3.1.4.1 Infra-red Spectral Studies of Bis2NO2I2CNi------109
5.6.3.1.4.2 Estimation of λmax for Ni Complex Bis2NO2I2CNi ------109
5.6.3.1.4.3 Estimation of Metal Ions in Bis2NO2I2CNi------111 5.6.3.1.4.4 Determination of Metal to Ligands Ratio by AAS------111
5.6.3.1.4.5 Thermal Gravimetric Analysis of Bis2NO2I2CNi ------112 5.6.3.2 Characterization of Cobalt Imine Complexes------113 5.6.3.2.1 Determination of Stability of Cobalt Imine Complexes------113 5.6.3.2.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)
-2H-chromen-2-one]Cobalt(II) [Bis4CH3I2CCo]------114
5.6.3.2.2.1 Infra-red Spectral Studies of Bis4CH3I2CCo------114
5.6.3.2.2.2 Estimation of λmax for Cobalt Complex Bis4CH3I2CCo------114
5.6.3.2.2.3 Estimation of Metal Ions in Bis4CH3I2CCo------116 5.6.3.2.2.4 Determination of Metal to Ligands Ratio by AAS------116
5.6.3.2.2.5 Thermal Gravimetric Analysis of Bis4CH3I2CCo------118 5.6.3.2.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl) -2H-chromen-2-one]Cobalt(II): [Bis4ClI2CCo]------119 5.6.3.2.3.1 Infra-red Spectral Studies of Bis4ClI2CCo------119
5.6.3.2.3.2 Estimation of λmax for Bis4ClI2CCo------119 5.6.3.2.3.3 Estimation of Metal Ions in Bis4ClI2CCo------120 5.6.3.2.3.4 Determination of Metal to Ligands Ratio by AAS ------121 5.6.3.2.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CCo ------122 5.6.3.2.3.6 Thermal Gravimetric Analysis of Bis4ClI2CCo------125 5.6.3.2.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)
-2H-chromen-2-one]Cobalt(II): [Bis2NO2I2CCo]------126
5.6.3.2.4.1 Infra-red Spectral Studies of Bis2NO2I2CCo------126
5.6.3.2.4.2 Estimation of λmax for Bis2NO2I2CCo------126
5.6.3.2.4.3 Estimation of Metal Ions in Bis2NO2I2CCo------128 5.6.3.2.4.4 Determination of Metal to Ligands Ratio by AAS------128
5.6.3.2.4.5 Thermal Gravimetric Analysis of Bis2NO2I2CCo------130 5.6.3.3 Characterization of Copper Imine Complexes------130 XVI
5.6.3.3.1 Determination of Stability of Copper Imine Complexes------130 5.6.3.3.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)-2H-
chrome-2-one]Copper(II) [Bis4CH3I2CCu]------131
5.6.3.3.2.1 Infra-red Spectral Studies of Bis4CH3I2CCu ------131
5.6.3.3.2.2 Estimation of λmax for Bis4CH3I2CCu------132
5.6.3.3.2.3 Estimation of Metal Ion in Bis4CH3I2CCu------133 5.6.3.3.2.4 Determination of Metal to Ligands Ratio by AAS ------134
5.6.3.3.2.5 Thermal Gravimetric Analysis of Bis4CH3I2CCu------135 5.6.3.3.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl) -2H-chromen-2-one]Copper(II): [Bis4ClI2CCu]------136 5.6.3.3.3.1 Infra-red Spectral Studies of Bis4ClI2CCu ------136
5.6.3.3.3.2 Estimation of λmax for Bis4ClI2CCu ------136 5.6.3.3.3.3 Estimation of Metal Ion in Bis4ClI2CCu------138 5.6.3.3.3.4 Determination of Metal to Ligands Ratio by AAS------139 5.6.3.3.3.5 Thermal Gravimetric Analysis of Bis4ClI2CCu ------140 5.6.3.3.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)
-2H-chromen-2-one]Copper(II): [Bis2NO2I2CCu]------140
5.6.3.3.4.1 Infra-red Spectral Studies of Bis2NO2I2CCu------140
5.6.3.3.4.2 Estimation of λmax for Bis2NO2I2CCu------141
5.6.3.3.4.3 Estimation of Metal Ion in Bis2NO2I2CCu------142 5.6.3.3.4.4 Determination of Metal to Ligands Ratio by AAS------143
5.6.3.3.4.5 Powder X-ray Diffraction Analysis of Bis2NO2I2CCu------144
5.6.3.3.4.6 Thermal Gravimetric Analysis of Bis2NO2I2CCu ------148 5.6.3.4 Characterization of Zinc Imine Complexes------149 5.6.3.4.1 Determination of Stability of Zinc Imine Complexes------149 5.6.3.4.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)
-2H-chromen-2-one]Zinc(II) [Bis4CH3I2CZn]------150
5.6.3.4.2.1 Infra-red Spectral Studies of Bis4CH3I2CZn ------150
5.6.3.4.2.2 Estimation of λmax for Bis4CH3I2CZn------150
5.6.3.4.2.3 Estimation of Metal Ions in Bis4CH3I2CZn------152 5.6.3.4.2.4 Determination of Metal to Ligands Ratio by AAS------153
5.6.3.4.2.5 Powder X-ray Diffraction Analysis of Bis4CH3I2CZn------154 XVII
5.6.3.4.2.6 Thermal Gravimetric Analysis of Bis4CH3I2CZn------157 5.6.3.4.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl) -2H-chromen-2-one]Zinc(II) [Bis4ClI2CZn]------158 5.6.3.4.3.1 Infra-red Spectral Studies of Bis4ClI2CZn------158
5.6.3.4.3.2 Estimation of λmax for Bis4ClI2CZn ------158 5.6.3.4.3.3 Estimation of Metal Ions in Bis4ClI2CZn------160 5.6.3.4.3.4 Determination of Metal to Ligands Ratio by AAS------161 5.6.3.4.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CZn------162 5.6.3.4.3.6 Thermal Gravimetric Analysis of Bis4ClI2CZn------165 5.6.3.4.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)
-2H-chromen-2-one]Zinc(II) [Bis2NO2I2CZn]------166
5.6.3.4.4.1 Infra-red Spectral Studies of Bis2NO2I2CZn------166
5.6.3.4.4.2 Estimation of λmax for Bis2NO2I2CZn------166
5.6.3.4.4.3 Estimation of Metal Ions in Bis2NO2I2CZn------168 5.6.3.4.4.4 Determination of Metal to Ligands Ratio by AAS------169
5.6.3.4.4.5 Powder X-ray Diffraction Analysis of Bis2NO2I2CZn------170
5.6.3.4.4.6 Thermal Gravimetric Analysis of Bis2NO2I2CZn.------173 5.7 Magnetic Properties of Prepared Metal Complexes------173 5.8 Study of Antibacterial Activity------174 5.8.1 Antibacterial Activity of Imine Ligands------174 5.8.2 Antibacterial Activity of Schiff base Metal complexes------176 5.8.2.1 Antibacterial activity of Ni(II) Complexes------176 5.8.2.2 Antibacterial activity of Co( II) Complexes------177 5.8.2.3 Antibacterial activity of Cu( II) Complexes------178 5.8.2.4 Antibacterial activity of Zn( II) Complexes------180 CONCLUSION………………………………………………………………….…182
Chapter 6
REFERENCES…………………..….……………………..…………………184-193
XVIII
Appendix-I
IR-SPECTRA…………………………………………..…………………….194-202
Appendix-II
NMR-SPECTRA……………………………………………..……………….203-207
Appendix-III
PUBLICATIONS……………………………………….…………………….208-211
XIX
List of Tables
Table No. Title Page No. 3.1 List of synthesized ligands 41 3.2 Data regarding the synthesized complexes and reactants 47 5.1 Abbreviations of Synthesized Ligands/Complexes 70 5.2 Physical properties of Ligands/Complexes 73 5.3 Solubilities of Ligands/Complexes in variety of solvents 75 5.4 Data for elemental analysis of Schiff base 76 ligands/metals’ complexes 5.5 1H NMR and 13C NMR of 3 – acetyl -2 H – chromen - 2 78 –one 5.6 IR data of synthesized Ligands 79 5.7 1H NMR of Imine Ligands 81 5.8 13C NMR of Imine Ligands 82 5.9 IR data of the synthesized metal complexes 90
5.10 λmax (nm) of Synthesized Metal Complexes 92 5.11 Data showing absorbance against different wavelengths 93
for Bis4CH3I2CNi 5.12 Calibration Data (Concentration of Ni+2 Vs Absorption) 95
for Bis4CH3I2CNi 5.13 Data of Ni+2 ions concentrations in Ni-Complexes 95 5.14 Data for molecular mass for calculating metal to ligand 96
ratio in Bis4CH3I2CNi 5.15 Estimated amounts of Ni-metal in Ni-complexes by 96 AAS 5.16 Calculation of Miller Indices by PXRD pattern for 98
Bis4CH3I2CNi 5.17 Data calculated for structural parameters for 99
Bis4CH3I2CNi 5.18 Data showing absorbance against different wavelengths 102 XX
for Bis4ClI2CNi 5.19 Calibration Data (Concentration of Ni+2 Vs Absorption) 103 for Bis4ClI2CNi 5.20 Data for molecular mass for calculating metal to ligand 104 ratio in Bis4ClI2CNi 5.21 Calculation of Miller Indices by PXRD pattern for 106 Bis4ClI2CNi 5.22 Data calculated for structural parameters for 107 Bis4ClI2CNi 5.23 Data showing absorbance against different wavelengths 110
for Bis2NO2I2CNi 5.24 Calibration Data (Concentration of Ni+2 Vs Absorption) 111
for Bis2NO2I2CNi 5.25 Data for molecular mass for calculating metal to ligand 112
ratio for Bis2NO2I2CNi 5.26 Data showing absorbance against different wavelengths 115
for Bis4CH3I2CCo 5.27 Calibration Data (Concentration of Co+2 Vs Absorption) 116
for Bis4CH3I2CCo 5.28 Data of Co+2 ions concentrations in Co-complexes 116 5.29 Data for molecular mass for calculating metal to ligand 117
ratio for Bis4CH3I2CCo 5.30 Estimated amounts of Co-metal in Co-complexes by 117 AAS 5.31 Data showing absorbance against different wavelengths 120 for Bis4ClI2CCo 5.32 Calibration Data (Concentration of Co+2 Vs Absorption) 121 for Bis4ClI2CCo 5.33 Data for molecular mass for calculating metal to ligand 122 ratio for Bis4ClI2CCo 5.34 Calculation of Miller Indices by PXRD pattern for 124 Bis4ClI2CCo XXI
5.35 Data calculated for structural parameters for 124 Bis4ClI2CCo 5.36 Data showing absorbance against different wavelengths 127
for Bis2NO2I2CCo 5.37 Calibration Data (Concentration of Co+2 Vs Absorption) 128
for Bis2NO2I2CCo 5.38 Data for molecular mass for calculating metal to ligand 129
ratio for Bis2NO2I2CCo 5.39 Data showing absorbance against different wavelengths 132
for Bis4CH3I2CCu 5.40 Calibration Data (Concentration of Cu+2 Vs Absorption) 133
for Bis4CH3I2CCu 5.41 Data of Cu+2 ions concentrations in Cu-complexes 134 5.42 Data for molecular mass for calculating metal to ligand 134
ratio for Bis4CH3I2CCu 5.43 Estimated amounts of Copper in Cu-complexes by AAS 135 5.44 Data showing absorbance against different wavelengths 137 for Bis4ClI2CCu 5.45 Calibration Data (Concentration of Cu+2 Vs Absorption) 138 for Bis4ClI2CCu 5.46 Data for molecular mass for calculating metal to ligand 139 ratio for Bis4ClI2CCu 5.47 Data showing absorbance against different wavelengths 141
for Bis2NO2I2CCu 5.48 Calibration Data (Concentration of Cu+2 Vs Absorption) 143
for Bis2NO2I2CCu 5.49 Data for molecular mass for calculating metal to ligand 143
ratio for Bis2NO2I2CCu 5.50 Calculation of Miller Indices by PXRD pattern for 146
Bis2NO2I2CCu 5.51 Data calculated for structural parameters for 147
Bis2NO2I2CCu XXII
5.52 Data showing absorbance against different wavelengths 151
for Bis4CH3I2CZn 5.53 Calibration Data (Concentration of Zn+2 Vs Absorption) 152
for Bis4CH3I2CZn 5.54 Data of Zn+2 ions concentrations in Zn-complexes 153 5.55 Data for molecular mass for calculating metal to ligand 153
ratio for Bis4CH3I2CZn 5.56 Estimated amounts of Zn-metal in Zn-complexes by 154 AAS 5.57 Claculation of Miller Indices through PXRD pattern for 155
Bis4CH3I2CZn 5.58 Data calculated for structural parameters for 156
Bis4CH3I2CZn 5.59 Data showing absorbance against different wavelengths 159 for Bis4ClI2CZn 5.60 Calibration Data (Concentration of Zn+2 Vs Absorption) 160 for Bis4ClI2CZn 5.61 Data for molecular mass for calculating metal to ligand 161 ratio for Bis4ClI2CZn 5.62 Calculation of Miller Indices by PXRD pattern for 163 Bis4ClI2CZn 5.63 Data calculated for structural parameters for 164 Bis4ClI2CZn 5.64 Data showing absorbance against different wavelengths 167
for Bis2NO2I2CZn 5.65 Calibration Data (Concentration of Zn+2 Vs Absorption) 168
for Bis2NO2I2CZn 5.66 Data for molecular mass for calculating metal to ligand 169
ratio for Bis2NO2I2CZn 5.67 Calculation of Miller Indices by PXRD pattern for 171
Bis2NO2I2CZn 5.68 Data calculated for structural parameters for 172 XXIII
Bis2NO2I2CZn 5.69 Magnetic properties of prepared metal complexes 174 5.70 Antibacterial activity data of prepared Imine Ligands 175 5.71 MIC of prepared Schiff Base Ligands 175 5.72 Antibacterial Activity of Ni(II) Complexes 176 5.73 MIC data of Ni(II) complexes 177 5.74 Antibacterial Activity of Co(II) Complexes 178 5.75 MIC data of Co(II) complexes 178 5.76 Antibacterial Activity of Cu( II) Complexes 179 5.77 MIC data of Cu(II) complexes 180 5.78 Antibacterial Activity of Zn(II) Complexes 180 5.79 MIC data of Zn(II) complexes 181
XXIV
List of Abbreviations
acacs Acetylacetonate en ethylenediimine
R.T Room Temperature
CDCl3 Chloroform-d DMSO-D8 Dimethylsulfoxide MIC Minimum inhibitory concentration AAS Atomic Absorption Spectroscopy XRD X-ray diffraction PXRD Powder X-ray diffraction TGA Thermal gravimetric analysis ESI-MS Electron Spray Ionization-Mass spectroscopy NMR Nuclear Magnetic Resonance Spectroscopy UV-VIS UV-Visible Spectroscopy IR Infra-red Spectroscopy DMF Dimethyl formamide VSM Vibrating Sample Magnetometer d.p Decomposition point m.p Melting point
XXV
Abstract
A variety of Schiff bases and their metal complexes have been synthesized from 3 – acetyl – 2 H – chromen – 2 - one and anils. 2-hydroxybenzaldehyde was reacted with ethyl acetoacetate (acacs) in the presence of piperidine to give 3 – acetyl – 2 H - chromen – 2 - one which was further reacted with different anils namely p-toluidine, p-chloroaniline and 2-nitroanilie to obtain Schiff bases. These Schiff bases were used as ligands in the current study. Schiff base metal complexes were then synthesized by reacting Schiff base ligands with 3d-transition metals nickel( II), cobalt( II), copper( II) and zinc( II). Both ligands and metal complexes were then characterized by various spectroscopic techniques which include UV-visible spectroscopy, 1H NMR, 13C NMR spectroscopy and powder X-ray diffraction (PXRD). Stability of complexes was estimated in solid and solutions form. Amounts of metals in complexes and metals’ to ligands ratios were estimated by Atomic Absorption Spectroscopy (AAS). These metal complexes were found diamagnetic by vibrating sample magnetometry. Schiff base complexes were found to have immense applications in biological fields. So all Schiff base ligands and their metal complexes were scanned against gram positive and gram negative bacterial strains and it was found that they show promising activities against selected bacterial strains.
XXVI
Chapter 1
Introduction
Introduction Chapter 1
Metal complexes find applications in a variety of fields like biology, medicines and catalysis. They are also used as diagnostic and therapeutic agents. Use of inorganic substances in medicines has origin from the time of Hippocrates who recommended medicinal use of metallic salts. The role of hemoglobin, vitamin B-12, chlorophyll and haemocyanin illustrated the linkage between biology and inorganic chemistry. Many metal complexes especially Schiff bases have been used as antibacterial and anticancer drugs. Imines played very important role and contributed a lot for developing co-ordination chemistry. A discussion of Imines, their complexes with transition metals and general applications are discussed in this chapter.
1.1 Studies on Metal Chelates: Among the large number of synthetic and naturally occurring nitrogen donor molecules, Schiff bases have been found of great interest. Imine metal complexes are broadly studied due to their attractive physical and chemical properties. They have wide range of applications in various scientific areas. Many of them are centered on the catalytic activity of Schiff base complexes in a large number of homogeneous and heterogeneous reactions. Owing to certain reasons like novel structural features, thermal stabilities, abnormal magnetic properties and relevant biological properties, the imines have extensive range of uses.
1.2 Schiff Bases: Ligands of Imines are deliberated as “Privileged ligands ” [ 1] containing azomethine group (-N=CH-) as functional group in which carbon is bonded to nitrogen through double bond and nitrogen atom is further attached to alkyl or aryl group; no hydrogen is directly attached to this nitrogen. A Schiff Base was named by Hugo Schiff; a
German chemist; who discovered it [2]. Their general formula is R2R3C=N-R1, where
R1 stands for alkyl or aryl group. An imine obtained from aniline is called an anil [
3] when R1 may be a phenyl or phenyl derivative.
2
Introduction Chapter 1
Anils are synthesized by condensing primary amine with a compound containing an active carbonyl compound (aldehyde or ketone) [4] giving a hemiaminal followed by elimination of water. Schiff bases are synthesized from both aldehydes and ketones; however, formation from ketones is less readily favored than that of aldehydes. In comparison to aromatic aldehydes, Schiff bases derived from aliphatic aldehydes are mostly unstable and polymerizable [5]. When this compounds are prepared by ketones they are known as ‘ketimines’ and when prepared by aldehydes, they are known as the ‘aldimines’.
They are also known as ‘azomethines’, ‘anils’ or ‘imines’. Azomethine group have capability to bind with transition metal ions via lone pair of nitrogen atom. If donor atoms are increased in addition to –C=N- group, Schiff bases act as polydentate chelating ligands or macrocycles. Schiff bases are synthesized under acidic or basic catalysis or with heat. Common Schiff bases are crystalline solids and basic in nature.
1.3 Importance of Schiff Bases: Schiff bases have recently assumed greater importance in view of the fact that several of them have been found to be biologically active and have found uses in biology, medicine as well as in industry. They have been widely used in pigments and dyes [6], photographic emulsions [7], heat resistant polymers [8], high temperature stabilizers [9], lubricating oils [10], anticorrosive agents [11], antiknocking agents [12] and liquid crystal display composition [13,14]. They also have been used as antibacterials [15], antivirals [16], antifungals [17,18], antitumors [19,20], insecticides [21], antihelmintics [22] and antiemetics [23].
3
Introduction Chapter 1
Several Schiff bases which are reported to be therapeutically active possess cytotoxic [24], anti-inflammatory [25], antipyretic [26], analgesics [27], diuretic [28], and antispasmodic [29,30] activity. The corrosion inhibition activity of Schiff bases have extensively been studied and reported [31-39]. The metal complexes of Schiff bases have been used as active drugs against tumor [40] and tuberculosis [41] and also as insect repellents [42] and fungicides [43]. Schiff bases derived from sulpha drugs and salicylaldehyde have been found to be good chelating agents [44,45]. They are widely used in inorganic, analytical, biological and drug synthesis, and have many interesting and important properties like catalytic activity and transferring of amino group [46] photochromic behavior [47] and complex formation capability with some toxic transition metals [48]. The literature shows that an organic reagent which forms a chelate with a metal ion is better suited than any other reagents for the quantitative determination of metal ions. The chelates are the complexes containing one or more rings in which one of the member is metal ion. The ligands which form chelate are generally multidentate. The chelates are characterized by their low solubility in water and many of them are highly colored, and have high molecular weight. Ethylene diamine tetra acetate (EDTA) which has changed a face of titrimetric methods is also a multidentate ligand and it is so strong ligand that it can form the complexes not only with transition elements but many of the pre and post transition elements. If an organic molecule is to form a chelate it should contain one or more acidic group such as –COOH, -SO3H, - OH, -SH, =N-OH, -NO, =NH etc. From these more or less weakly ionized acids, hydrogen can be replaced by metal. The chelate formation also depends on the relative positions of the groups present in an organic compound. The above groups must be so located with respect to one another that the ring formed will contain four to eight atoms and the ring has less strain. Several workers have studied a variety of chelates of metal ions with organic reagents having two coordination sites. They reported that when a group like –COOH, -SO3H or –OH is suitably placed with a =S, -NH2, =NH, -OH, of =N-OH, the later groups are found to be coordinating with a metal ion which is linked through a primary valence to the former. Some Schiff bases are employed as fluorescent indicators [49]. (Fig 1.2)
4
Introduction Chapter 1
1.4 Biological Importance of Schiff Bases: Azomethines, Schiff bases or imines are very interesting and fascinating because of their striking structural features. In many biological practices, carbonyl compounds react with various amines.
1. Pyridoxal phosphate is a dynamic form of vitamin B6 and has been used as coenzyme for numerous reactions of alpha amino acid. In such chemical reactions, amino acid combines with coenzyme and then reaction occurs at amino acid part imine. Hydrolysis catalyzed by enzyme breaks this imine and results into pyridoxal with modifications of amino acid [50]. 2. Oxidation of vitamin ‘A’ gives the aldehyde cis-retinal. In eye, the aldehyde reacts with amino group of the protein, opsin and results into an imine known as rhodopsin which has ability to absorb a photon of visible light and causes a change in conformation which is translated into a nerve impulse and brain perceives it as a visual image [51]. 3. Biosynthetic route of porphyrin involves the formation of Schiff base as intermediate by reacting keto-group of one molecule of δ-amino levulinic acid and ε-amino group of lysine. . 4. Certain polymeric Schiff bases were found active against tumors [52] and find applications as antitumors. At pH=5, Schiff bases show maximum solubility in water and uppermost level of hydrolysis. With slight increase of solubility in water, there is a considerable increase in antitumor activity of Schiff bases.
5
Introduction Chapter 1
5. An important role of these Schiff bases have been found in transamination [53]. Transaminases occur in mitochondria and cytosol of eukaryotic cells; and have same prosthetic groups named as pyridoxal phosphate. This pyridoxal phosphate links non-covalently with protein of enzyme.
1.5 Types of Ligands: In co-ordination chemistry, a ligand is a species, molecule or an ion which attaches to the central metal atom by coordinate bonding in a co-ordination complex. A ligand donates one or more electron pairs to central transition metal. Nature of metal-ligand bond usually ranges from covalent to ionic.
1.5.1 Mono-dentate Ligands: They are Lewis bases which have excessive electron density and donate only one pair of electrons to central transition metal atom [54]. They may be negatively charged ions i.e. anions or neutral molecules which have some lone pair of electrons. Neutral molecules have one or more lone pairs of electrons.
1.5.2 Bi-dentate Ligands: They are also Lewis bases which can donate two electron pairs to central metal atom in the coordination sphere. They are also called chelating ligands, since they grasp the metal ion between the two or more donor atoms.
6
Introduction Chapter 1
Ligands with three, four, five and six donor atoms are called tridentate, quadridentate, quinquidentate and hexadentate ligands respectively [55]. Most common of the polydentate ligands are bidentate as they have two sites of attachment to the metal ion. Neutral bidentate ligands include diamines, diphosphines and diethers, all of which form five membered rings with a metal atom. The anionic bidentate ligands include acetylacetone and acetylacetonate form a six-membered ring with the metal ion [56].
1.6 Chelate Formation: Coordination by polydentate ligands leads to the formation of ring structures in which the metal is incorporated and process is known as Chelation. The product resulting from the formation of cyclic arrangement of ligands and metal is known as chelate [55].
Organic Schiff bases are good chelating agents. The prepared Schiff bases are bidentate nitrogen and oxygen donor chelating agents forming two six membered rings around the central metal atom.
The chelated species become much more stable than respective components. Non- ionic species are sparingly soluble in water but quite soluble in organic solvents such as benzene or chloroform. For a ligand to act as a chelating agent, it must have at least
7
Introduction Chapter 1
two pairs of unshared electrons. Moreover, these electron pairs must be far enough from one another to give a chelate ring with a stable geometry [57]. As in the case of N, O donor bidentate Schiff ligand, N and O donor atoms are separated by three atoms, forming a six membered ring with the metal atom forming a rigid structure.
1.7 Stability of Schiff Bases: Carbonyl compounds both aldehydes and ketones are reacted with primary amine to form Schiff bases. However reactivity of ketones is found lesser than aldehydes for its synthesis. Both aliphatic and aromatic aldehydes have been investigated [5]. Stability of Schiff bases depends upon the nature of aldehydes used. Schiff bases derived from aromatic aldehydes are more stable than those derived from aliphatic aldehydes. Aromatic aldehydes react readily with primary amines under mild conditions at low temperatures; if in liquid state react even without a suitable solvent. While in the case of aromatic ketones high temperatures and long reaction times are usually required [58]. Under inert atmosphere, aldehydes of ketones when reacted with primary amines results into stable imines. These imines have greater tendency to hydrolyze or oligomerize in the presence of water or even oxygen. On the other hand, by using aryl group or some stabilizing alkyl group on nitrogen, the imine formed become quite stable towards ware and oxygen.. So the Schiff base obtained from condensation reactions of aromatic amines with aromatic aldehydes are stable colored crystalline solids [59].
1.8 Methods for Preparation of Imines: Imines are synthesized by condensing primary amines with aldehydes; ketones are less commonly used. These reactions proceed via nucleophilic addition producing hemi-aminal [–C(OH)(NHR)-] which results into an imine by the loss of water. The equilibrium for this reaction favors the carbonyl compound and amine, so dehydrating agents like the use of molecular sieves or magnesium sulphate favors the equilibrium to right into the formation of imine. In addition to above following methods are also used for synthesis of imines. i. By dehydration of hemiaminals [60].
8
Introduction Chapter 1
ii. By condensing carbon acids and nitroso compounds. iii. By re-arrangement of trityl N-haloamines in Stieglitz re-arrangement. iv. Hoesch reaction involving reaction of nitrile, HCl and arenes.
v. Schmidt reaction involving reaction of alkenes with hydrazoic acid (HN3). vi. Multicomponent synthesis of 3-thiazolines in Asinger reaction.
1.9 Synthesis of Imines: Synthesis of Imine is an equilibrium process [61,62] (Scheme 2) and reaction occurs at slightly acidic conditions (pH=4.5). As nitrogen atom of primary amine has lone pair of electrons, it attacks on electrophilic carbonyl carbon of aldehyde. Then a proton attached to positively charged nitrogen of amine shifts to negatively charged + oxygen of carbonyl group and results into neutral carbinolamine. As OH2 is a better + leaving group so OH is converted into OH2 by protonating with an acid. As dehydration occurs, an iminium ion is formed. Finally, deprotonation of nitrogen of iminium ion by water takes place and results into an imine. By using some dehydrating agents, removal of water disturbs equilibrium to right and results in maximum yield of imine.
9
Introduction Chapter 1
1.10 Synthesis of Imine Metal Complexes: Schiff base metal complexes are prepared by treating metal salts with Schiff base ligands under suitable conditions. However, Schiff base metal complexes care usually prepared in situ in order to use them as catalysts. Cozzi has outlined five synthetic routes which are mostly employed for synthesis of imine metal complexes [63]. Route
# 1 shows the involvement of metal alkoxides [M(OR)n] as they are easy to handle and commercially available.
10
Introduction Chapter 1
Fig 1.4: Synthesis of Imine Metal Complexes:
It is not easy to use other derivatives of alkoxides particularly when such derivatives of lanthanides are used which are moisture sensitive. Imine metal complexes are also synthesized by using metal amides M(NMe2)4 [M = Ti, Zr] (Route 2). In this reaction acidic phenolic proton of imine is eliminated through the formation of volatile
NHMe2. Route 3 includes treatment of metal alkyl complexes with Schiff bases. Other involves reaction of imine with corresponding metal acetate under reflux. Route 5 is an efficient way to form salen-type metal complexes. It involves two steps; 1st deprotonation of imines which is followed by the reaction with MX (metal halides). In order to remove acidic phenolic hydrogen, NaH or KH is used along the coordinating solvents which are then removed by filtration. At room temperature deprotonation is rapid and no decomposition occurs if reaction mixture is heated to reflux.
11
Introduction Chapter 1
1.11 Applications of Imine Metal Complexes: Schiff base complexes were found very selective in catalyzing variety of chemical reactions like aldol condensation, epoxidation and hydroxylation. They are also used as catalysts in synthesis of polymers, dyes and bundle of biological systems. Some of the applications are given below.
1.11.1 Imine Metal Complexes used as Catalysts: They show catalytic activity in both solutions and solid states. They have been used in both homogenous and heterogeneous catalysis. Activity of Schiff base complexes depends upon different factors such as nature of metal ions, coordination number and nature of ligands. Metal complexes which have vacant coordination sites act as catalysts because of two reasons. Firstly, metal complexes have several oxidation states so they take part in various electron transfer reactions. Secondly they can provide the sites where chemical reactions can take place. These features results in the formation of suitable intermediates required for proceeding catalytic reactions.
1.11.2 Use of Imine Metal Complexes in Oxidation Reactions: Organic synthesis frequently involves the oxidation of primary and secondary alcohols to corresponding carbonyl compounds [64,65]. The role of oxidants like hydrogen peroxide, oxygen (O2) or air for these reactions remained a great challenge during development of industrial processes. Synthesis pf catechol by oxidizing phenol has been carried out in presence of numerous imine metal complexes [66-68]. Similarly, ketones have been synthesized by oxidizing cycloalocohols such as cyclopentanol, cyclohexanol in the presence of binuclear ruthenium( III) Schiff base complexes [69]. Tetradendate Schiff base complexes of Ru are found efficient catalysts for oxidation reactions [70-73].
12
Introduction Chapter 1
Cobalt (II) Schiff base complex shows high catalytic activity for aerobic oxidation where secondary alcohols are oxidized to ketones [74]. Sulfides are oxidized into sulfoxides for this manganese( III) imine complex has been found very effective catalyst [75]. For the oxidation of cyclohexene, polymer-anchored imine complexes of Co (II), Cu( II), Ni( II), Fe(III) and Mn( II) have shown excellent catalytic activity [76].
1.11.3 Use of Imine Metal Complexes in Hydrogenation Reactions: BINAP-Ru(II) complex has been found unable for hydrogenation of simple ketones having no hetero atoms anchoring ruthenium metal, however, it has been found very effective to hydrogenase the functionalized ketones [77]. Ruthenium based catalysts are very efficient transfer hydrogenation of ketones and imines [78]. Under mild conditions, Ruthenium( II) Schiff base complex system having di-phosphine and 1,2- diamine ligands were found very effective catalyst for hydrogenation of ketones [79]. Similarly, for the reduction of benzene, the catalysts, Ruthenium( II) complexes have been found very effective [80]. During transfer hydrogenation of imines to amines, following Ruthenium Schiff base complex has been used as effective catalyst [81].
13
Introduction Chapter 1
Polymer supported Palladium( II) Schiff base complexes are found efficient catalyst for hydrogenation reactions [82-84]. Hydrogenation of a variety of ketones by rhodium complexes has also been reported [85]. Costa et al. [86] synthesized a range of Palladium( II) complexes of Schiff bases having nitrogenous ligands and applied them as catalyst during hydrogenation of unsaturated aliphatic hydrocarbons under mild conditions (with 1 atm dihydrogen pressure at 40 °C). Two representative examples of these Schiff base complexes are given below
1.11.4 Use of Imine Metal Complexes in Epoxidation Reactions: McGarrigle and Gilheany focused on the mechanism, catalytic cycle, intermediates, and mode of selectivity. They gave a detailed discussion on the achiral and asymmetric epoxidations of alkenes catalyzed by chromium and manganese-salen complexes [87]. Manganese Schiff base chelate, synthesized by Zhao et al. exhibits moderate asymmetric induction in epoxidation of dihydronaphthalene with higher turnover number [88]. Fernandez et al. epoxidized various unfunctionalized olefins with very high yield and poor asymmetric induction in presence of the manganese Schiff base complex [89].
14
Introduction Chapter 1
Kureshy et al have reported the catalytic activity nickel( II) imine complexes of N, N’ – bis ( 2 – hydroxyphenyl ) ethylenediimine and N,N’-(2- hydroxyphenyl)acetylaldimine N-( 2 – hydroxyphenyl ) acetamide to form olefin epoxides like 1-hexene, cis and trans isomers of stilbenes, indene with NaOCl [90].
Ruthenium(III) complexes, of the tetra-dentate Schiff base ligands were obtained by reacting 3- acetyl – 6 – methylpyran - 2, 4 - dione with different diamines. They were found efficient catalysts for styrene and substituted styrenes epoxidation [91].
15
Introduction Chapter 1
1.11.5 Use of Imine Metal Complexes in Polymerization Reactions: Literature reveals many polymerization reactions catalyzed by Schiff base metal complexes. Verpoort et al. reported catalytic activity in the atom transfer radical polymerization and ring opening metathesis polymerization of various substrates using Ru-catalysts having salicylaldiminato-type Schiff bases [92].
Cobalt( II) and Pyridine bis (imine) complexes of iron( III) showed prominent activity when ethylene was polymerized with 1-hexene [93]. Salicylaldiminato complexes of zirconium have been found effective catalysts in ethylene polymerization [94].
1.12 Biological Activities of Imine Metal Complexes: Many Imine ligands and their metal complexes have shown antimicrobial and antifungal activities and their activity increases or decreases upon chelation with different metal ions [95,96].
1.12.1 Antimicrobial Activities: Zn(II) and Cr(III) Schiff base complexes having ethyl 2 - (( 1 – hydroxynaphthalen – 2 –yl ) methyleneamino ) - 5,6 – dihydro – 4 H – cyclopenta [b] thiophene – 3 - carboxylate have been found active against pathogenic strains L.monocytogenes and S. aureus [97]. Zn( II), Nickel( II), Copper( II) and Cadmium( II) complexes with furfurylidene diamine Schiff bases also show antibacterial affects [98]. Similarly Platinum(IV) complexes exhibit antibacterial activities [99]. Pd(II) complexes with N- substituted thiosemicarbazone show antibacterial activities against pseudomonas aeruginosa, Staphylococcus and Escherichia Coli [100]. Ruthenium(II) carbonyl complexes have shown antibacterial activities against gram-negative Escherichia coli and Staphylococcus aureus [101]. Schiff bases complexes derived from aniline with
16
Introduction Chapter 1
metal in IInd and IVth oxidation states show activities against many types of bacteria [102,103].
1.12.2 Antifungal Activities: Imines and their metal complexes also show antifungal activities. Schiff base complexes of Nickel( II), Manganese( II), Zinc( II), Cu( II), Co( II) and Cadmiun( II) derived from acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid showed antifungal activities against Candida albicans, Trichoderma harizanum, Rhizopus stolonifer and Aspergillus flavus [104]. Similarly, diethyl phthalate and benzidine with Cu(II) complex has antifungal effect against A. flavus, T. Viridae and Aspergillus niger [105].
1.12.3 Antitumor and Cytotoxic Activities: DNA is the most important hereditary material in all living organisms. Gene expression is based on it. DNA shows interactions with transition metal complexes and it became interesting because of its applications in cancer research and nucleic acid chemistry [106,107].
1.13 Photochromism and Thermochromism in Schiff Bases: An interesting property of salicylaldehyde aniline Schiff bases and its substituted derivatives is their ability to show intense color under UV irradiation. This property is called photochromism [108]. Photochromism has been attributed to the possible formation of geometric isomer of the quinoid tautomer. The compounds also exhibit thermochromism which consist of a thermally induced change in color which increases with an increase of the temperature. This phenomenon has been attributed to intramolecular hydrogen transfer. Both processes are reversible and mutually exclusive for same compound in a given crystalline form. However, since the same Schiff bases may exhibit polymorphism, it may be thermochromic in one crystalline form and photochromic in the other form [109]. Therefore these processes are correlated with difference in the crystalline structure rather than with the inherent properties of the molecules. All the crystallographic
17
Introduction Chapter 1
results confirmed that the molecules which exhibit thermochromism are planar while others are non-planar [110].
1.14 Stability of Metal Complexes: The metal complexes exist in solid state and can be stored for a long time. However when dissolved in a solvent it may retain its composition or may decompose. Complexes which do not change their composition on dissolution in suitable solvent are considered are stable in solution form. The stability of a complex in solution means: a. There is no reaction with the solvent which would lead to a lower free energy of the system and is known as thermodynamic stability. b. Reaction of a complex with the solvent could lead to a more stable species, there are no available intermediate routes and is called the kinetic stability [111]. There are several factors involved in the stability of metal complexes. With reference to the role of ligands, following important factors play role in determining the stability of metal complexes: 1. Chelate effect 2. Steric effect 3. Chelate ring size 4. Base strength The stability of the complex also depends on the nature of metal. With reference to the metal important factors are: 1. Size and charge 2. Crystal field effect [112]. Stability constants of complexes are also influenced by the nature of ligands. Certain metal complexes form more stable complexes with the ligands containing nitrogen donor atoms [113].
18
Introduction Chapter 1
1.15 Reactions of Transition Metal Complexes: Transition metals complexes undergo a number of chemical reactions, some of which are given below: 1. Substitution reactions 2. Thermal dissociation of solid complexes 3. Oxidation reduction reactions 4. Catalysis
1.15.1 Substitution Reactions: Following types of substitution reactions are given by transition metal complexes. 1. Substitution reactions in aqueous solutions 2. Substitution reactions in non-aqueous solvents 3. Substitution reactions in the absence of solvent 4. Substitution reactions without metal-ligand bond cleavage
1.15.1.1 Substitution Reactions in Aqueous Solutions: An aqueous solution of metal salt and a coordinating agent are reacted together, it is one of the most famous route for synthesis of Schiff base metal complexes. For example, the complex [Cu(NH3)4]SO4 is readily prepared by the reaction between an aqueous solution of CuSO4 and excess NH3
1.15.1.2 Substitution Reactions in Non-Aqueous Solvents: Reactions in solvents other than water are used for the metal ions that has a large affinity for water or the ligand is insoluble in water. Organo-metallic complexes are prepared in this way. For example the addition of an alcoholic solution of bipy to an aqueous solution of FeCl2 readily yields the complex [Fe(bipy)3]Cl2
1.15.1.3 Substitution Reactions in absence of Solvent: The direct reaction between an anhydrous salt and a liquid ligand can be used to prepare metal complexes. In such cases the liquid ligand present in very large excess
19
Introduction Chapter 1
also serves as a solvent for the reaction mixture. For example the addition of anhydrous nickel chloride to the excess of liquid ammonia gives [Ni(NH3)6]Cl2
1.15.1.4 Substitution Reactions without Metal-Ligand Bond Cleavage: The formation of some metal complexes has been found to occur without the 3+ breakage of a metal-ligand bond. In the preparation of [Co(NH3)5OH2] salts from + [Co(NH)3CO3] , CO2 is produced by cleavage of a carbon-oxygen bond which leaves the metal oxygen bond intact.
1.15.2 Thermal Dissociation of Solid Complexes: Thermal dissociation amounts to a substitution reaction in the solid state. At some elevated temperature, volatile coordinated ligands are lost and their place in the coordination sphere is taken by the anions of the complex. For example the loss of water by CuSO4.5H2O when it is heated. The blue hydrate yields the almost white anhydrous copper sulfate.
1.15.3 Oxidation-Reduction Reactions: The preparation of many metal complexes often involves oxidation-reduction reactions. The reaction product may sometimes depend upon the particular oxidizing agent employed. For example, [Co(EDTA)]- is prepared by the oxidization of 2- 3- [Co(EDTA)] with [Fe(CN)6]
1.15.4 Catalysis: Catalysis has been used successfully to prepare metal complexes with high speed of reaction. There are two types of catalysis. a. Heterogeneous catalysis b. Homogeneous catalysis
20
Introduction Chapter 1
1.15.4.1 Heterogeneous Catalysis: It takes place when the catalyst is in a different phase than that of reactants. For example the reactions of cobalt(III) complexes are catalyzed by certain solid surfaces such as decolorizing charcoal.
1.15.4.2 Homogeneous Catalysis: It occurs when the catalyst and the reacting materials are in the same phase. For example the reactions of several platinum(IV) complexes occur readily without need for drastic experimental conditions in the presence of catalyst platinum( II) [114].
1.16 Transition Metals used for Synthesis of Complexes: Those elements in which d or f sub-shells are in the process of filling i.e. imcomplete, in neutral or in their cationic states are called transition elements. There are 56 transition out of 103 elements. Transition metals are classified into the d- and f- blocks. d-block consists of three transition series; 3d-series from Sc to Cu, 4d-series from Y to Ag, and 5d-series from Hf to Au. f-block consists of lanthanide and actinide series. Lanthanides starts from La and ends at Lu and actinides starts from Ac and ends at Lr. Although Sc and Y belong to the d-block, but they are quite similar in properties to elements of lanthanides. Both d-and f-block elements are considerably different from each other with respect to their electronic configurations and properties. In a transition metal complex, a transition metal called central metal atom binds to one or more ligands. Ligands may be neutral or anionic. Transition metal complexes have shown many chemical, optical and magnetic properties and played a significant role in catalysis, photochemistry and biological systems as well.
1.16.1 Copper: Copper is the third most abundant and essential metallic element. The oxidation state of copper in its complexes are Cu(I), Cu(II) and Cu(III). Cu(III) being very easily reduced, is generally regarded as uncommon. All the complexes of copper(III) are low spin diamagnetic except K3CuF6 [115].
21
Introduction Chapter 1
Cu(II) form stable complexes with nitrogen and oxygen donor ligands. Cu(II) may undergo redox reactions with thiols. The Cu(II) complexes of nitrogenous ligands are commonly extra-ordinary stable than Cu( II) complexes [116]. Cu( II) is found in 4, 5 and 6 coordination numbers but rarely found in regular geometries; that’s why, it is very hard to distinguish between square planar and tetragonally distorted octahedron. Imines [117] which have usually Mixed N- and O-donor ligands have remained of particular interest because Schiff base Cu(II) complexes provide examples of square planar and square pyramidal coordination geometries by dimerization. The stereochemistry of Cu(I) complexes are quite different from that of Cu(II) complexes. The complete d10 electronic structure means that more symmetrical environment is possible for Cu(I) complexes and they are found in regular tetrahedral, trigonal and linear geometries. Considerable distortion in geometries have been observed in Cu(II) complexes. A great majority of Cu( II) complexes are found in blue or green color due to absorption of a single broad band in region of 600-900 nm. Copper has an important role in sustaining life. Copper in trace quantities is required by all living organisms to maintain proper cellular functions [118]. An adult human contains 100mg of copper, mostly attached to proteins. Copper deficiency results in anemia. Copper in the whole blood is distributed in several fractions between erythrocytes and plasma. Copper is transported through blood as complexes of ceruloplasmin (95%), albumin (5%) and low molecular weight copper complexes [119].
1.16.2 Zinc: Zinc is the 28th most abundant element in the earth crust. The almost invariable oxidation state of zinc is 2+ because of its complete d-shell and two additional s electrons. It generally forms planar complexes but many octahedral complexes are also known. The coordination number of Zn(II) are 4,5 and 6. Zinc forms stable complexes with ligands containing N, S, O, CN-1 and halides. Compounds of Zn(II) ions are characteristically diamagnetic and are colorless. The d10 configuration do not favor the crystal field stabilization. Size and polarizing power
22
Introduction Chapter 1
of Zn( II) cation and steric requirements of ligands are responsible to determine the stereochemistry of particular metal complex. Thus Zn( II) favors four coordinated tetrahedral complexes. Tetrahedral complexes are formed with a variety of N and O donor ligands. Complexes of higher coordination number are often in equilibrium with the tetrahedral form and may be isolated by increasing the ligand’s concentration or by adding large counter ions. With acetylacetone zinc forms 5 and 6 coordinate complexes. Coordination numbers higher than six are rare. Zinc is biologically one of the most important metals and is necessary to all forms of life. Zinc because of its d10 electronic configuration tends to form stable complexes with proteins and enzymes [120]. It is an integral part of carboxypeptidase-A and carbonic anhydrase without which CO2 exchange could not take place. Zinc is believed to participate in the synthesis and storage of insulin in β-cells. Its deficiency causes a prediabetic condition [121]. Zinc has antiseptic properties and is widely used in cosmetics.
1.16.3 Nickel: Nickel is one of the important transition metal elements which is magnetic at or near room temperature. Although a +6 oxidation state may also exist but in many known complexes, nickel has been found in +2 oxidation state. As predicted in Irving Williams series, Ni(II) ion with d8 configuration forms stable complexes. The Ni( II) ion has capability to exist in a diversity of coordination numbers. In case of coordination number 4, two complexes with tetrahedral and square planar geometries can exist. Similarly, for coordination number 5 square pyramid and trigonal bipyramid geometries are found. For coordination number 6 octahedral complexes are formed. This makes the coordination chemistry more complicated. In the nickel complexes, equilibria often exist between these geometrical forms so the axiom “anomalous nickel” well describes this behavior. For example: i. Ligands are added to square planar complexes to form 5 or 6 coordinate species ii. Monomer/Polymer chemical equilibria
23
Introduction Chapter 1
iii. Square-planar/tetrahedral equilibria iv. Trigonal-bipyramid/square pyramid equilibria. i. Ni2+ reacts with substituted acacs to give green dihydrates with C.N=6. When heated, two coordinated molecules of water remove and results in tetrahedral geometry.
ii. Ni( acac)2 in solvents like pridine is a 6-coordinate species at R.T but in solid state it is a trimer with coordination number 6.
iii. NiL2X2 type of complexes, where L is a ligand like phosphine; it can for two geometries either tetrahedral or square planar complexes with coordination number 4. 3- 3+ iv. When [Ni(CN)5] is added to [Cr(en)3] a double salt is formed. Its structure reveals that Nickel has two types of stereochemistry in same ratios, i.e. 50% as trigonal bipyramid and 50% as square pyramid. Nickel plays frequent roles in biological systems for living micro-organisms and plants [122]. The enzyme urease, used for the hydrolysis of urea also comprises of nickel. The [NiFe ] - hydrogenases characteristically oxidise H2.
1.16.4 Cobalt: It is essentially required by all the animals. It is the major component of vitamin-B12 also called as cobalamin. Vitamin-B12 is considered as the biological reservoir of cobalt as "ultratrace" element [123]. In the guts of ruminant animals’ bacteria changes salts of cobalt into vitamin-B12 and this can only be produced by archaea or bacteria. Different bacteria, fungi and algae use inorganic form of cobalt as nutrient. Vitamin-B12 is produced salts of cobalt by bacteria in non-ruminant herbivores in their colons. As this vitamin is not absorbed from colon so non-ruminants ingest feces to gain the nutrients. Animals which don’t get vitamin-B12 by their gastrointestinal bacteria or that of any other animals must obtain it from diet, such animals gain no benefit from the simple salts of cobalt. Coenzyme B12 has a very reactive C-Co bond responsible for its chemical reactivity [124]. There are two types of ligands namely methyl and adenosyl, in vitamin-B12 found in humans. B12 with methyl ligands favours the transfer of methyl group which adenosyl ligands attached to B12
24
Introduction Chapter 1
promoted rearrangements; hydrogen is directly shifted between two neighborhood atoms with simultaneous exchange of second group. During the extraction of energy from fats or proteins, and important step is the conversion of MM1-CoA to Su-CoA which is carried out by Methylmalonyl coenzyme A mutase (MUT) [125]. There are some other cobaltproteins aside from B12, no doubt they are far less than other metalloproteins of zinc and iron. Humans and other mammals which don’t use corrin ring of B12, consume an enzyme named as methionine aminopeptidase 2 and it binds directly. Nitrile hydratase is another non-corrin cobalt enzyme in bacteria able to metabolize nitriles [126].
25
Chapter 2
Instrumentation
Instrumentation Chapter 2
Chemistry involves the study of syntheses of new compounds, separation and isolation of desired components and chemical analysis. Chemical analysis involves qualitative and quantitative analysis. Qualitative analysis helps in identification of chemical species in certain samples while quantitative is used for determination of amounts of those species in that sample. For the characterization of both imine ligands and their metals’ complexes, a number of techniques and instruments were used which are given below, 1. UV-Visible Spectrophotometry 2. Infra-red Spectroscopy 3. Atomic Absorption Spectrophotometry (AAS) 4. Thermal Gravimetric Analysis (TGA) 5. Powdered X-ray Diffraction (PXRD) 6. Nuclear Magnetic Spectroscopy (NMR) 7. Electron Spray Ionization-Mass Spectroscopy (ESI-MS):
2.1. Melting/Decomposition Points: Melting or decomposition points were determined by Stuart SMP3 digital melting point apparatus.
2.2 UV-Visible Spectrophotometry: UV-visible spectroscopy is a very common and well-known analytical technique used both as quantitatively (such as Beer’s Law analysis) and qualitatively (compound identification and purity). Absorption or transmission of UV/Vis light, ranging from 180-820nm, by the sample is measured by it. In this technique, with the help of calibration curves, the concentrations of absorbing samples can be determined. Samples of known concentrations are prepared and UV/Vis beam is passed through them by UV/Vis spectrophotometer and a graph is plotted between absorbance of transmittance versus wavelength. Results thus obtained are used to plot a graph (calibration curve) from which the unknown concentration can be determined by its absorbance.
27
Instrumentation Chapter 2
When electromagnetic radiations fall on solids, liquids or gases, they may be absorbed, reflected or even scattered. This techniques explores the interactions of UV/Vis radiations with matter. Atoms or molecules absorb a certain wavelength pf light and jumps from ground sate to excited state. Molecular states relatively requires high energy in comparison to atoms. Transmittance is the ratio of intensity of the light entering the sample (I0) to that exiting the sample (It) at a particular wavelength. Absorbance of particular wavelengths of (packets of energy) by valence shell electrons is measured easily by this technique. Energy of these quanta is measured in terms of wavelengths of radiations. Shorter the wavelength greater the energy of quantum and vice versa. To find location of absorbance and its magnitude UV-VIS spectrophotometers are used. Spectrophotometer is used to measure absorbance or transmittance of a sample as a function of electromagnetic radiation. Shimadzu 1201 spectrophotometer was used in this study. This spectrophotometer have wavelength range from 200-1100nm and has beam splitting photometric system, absorbance range is
0.3-3 and transmittance range is 0-200%. Fig 2.1: UV-Visible Spectrometer 2.3 Infra-red ( IR) Spectroscopy: IR-spectroscopy is one of the spectroscopic techniques which is widely used during organic and inorganic analyses. Different samples when placed in the path of IR beam, they absorb certain frequencies. Infrared absorption spectrum of a substance is characteristic of its chemical structure. IR spectroscopic analysis is majorly used find functional groups present in the experimental samples. Absorption of certain IR frequencies is the characteristic of each functional group. Hence it is an important and famous technique used for identification but also for determination of structures of compounds. It is equally important analytical tool to check the purity of different compounds. In this technique, vibrations of atoms present in a molecule are considered and samples are identified by measuring absorption of infrared radiation of wavenumbers
28
Instrumentation Chapter 2
in a region of 4,000 to 400 cm-1, at various wavenumbers. To obtain an IR spectrum, infrared radiations are passed through the sample and fraction of incident radiation absorbed corresponding to particular energy is measured. Necessary condition for a molecule to have infrared absorptions is to undergo change in dipole moment during expansions and contractions of bonds.
2.3.1 Preparation of Samples: During IR study, samples are prepared so that transmittance of the most intense absorption bands should be within a range of 20 to 80%. For the optic plate, sodium chloride, potassium bromide, or thallium iodide bromide are used. Samples can be prepared by one of the following methods. i. Potassium Bromide Disk Method: 1-2 mg of a solid sample were mixed with 100-200 mg of dried potassium bromide in an agate mortar and quickly reduced to fine particles protecting from moisture and transferred into a die. Pressed the surface of the disk at 500 to 1,000 N/cm2 for 5-8min under low pressure of 0.7kPa and resulting disk was used for the measurement. KBr disk method was used in current study. Some other methods are given under: ii. Solution Method: A solution is formed by dissolving the solid or liquid sample in the specified solvent. Solution is injected into a fixed cell, thickness generally 0.1-0.5 mm, and is used for the measurement. Similar cell containing the same solvent is placed for the compensation beam. iii. Paste Method Solid sample is crushed finely and knead well with liquid paraffin in the mortar. The paste is held between two optic plates without any air gap, and absorption is measured. iv. Liquid Film Method 1-2 drops of liquid sample are held as a capillary film between optic plates and liquid layer between the plates is measured. When it is necessary to thicken
29
Instrumentation Chapter 2
the liquid layer, aluminum foil or other alike material is placed between optic plates so that the liquid sample lies between the plates. v. Thin Film Method Dissolve the sample in the specified solvent, and apply it to one optic plate. Evaporate the solvent by drying with hot air, and measure the thin film adhered on the plate. If the sample is a film with a thickness of not more than 0.02 mm, measure the film just as it is. vi. Gas Sample Measurements: Sample is evacuated under some pressure mentioned in individual monograph. Sample gas is putted in the gas cell with light path length of 5-10cm and measured. Fig 2.2: FT-IR Spectrometer 2.3.2 Method for Analyzing a Sample: Analysis of a sample by FT-IR spectrometer involves following instrumentation. 1. IR Source: A beam of infra-red energy is radiated from a glowing black-body source. An aperture controls this amount of IR-energy presented on sample and detector as well. 2. Interferometer: Spectral encoding takes place when this beam enters into interferometer and results into interferogram signals which emits from interferometer. 3. Sample Compartment: beam enters sample compartment and is reflected by the sample under examination. This reflection depends upon the surface of the sample. Here specific frequencies of energy are absorbed which are the characteristics of the sample. 4. Detector: Detectors are designed to calculate the absorption of interferogram signals. 5. Computer: from the detector, the digitized signal is sent to the computer, here Fourier transformation takes place and finally IR-spectrum is presented for further interpretation.
30
Instrumentation Chapter 2
2.4 Atomic Absorption Spectrophotometry (AAS): With the help of this technique, concentrations of different metals in the complexes are measured. It is a very sensitive technique by which small concentrations of samples upto part per billion of a gram (μgdm–3) can be determined. Amount of sample is estimated by the wavelength absorbed; these wavelengths correspond to the energies required to promote electrons from lower energy levels to higher energy levels. The technique makes use of the wavelengths of light specifically absorbed by an element. They correspond to the energies needed to promote electrons from one energy level to another, higher, energy level. Flame is used to atomize the experimental sample. It involves 1. Desolvation: Evaporation of liquid solvent occurs and dry sample is left behind 2. Vaporization: Solid sample is vaporized into gaseous phase 3. Volatilization: Sample is vaporized and cracked into free atoms A beam of light is focused through this flame on to a detector. In the instrument, a hollow cathode lamp is used to produce light. A voltage is applied across cathode and anode, as a result metals atoms of cathode become excited. Emission spectrum is produced by de-excitation of atoms. Selection of cathode tube depends on the nature of experimental metal. For example, for the analysis of copper in a particular sample, cathode tube made of copper is used. Amount of metals in all synthesized complexes were estimated by AAS. Hitachi Z- 800 polarized Zeeman atomic absorption spectrophotometer was used to analyze the samples.
2.5 Thermal Gravimetric Analysis (TGA): It is a very important, efficient and essential technique which is used for characterization and verification of different materials. It has wide applications in pharmaceutical, food, petrochemical and environmental fields for the characterizations of many materials. A substance is heated or cooled at particular rate and change in mass is studied as a function of time or temperature. By this thermal stability of a sample is estimated. From the results of TGA, a temperature is found
31
Instrumentation Chapter 2
where sample don’t lose further weight or decompositions starts. By this technique, it is also found that decomposition of material occurs in one or more stages. When sample is heated or cooled, crystalline structure and chemical composition of substance undergo changes like oxidation, fusion, crystallization, contraction, expansion or some phase transition. Differential thermal analysis is efficient technique to detect such changes.
F Fig 2.3: Perkin Elmer TGA 7 2.6 Powdered X-ray Diffraction (PXRD): It is a technique used to get information about crystalline structure, distance between atoms and bond angles. X-rays when passed through a crystalline material bent at various angles and produce different patterns. These patterns contain information regarding shape and size of unit cell of crystal. On striking with the matter, these x- rays are scattered by the electron densities of atoms. Angles of diffractions of x-rays are directly related to distance between layers of atoms or ions in crystal lattice. X- rays striking on adjacent layers add their energies constructively if in the same phase; as a result dark dots (spots) are produced on the detector. The x-ray diffraction pattern of substance contains all the information of crystalline structure, hence called as fingerprint of that substance. For polycrystalline phases, powder diffractions method is very efficient and helps for its identification and characterization. Fig 2.4: PANalytical X’Pert PRO MPD diffractometer PXRD can be applied to various types of samples. In a particular analysis, x-rays of some particular fixed wavelength is fallen on the powdered sample. X-rays undergo reflections and their intensities are recorded by goniometer. From the collected data,
32
Instrumentation Chapter 2
reflection angle are determined from which interatomic spacing is calculated. Intensity is found to distinguish various D-spacing. To find possible matches results are compared with the known data. A powdered crystalline sample contains a number of crystallites adopting all possible orientations. A cone of diffraction is given out by each set of planes and there are a number of closely spaced dots in each cone; every set of these dots shows diffraction from one crystallite.
2.7 Nuclear Magnetic Resonance (NMR) Spectroscopy: One of the powerful technique which is used for estimation of structure of experimental molecule. It is done by identifying the carbon-hydrogen frameworks in the molecule. There are two types of NMR spectroscopy named as 1H NMR and 13C NMR. In 1H NMR, total number of protons with their different types are determined while 13C NMR determines types of carbons in different environments in the molecule. Source of energy in nuclear magnetic resonance spectroscopy are radio waves with longer wavelengths having low energy and frequency as well. These waves after interacting with experimental molecule, change nuclear spins of protons (1H) and carbons (13C). Actually, an atomic nucleus is a spinning charged particles which produces magnetic field. In these absence of external magnetic field, these nuclear spins are random. But when external magnetic field is applied, the nuclei are aligned with or against it. In an NMR-spectrometer, magnet, console and host computer are the basic and major components and its functioning is similar to a radio system and components have same terms used, like transmitter, synthesizer and receiver. The magnet in NMR-spectrometer generates a strong static magnetic field which results in generations of macroscopic magnetization in experimental sample. The linear oscillating electromagnetic field B1 is induced by transmitter which interact with nuclei of molecule.
33
Instrumentation Chapter 2
Fig 2.5: Jeol ECS 300 NMR Spectrometer
NMR signal named as free induction decay (FID) is produced in probe coil when irradiated by radio frequency (RF). This FID is then amplified and detected by the receiver. This detected signal is digitized by an analog-to-digital converter (ADC) for further data processing and display. And it is done on the host computer.
2.8 Electron Spray Ionization-Mass Spectroscopy (ESI-MS): It is an analytical technique which involves the study of ionized molecules in gas phase. One or more of the following aims can be achieved by ESI-MS: Determination of molecular mass of molecule Estimation of structure of molecule Qualitative and quantitative analysis of different components of a mixture ESI-mass spectrometer consists of three components named as ion source, mass analyzer and detector. In the ionization chamber, molecular ions are produced by bombarding fast moving electrons (70eV). Some of the molecular ions result into fragment ions by decomposition. In gas phase, the ions are very reactive and very short lived; so their formation and manipulation is conducted in high vacuum. For this reason, ion optics (skimmer, focusing lens and multipole etc), analyzer and detector are kept at vacuum (pressure about 10-3 to 10-6 torr). These ions are then transferred to mass analyzer region via ion optics to focus ions’ stream to maintain a stable route of
34
Instrumentation Chapter 2
ions. Ions with same m/z values move in the form of groups. Mass analyzer separates ions w.r.t the m/z values. The separated ions then reach to detector to calculate their concentrations. Results are shown in the form of mass spectrum. EI mass spectra contain intense fragment ion absorption bands and much less intense molecular ion peak. Quantity of sample used for ESI-MS was less than 1mg. (Fig 2.6)
Fig 2.6: Components of ESI-mass spectrometer
2.9 Vibrating Sample Magnetometer (VSM): Magnetism M(H) measurements were made using vibrating sample magnetometer (VSM). It is used to study the diamagnetic, paramagnetic, ferromagnetic, ferromagnetic, anti-ferromagnetic and anisotropic materials. Sample is attached to vibrator using a Teflon coupling with a glass rod. Vibration is along z-axis with a fixed amplitude of 5mm and fixed frequency of 23Hz. Magnetic field producing fields of 2 tesla is applied along x-axis. Electromotive force is induced by the magnetic moment of vibrating sample. System is calibrated by using standard Nickel sample. . Single from the lock in amplifier was fed into digital multimeter which is attached to computer for data acquirement.
35
Instrumentation Chapter 2
Fig 2.7: Vibrating Sample Magnetometer, Model 7407
The specifications are as Model 7407, dynamic range is 0.5 x 10-6 to 103 emu, noise 0.5 x 10-6, time constant is 0.1 sec, 0.3 sec, 1 sec, 3 sec or 10 seconds, gaussmeter ranges: 300 G, 3 kG, 30 kG, 300 kG, field noise in gauss: 0.05 G for high stability probe.
36
Chapter 3
Experimental Work
Experimental Work Chapter 3
3.1 Chemicals and Reagents: The chemicals and reagents that were used during this study are 2- hydroxybenzaldehyde, ethyl acetoacetate, piperidine, p-chloro aniline, 2-nitro aniline, p-toluidine, Zn(CH3COO)2.H2O, CuSO4.5H2O, NiSO4.6H2O, Co(NO3)2.6H2O, NaCl, solvents such as ethanol, methanol, chloroform, dimetylsulfoxide (DMSO), acetone, dichloromethane and water. These chemicals utilized during this work were of Analytical grade. Methanol and ethanol were distilled for further purification.
3.2 Synthesis of 3 – acetyl -2 H – chromen - 2 -one: 3 – acetyl -2 H – chromen - 2 -one was prepared according to the method mentioned in the advanced organic chemistry by M. Jerry [2]. A mixture of 2- hydroxybenzaldehyde (12.2g, 0.1mol) and ethyl acetoacetate (13.0g, 0.1mol) in 10cm3 of ethyl alcohol was stirred at room temperature by using few drops of piperidine for 8hrs. Yellow colored solid obtained was filtered, washed with excess of chilled ethanol, dried and crystallized as silky needles of 3 – acetyl -2 H – chromen - 2 -one. m.p:120oC
3.3 Synthesis of Schiff Bases: All Schiff bases (imines) were synthesized by the condensation of 3 – acetyl -2 H – chromen - 2 -one (synthesized in section 3.2) with different derivatives of aniline. Complexes of Cobalt( II), Nickel( II) , Copper( II) and Zinc( II) were prepared with these Schiff bases by one pot synthesis method (template method).
3.3.1 General Procedure: The Schiff bases (imines) were prepared by adding 25 cm3 of aromatic ketone solution (1.0eq) to the equal volume of derivative of aniline (1.0eq) ethanolic 38
Experimental Work Chapter 3
solution. The reaction mixture was stirred for 3hrs at 60-70°C. Progress of reaction was monitored by TLC. From the resulting solution, solvent was removed by evaporating under vacuum. By filtration product was collected, washed several times with ethanol. After recrystallizing with hot ethanol, product was dried under vacuum. TLC technique was followed to confirm the purity of product. [127].
3.3.2 Synthesis of (E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) -2 H- chromen- 2 - one: (E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) -2 H- chromen- 2 - one was synthesized from 3 – acetyl -2 H – chromen - 2 -one and p-toluidine. 25 cm3 of 3 – acetyl -2 H – chromen - 2 -one ethanolic solution (1.88g; 0.0l mol, 1.0eq) was added into the equal volume of ethanolic solution of p - toluidine (1.07g; 0.0l mol, 1.0eq) and mixture was stirred for 3.5hrs at 65 - 70°C. The color of crystalline product was bright yellow (71.9%). Detailed procedure given in section 3.3.1.
3.3.3 Synthesis of (E) – 3 - ( 1 - (( 4 – chlorophenyl ) imino ) ethyl) - 2 H – chromen - 2 - one: The Schiff base (E) – 3 - ( 1 - (( 4 – chlorophenyl ) imino ) ethyl) - 2 H – chromen - 2 - one was prepared by adding 25 cm3 of 3 – acetyl -2 H – chromen - 2 -one ethanolic solution (1.88g; 0.0lmol, 1.0eq) to the equal volume of 4-chloroaniline (1.27g; 0.0lmol, 1.0eq) ethanolic solution. The reaction mixture was stirred for 3hrs at 60- 70°C. From the resulting solution, solvent was removed by evaporating under vacuum. The color of obtained crystalline product was light yellow (76.5%). Detailed procedure given in section 3.3.1.
39
Experimental Work Chapter 3
3.3.4 Synthesis of (E) – 3 - ( 1 - (( 2 – nitrophenyl ) imino ) ethyl ) - 2 H - chromen – 2 - one: 25 cm3 of 3-acetyl-2H-chromen-2-one ethanolic solution (1.88g; 0.0l mol, 1.0eq) was added to equal volume of ethanolic solution of 2-nitroaniline (1.38g; 0.0l mol, 1.0eq). The reaction mixture was stirred for 4hrs at 65 - 70°C. From the resulting solution, solvent was removed by evaporating under vacuum. The color of crystalline product was golden yellow (77.1%). Product was purified according to the method given in section 3.3.1.
40
Experimental Work Chapter 3
3.3.5 List of Prepared Ligands: Following ligands has been prepared by condensation of 3-acetyl-2H-chromen-2-one and aniline derivatives.
Table 3.1: List of synthesized ligands Aromatic Aniline Sr. # Carbonyl Schiff Bases Derivative Compound 1 3-acetyl-2H- p-chloro aniline (E)-3-(1-((4- chromen-2-one chlorophenyl)imino)ethyl)-2H- chromen-2-one 2 3-acetyl-2H- p-toluidine (E)-3-(1-(p-tolylimino)ethyl)-2H- chromen-2-one chromen-2-one 3 3-acetyl-2H- 2-nitroaniline (E)-3-(1-((2- chromen-2-one nitrophenyl)imino)ethyl)-2H- chromen-2-one
3.4 Synthesis of Imine Metal Complexes: All the complexes were prepared by one pot synthesis method (template method) and reactants were added in the same pot one by one for synthesis of complexes.
3.4.1 General Procedure: The metal salt solution (0.005 mol, 1.0eq) in methanol (10ml) was slowly added to the solution of the aromatic ketone (0.01 mol, 2.0eq) in methanol (10 ml). The reaction mixture was refluxed for 15 min at 60 - 70 °C with continuous stirring. After 15 min a solution of aromatic amine derivative (0.01mol, 2.0eq) was added dropwise in the mixture with continuous stirring. The reaction mixture was further refluxed for 4-5 hrs at 60 - 70°C with continuous stirring. On cooling precipitates formed were obtained through filtration and washed many times with cold methanol and recrystallized from methanol.
41
Experimental Work Chapter 3
3.4.2 Mechanism of Reaction: It is a two-step reaction. In the first step, the amine is added to the carbonyl group resulting into a species known as a carbinolamine. This initially formed tetrahedral intermediate is not stable. In the second step, the stabilization is achieved by the elimination of a water molecule resulting in the ultimate formation of imine.
42
Experimental Work Chapter 3
3.4.3 Synthesis of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) – 2 H – chromen – 2 – one ]Nickel( II):
After refluxing nickel sulphate NiSO4.6H2O solution (1.31g, 0.005mol, 1.0eq) and 3- acetyl-2H-chromen-2-one (1.88g, 0.01 mol, 2.0eq) in methanol for 15min, p-toluidine (1.07g, 0.01 mol, 2.0eq) was added dropwise in the reaction mixture. After refluxing this reaction mixture at 60 - 70oC for 4 hrs and 20min (See section 3.4.1), desired product was obtained as light green precipitates (68.3%).
3.4.4 Synthesis of Bis[(E) - 3 -( 1- (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Nickel( II):
Nickel sulphate NiSO4.6H2O solution (1.31g, 0.005mol, 1.0eq) made in methanol (10ml) was slowly added to the solution of 3-acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). The reaction mixture was refluxed for 15min at 60-70 °C with continuous stirring and p-chloroaniline (1.27g, 0.01mol, 2.0eq) was added dropwise according to the method in section 3.4.1. On refluxing for 4hrs light green precipitates of desired product were obtained (61.2%).
3.4.5 Synthesis of Bis[(E) – 3 - ( 1 - (( 2 – nitrophenyl ) imino ) ethyl ) – 2 H – chromen – 2 – one ]Nickel(II):
According to procedure in section 3.4.1, Nickel sulphate NiSO4.6H2O solution (1.31g, 0.005mol, 1.0eq) in methanol (10ml) was slowly added to the solution of 3-acetyl-2H- chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). After refluxing for 15min at 60-70°C, a solution of 2-nitroaniline (1.38g, 0.01 mol, 2.0eq) was added dropwise and refuxed for 4hrs and 30min to obtain desired product as light green solid (65.4%).
3.4.6 Synthesis of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) – 2 H – chromen – 2 - one ]Cobalt( II):
After refluxing Cobalt nitrate Co(NO3)2.6H2O solution (1.46g, 0.005mol, 1.0eq) and 3-acetyl-2H-chromen-2-one (1.88g, 0.01 mol, 2.0eq) in methanol for 15min, p- toluidine (1.07g, 0.01 mol, 2.0eq) was added dropwise in the reaction mixture. After
43
Experimental Work Chapter 3
refluxing at 60-70oC for 4 hrs and 20min (See section 3.4.1), desired product was obtained as light pink precipitates (65.9%).
3.4.7 Synthesis of Bis[(E) – 3 - ( 1 - (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Cobalt(II):
Cobalt nitrate Co(NO3)2.6H2O solution (1.46g, 0.005mol, 1.0eq) made in methanol (10ml) was slowly added to the solution of 3-acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). The reaction mixture was refluxed for 15min at 60-70 °C with continuous stirring and p-chloroaniline (1.27g, 0.01mol, 2.0eq) was added dropwise according to the method in section 3.4.1. On refluxing for 4hrs light pink precipitates of desired product were obtained (61.1%).
3.4.8 Synthesis of Bis[(E) – 3 - ( 1 - (( 2- nitrophenyl ) imino ) ethyl ) – 2 H – chromen - 2 – one ]Cobalt(II):
According to procedure in section 3.4.1, Cobalt nitrate Co(NO3)2.6H2O solution (1.46g, 0.005mol, 1.0eq) in methanol (10ml) was slowly added to the solution of 3- acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). After refluxing for 15min at 60-70°C, a solution of 2-nitroaniline (1.38g, 0.01 mol, 2.0eq) was added dropwise and refuxed for 4hrs and 30min to obtain desired product as light pink solid (59.9%).
3.4.9 Synthesis of Bis[(E) - 3 - ( 1 - ( p - tolylimino ) ethyl) - 2 H – chromen - 2 - one ]Copper( II):
After refluxing Copper sulphate CuSO4.5H2O solution (1.24g, 0.005mol, 1.0eq) and 3-acetyl-2H-chromen-2-one (1.88g, 0.01 mol, 2.0eq) in methanol for 15min, p- toluidine (1.07g, 0.01 mol, 2.0eq) was added dropwise in the reaction mixture. After refluxing this reaction mixture at 60 - 70oC for 4 hrs and 20min (See section 3.4.1), desired product was obtained as green precipitates (68.6%).
44
Experimental Work Chapter 3
3.4.10 Synthesis of Bis[(E )- 3 - ( 1- (( 4 – chlorophenyl ) imino) ethyl ) -2 H - chromen- 2 – one ]Copper(II):
Copper sulphate CuSO4.5H2O solution (1.24g, 0.005mol, 1.0eq) made in methanol (10ml) was slowly added to the solution of 3-acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). The reaction mixture was refluxed for 15min at 60-70 °C with continuous stirring and p-chloroaniline (1.27g, 0.01mol, 2.0eq) was added dropwise according to the method in section 3.4.1. On refluxing for 4hrs light green precipitates of desired product were obtained (67.3%).
3.4.11 Synthesis of Bis[(E) - 3 - ( 1 - (( 2 - nitrophenyl ) imino ) ethyl ) – 2 H – chromen - 2 –one ]Copper(II):
According to procedure in section 3.4.1, Copper sulphate CuSO4.5H2O solution (1.24g, 0.005mol, 1.0eq) in methanol (10ml) was slowly added to the solution of 3- acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). After refluxing for 15min at 60-70°C, a solution of 2-nitroaniline (1.38g, 0.01 mol, 2.0eq) was added dropwise and refuxed for 4hrs and 30min to obtain desired product as light green solid (64.4%).
3.4.12 Synthesis of Bis[(E) - 3 - ( 1 -( p - tolylimino) ethyl ) - 2 H - chromen – 2 – one ]Zinc( II): After refluxing Zinc acetate solution (1.09g, 0.005 mol, 1.0eq) and 3-acetyl-2H- chromen-2-one (1.88g, 0.01 mol, 2.0eq) in methanol for 15min, p-toluidine (1.07g, 0.01 mol, 2.0eq) was added dropwise in the reaction mixture. After refluxing reaction mixture for 4 hrs 20min at 60 - 70oC (See section 3.4.1), desired product was obtained as yellow precipitates (66.0%).
3.4.13 Synthesis of Bis[(E) - 3- ( 1- (( 4- chlorophenyl) imino ) ethyl ) - 2 H- chromen - 2 – one ]Zinc(II): Zinc acetate solution (1.09g, 0.005 mol, 1.0eq) made in methanol (10ml) was slowly added to the solution of 3-acetyl-2H-chromen-2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). The reaction mixture was refluxed for 15min at 60-70 °C with
45
Experimental Work Chapter 3
continuous stirring and p-chloroaniline (1.27g, 0.01mol, 2.0eq) was added dropwise according to the method in section 3.4.1. On refluxing for 4hrs yellow precipitates of desired product were obtained (69.8%).
3.4.14 Synthesis of Bis[(E)- 3 -( 1- (( 2 – nitrophenyl ) imino ) ethyl) -2 H – chromen - 2 – one ]Zinc(II): According to procedure in section 3.4.1, Zinc acetate solution (1.09g, 0.005mol, 1.0eq) in methanol (10ml) was slowly added to the solution of 3-acetyl-2H-chromen- 2-one (1.88g, 0.01mol, 2.0eq) in methanol (10ml). After refluxing for 15min at 60- 70°C, a solution of 2-nitroaniline (1.38g, 0.01 mol, 2.0eq) was added dropwise and refuxed for 4hrs and 30min to obtain desired product as lemon yellow solid (62.2%).
3.5 Methods for Purification and Recrystallization: For getting the pure, fine crystals a number of purification and crystallization methods were adopted, which are given below.
3.5.1 By Slow Evaporation: After dissolving the sample in suitable solvent, it was placed in a conical flask covered with a perforated foil and was left for many days at R.T. As the solvent evaporates slowly with time, crystals appeared at the bottom of the conical flask. Remaining solvent was drawn out by using a fine pipette. Dried the crystals for one or two days more. The crystals obtained in this way were fine, pure and quite suitable for X-ray analysis.
3.5.2 By Cooling at Low Temperature: The sample was dissolved in methanol by heating and prepared its supersaturated solution. The solution was covered with a perforated covering and allowed to become cool slowly at R.T and then placed in a refrigerator for crystallization at low temperature (0-5°C). On cooling flaky and large size crystals appeared which were staked together and were not enough for X-ray analysis.
46
Experimental Work Chapter 3
3.5.3 List of Synthesized Metal Complexes: A number of metal complexes were synthesized by reacting different 3d metals including Nickel, Cobalt, Copper and Zinc. Following table shows all different types of ketones, anilines, metals and synthesized metal complexes.
Table 3.2: Data regarding the synthesized complexes and reactants Metal Sr. # Metal Complexes Ketones Aniline Salt 1 Bis[(E)-3-(1-((4- 3-acetyl-2H- 4- Zinc chlorophenyl)imino)ethyl)-2H- chromen-2- chloroaniline Acetate chromen-2-one]Zinc(II) one 2 Bis[(E)-3-(1-(p- 3-acetyl-2H- p-toluidine Zinc tolylimino)ethyl)-2H-chromen- chromen-2- Acetate 2-one]Zinc(II) one 3 Bis[(E)-3-(1-((2- 3-acetyl-2H- 2-nitroaniline Zinc nitrophenyl)imino)ethyl)-2H- chromen-2- Acetate chromen-2-one]Zinc(II) one 4 Bis[(E)-3-(1-((4- 3-acetyl-2H- 4- Copper chlorophenyl)imino)ethyl)-2H- chromen-2- chloroaniline sulphate chromen-2-one]Copper(II) one 5 Bis[(E)-3-(1-(p- 3-acetyl-2H- p-toluidine Copper tolylimino)ethyl)-2H-chromen- chromen-2- sulphate 2-one]Copper(II) one 6 Bis[(E)-3-(1-((2- 3-acetyl-2H- 2-nitroaniline Copper nitrophenyl)imino)ethyl)-2H- chromen-2- sulphate chromen-2-one]Copper(II) one 7 Bis[(E)-3-(1-((4- 3-acetyl-2H- 4- Nickel chlorophenyl)imino)ethyl)-2H- chromen-2- chloroaniline sulphate chromen-2-one]Nickel(II) one 8 Bis[(E)-3-(1-(p- 3-acetyl-2H- p-toluidine Nickel tolylimino)ethyl)-2H-chromen- chromen-2- sulphate 2-one]Nickel(II) one 9 Bis[(E)-3-(1-((2- 3-acetyl-2H- 2-nitroaniline Nickel nitrophenyl)imino)ethyl)-2H- chromen-2- sulphate chromen-2-one]Nickel(II) one 10 Bis[(E)-3-(1-((4- 3-acetyl-2H- 4- Cobalt chlorophenyl)imino)ethyl)-2H- chromen-2- chloroaniline Nitrate chromen-2-one]Cobalt(II) one 11 Bis[(E)-3-(1-(p- 3-acetyl-2H- p-toluidine Cobalt
47
Experimental Work Chapter 3
tolylimino)ethyl)-2H-chromen- chromen-2- Nitrate 2-one]Cobalt(II) one 12 Bis[(E)-3-(1-((2- 3-acetyl-2H- 2-nitroaniline Cobalt nitrophenyl)imino)ethyl)-2H- chromen-2- Nitrate chromen-2-one]Cobalt(II) one
3.6 Techniques used for Characterization of Ligands and Complexes: All the ligands and metal complexes synthesized during this study were analyzed by different analytical and spectral techniques which helped to investigate the structures and formulas of both ligands and metal complexes. Following section reveals the procedures adopted for the preparation of sample used during different techniques.
3.6.1 UV-Visible Spectroscopy (UV-VIS): 3.6.1.1 Preparation of Sample and Measurements: Being colored complexes their UV-Visible study was quite easy. As all the synthesized metal complexes were colored and no preparation of samples was required. λmax for each synthesized complex was determined, for that, 0.1 ppm concentrations of complexes were prepared in chloroform and absorbance was measured at varying wavelengths using chloroform as blank. Graphs were plotted between wavelengths (λ) and absorbance (A) and λmax were calculated.
3.6.2 Infra-red ( IR) Spectroscopy: 3.6.2.1 Preparation of Sample and Measurements: Particle size of samples was reduced by grinding to powder level with the help of pestle and mortar and a pinch of each powdered sample was placed on transparent window of ATR based FTIR. Infra-red radiations were passed through experimental samples and spectra were measured. Brucker FTIR was used to measure the spectra.
3.6.3 Atomic Absorption Spectrophotometry (AAS): 3.6.3.1 Preparation of Sample and Measurements:
All the experimental samples were digested in HNO3. 0.01 g of the metal complex was taken in a china dish. 10ml of concentrated nitric acid was added in it and heated
48
Experimental Work Chapter 3
on a sand bath until whole acid evaporated and only a thin film of complex was left at the bottom of china dish. To this film again 10ml of concentrated nitric acid was added and heated on the sand bath. The procedure was repeated several times until a thin brownish pasty film left, showing that the whole metal M (M = Ni, Co, Cu and Zn) has been converted into its nitrate salt. These nitrate salts were dissolved completely in small amount of distilled, de-ionized water. This solution was poured in a 100ml measuring flask and filled with distilled water upto the mark. Weights of metals’ complexes were measured by using digital weigh balance and volumes were maintained carefully. Standards solutions of respective metal salts were prepared from 05-25 ppm range to get the calibration graph covering the concentration range expected in the sample.
3.6.4 Thermo Gravimetric Analysis (TGA): 3.6.4.1 Preparation of Sample and Measurements: About 05-20 mg of metal complexes were ground to fine powder to increase its surface area. Sample is grinded because it is more exposed to sample purge than one large chunk. The bottom of pan was covered with sample material. In this instrument weight of the sample is continuously measured as the temperature is raised to up to 20000C and coupled with FTIR and mass spectrometer gas analysis. With rise in temperature, components of sample decompose and weight percentage of resulting mass change is recorded. Results were calculated by plotting graph between temperature and weight loss.
3.6.4.2 Experimental: The Thermal gravimetric analyses (TGA) of the samples were carried out by using Perkin Elmer TGA 7. During analyses a slow stream of air was used. Samples were pre-weighed using a TGA balance. Boat made up of platinum foil was properly washed and dried; and powdered sample, about 05 mg, was kept into it for analysis and covered by quartz tube and air flow was kept up. The whole assemblage was then moved into the furnace and allowed to heat up at a constant rate of 10 °C / min. At same time, change in the weight of sample was automatically recorded with
49
Experimental Work Chapter 3
time/temperature. Data revealed %age loss in weight of sample as function of the time and temperature. At temperature about 650°C, experiment was stopped as no further loss in weight was observed. The thermograms were plotted and further analyzed. Data was collected to get information about the %age loss in weight of sample at different temperatures.
3.6.5 Powdered X-ray Diffraction (PXRD): 3.6.5.1 Preparation of Sample and Measurements: For X-ray study, an ideal sample must be homogenous and the crystallites must be randomly distributed. To get random sampling of all crystal faces (atomic planes), samples were ground to powdered form with particles cross section of about 0.002mm to 0.005mm. Grinding of sample gives a number of small crystals. A smooth flat surface of the sample was obtained by pressing it in the sample holder.
3.6.6 Nuclear Magnetic Resonance (NMR) Spectroscopy: 3.6.6.1 Preparation of Samples and Measurements: To obtain high resolution NMR spectra, suspended materials were removed by filtering it using cotton wool. As NMR samples need, 10-25mg of complexes were dissolved in deuterated solvents (CDCl3, DMSO-D8 etc.). Experimental samples were dissolved in respective deuterated solvent in glass vials using less than final volume required for NMR sample. After passing through the cotton filter, samples were transferred to NMR tube and required volume was maintained by adding more deuterated solvent finally ~55mm sample height was attained. NMR tubes were vigorously shaken for effective mixing. Presence of different protons in ligands and complexes was interpreted by splitting patterns of absorption bands.
3.6.7 Electron Spray Ionization-Mass spectroscopy (ESI-MS): 3.6.7.1 Preparation of Samples and Measurement: Samples for injection into the electrospray ionization mass spectrometer work the best if they are first purified. 10-100 µg of highly purified metal complexes were dissolved
50
Experimental Work Chapter 3
in 1ml of suitable solvent to gain a transparent solution. This sample solution was injected into spectrometer with help of microsyringe.
3.7 Antibacterial Activity of Metal Imine Complexes: 3.7.1 Materials: All the materials required during the study were bought from Sigma Aldrich. All chemicals were of analytical grade and pure enough; and were used as received. Pathogenic microorganisms Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), Bacillus subtilis, MRSA and S. typhi were used for the present study. Bacterial strains were collected from Department of Botany, University of Punjab, Lahore and Sheikh Zaid Research Hospital Lahore.
3.7.2 Preparation of LB Agar Plates: LB Agar, Miller and LB Broth, Miller are based on LB Medium for the growth and maintenance of E. coli strains used in molecular microbiology procedures [128-129]. It is rich in nutrition and is specially designed for the growth of pure cultures of recombinant strains. E. coli grows more rapidly because they provide the cells with amino acids, nucleotide precursors, vitamins and other metabolites which other micro- organism have to synthesize [130]. In order to prepare LB agar plates, following materials were taken: a. Tryptone: 10g b. Yeast Extract: 5g c. Sodium Chloride (NaCl): 10g d. Agar: 15g 1. Added all ingredients to a clean 1-liter flask (or beaker) that has been rinsed with distilled water. 2. Added250ml of de-ionized or distilled water. 3. Added 0.5 ml of 4N NaOH. 4. Dry ingredients were dissolved by stirring, preferably using a magnetic stir bar. 5. After covering flask mouth with aluminum foil/cotton, it was autoclaved for 15 minutes at 121 ºC.
51
Experimental Work Chapter 3
6. When the agar flask was cool enough to hold, lifted lid of culture plate only enough to pour solution. Tilted the plate to spread the agar. 7. To remove any bubbles in the surface of the poured agar, touched plate surface with the flame from the Bunsen burner. Then agar was allowed to solidify undisturbed for 5-10 minutes. 8. Incubated plates were kept lidside down for several hours at 37ºC (overnight). It allowed the ready detection of any contaminated plates.
3.7.3 Obtaining Single Colony of Bacterial Strain: During culture growth of bacteria, transformed bacterial cell may lose their plasmids or some parts of plasmids so it is ensured that each cell in the bacterial populations was descended from a single cell, it confirmed that all cells had same genetic makeup. Single colonies are obtained by streaking (procedure mentioned in section 3.7.4).
3.7.4 Streaking of Plates: The objective of streaking of plates is get a single colony representing a clone of one bacterium. Streaking is a technique which used for isolation of pure strain from bacterial species. Samples are then taken from the resulting colony and culture is grown on a new plate for further testing. Sterilized the loop in the Bunsen burner flame until red hot. Inoculating loop was carefully handled to avoid contamination. After cooling the loop for 05 seconds, removed the lid from the culture plate and stabbed inoculating loop into a free zone of the agar several times to cool. With the tipoff loop a visible cell mass was scraped from a colony and streaked as follows (Fig 3.7). Streak 1: Inoculating loop tip was glided back and forth across the agar surface to make a streak across the top of the plate and replaced lid of plate between streaks. Streak 2: Reflamed inoculating loop and cooled by stabbing it into the agar away from the first (primary) streak. Drew loop tip through the end of the primary streak and, without lifting loop, made a zigzag streak across one quarter of the agar surface.
52
Experimental Work Chapter 3
Fig 3.7: Streaking of Plates
Streak 3: Reflamed loop and cooled in the agar as described above. Drew loop tip through the end of the secondary streak, and made another zigzag streak in the adjacent quarter of the plate without touching the previous streak. After labeling the plates, placed them upside down in 37oC incubator overnight for about 12-16hrs.
3.7.5 Spreading diluted Stock Culture to obtain Single Colony: Bacterial suspensions were diluted before plating them out on a plate, if not diluted then these suspensions grow into post-log phase with 109 cells/ml. For each culture, sub aliquot of selected culture was diluted so that it had had no more than 103 cells/ml. Much care was taken to avoid the mixing up of experimental bacterial cultures, so they were properly labelled. In order to get dilution with 103 cells/ml, a million fold (10-6) dilution was done. Agitated cell suspension was added in 1ml (1000µl) of LB medium resulting in 10-3 dilution. 1µl of this 10-3 dilution was then added into another 1ml of LB medium, this resulted in 103 cells/ml. 100µl of each culture was spread by using a bent glass and plates were incubated with upside down at 37oC overnight (16-20hrs). After removing plates from incubator, plate edges were wrapped with paraffin film and were stored at 4oC. Number of colonies were counted, recorded and the compared with calculated number of colonies.
53
Experimental Work Chapter 3
3.7.6 Preparation of Antibacterial Solution: All the complexes were dissolved in dimethyl formamide (DMF). (Fig 3.8) Ligands/complexes were taken at concentration of 100 μg/ml for testing antibacterial activity. They diffused into the medium produced a concentration gradient. After the incubation period, the zones of inhibition were measured in mm.
Fig 3.8: Test Tubes containing solution of bacteria
3.7.6.1 Antibacterial Activity assay Procedure: Agar plate diffusion technique [131] was used to develop L.B nutrient medium. Yeast extract (0.5 g), tryptone (1 g), sodium chloride (0.5 g) and agar (1.5-2 g) were weighed and each component was dissolved in 1 L Erlenmeyer flask. After maintaining the volume up to 1 L, solution was autoclaved to ensure that LB was sterilized of all foreign matter and contaminants. LB medium was used for bacterial culture growth in solution and bacterial growth on petri plates. After adding 25-30ml of LB medium in petri-dish, it was allowed to solidify; then 1 ml of bacterial suspension was transferred to plate at 27oC for 24hrs. With the help of autoclaved pasture pipette, wells were made in plates and were then filled with solution of ligands/complexes (50µg/ml) in DMSO. Inhibition zone were measured for both ligands and complexes. Each synthesized ligands and complexes were investigated according to pre mentioned concentrations dissolved in DMSO, while DMSO itself was used as control for comparison. For the determination of MIC values guidelines given in NCCLS document M27-A [132] were followed. 100 μg/ml solutions of
54
Experimental Work Chapter 3
ligands and complexes were made in DMSO and serial dilutions 50, 40, 30, 20, 10, 5 μg/ml were prepared to determine the MIC.
3.7.6.2 Concentrations of Test Ligands/Complexes: 2mg of each ligand and complex was dissolved in 1ml of DMSO. From this stock three concentrations 0.2mg/0.1ml, 0.02mg/0.1ml and 0.002g/0.1ml were prepared and used for investigation of antibacterial activities.
55
Chapter 4
Antibacterial Activity
Antibacterial Activity Chapter 4
4.1 Introduction: Transition metals has played a significant role in the field of medicinal chemistry. Transition elements can interact with a number of negatively charged ligands as they exhibit different oxidation states. This activity of transition metals results in the development of drugs based on metal complexes with promising pharmacological applications. A number of metal complexes of platinum, palladium andiridium have been reported which show antimicrobial activities [133]. Cr( III) and Zn( II) Schiff base complexes with ethyl – 2 - (( 1 – hydroxynaphthalen – 2 – yl ) methyleneamino ) - 5, 6 – dihydro – 4 H – cyclopenta [b] thiophene – 3 - carboxylate were found active against pathogenic strain [134]. Because of their unique applications, researchers are still interested to discover more effective therapeutic regimen to treat bacterial infections. Control of spreading of antibiotic-resistant bacteria and treatment by their infections had been a great problem worldwide. The science dealing with the study of the prevention and treatment of diseases caused by micro-organisms is known as medical microbiology. Medical microbiology is divided into different sub-disciplines: Virology involves the study of different kinds of viruses. Bacteriology: it involves bacterial studies. Different classes’ of fungi are studied in Mycology. Phycology involves the study of algae and Protozoology is the study of protozoa. To prevent the growth or to kill the micro-organisms and for the treatment of diseases, different inhibitory chemicals so called antimicrobial agents are used. Antimicrobial agents are classified according to their applications and spectrum of activity, as germicides that kill micro-organisms. The germicides show selective toxicity depending on their spectrum of activity. They act as viricides and kill viruses. Bacteriocides which kill bacteria. Algicides which kill algae. Fungicides that kill fungi.
57
Antibacterial Activity Chapter 4
Antimicrobial drugs may either kill microorganisms or simply prevent their growth. There are various ways in which these agents exhibit their antimicrobial activity [135].They may inhibit Syntheses of Cell wall Preparations of Protein Syntheses of Nucleic acids Enzymatic activity Folate metabolism Damage cytoplasmic membrane
4.2 Mode of Action: Antimicrobial drugs interfere chemically with the synthesis of function of vital components of microorganisms. The cellular structure and functions of eukaryotic cells of the human body. These differences provide us with selective toxicity of chemotherapeutic agents against bacteria. Anti-microbial drugs are used to kill microorganisms outright or simply used for the prevention of their growth. There are various ways in which these agents exhibit their antimicrobial activity [135].They may inhibit Syntheses of Cell wall Preparations of Protein Syntheses of Nucleic acids Enzymatic activity Folate metabolism Damage cytoplasmic membrane
4.3 Test Cultures: All the synthesized imine ligands and their complexes were screened for anti-bacterial activities. Different bacterial strains used for this are: MRSA [Gram positive] Bacillus subtilis [Gram positive]
58
Antibacterial Activity Chapter 4
Staphylococcus aureus [Gram positive] Escherichia coli [Gram negative] Pseudomonas aeruginosa [Gram negative] S. typhi [Gram negative]
4.4 Classification of Bacteria: The bacteria are microscopic organisms with relatively simple and primitive forms of prokaryotic type. Danish Physician Christian Grams, discovered the differential staining technique known as Gram staining, which differentiates the bacteria into two groups “Gram positive” and “Gram negative”. Gram positive bacteria retain the crystal violet and resist decolorization with acetone or alcohol and hence appear deep violet in colour while Gram negative bacteria, which loose the crystal violet, are counter-stained by saffranin and hence appear red in color. These two groups of bacteria are classified into following four different categories: 1. “Ordinary ” Gram positive bacteria. 2. “Ordinary ” Gram negative bacteria. 3. Gram positive filamantous bacteria of complex morphology. 4. “Bacteria ” with unusual properties.
4.4.1 Methicillin-Resistant Staphylococcus Aureus (MRSA): The methicillin-resistant Staphylococcus aureus (MRSA), is also known as the “superbug”. Methicillin resistant Staphylococcus aureus (MRSA) were identified within one year of introduction of Methicillin into clinical practice and first reported in Britain in1961. The microbiological underpinning of MRSA is a subtype of the Staphylococcus bacteria. MRSA is a common skin bacterium caused by Staphylococcus aureus which is resistant to a number of antibiotics. Staphylococcus aureus (SA) is a commonly occurring bacterium that has been around, for thousands of years. Around a third of the world’s population carries MRSA harmlessly on the skin, nose or throat. Its size is about 0.6µm in diameter. It lives in groups which look like small masses of grapes, as
59
Antibacterial Activity Chapter 4
implied by its name (Greek for “bunch of grapes”). Staphylococcus bacteria developed resistance against two powerful antibiotics named as methicillin and cloxacillin which belong to penicillin family. This is due to the development of ability to produce an enzyme “Penicillinase” which neutralizes antibacterial characteristics of penicillin. As a result is becomes resistant to most of the types of antibiotics.
Fig 4.1: Scanning electron micrograph of MRSA
It is most commonly found in hospitals, as there are greater number of infected surfaces and people. In hospital, a large number of people are normally elder who are sicker and weaker than the general population, as they have weaker immune systems so are more susceptible to infection. MRSA is transferred through the contact of skins, touching contaminated surfaces and equipments like razors, towels etc. So its prevention involves early detection, avoiding sharing items, proper bandaging of cuts, wounds and most importantly washing hands. As reported by Klevens [136], the average MRSA-induced mortality rate among the general population is 6.3 per 100,000 (indicating about 20% rate among those infected), although this figure is much higher among weak populations such as HIV-positive patients and the elderly. MRSA are considered more dangerous than other staphylococci because they do not response to mainstream of antibiotics. Another major threat is their ability to continue modify themselves particularly in environment of hospital.
60
Antibacterial Activity Chapter 4
4.4.2 Bacillus Subtilis: Family (Bacillaceae) It was originally called Vibrio subtilis in 1835 and was renamed as Bacillus subtilis in 1872. It is also known by some other names including Bacillus uniflagellatus, Bacillus globigii, and Bacillus natto. Bacillus subtilis was the first bacteria being studied. They are considered as an excellent model for cellular development and differentiation. These gram positive bacteria consists of rod-shaped cells [137] and are naturally found in soil and vegetation. They normally grow in mesophilic temperature range and optimum temperature is 25-35oC. As stress and starvation are usually common under this environment so these bacteria form stress-resistant endospores to face these tough conditions. These bacteria are considered as aerobic as they need oxygen for their growth. However, advance studies have shown that they can indeed grow under anaerobic conditions. During anaerobic respiration, B. subtilis utilizes nitrate and nitrite as terminal electron acceptor. They contain two nitrate reductases, one is used for nitrogen absorption of nitrate and other for nitrate respiration. On the other hand there is only one nitrite reductase and it serves both purposes. Cell wall outside the cell is a rigid structure composed of peptidoglycan, a polymer of sugars and amino acids. Cell wall works as barrier between cell and environment; responsible for shape of the cell and withstands high internal turgor pressure of the cell [138].
Fig 4.2 Rod-shaped Bacillus subtilis
Bacillus subtilis is readily present everywhere; the air, soil and in plant compost. It is predicted that it spends most of it time inactive and in spore form. When the
61
Antibacterial Activity Chapter 4
bacterium is active though, it produces many enzymes. One enzyme contributes to the plant degradation process. Bacillus subtilis can also be found in the human body, mostly on the skin or in the intestinal tract. However it is very rare for this bacterium to colonize on the human body. These bacteria are non-pathogenic. They contaminate food and results in food poisoning. In agriculture, they are used as fungicides; they form colonies on root systems and compete with disease causing fungal organisms. Some strains of B. subtilis cause rots in potatoes. Some Bacillus species like Bacillus cereus cause food poisoning. B. cereus may cause two types of intoxications. It can either cause nausea or abdominal cramps for 1-6hrs. Some bacillus species cause severe illness. For example Bacillus anthracis causes Anthrax. Besides its many uses and applications, Bacillus subtilis has become the model agent in laboratory research because of its easy genetic manipulation.
4.4.3 Staphylococcus aureus: Family (micrococcaceae) In 1878, Koch observed micrococcus like organisms in pus; Pasteur (1880) cultivated these cocci in liquid media. They are Gram-positive cocci, ovoid or spheroidal, non- motile, arranged in group of clusters; they grow on nutrient agar and produce colonies, which are golden yellow, white or lemon yellow in colour; pathogenic strains produce, coagulated and ferment glucose lactose, mannitol with production of acid, liquefy gelation and produce pus in the lesion.
Genus: Staphylococcus The word staphylococcus is derived from the Greek language (Gr. Staphylo = bunch of grapes; Gr. Coccus = a grain or berry), while the species name is derived from Latin language (L. aureus = golden). Staphylococcus is discriminated from micrococcus and another genus of this family by its anaerobic consumption of glucose, mannitol and pyruvate. Staphylococci which are slightly smaller than the cells of Micrococci, are found on the skin or mucus membrane of animal body.
62
Antibacterial Activity Chapter 4
Species: S taphylococcus aureus Basic habital of St. aureus is the anterior naves, though it is also a normal flora of human skin, and of the respiratory and gastrointestinal tracts. The individual cells are 0.8-0.9 μ in diameter with oval or spherical, nonmotile, non-capsulated, non- sporulating strains and are Gram-positive, typically arranged in groups. They easily grow on nutrient agar; the optimum temperature for the growth is 35oC.
Fig 4.3: Scanning electron micrograph of S.aureus
They are notorious as they cause suppurative (pyogenic or pus-forming ) circumstances, mostitis of females and cows and food poisioning. St. aureus grows rapidly and produce circular (1-2 mm) endive edge, convex, soft, glistening colonies having a golden yellow pigment. St.aureus can tolerate moderately high concentration of NaCl, hence they can be selectively isolated on the nutrient medium containing 7.5 % sodium chloride. It is also able to ferment mannitol to organic acid. S. aureus also produce the coagulase which is able to clot citrated plasma. It also produces the enzymes catalase, hyaluronidase as well as other virulent factors like hemolysins, leucocidins, enterotoxins and exofoliatin.
4.4.4 Escherichia coli: Family (Enterobacteriaceae) They are Gram-negative rods, motile with peritrichate flagella or nonmotile. They do not form spores. All are sometimes (i.e. from rarely to, invariably) found in intestinal treatment of man or lower animals.
63
Antibacterial Activity Chapter 4
Genus: E scherichia This genus comprises Escherichia coli and several variants. Species: E scherichia col i Escherichia in 1885 discovered Escherichia coli is a commensal of the human intestine. It originates in the sewage, water or soil polluted by faecal matters. These are Gram-negative rods, 2-4μ, commonly seen in coccobacillary form, which do not form any spore and have 4 to 8 paritrichate flagella, are sluggishly motile, are facultative anaerobes and they cultivate readily in laboratory media.
Fig 4.4 Rod shaped structure of E.coli
E. coli are mostly non-pathogenic and are convicted as pathogens, as in some strains have been found to yield septicemia, inflammation of liver and gall bladder, appendix and other infections. It is a renowned pathogen in field of veterinary.
4.4.5 Pseudomonas aeruginosa: Genus: P seudomonas Pseudomonas is a Greek word (Gr. Pseudo = false, Gr. Monas = a unit) while the word aeruginosa is of Latin origin (L. aeruginosa = full of copper rust i.e. green).
Species: P seudomonas aeruginosa P.aeruginosa is Gram-negative short rod with variable length (1.5-3.0 x 0.5μm). They are motile by means of one or two polar flagella. Organisms are nonsporulating and
64
Antibacterial Activity Chapter 4
non-capsulated, however, few strains possess slime layer up of polysaccharide. Primary habitat of P.aeruginosa is human and animal gastro- intestinal tract, water, sewage, soil and vegetation. It is physiologically versatile and flourishes as a saprophyte in warm moist situations in the human environment, including sinks, drains, respirators, humidifiers, etc. P.aeruginosa produces several virulence factors, including exotoxin A., proteases, a leukocidin, and phospholipase C. pseudomonas is an unprincipled pathogen which can produce infections when the natural resistance of the body is low.
Fig 4.5: Cells of P. aeruginosa
They are mostly related with hospital infections and post burn infections. They also cause infections of middle ear, eyes and urinary tracts. It is also associated with diarrhoea, pneumonia and osteomyelitis. Due to drug resistant nature of P. aeruginosa it causes infection in patients receiving long term antibiotic therapy for wounds, burns and cystic fibrosis and other illness. Approximately 25% of burn victims develop infection which frequently leads to fatal septicemia.
4.4.6 Salmonella Typhi (S. Typhi): Typhoid is very common in under-developed countries where the incidence is usually highest in school-aged children. It has been estimated that typhoid fever cases exceed 50 million/year and results in 5,00,000 deaths annually [139]. Sometimes it results into serious fatal disease. Typhoid has not been controlled over years because the two vaccines used for it has some major limitations. First vaccine which is composed of
65
Antibacterial Activity Chapter 4
inactivated S. typhi cells requires two injections and results in 60-70% protection. But this vaccine has many notable adverse reactions occurring with high frequencies [140- 142]. In second vaccine an attenuated strain S. typhi Ty2 has been formed as enteric- coated tablet. It needs at least 3-doses for 60-70% protection [143].
Fig 4.6: Cells of S. typhi
Originally isolated in 1880 by Karl J. Erberth, S. typhi is a multi-organ pathogen that inhabits the lympathic tissues of the small intestine, liver, spleen, and bloodstream of infected humans. It is not known to infect animals and is most common in such countries which have poor sanitary systems and lack of antibiotics. It belongs to family Enterobacteriaceae. It is a motile, facultative anaerobe that is susceptible to various antibiotics. Currently, 107 strains of this organism have been isolated, many containing varying metabolic characteristics, levels of virulence, and multi-drug resistance genes that complicate treatment in areas that resistance is prevalent. S. Typhi is the major cause of typhoid fever. Unlike other Salmonella, S. Typhi only infects human beings and no more host is identified. It is an obligate parasite that has no known natural reservoir outside of humans. This bacterium is spread by drinking infected water or by contaminated food if it was washed or irrigated with water containing S. Typhi. Symptoms of typhoid are nausea, vomiting, fever and ultimately death. The key to avoid its infection is prevention of fecal contamination in drinking water and food supplies. Since the only source of this agent is infected humans, it is possible to control transmission by proper hygiene, waste management, water purification, and treatment of the sick. These measures are attained in developed societies, attributing to the low incidence. The
66
Antibacterial Activity Chapter 4
United States has an average of around 400 infections annually, almost exclusively among people who have recently traveled to developing countries.
4.5 Evaluation Techniques: Following conditions must be fulfilled in order to screen anti-bacterial activity: 1. There must be close contact between the test organisms and substance under evaluation. 2. Suitable conditions must be fulfilled for growth of micro-organisms. 3. Experimental conditions must not alter during study. 4. Aseptic/sterile environment must be sustained. The evaluation may be performed by one of the following methods: 1. Turbidometric method. 2. Agar streak dilution method. 3. Serial dilution method. 4. Agar diffusion method. Following Techniques are used as agar diffusion method: 1. Agar Cup method. 2. Agar Ditch method. 3. Paper Disc method.
67
Chapter 5
Results and Discussion
Results and Discussion Chapter 5
5.1 Results and Discussion: All the synthesized imine ligands and their complexes with 3d metals were analyzed and characterized by means of different techniques. For characterization, their physical properties, solubilities and melting points were determined. Various spectroscopic techniques like infra-red (IR) spectroscopy, UV-visible spectrophotometry were used. Amounts of metal ions (Ni+2, Co+2, Cu+2, Zn+2) were estimated by atomic absorption spectroscopy (AAS). 1H NMR, 13C NMR were taken which helped for confirmation of structure of synthesized complexes. For the determination of structural parameters of the synthesized complexes, powder X-ray diffraction (PXRD) was used. Thermal stability was estimated by Thermal gravimetric analysis (TGA). In IR-spectra, absorption bands were found in specific region for particular functional groups; it confirmed the formation of the expected imine and their 3d metal complexes. As the imine metal complexes has wide biological applications; so all the newly synthesized complexes was screened against different selected bacterial strains. Both ligands and complexes were tested against bacterial strains and were found inhibiting the growth of bacteria.
5.2 Proposed Structures of Ligand/Complexes and Abbreviations: During this study, a number of imine ligands and their 3d transition metal complexes have been synthesized. These ligands form stable coordinate complexes with metal ions (Ni+2, Co+2, Cu+2, Zn+2) under investigation. Both imine ligands and their metal complexes were given some abbreviations. This made the current study more easy and gave more convenient was to compile regarding data. Table 5.1 contains data showing the proposed structures, molecular formulas and abbreviations for the synthesized ligands and their metal complexes.
69
Results and Discussion Chapter 5
Table 5.1: Abbreviations of Synthesized Ligands/Complexes Sr. Proposed Structural Formula Molecular Abbreviations # (Ligands/Complexes) Formula Used
1 C18H15NO2 4CH3I2C
2 C17H12ClNO2 4ClI2C
3 C17H12N2O4 2NO2I2C
4 C36H30N2NiO4 Bis4CH3I2CNi
5 C34H24Cl2N2NiO4 Bis4ClI2CNi
6 C34H24N4NiO8 Bis2NO2I2CNi
70
Results and Discussion Chapter 5
7 C36H30CoN2O4 Bis4CH3I2CCo
8 C34H24Cl2CoN2O4 Bis4ClI2CCo
9 C34H24CoN4O8 Bis2NO2I2CCo
10 C36H30CuN2O4 Bis4CH3I2CCu
11 C34H24Cl2CuN2O4 Bis4ClI2CCu
71
Results and Discussion Chapter 5
12 C34H24CuN4O8 Bis2NO2I2CCu
13 C36H30N2O4Zn Bis4CH3I2CZn
14 C34H24Cl2N2O4Zn Bis4ClI2CZn
15 C34H24N4O8Zn Bis2NO2I2CZn
5.3 Physical Properties: All imine ligands were crystalline solids and their metal chelates were yellow, green and pink amorphous solids. The melting points of Schiff base ligands were found in o the range of 121-127 C. Melting points of ligands 4CH3I2C, 4ClI2C and 2NO2I2C were found 125oC, 121oC and 127oC with good yields 71.9%, 76.5% and 77.1% respectively. Detail is given in the table 5.2 below:
72
Results and Discussion Chapter 5
Table 5.2: Physical properties of Ligands/Complexes Sr. Ligands/Metal Physical %age Colors m.p d.p # Complexes States Yield o 1 4CH3I2C Bright Yellow Solid 125 C -- 71.9% 2 4ClI2C Light Yellow Solid 131oC -- 76.5% o 3 2NO2I2C Golden Yellow Solid 127 C -- 77.1% o 4 Bis4CH3I2CNi Light Green Solid -- 205 C 68.3% 5 Bis4ClI2CNi Light Green Solid -- 201oC 61.2% o 6 Bis2NO2I2CNi Light Green Solid -- 207 C 65.4% o 7 Bis4CH3I2CCo Light Pink Solid -- 210 C 65.9% 8 Bis4ClI2CCo Light pink Solid -- 214oC 61.1% o 9 Bis2NO2I2CCo Light Pink Solid -- 211 C 59.9% o 10 Bis4CH3I2CCu Green Solid -- 185 C 68.6% 11 Bis4ClI2CCu Light Green Solid -- 240oC 67.3% o 12 Bis2NO2I2CCu Light Green Solid -- 187 C 64.4% o 13 Bis4CH3I2CZn Yellow Solid -- 155 C 66.0% 14 Bis4ClI2CZn Yellow Solid -- 210oC 69.8% o 15 Bis2NO2I2CZn Lemon yellow Solid -- 215 C 62.2%
On the other hand, all the metal complexes were decomposed on heating and yields were lower as compared to Schiff base ligands. Nickel metal complexes,
Bis4CH3I2CNi, Bis4ClI2CNi and Bis2NO2I2CNi were found in light green colors and their decomposition points were 205oC, 201oC and 207oC. Yields of these nickel complexes were comparable and ranged from 61.2% to 68.3%. Respective yields for complexes Bis4CH3I2CNi, Bis4ClI2CNi and Bis2NO2I2CNi were 68.3%, 61.2% and 65.4%. Complexes of Cobalt were in light pink color. Decomposition points and o o yields for Bis4CH3I2CCo, Bis4ClI2CCo and Bis2NO2I2CCo were 210 C, 214 C and 211oC while yields were 65.9%, 61.1% and 59.9%.
Among the Cobalt complexes, Bis2NO2I2CCo was found least in yield. In comparison to Cobalt, the complexes of Copper Bis4CH3I2CCu, Bis2NO2I2CCu had lower d.p 185oC and 187oC respectively except Bis4ClI2CCu with d.p 240oC. Yields
73
Results and Discussion Chapter 5
of Copper complexes were found better. Zinc Complexes, Bis4CH3I2CZn and
Bis4ClI2CZn were yellow amorphous solids. Decomposition point of Bis4CH3I2CZn o was quite less 155 C with good yield 66.0%. Bis2NO2I2CZn was in lemon yellow color with d.p 215oC and yield 62.2%. Among all the synthesized metal complexes
Bis4ClI2CZn had highest (69.8%) while Bis2NO2I2CCo had lowest yield (59.9%). For details see table 5.2.
5.4 Solubilities of Imine Ligands and Metal Complexes: Solubilities of all synthesized ligands and their complexes were checked in both polar and non- polar solvents. Selected polar solvents were water, methanol, ethanol and chloroform while non-polar solvents taken were acetone, n-hexane and benzene. All anils (Schiff base ligands) were completely insoluble in water, methanol and ethanol but fairly soluble in chloroform and non-polar organic solvents. All the metal complexes were insoluble in water methanol and ethanol but partially or completely soluble in chloroform, acetone, n-hexane and benzene. Details are given in table 5.3 below.
74
Results and Discussion Chapter 5
Table 5.3: Solubilities of Ligands/Complexes in variety of solvents
Polar Solvents Non-polar Solvents Ligands/
Sr. # Complexes 3
exane
H
-
Water Methanol Ethanol CHCl Acetone n Benzene 1 4CH3I2C IS IS IS S S S S 2 4ClI2C IS IS IS S S S S
3 2NO2I2C IS IS IS S S S S
4 Bis4CH3I2CNi IS IS IS S S S S
5 Bis4ClI2CNi IS IS IS PS S S S
6 Bis2NO2I2CNi IS IS IS S S S S
7 Bis4CH3I2CCo IS IS IS PS S S S
8 Bis4ClI2CCo IS IS IS PS S S S
9 Bis2NO2I2CCo IS IS IS PS S S S
10 Bis4CH3I2CCu IS IS IS S S S S
11 Bis4ClI2CCu IS IS IS S S S S
12 Bis2NO2I2CCu IS IS IS PS S S S
13 Bis4CH3I2CZn IS IS IS S S S S 14 Bis4ClI2CZn IS IS IS PS PS PS PS
15 Bis2NO2I2CZn IS IS IS S S S S
S = Soluble IS = Insoluble PS = Partially Soluble
5.5 Elemental Analysis: In order to investigate molecular formulae of imine ligands and their 3d metal complexes, elemental analyses was used. During elemental analyses, %ages of carbon, hydrogen, nitrogen found were comparable with the calculated %ages of elements. It suggested that in all the metal complexes, the metal to Schiff base ratio is
75
Results and Discussion Chapter 5
1:2. So the estimate formulae for all metal complexes might be M(Ligands)2. Data is compiled in Table 5.4.
Table 5.4: Data for elemental analysis of Schiff base ligands/metals’ complexes Elemental Analysis Sr. Ligands/Complexes % Found (Calculated) # C H N M 77.81 5.26 5.31 1 4CH3I2C --- (77.96) (5.45) (5.05)
68.43 4.34 4.96 2 4ClI2C --- (68.58) (4.06) (4.70)
Ligands 66.09 3.76 9.41 3 2NO2I2C --- (66.23) (3.92) (9.09) 70.39 4.74 4.26 9.96 4 Bis4CH3I2CNi (70.50) (4.93) (4.57) (9.57) 62.26 3.98 4.56 8.63 5 Bis4ClI2CNi (62.43) (3.70) (4.28) (8.97) 60.68 3.79 8.06 8.91 6 Bis2NO2I2CNi (60.47) (3.58) (8.30) (8.69) 70.59 4.69 4.39 9.23
7 Bis4CH3I2CCo (70.47) (4.93) (4.57) (9.61) 62.19 3.53 4.63 9.45 8 Bis4ClI2CCo (62.40) (3.70) (4.28) (9.01) 60.64 3.41 8.63 8.44
9 Complexes Metal Bis2NO2I2CCo (60.45) (3.58) (8.29) (8.72) 69.73 4.64 4.89 10.06 10 Bis4CH3I2CCu (69.94) (4.89) (4.53) (10.28) 61.81 3.98 4.59 9.32 11 Bis4ClI2CCu (61.97) (3.67) (4.25) (9.64) 60.26 3.72 8.51 9.66 12 Bis2NO2I2CCu (60.04) (3.56) (8.24) (9.34)
76
Results and Discussion Chapter 5
69.92 4.63 4.23 10.89 13 Bis4CH3I2CZn (69.74) (4.88) (4.52) (10.54) 61.58 3.49 4.75 9.54 14 Bis4ClI2CZn (61.79) (3.66) (4.24) (9.89) 59.64 3.76 8.56 9.23 15 Bis2NO2I2CZn (59.88) (3.55) (8.22) (9.59)
5.6 Characterization of Ligands/Complexes: This study involves the synthesis of starting material, imine ligands and their complexes with 3d transition elements. The metals used during this study are Nickel, Cobalt, Copper and Zinc. These ligands and complexes were characterized for their structure determination. Different techniques used for characterization are UV/Visible Spectroscopy, IR Spectroscopy, Atomic Absorption Spectroscopy (AAS), NMR Spectroscopy, Electron Spray Mass Spectroscopy, Thermal gravimetric analysis (TGA), Powder X-ray diffraction (PXRD) and Magnetic Behavior (VSM).
5.6.1 Characterization of 3 – acetyl -2 H – chromen - 2 -one:
In this research work 3 – acetyl -2 H – chromen - 2 –one was uses d as the starting material which was synthesized by reacting 2-hydroxybenzaldehyde with ethyl acetate in the presence of piperidine. It was characterized and the data found was according to the literature. m.p:120oC
5.6.1.1 IR Study of 3 – acetyl -2 H – chromen - 2 –one: IR (film): ν (cm-1) 3406.59 (Ar CH Str), 3056.39 (CH str), 1723.26 (C=O), 1162.13 (C-O str). (Scan 5.1 given in appendix-I).
77
Results and Discussion Chapter 5
5.6.1.2 NMR Spectroscopic Study of 3 – acetyl -2 H – chromen - 2 –one: Structure of 3 – acetyl -2 H – chromen - 2 –one was confirmed by NMR spectroscopy. Both 1H NMR and 13C NMR were taken in deuterated chloroform. In 1H NMR spectrum peaks were found in at specific regions ( ppm) in the form of singlet, doublet, triplet and multiplets. 1H NMR spectrum is given in appendix-II, Scan 5.2. 13C NMR spectrum also contained peaks for all the carbons in the complex. 13C NMR spectrum is given in appendix-II, Scan 5.3. Both proton and carbon NMRs’ proved the structure of 3 – acetyl -2 H – chromen - 2 –one. Table 5.5 shows data compiled from NMR study.
Table 5.5: 1H NMR and 13C NMR of 3 – acetyl -2 H – chromen - 2 –one [Recorded in
CDCl3] Structure Peaks Assigned (ppm) Integral Multiplicity
C4H 8.49 1 s
C5H 7.86 1 d
C7H 7.71 1 t
C6H, C8H 7.43-7.39 2 m
-CH3 2.71 3 s
13 C NMR (75.5 MHz, CDCl3) δ ppm 198.8 (1C, ArCOCH3), 159.4 (1C, COO), 153.1 (1C, CO), 136.9 (1C, ArCH), 131.1 (1C, ArCCO), 128.3 (1C, ArCH)), 127.6 (1C, ArCH), 125.4 (1C, ArCH), 118.1 (1C, ArC), 116.0 (1C, ArCH), 29.6
(1C, CH3)
5.6.2 Characterization of Imine Ligands: Starting material 3 – acetyl -2 H – chromen - 2 –one was reacted with different derivatives of aromatic amine to prepare Schiff bases. Aromatic amine derivatives used are 4-chloroaniline, p – toluidine and 2-nitroaniline respectively. These imines were used as ligands. Characterization of these synthesized ligands is given below;
78
Results and Discussion Chapter 5
5.6.2.1 Characterization of (E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) -2 H- chromen-
2 - one [4CH3I2C]:
m.p: 125oC
The reactants for formation of 4CH3I2C are 3 – acetyl -2 H – chromen - 2 –one and p - toluidine with melting points 120oC and 43oC respectively. The melting point of the produced imine was found 125oC which is quite different from the melting points of reactants and this ensures the formation of imine 4CH3I2C.
5.6.2.1.1 IR study of 4CH3I2C: In order to insure the structures of all synthesized imine ligands, their IR spectra were collected. In IR spectra the presence of specific functional groups in the ligands were confirmed by absorptions bands in particular regions. New bands at 1612-1603 cm-1 due to CH=N in Schiff base ligands were observed. Important absorption bands with their frequencies are given the Table 5.6.
Table 5.6: IR data of synthesized Ligands
)
)
H) O)
Imine - -
N)
=N
C C
- Entry C=O
3 2
2
C
Ligands (
HC
ν
Sp
(sp
ν(
ν ν(sp
ν(
1 4CH3I2C 3031.69 1296.86 1612.15 1680.03 1209.73
2 4ClI2C 3085.33 1228.80 1610.96 1683.88 1198.11
3 2NO2I2C 3057.46 1228.69 1603.30 1684.57 1200.22
79
Results and Discussion Chapter 5
During the IR study of imine ligand abbreviated as 4CH3I2C, absorption bands were found in the spectrum at particular regions for specific functional groups. The presence of these absorption bands confirmed the structure of 4CH3I2C. Important absorption bands are given here. An absorption band was found at 3031.69 cm-1 which confirmed the presence of sp3 C-H and a peak at 1296.86 cm-1 was for C-N bond. Absorption bands at 1612.15 cm-1 and 1680.03 cm-1 confirmed the presence of CH=N and C=O respectively. This newly formed CH=N bond convinced the formation of imine ligands [144-146]. An absorption band was found at 1209.73 cm-1 which stands for sp2 C-O. For detail Table 5.6, entry 1. (IR spectrum given in appendix-II, Scan 5.4)
5.6.2.1.2 NMR-Studies of 4CH3I2C: NMR studies played important role to determine the structures of all imine ligands. Both proton and carbon spectra were collected during current study. For ligand 1 4CH3I2C, (Table 5.7, entry 1) during H NMR, the protons attached to carbon atoms were confirmed by the peaks with different multiplicity. Protons being present in different chemical environment gave different splitting pattern and found in particular region with specific (ppm) values. For methyl (CH3) group, there was a singlet at
2.08ppm while for ArCH3 there was a singlet at 2.18ppm. Aromatic protons attached to C4H, C5H and C7H gave singlet, doublet and multiplet respectively. Aromatic protons of C6H and C8H being in same environment appeared as multiplet at 7.31-
7.27ppm. Similarly, C14H and C16H gave doublet at 7.21ppm and C13H and C17H gave doublet at 7.12ppm. Detail is given in Table 5.7, entry 1. (Scan if given in appendix- II, Scan 5.5)
80
Results and Discussion Chapter 5
1 Table 5.7: H NMR of Imine Ligands [Recorded in CDCl3] Entry Imine Ligand Peaks Assigned (ppm) Integral Multiplicity
C5H 7.83 1 d
C7H 7.67-7.63 1 m
C4H 7.55 1 s
C6H, C8H 7.31-7.27 2 m 1 C14H, C16H 7.21 2 d
C13H, C17H 7.12 2 d
CH3 (Ar) 2.18 3 s
CH3 2.08 3 s
C5H 7.81 1 d C7H 7.65-7.61 1 m C4H 7.53 1 s 2 C6H, C8H, C14H, 7.32-7.25 4 m C16H 6.99 2 d C13H, C17H 2.10 3 s CH3
C14H 8.07 1 d
C5H, C16H 7.85-7.81 2 m
C7H, C15H, C17H 7.72-7.68 3 m 3 C4H 7.58 1 s
C6H, C8H 7.37-7.29 2 m
CH3 2.13 3 s
13C NMR also confirmed the total number of carbons present in the ligands. Table 5.7 shows the detailed study of 13C NMR of ligands. Peaks in different regions confirmed
the structure of ligand 4CH3I2C. This is because each carbon in imine ligand is present in different environment. Detail of values for all the labelled carbon atoms of synthesized ligand is given in table 5.7, entry 1. (Scan if given in appendix-II, Scan 5.6)
81
Results and Discussion Chapter 5
13 Table 5.8: C NMR of Imine Ligands (75.5 MHz, CDCl3) δ ppm Entry Imine Ligand Peaks Assigned and (ppm) values
175.5 (C11), 159.4 (C2), 153.1 (C10), 148.7 (C12),
136.7 (C15), 132.16 (C4), 130.4 (C14, C16), 128.3
1 (C7), 128.2 (C5), 125.0 (C6), 122.0 (C13, C17),
118.3 (C9), 116.0 (C8), 113.5 (C3), 21.6 (Ar CH3),
19.9 (-CH3)
175.4 (C11), 159.4 (C2), 153.0 (C10), 148.8 (C12),
132.0 (C15), 131.9 (C4), 130.4 (C14, C16), 128.4 2 (C7), 128.1 (C5), 125.2 (C6), 122.0 (C13, C17),
118.3 (C9), 116.0 (C8), 113.5 (C3), 19.9 (-CH3)
175.6 (C11), 159.3 (C2), 153.2 (C10), 145.2 (C13),
142.2 (C12), 132.6 (C4), 131.3 (C16), 130.0 (C17), 3 128.4 (C7), 128.2 (C15), 124.8 (C6), 124.7 (C14),
118.4 (C9), 115.9 (C8), 113.2 (C3), 19.9 (-CH3)
5.6.2.1.3 ESI Mass Spectrum of 4CH3I2C: + HRMS (ESI) calcd. for C18H15NO2 [M+H] 278.1181, found 278.1156 In order to confirm the molecular mass of synthesized imine ligand, ESI-MS spectrum was recorded. A molecular ion peak was found at m/z 278.1156 which was related to + + [C18H15NO2 +H] . Molecular ion peak [M+1] confirmed the structure of imine ligand. There were some other peaks in the spectrum at m/z 108.0849, 141.0271, 153.0715 which correspond to the fragment molecular ions. Further confirmation of proposed structure come by the presence of peak at m/z 301.0977 which attributed to + [C18H15NO2 +Na] . (See scan 5.7 below)
82
Results and Discussion Chapter 5
Scan: 5.7: ESI Mass Spectrum of 4CH3I2C
5.6.2.2 Characterization of (E) – 3 - ( 1 - (( 4 – chlorophenyl ) imino ) ethyl) - 2 H – chromen - 2 – one [4ClI2C]:
m.p: 131oC The reactants for formation of this imine are 3 – acetyl -2 H – chromen - 2 –one and 4-chloroanile with melting points 120oC and 72.5oC respectively. The melting point of the produced imine was found 131oC which is quite different from the melting points of reactants and this ensures the formation of product.
83
Results and Discussion Chapter 5
5.6.2.2.1 IR Studies of 4ClI2C: IR study supported to confirm the formation of imine ligand 4ClI2C. Absorption bands were found in particular regions for specific functional groups in the IR spectrum which helped to estimate the structure of 4ClI2C. Presence of sp3 C-H was confirmed by the presence of absorption band at 3085.33 cm-1. For C-N and CH=N, absorption bands were found at 1228.80 cm-1 and 1610.96 cm-1 respectively. In the same way, absorption bands at 1683.88 cm-1and 1198.11 cm-1 confirmed sp2 C=O and sp2 C-O functional groups in the ligand 4ClI2C. Newly formed CH=N bond confirmed the synthesis of imine ligand 4ClI2C. Detail is given in Table 5.6 entry 2. (IR spectrum given in appendix-I, Scan 5.8)
5.6.2.2.2 NMR Studies of 4ClI2C: During 1H NMR study, peaks were found in the form of singlets, doublets and multiplets for specific protons’ attached to different carbons. For ligand 4CH3I2C, (Table 5.7, entry 2) during 1H NMR, the protons attached to carbon atoms were confirmed by the peaks with different multiplicity. Protons being present in different chemical environment gave different splitting pattern and found with specific (ppm) values. For methyl (CH3) group, a singlet was found at 2.10ppm. Aromatic protons attached to C4H, C5H and C7H gave singlet (7.53ppm), doublet (7.81pp) and multiplet
(7.65-7.63ppm) respectively. Aromatic protons of C6H, C8H, C14H and C16H being in same environment appeared as multiplet at 7.32-7.25ppm and C13H and C17H gave doublet at 6.99ppm. It confirmed the structure of 4ClI2C. Detail is given in Table 5.7, entry 2. (Scan if given in appendix-II, Scan 5.9) 13C NMR also confirmed the total number of carbons present in the ligands. Table 5.8 shows the detailed study of 13C NMR of ligands. Peaks in different regions confirmed the structure of ligand 4ClI2C. Detail is given in Table 5.8, entry 2. (Scan if given in appendix-II, Scan 5.10)
84
Results and Discussion Chapter 5
5.6.2.2.3 ESI Mass Spectrum of 4ClI2C: + HRMS (ESI) calcd. for C17H12ClNO2 [M+H] 298.0635, found 298.0977 In MS spectrum a peak was found at m/z 298.0977 which corresponds to + [C17H12ClNO2+H] there were some other peaks at m/z 128.0578, 141.0174 and 189.0849 which are related to fragment molecular ions. Presence of some peaks showed the presence of impurities. Like 4CH3I2C, a sharp peak at m/z 320.0797 + associated to [C17H12ClNO2+Na] further helped in confirmation of structure of ligand. MS-spectrum is shown in scan 5.11 below,
Scan 5.11: ESI Mass Spectrum of 4ClI2C
85
Results and Discussion Chapter 5
5.6.2.3 Characterization of (E) – 3 - ( 1 - (( 2 – nitrophenyl ) imino ) ethyl ) - 2 H - chromen – 2 – one [2NO2I2C]:
m.p: 127oC The reactants for formation of this imine are 3 – acetyl -2 H – chromen - 2 –one and 2-nitroaniline with melting points 120oC and 71.5oC respectively. The melting point of the produced imine was found 127oC which is quite different from the melting points of reactants and this ensures the formation of desired product.
5.6.2.3.1 IR Studies of 2NO2I2C:
As discussed for ligands 4CH3I2C and 4ClI2C, the structure of ligand 2NO2I2C was confirmed by IR spectrum, as all important absorption bands were there to confirm specific functional groups. There was an absorption band at 3057.46 cm-1 which convinced the presence of sp3 C-H and an absorption band was found at 1228.69 cm-1 indicating the presence of C-N functional group. An absorption band at 1603.30 cm-1 confirmed the presence of newly formed CH=N bond. Absorption bands at 1684.57 cm-1 and 1200.22 cm-1 confirmed the presence of sp2 C=O and sp2 C-O. Detail is given in Table 5.6 entry 3. (IR spectrum given in appendix-I, Scan 5.12)
5.6.2.3.2 NMR Studies of 2NO2I2C: 1 As in imine ligands 4CH3I2C and 4ClI2C, H NMR proved the structure of 2NO2I2C. In 1H NMR spectrum, singlets, doublets and multiplets were found at specific ppm confirming the attachments of protons to certain carbon atoms in the ligand. In
2NO2I2C, a singlet appeared at 213ppm due to the coupling of proton of CH3 with proton of C11H. Similarly, a singlet was found at 7.58ppm for aromatic proton on
C4H. For protons on C-5, C-6, C-7, C-8, C-15, C-16 and C-17, multiplets were founds. A singlet was found for aromatic C-4 at 7.58ppm. Detail is given in table 5.7, entry 3. (Scan if given in appendix-II, Scan 5.13). Table 5.7, entry 3 shows the detail
86
Results and Discussion Chapter 5
13 of C NMR spectrum of ligand 2NO2I2C. Spectrum successfully confirmed the structure of title ligand. (Table 5.8, entry 3). (Scan if given in appendix-II, Scan 5.14)
5.6.2.3.3 ESI Mass Spectrum of 2NO2I2C: + HRMS (ESI) calcd. for C17H12N2O4 [M+H] 309.0875, found 309.0675
MS spectrum of imine ligand 2NO2I2C was taken to check its purity and molecular mass which helped to confirm the proposed structure. A prominent peak stands at m/z + 309.0675 for [C17H12N2O4+H] molecular ion. There are some other peaks which might be due to degradation of components of 2NO2I2C. Another prominent peaks was found at m/z 331.0659 which convinced the presence of molecular ion + C17H12N2O4+Na] MS-spectrum is shown in scan 5.15.
Scan 5.15: ESI Mass Spectrum of 2NO2I2C
87
Results and Discussion Chapter 5
5.6.3 Characterization of Imine Metal Complexes: The above synthesized Imine ligands were then reacted with the selected 3d-metals i.e. Ni, Co, Cu and Zn. The metal complexes were then characterized. Following different techniques were used for the characterization and structure determination of metal complexes.
5.6.3.1 Characterization of Ni-Imine Complexes:
All the synthesized imine ligands abbreviated as 4CH32IC, 4Cl2IC and 2NO2IC were then reacted with NiSO4.6H2O to form their respective Ni-complexes. For the characterization of these synthesized imine complexes, a number of spectroscopic techniques had been used. Detailed assay on these characterization techniques is as under
5.6.3.1.1 Determination of Stability of Ni-Imine Complexes: Solutions for all Ni-metal complexes were prepared by dissolving specific amounts in chloroform and λmax were taken periodically over a period of four weeks. The λmax was found stable throughout this period. As no change in λmax occurred with time so it was concluded that these complexes were stable in solutions.
λmax of ligand and complexes solution in chloroform was determined when synthesized.
The above solution was kept for four weeks and its λmax was periodically noted
as following and a graph of λmax was plotted against time. a) After every 3 hours for first 24 hours. b) After 24 hours for first week. c) After 48 hours for rest of the 3 weeks.
No change in λmax was noted during the experimental periods. In the above mentioned time periods, freshly prepared solutions of complexes were also run for λmax and no change in λmax value confirmed their stability in solid state.
88
Results and Discussion Chapter 5
5.6.3.1.2 Characterization of Bis[(E) – 3 - ( 1 - ( p – tolylimino ) ethyl ) – 2 H – chromen – 2 – one ]Nickel( II): [Bis4CH3I2CNi]:
5.6.3.1.2.1 Infra-red Spectral Studies of Bis4CH3I2CNi: All the complexes prepared were characterized by IR spectroscopy. All the spectra being recorded by KBr pellet method. Ground salt was pressed under a pressure of 500 to 1,000 N/cm2 and KBR pellets of different purities were prepared. KBr crystals were grown-up by an open Kyropoulos method. The measurements of IR spectra of KBr pellets and complexes are given in the following table 5.9.
89
Results and Discussion Chapter 5
Table 5.9: IR data of the synthesized metal complexes
)
H)
O)
-
-
N)
O
N)
=N)
Cl)
C -
-
C
- C=O)
-
3
2
Entry Metal Complexes 2
(C
(M
(C (M
HC
ν
(
ν
ν ν
(sp
(Sp
ν
(Sp
ν
ν
ν
1 Bis4CH3I2CNi 3030.12 1300.21 1703.04 --- 1755.54 1231.77 457.78 348.57 2 Bis4ClI2CNi 3231.58 1384.96 1645.29 3471.45 1743.52 1232.04 440.13 350.49
3 Bis2NO2I2CNi 3251.08 1295.51 1651.83 --- 1734.66 1211.51 454.37 349.75
4 Bis4CH3I2CCo 3386.66 1383.64 1655.05 --- 1712.14 1164.53 451.66 348.82 5 Bis4ClI2CCo 3276.93 1384.44 1647.07 3494.52 1740.05 1120.91 458.44 346.47
6 Bis2NO2I2CCo 3481.48 1384.05 1611.17 --- 1727.62 1120.52 455.17 338.74
7 Bis4CH3I2CCu 2922.62 1297.08 1678.11 --- 1739.77 1166.37 437.32 353.54 8 Bis4ClI2CCu 3233.40 1296.81 1678.11 3440.48 1739.29 1163.05 438.74 344.65
9 Bis2NO2I2CCu 3223.17 1218.22 1635.66 --- 1711.11 1218.22 445.29 340.73
10 Bis4CH3I2CZn 3345.15 1301.69 1663.85 --- 1736.42 1175.17 458.42 339.91 11 Bis4ClI2CZn 3038.04 1323.78 1600.00 3460.98 1739.44 1194.81 453.28 341.54
12 Bis2NO2I2CZn 3036.59 1297.83 1690.03 --- 1740.00 1209.06 443.59 343.05
90
Results and Discussion Chapter 5
All the characteristic bonds (C-O, C-N, CH=N, C-Cl) in the metal complexes gave bands in their respective regions. The ν(C-N) absorption bands were in region of 1400-1200 cm-1. These bands were from strong to medium to weak. Strong absorption bands for ν(C-O) were found in the expected region of 1230-1100 cm-1. The IR spectra of the complexes were compared with those of the free ligands in order to determine the coordination sites that may be involved in chelation. There were some guide absorption bands in the spectra of the ligands, which were helpful in achieving this goal. IR-spectra of metal complexes contained all the absorption bands from ligands and some new absorption bands were found. These new absorption bands indicate the coordination of ligands with metals through nitrogen and oxygen. The position and/or the intensities of these absorption bands are expected to change upon chelation. Upon comparison, it was determined that the ν(C=N) stretching vibration in azomethine group is found at 1610.96 cm-1, 1603.30 cm-1 and 1612.15 cm-1 for the
4ClI2C, 2NO2I2C and 4CH3I2C free ligands, respectively. These bands were shifted to higher or lower wavenumbers in the complexes, indicating the coordination of metal ion to ligands. [147-149]. A strong sharp band observed at 1750-1700 cm-1 is assigned to ν(C=O), the intensity of this band has not only reduced but has shifted to lower wave numbers in the corresponding metal complexes confirming the involvement of the carbonyl group in complexation with metal ion [150]. New absorption bands ν(M-N) and ν(M-O) were appeared at 435-460 cm-1 and 335-355 cm-1 respectively [151] indicating coordination of ligands through nitrogen and oxygen. The important bands along with their assignments are listed in table 5.9. These assignments were made by comparison with related Schiff base complexes [152-154]. The important bands along with their assignments are listed in Table 5.9.
In IR studies of the Ni-complex Bis4CH3I2CNi, for specific functional groups, all the absorption bands were found in the specified regions. An absorption band was found at 3030.12 cm-1 for sp3 C-H, an absorption band at 1300.21 cm-1 confirmed the presence of C-N bond. For CH=N, there was an absorption band at 1703.04 cm-1. Presence of an absorption band at 1755.54 cm-1 confirmed sp2 C=O. Similarly the
91
Results and Discussion Chapter 5
absorption band at 1231.77 cm-1 confirmed the presence of sp2 C-O. An absorption band at 457.78 cm-1 confirmed the formation of nickel to nitrogen bond (M-N). Similarly a new absorption band was seen at 348.57 cm-1 which was standing for nickel to oxygen bond. This confirmed the formation of nickel complex with this imine ligand. Brief summary for IR spectrum is given in the table 5.9, entry 1. (Appendix-I, Scan 5.16)
5.6.3.1.2.2 Estimation of λmax for Bis4CH3I2CNi: All the imines and their complexes gave bands in the UV-Visible region, in the range of 340-485nm. The λmax were found close to each other due to the similar parent complexes and some with different absorbance values. The graph of absorbance vs wavelength gave curve in each case which can be divided into three parts. First part show ascending of curve which then becomes straight for a few points is the second part and third part of the curve was descending of absorbance with the increase of wavelength. The λmax was confirmed by repeatedly determining the λmax for several days using fresh sample solution each time. Table 5.10 shows the λmax (nm) for all the synthesized complexes.
Table 5.10: λmax (nm) of Synthesized Metal Complexes
Entry Metal Complexes λmax (nm)
1 Bis4CH3I2CNi 450 2 Bis4ClI2CNi 385
3 Bis2NO2I2CNi 380
4 Bis4CH3I2CCo 395 5 Bis4ClI2CCo 410
6 Bis2NO2I2CCo 415
7 Bis4CH3I2CCu 350 8 Bis4ClI2CCu 340
9 Bis2NO2I2CCu 395
10 Bis4CH3I2CZn 425 11 Bis4ClI2CZn 425
12 Bis2NO2I2CZn 485
92
Results and Discussion Chapter 5
After preparing the 0.01 ppm concentration of Bis4CH3I2CNi, it was taken into the cell and absorbance against different wavelengths was measured. As the wavelength was increased, the absorbance increased until it reached to a maximum 0.381. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the table 5.11 below.
Table 5.11: Data showing absorbance against different wavelengths for
Bis4CH3I2CNi Sr. # Wavelength (nm) Absorbance 1 400 0.125 2 410 0.171 3 420 0.201 4 430 0.250 5 440 0.281 6 450 0.381 7 460 0.265 8 470 0.204 9 480 0.196
In order to find λmax for Bis4CH3I2CNi, a graph was plotted between wavelength and absorbance. Wavelength was taken along abscissa and absorbance was taken along Y- axis. Graph started with wavelength 400nm and absorbance 0.125; graph was going in upward direction showing that absorbance was increasing with increase in wavelength. It was noted that complex Bis4CH3I2CNi had maximum absorbance at 450nm which can be observed in Graph 5.1 below. After then curve moved in downward direction representing the decrease in absorbance of uv-visible light with increase in wavelength.
93
Results and Discussion Chapter 5
Graph 5.1: Graph of wavelength vs absorbance for Bis4CH3I2CNi
5.6.3.1.2.3 Estimation of Metal Ion in Bis4CH3I2CNi: In order to determine the amount of metal reacted with Schiff base ligands, spectroscopic techniques were used. Amount of the metals present in the solution of the prepared complexes was estimated by Atomic Absorption Spectroscopy (AAS). Very dilute sample solutions (0.01ppm) were prepared after the complete digestion of the metal chelates. Metal estimation helps to determine the amount of the reacted metal with Schiff bases to form chelates. Schiff base metal complexes were treated with concentrated nitric acid to convert metals in complexes into their corresponding nitrates. After preparing the corresponding standard metal salt solutions calibration graph was obtained and amount of metal in each complex was estimated by AAS. Standard solutions with concentrations 05-25ppm were prepared in chloroform and absorbance was noted by atomic absorption spectrophotometer (AAS). Table 5.12 shows the absorbance for each concentration. And a calibration curve was obtained as under
94
Results and Discussion Chapter 5
Table 5.12: Calibration Data (Concentration of Ni+2 Vs Absorption) for
Bis4CH3I2CNi Sr. # Conc. (ppm) Absorbance 1 05 0.085 2 10 0.126 3 15 0.172 4 20 0.226 5 25 0.267
The difference between estimated and calculated amounts was very less and insignificant, data is given in table 5.13, entry 1.
Table 5.13: Data of Ni+2 ions concentrations in Ni-Complexes Calculated Amount of Metal Difference Entry amount of metal metal estimated by Complexes (ppm) (ppm) AAS (ppm)
1 Bis4CH3I2CNi 9.46 10.35 0.89 2 Bis4ClI2CNi 8.88 10.01 1.13
3 Bis2NO2I2CNi 8.59 9.47 0.88
5.6.3.1.2.4 Determination of Metal to Ligands Ratio by AAS:
Metal to ligand ratio was determined by AAS. First, Ni-metal to ligand (4CH3I2C) ratio was theoretically calculated (Table 5.14) and then the experimentally determined ratios were compared with calculated ratios, by this metal to ligand ratio was determined which confirms the structure of the complex formed. Calculated molecular masses and metal to ligands ratios are given in the following table 5.14. Atomic mass of Ni-metal = 57.94 g
Molecular mass of ligand (4CH3I2C) = 277.11 g
95
Results and Discussion Chapter 5
Table 5.14: Data for molecular mass for calculating metal to ligand ratio in
Bis4CH3I2CNi No. of Ni No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 335.05 17.29% 2 1 2 612.16 9.46% 3 1 3 889.27 6.52% 4 1 4 1108.44 5.28%
Standard solutions of the Ni-complex (Bis4CH3I2CNi) in chloroform with concentrations ranging from 05-25ppm were prepared and their respective absorptions were noted (table 5.12) and a calibration curve was drawn. By this calibration curve, the amount of Ni-metal was estimated in the corresponding Ni-complexes (Table 5.15, entry 1).
Table 5.15: Estimated amounts of Ni-metal in Ni-complexes by AAS Amount of Ni- Entry Ni-Complexes metal (ppm)
1 Bis4CH3I2CNi 10.35 2 Bis4ClI2CNi 10.01
3 Bis2NO2I2CNi 9.47
Amount of Ni-metal estimated from calibration graph = 10.35 ppm Total concentration of Ni-metal = 10.35 × 10 = 103.5 ppm Experimental %age of Ni-metal = 10.35% Calculated %age of Ni-metal (table 5.14, entry 2) = 9.46% The amount of Ni-metal estimated from graph is 10.35% which is associated with entry 2 in table5.17 Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and this confirm the proposed structure of the complex.
96
Results and Discussion Chapter 5
5.6.3.1.2.5 Powder X-ray Diffraction Analysis of Bis4CH3I2CNi: When Bragg equation is obeyed for a particular planes diffraction occurs as diffraction occurs only when Bragg equation is obeyed. Crystals contain a number of planes but there is a very less chance that a plan might be at a correct angle θ to satisfy Bragg equation. When a crystal is rotated then sooner or later a position will reach when the plane may satisfy the Bragg equation and diffraction occur. So, in case of single crystal there are mere chances that a plane satisfy Bragg equation. When a powdered sample in placed in monochromatic X-ray beam, there might be at least few planes satisfying Bragg equation resulting in diffraction. Since different planes have different values for ‘d’ so diffraction cones will have different values for semi-vertical angle ‘2θ’. This results in a series of concentric cones travelling in the same direction being called as incident beams while those which travel in reverse direction are known as back reflections.
For PXRD studies, Ni-complex (Bis4CH3I2CNi) was first grinded and X-ray powder diffractometer was used to study the complex. Diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. The spectrum obtained was studied to estimate the structure of metal complex.
Scan 5.17: PXRD spectrum of Bis4CH3I2CNi
97
Results and Discussion Chapter 5
From the diffraction pattern obtained in PXRD spectrum, a number of absorption bands were selected for the determination of structural parameters. Table 5.16 shows the calculations of miller indices from the selected absorption bands. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern have no correlation with reported patterns.
This convinces that synthesized metal complex (Bis4CH3I2CNi) was novel with its unique pattern.
Table 5.16: Calculation of Miller Indices by PXRD pattern for Bis4CH3I2CNi
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin Integers 10.7910 5.3955 0.0088 1 2 3 3 111 300, 18.3717 9.1859 0.0255 2.8823 5.7645 8.6468 9 221 300, 18.6136 9.3068 0.0262 2.9580 5.9160 8.8740 9 221 21.8850 10.9425 0.0360 4.0758 8.1507 12.2261 12 222 22.8383 11.4192 0.0392 4.4333 8.8666 13.3000 13 320 25.0042 12.5021 0.0469 5.3000 10.6001 15.9002 16 400 27.3197 13.6599 0.0558 6.3077 12.6153 18.9230 19 331 27.4893 13.7446 0.0564 6.3847 12.7694 19.1541 19 331 27.8839 13.9419 0.0581 6.5656 13.1313 19.6970 20 420 37.1897 18.5948 0.1016 11.5001 23.0003 34.5005 35 531 41.7056 20.8528 0.1267 14.3314 28.6628 42.9942 43 533
Grain size, dislocation line density and strain of nickel complex (Bis4CH3I2CNi) were calculated. The formulae used are as under, Grain size (D) = 0.9λ/βcosθ Where, λ= wavelength of x-ray used (1.5406 nm) θ= Bragg’s angle β= value of full width at half maximum.
98
Results and Discussion Chapter 5
Dislocation line density (δ) = 1/D2 Where D= grain size Strain (S) = 0.9λ/4D Where λ =1.5406 nm. The results are tabulated in table 5.17 given below;
Table 5.17: Data calculated for structural parameters for Bis4CH3I2CNi
Dislocation FWHM d-spacing Intensity Grain size Strain (S) 2θ/0 Density (δ) [°2Th.] [Å] counts (D) (nm) (lines-2cm-4) (lines/cm-2) 10.7910 0.1535 8.19886 38.41 9.0742 0.0121 0.0382 18.3717 0.0768 4.82930 39.79 18.2921 0.0030 0.0189 18.6136 0.1279 4.76709 49.20 10.9868 0.0083 0.0316 21.8850 0.1791 4.06133 45.14 7.8870 0.0161 0.0440 22.8383 0.1535 3.89391 30.03 9.2129 0.0118 0.0376 25.0042 0.1535 3.56132 14.50 9.2498 0.0117 0.0375 27.3197 0.1279 3.26451 14.04 11.1548 0.0080 0.0311 27.4893 0.1279 3.24475 16.47 11.1638 0.0080 0.0310 27.8839 0.1279 3.19973 14.36 11.1718 0.0080 0.0310 37.1897 0.2047 2.41769 10.57 7.1471 0.0196 0.0485 41.7056 0.2303 2.16575 10.78 6.4431 0.0241 0.0538
Since PXRD pattern was taken at higher temperature, so variation in particle size was observed. This variation in grain size might be due to the rearrangement of particles during growth of material particles. The variations in intensities convinced about the imperfections of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155]. (See Graph 5.2 for detail)
99
Results and Discussion Chapter 5
19 0.24 18 o d-spacing(A ) 0.22 17 Grain Size(nm) (b) 16 0.20 15 0.18 14 0.16 13 0 12 FWHM( 2Th) (a) 0.14 -2 11 Sigma(lines/cm ) 10 0.12 Strain(lines-2cm-4) 9 0.10 8 0.08
Material Parameters(a.u.) Material Material Parameters(a.u.) Material 7 6 0.06 5 0.04 4 3 0.02 2 0.00 10 15 20 25 30 35 40 45 10 15 20 25 30 35 40 45 2Theta(o) 2Theta(o)
Graph 5.2: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
The graph based on these calculations (Graph 5.2) indicates the grain size in the range o o between 6.4431 nm at 2θ/ = 41.7056 to 18.2921 nm at 2θ/ = 18.3717.
5.6.3.1.2.6 Thermal Gravimetric Analysis of Bis4CH3I2CNi:
Thermal stability of Bis4CH3I2CNi was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Ni-complex was observed with increase in temperature. Graph 5.3 shows the loss of weight of title complex. First loss of weight occurred at 50oC to 380oC and undergo 61.18% loss of weight. Second loss of weight occurred from 380oC to 540oC and undergone 26.47% weight loss. There is no loss in weight from 540oC to 600oC. Total loss in weight from 50oC to 540oC is 87.65 %.
Graph 5.3: TGA of Bis4CH3I2CNi
100
Results and Discussion Chapter 5
5.6.3.1.3 Characterization of Bis[(E) - 3 -( 1- (( 4 -chlorophenyl) imino ) ethyl ) – 2 H – chromen - 2 – one ]Nickel( II): [Bis4ClI2CNi]:
5.6.3.1.3.1 Infra-red Spectral Studies of Bis4ClI2CNi: In IR studies of the Ni-complex Bis4ClI2CNi, for specific functional groups, all the absorption bands were found in the specified regions. An absorption band was found at 3231.58 cm-1 for sp3 C-H, an absorption band at 1384.96 cm-1 confirmed the presence of C-N bond. Presence of an absorption band at 3471.45 cm-1 confirmed C- Cl. Sp2 C=O was confirmed by the presence of a band at 1743.52 cm-1.Similarly the absorption band at 1232.04 cm-1 confirmed the presence of sp2 C-O. An absorption band at 440.13 cm-1 confirmed the formation of metal nitrogen bond (M-N). This confirms the formation of nickel complex with this imine ligand. And a band at 350.49 cm-1 confirmed the coordination of nickel with ligand through oxygen atom. Brief summary for IR spectrum is given in the Table 5.9, entry 2. (Scan is given in appendix-1, Scan 5.18)
5.6.3.1.3.2 Estimation of λmax for Ni Complex Bis4ClI2CNi: After preparing the 0.01 ppm concentration of Bis4ClI2CNi, absorbance against different wavelengths was measured. As the wavelength was increased, the absorbance increased until it reached to a maximum 0.302. At this maximum absorbance, corresponding wavelength (385nm) was noted. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the table 5.18 below.
101
Results and Discussion Chapter 5
Table 5.18: Data showing absorbance against different wavelengths for Bis4ClI2CNi Sr. # Wavelength (nm) Absorbance 1 360 0.134 2 365 0.171 3 370 0.209 4 375 0.239 5 380 0.265 6 385 0.302 7 390 0.288 8 395 0.241 9 400 0.201 10 405 0.174
For the determination of λmax, a graph was plotted between wavelength and absorbance. This graph started from 350nm with corresponding absorbance 0.134. Initially, there was rise in graph as the absorbance increased with increase in wavelength. Absorbance increased to the maximum 0.302 and then there was fall in curve. It was noted that maximum absorbance for Bis4ClI2CNi was found at wavelength 385nm (Graph 5.4).
Graph 5.4: Graph of wavelength vs absorbance for Bis4ClI2CNi
102
Results and Discussion Chapter 5
5.6.3.1.3.3 Estimation of Metal Ions in Bis4ClI2CNi: Atomic absorption spectroscopy was used to estimate the amount of nickel metal in the complex Bis4ClI2CNi. Standard solutions with concentrations 05-25ppm were prepared and absorbance was noted by atomic absorption spectrophotometer (AAS). As usual absorbance increased with increase of concentration. Data regarding wavelength and corresponding absorbance is compiled in table 5.19. Calibration curve was obtained in the light of table 5.19.
Table 5.19: Calibration Data (Concentration of Ni+2 Vs Absorption) for Bis4ClI2CNi Sr. # Conc. (ppm) Absorbance 1 05 0.097 2 10 0.136 3 15 0.171 4 20 0.209 5 25 0.217
The difference between estimated and calculated amounts was very less and insignificant, data is given in table 5.13, entry 2.
5.6.3.1.3.4 Determination of Metal to Ligands Ratio by AAS: AAS was used to determine the metal to ligand ratio in complex Bis4ClI2CNi. First, Ni-metal to ligand (4ClI2C) ratio was theoretically calculated (Table 5.20) and then the experimentally determined ratios were compared with calculated ratios, by this metal to ligand ratio was determined which confirms the structure of the complex formed. Atomic mass of Ni-metal = 57.94 g Molecular mass of ligand (4ClI2C) = 297.06 g
103
Results and Discussion Chapter 5
Table 5.20: Data for molecular mass for calculating metal to ligand ratio in Bis4ClI2CNi No. of Ni No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 355.00 16.32% 2 1 2 652.06 8.88% 3 1 3 949.12 6.10% 4 1 4 1246.18 4.65%
Standard solutions for this experimental metal complex with concentrations ranging from 05-25ppm were prepared in chloroform. After noting the absorptions (table 5.19), a calibration curve was obtained; from it the amount of Ni-metal was estimated in the Ni-complexes (table 5.15, entry 2). Amount of Ni-metal estimated from calibration graph = 10.01 ppm Total concentration of Ni-metal = 10.01 × 10 = 100.1ppm Experimental %age of Ni-metal = 10.01% Theoretical calculated %age of Ni-metal (Table 5.20, entry 2) = 8.88% The amount of Ni-metal estimated from graph is 10.01% which is associated with entry 2, table 5.20. Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and by this propose structure of metal complex is confirmed.
5.6.3.1.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CNi: X-ray powder diffractometer was used during PXRD studies of Bis4ClI2CNi. For this Ni-complex was grinded. Diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. The spectrum obtained was studied to estimate the structure of metal complex.
104
Results and Discussion Chapter 5
Scan 5.19: PXRD spectrum of Bis4ClI2CNi
From the diffraction pattern obtained in PXRD spectrum, a number of absorption bands were selected for the determination of structural parameters. Table 5.21 shows the calculations of miller indices from the selected absorption bands. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern had no correlation with reported patterns. This convinced that synthesized metal complex (Bis4ClI2CNi) was novel with its unique pattern.
105
Results and Discussion Chapter 5
Table 5.21: Calculation of Miller Indices by PXRD pattern for Bis4ClI2CNi
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin Integers 10.5650 5.2825 0.0084 1 2 3 3 111 11.4485 5.7242 0.0099 1.1737 2.3473 3.5210 4 200 14.4780 7.2390 0.0159 1.8733 3.7465 5.6198 6 211 17.2014 8.6007 0.0224 2.6385 5.2770 7.9155 8 220 300, 18.5973 9.2987 0.0261 3.0802 6.1604 9.2405 9 221 20.2505 10.1253 0.0309 3.6462 7.2924 10.9385 11 311 22.9693 11.4847 0.0396 4.6770 9.3539 14.0309 14 321 24.5223 12.2612 0.0451 5.3208 10.6415 15.9623 16 400 25.2022 12.6011 0.0476 5.6151 11.2301 16.8452 17 322 26.0180 13.0090 0.0507 5.9781 11.9562 17.9343 18 411 27.5824 13.7912 0.0568 6.7043 13.4086 20.1128 20 420 28.1871 14.0936 0.0593 6.9955 13.9909 20.9864 21 421 29.9697 14.9848 0.0669 7.8873 15.7747 23.6621 24 422 31.9622 15.9811 0.0758 8.9428 17.8856 26.8284 27 511 33.8810 16.9405 0.0849 10.0164 20.0328 30.0492 30 521
Grain size, dislocation line density and strain of nickel complex (Bis4ClI2CNi) were calculated by using the formulae used in section 5.6.3.1.2.5. The results are tabulated in table 5.22 given below;
106
Results and Discussion Chapter 5
Table 5.22: Data calculated for structural parameters for Bis4ClI2CNi
Grain Dislocation FWHM d-spacing Intensity Strain (S) 2θ/0 size (D) Density (δ) [°2Th.] [Å] counts (lines-2cm-4) (nm) (lines/cm-2) 10.5650 0.2558 8.37368 19.92 5.4438 0.0337 0.0637 11.4485 0.2814 7.72940 100.00 4.9519 0.0408 0.0700 14.4780 0.2814 6.11815 32.42 4.9661 0.0405 0.0698 17.2014 0.3326 5.15512 63.36 4.2157 0.0563 0.0822 18.5973 0.3326 4.77122 85.64 4.2247 0.0560 0.0821 20.2505 0.3326 4.38529 41.34 4.2350 0.0558 0.0819 22.9693 0.2047 3.87200 35.16 6.9120 0.0209 0.0501 24.5223 0.2558 3.63020 20.49 5.5462 0.0325 0.0625 25.2022 0.3070 3.53378 73.36 4.6280 0.0467 0.0745 26.0180 0.3326 3.42481 38.25 4.2781 0.0546 0.0810 27.5824 0.3070 3.23400 33.16 4.6513 0.0462 0.0745 28.1871 0.3326 3.16599 31.94 4.2980 0.0541 0.0807 29.9697 0.4605 2.98161 76.57 3.1172 0.1029 0.1112 31.9622 0.3582 2.80015 45.21 4.0260 0.0617 0.0861 33.8810 0.2814 2.64583 21.14 5.1506 0.0377 0.0673
Variation in grain size might be due to the rearrangement of particles during growth of material particles at higher temperatures. The variations in intensities convinces about the inadequacies of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155]. Smaller values of dislocation density indicated the purity of metal complex.
107
Results and Discussion Chapter 5
9 0.50 FWHM(02Th) -2 d-spacing(Ao) 0.45 Sigma(lines/cm ) 8 -2 -4 Grain Size(nm) 0.40 Strain(line cm )
7 0.35
0.30 6 0.25 5 0.20
Material parameters(a.u.) Material Material Parameters(a.u.)Material (b) 4 0.15
0.10 3 (a) 0.05
2 0.00 10 15 20 25 30 35 10 15 20 25 30 35 2Theta(o) 2Theta(o)
Graph 5.5: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
The graph based on these calculations (Graph 5.5) indicates the grain size in the range o o between 6.9120 nm at 2θ/ = 22.9693 to 3.1172 nm at 2θ/ = 29.9697.
5.6.3.1.3.6 Thermal Gravimetric Analysis of Bis4ClI2CNi: Thermal stability of Bis4ClI2CNi was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Ni-complex was observed with increase in temperature. Graph 5.6 shows the loss of weight of title complex. Loss of weight occurred in one stage from 28oC to 300oC and undergo 75.57% loss of weight. There is no loss in weight from 300oC to 600oC. Total loss in weight from 28oC to 300oC is 75.57%.
Graph 5.6: TGA of Bis4ClI2CNi 108
Results and Discussion Chapter 5
5.6.3.1.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)-2H- chromen-2-one]Nickel(II) [Bis2NO2I2CNi]:
5.6.3.1.4.1 Infra-red Spectral Studies of Bis2NO2I2CNi:
Similar to other Ni- complexes, IR spectrum of Bis2NO2I2CNi was studied and absorption bands were found in specified regions for particular functional groups. An absorption band at 3251.08 cm-1 convinces the presence of sp3 C-H, an absorption band at 1295.51 cm-1 confirmed the presence of C-N bond. An absorption band for CH=N was found at 1651.83 cm-1. Similarly an absorption band at 1734.66 cm-1 confirmed the sp2 C=O functional group. An absorption band at 1211.51 cm-1 confirmed the presence of sp2 C-O in this metal complex. An absorption bands at 454.37 cm-1 and 349.75 cm-1 confirmed the coordination of nickel with ligand through nitrogen (Ni-N) and oxygen (Ni-O) respectively. This information collected from spectrum convinces the formation of Bis2NO2I2CNi. Brief summary for IR spectrum is given in the Table 5.9, entry 3. (Scan is given in appendix-1, Scan 5.20)
5.6.3.1.4.2 Estimation of λmax for Ni Complex Bis2NO2I2CNi:
0.01ppm solution of Bis2NO2I2CNi was prepared and its absorbance was measured against different wavelengths. Absorbance increased with increased wavelength. Absorbance increased to the maximum 0.227 corresponding to wavelength 380nm i.e.
λmax = 380nm. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the table 5.23 below.
109
Results and Discussion Chapter 5
Table 5.23: Data showing absorbance against different wavelengths for
Bis2NO2I2CNi Sr. # Wavelength (nm) Absorbance 1 350 0.099 2 360 0.139 3 370 0.186 4 380 0.227 5 390 0.201 6 400 0.179 7 410 0.143 8 420 0.117
Graph started with wavelength 350nm and absorbance 2.31; graph was going in upward direction showing that absorbance was increasing with increase in wavelength. It was noted that complex Bis2NO2I2CNi had maximum absorbance at 380nm which can be observed in Graph 5.7 below. After then curve moved in downward direction representing the decrease in absorbance of uv-visible light with increase in wavelength.
Graph 5.7: Graph of wavelength vs absorbance for Bis2NO2I2CNi
110
Results and Discussion Chapter 5
5.6.3.1.4.3 Estimation of Metal Ions in Bis2NO2I2CNi: In order to determine the amount of metal in the synthesized nickel-complex
Bis2NO2I2CNi, atomic absorption spectroscopy was used. Standard solutions with concentrations 05-25ppm were prepared and absorbance was noted by atomic absorption spectrophotometer (AAS). Table 5.24 shows the absorbance for each concentration. And a calibration curve was obtained as under
Table 5.24: Calibration Data (Concentration of Ni+2 Vs Absorption) for
Bis2NO2I2CNi Sr. # Conc. (ppm) Absorbance 1 05 1.019 2 10 1.471 3 15 1.924 4 20 2.211 5 25 2.593
The difference between estimated and calculated amounts was very less and insignificant, data is given in table 5.13, entry 3.
5.6.3.1.4.4 Determination of Metal to Ligands Ratio by AAS: In order to estimate the metal to ligand ratio AAS was used. For the metal complex
Bis2NO2I2CNi, metal to ligand ratio was theoretically calculated (table 5.25) and experimentally determined ratios were compared with these ratios. Calculated and experimental ratios were found much closed to eachother which confirmed the structure of newly formed metal complex Bis2NO2I2CNi. Calculated molecular masses and metal to ligands ratios are given in the following table 5.25. Atomic mass of Ni-metal = 57.94 g
Molecular mass of ligand (2NO2I2C) = 308.08 g
111
Results and Discussion Chapter 5
Table 5.25: Data for molecular mass for calculating metal to ligand ratio for
Bis2NO2I2CNi No. of Ni No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 366.02 18.81% 2 1 2 674.10 8.59% 3 1 3 982.18 5.89% 4 1 4 1232.32 4.70%
Standard solutions of the Ni-complex (Bis2NO2I2CNi) in chloroform with concentrations ranging from 05-25ppm were prepared and their respective absorptions were noted (table 5.24) and a calibration curve was drawn. By this calibration curve, the amount of Ni-metal was estimated in the corresponding Ni-complexes (Table 5.15, entry 3). Amount of Ni-metal estimated from calibration graph = 9.47 ppm Total concentration of Ni-metal = 9.47 × 10 = 94.7 ppm Experimental %age of Ni-metal = 9.47% Theoretically calculated %age of Ni-metal (Table 5.25, entry 2) = 8.59% The amount of Ni-metal estimated from graph is 9.47% which is comparable with entry 2, table 5.25. Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and this confirm the proposed structure of the complex.
5.6.3.1.4.5 Thermal Gravimetric Analysis of Bis2NO2I2CNi:
Thermal stability of Bis2NO2I2CNi was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Ni-complex was observed with increase in temperature. Graph 5.8 shows the loss of weight of title complex. First loss of weight occurred at 40oC to 140oC and undergo 19.08% loss of weight. Second loss of weight occurred from 140oC to 290oC and undergone 28.29% weight loss. In 3rd stage loss of weight occurred from 290oC to 455oC and loss in weight was 32.89%. There is no
112
Results and Discussion Chapter 5
loss in weight from 455oC to 600oC. Total loss in weight from 40oC to 455oC is 80.26 %.
Graph 5.8: TGA of Bis2NO2I2CNi
5.6.3.2 Characterization of Cobalt Imine Complexes:
When imine ligands 4CH32IC, 4ClI2C and 2NO2I2C were reacted with
Co(NO3)2.H2O, different Co-complexes had been synthesized abbreviated as
Bis4CH3I2CCo, Bis4ClI2CCo and Bis2NO2I2CCo. Following assay describes the different techniques used for their complete characterization.
5.6.3.2.1 Determination of Stability of Cobalt Imine Complexes: Specific amounts of Co-Imine complexes were dissolved in chloroform to form solutions of specific concentrations. λmax was taken periodically for these solutions over a period of four weeks. There was no change in λmax as time passed. Constant values of λmax convinces that Co-complexes are stable in solution form.
λmax of ligand and complexes solution in chloroform was determined when synthesized.
The above solution was kept for four weeks and its λmax was periodically noted
as following and a graph of λmax was plotted against time. a) After every 3 hours for first 24 hours. b) After 24 hours for first week. c) After 48 hours for rest of the 3 weeks.
113
Results and Discussion Chapter 5
During the above mentioned periods, freshly prepared solutions of Co-complexes were also run for λmax. No change in λmax value confirmed that these Co-complexes were stable in solid state.
5.6.3.2.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)-2H-chromen-2- one]Cobalt(II) [Bis4CH3I2CCo]:
5.6.3.2.2.1 Infra-red Spectral Studies of Bis4CH3I2CCo: Like nickel complexes, presence of functional groups was estimated through study of
IR- spectrum. In IR studies of the Co-Imine complex Bis4CH3I2CCo, all the absorption bands were found in the specified regions for specific functional groups. An absorption band was found at 3386.66 cm-1 for sp3 C-H, an absorption band at 1383.64 cm-1 confirmed the presence of C-N bond. For CH=N, there was an absorption band at 1655.05 cm-1. Presence of an absorption band at 1712.14 cm-1 confirmed sp2 C=O. Similarly the absorption band at 1164.53 cm-1 confirmed the presence of sp2 C-O. An absorption band at 451.66 cm-1 confirmed the formation of nickel nitrogen bond (Ni-N). An absorption band at 348.82 cm-1 showed the coordination of nickel through Ni-O bond. This confirmed the formation of Cobalt complex with this imine ligand. Brief summary for IR spectrum is given in the table 5.9, entry 4. (Scan is given in appendix-1, Scan 5.21)
5.6.3.2.2.2 Estimation of λmax for Cobalt Complex Bis4CH3I2CCo:
0.01ppm solution of Bis2NO2I2CCo was prepared and its absorbance was measured against different wavelengths. Absorbance increased with increased wavelength and increased to the maximum 0.286 corresponding to wavelength 395nm i.e. λmax = 395nm. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the table 5.26 below.
114
Results and Discussion Chapter 5
Table 5.26: Data showing absorbance against different wavelengths for
Bis4CH3I2CCo Sr. # Wavelength (nm) Absorbance 1 370 0.115 2 375 0.143 3 380 0.179 4 385 0.211 5 390 0.247 6 395 0.286 7 400 0.253 8 405 0.227 9 410 0.199
For the determination of λmax for Bis4CH3I2CCo, a graph was plotted between wavelength and absorbance (values given in table 5.26). Graph started with wavelength 370nm and absorbance 0.115.; as wavelength was increased the respective absorbance of the solution increased and curve was going in upward direction. At 395nm, absorbance of uv-visible light was maximum; after it absorbance decreased with increase in wavelength (Graph 5.9). So the λmax for Bis4CH3I2CCo was found to be 395nm i.e. λmax = 395nm.
Graph 5.9: Graph of wavelength vs absorbance for Bis4CH3I2CCo
115
Results and Discussion Chapter 5
5.6.3.2.2.3 Estimation of Metal Ions in Bis4CH3I2CCo: Atomic absorption spectroscopy (AAS) was used for the determination of amount of cobalt metal in all synthesized cobalt imine complexes (Bis4CH3I2CCo, Bis4ClI2CCo and Bis2NO2I2CCo). Standard solutions with concentrations ranging from 05-25ppm were prepared and absorbance was noted by atomic absorption spectrophotometer (AAS). Data is given in Table 5.27; at the basis of this data a calibration curve was drawn as under.
Table 5.27: Calibration Data (Concentration of Co+2 Vs Absorption) for
Bis4CH3I2CCo Sr. # Conc. (ppm) Absorbance 1 05 0.097 2 10 0.142 3 15 0.183 4 20 0.219 5 25 0.258
The difference between estimated and calculated amounts of cobalt was very less and insignificant, data is given in Table 5.28, entry 1.
Table 5.28: Data of Co+2 ions concentrations in Co-complexes Calculated Amount of Metal Difference Entry amount of metal metal estimated by Complexes (ppm) (ppm) AAS (ppm)
1 Bis4CH3I2CCo 9.61 10.52 0.91 2 Bis4ClI2CCo 9.02 10.18 1.16
3 Bis2NO2I2CCo 8.73 9.79 1.06
5.6.3.2.2.4 Determination of Metal to Ligands Ratio by AAS: In order to estimate the metal to ligand ratio AAS was used. For the metal complex
Bis4CH3I2CCo, metal to ligand ratio was theoretically calculated (Table 5.29) and
116
Results and Discussion Chapter 5
experimentally determined ratios were compared with these ratios. Calculated and experimental ratios were found much closed to eachother which confirmed the structure of newly formed metal complex (Bis4CH3I2CCo). Calculated molecular masses and metal to ligands ratios are given in the following Table 5.29. Atomic mass of Co-metal = 58.93 g
Molecular mass of ligand (4CH3I2C) = 277.11 g
Table 5.29: Data for molecular mass for calculating metal to ligand ratio for
Bis4CH3I2CCo No. of Co No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 336.04 17.54% 2 1 2 613.15 9.61% 3 1 3 890.26 6.62% 4 1 4 1167.37 5.05%
Standard solutions of cobalt complex (Bis4CH3I2CCo) in chloroform with concentrations ranging from 05-25ppm were prepared and their respective absorptions were noted (Table 5.27) and a calibration curve was drawn. By this calibration curve, the amount of Co-metal was estimated in the corresponding Co-complexes (Table 5.30, entry 1).
Table 5.30: Estimated amounts of Co-metal in Co-complexes by AAS Amount of Co- Entry Co-Complexes metal (ppm)
1 Bis4CH3I2CCo 10.52 2 Bis4ClI2CCo 10.18
3 Bis2NO2I2CCo 9.79
Amount of Co-metal estimated from calibration graph = 10.52 ppm Total concentration of Co-metal = 10.52 × 10 = 105.8 ppm 117
Results and Discussion Chapter 5
Experimental %age of Co-metal = 10.52% Theoretical %age of Co-metal (Table 5.29, entry 2) = 9.61% The amount of Co-metal obtained from graph is 10.52% which is very close to the entry 2, Table 5.29 i.e. 9.61%. Hence it convinced that metal to ligands ratio is 1:2 and confirmed the expected structure of metal complex.
5.6.3.2.2.5 Thermal Gravimetric Analysis of Bis4CH3I2CCo:
Thermal stability of Bis4CH3I2CCo was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Co-complex was observed with increase in temperature. Graph 5.10 shows the loss of weight of title complex. First loss of weight occurred at 60oC to 295oC and undergo 59.41% loss of weight. Second loss of weight occurred from 295oC to 470oC and undergone 24.71% weight loss. There is no loss in weight from 470oC to 600oC. Total loss in weight from 60oC to 470oC is 84.12%.
Graph 5.10: TGA of Bis4CH3I2CCo
118
Results and Discussion Chapter 5
5.6.3.2.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl)-2H- chromen-2-one]Cobalt(II): [Bis4ClI2CCo]:
5.6.3.2.3.1 Infra-red Spectral Studies of Bis4ClI2CCo: In the IR spectrum of the Co-complex, Bis4ClI2CCo, for particular functional groups present in complex, absorption bands were found in specific regions. An absorption band was found at 3276.93 cm-1 representing the presence of sp3 C-H, an absorption band at 1384.44 cm-1 convinced the presence of C-N bond in the Co-complex. Presence of CH=N was confirmed by the absorption band at 1647.07 cm-1 and there was an absorption band at 3494.52 cm-1 in spectrum for C-Cl. Likewise, absorption bands at 1740.05 cm-1 and 1120.91 cm-1 convinced the presence of sp2 C=O and sp2 C-O. A new absorption band which was not present in the IR-spectrum of ligand was found at 458.44 cm-1, this absorption band confirmed the formation of cobalt-nitrogen bond (Co-N). Similarly, an absorption band was there at 346.47 cm-1 showing the coordination of cobalt metal with ligand through oxygen atom (Co-O).This data convinced the formation of Co-complex Bis4ClI2CCo. Brief summary for IR spectrum is given in the table 5.9, entry 5. (Scan is given in appendix-1, Scan 5.22)
5.6.3.2.3.2 Estimation of λmax for Bis4ClI2CCo: First 0.01ppm solution of Bis4ClI2CCo was prepared in chloroform. Then by using uv-visible spectrometer absorbance was noted at different wavelengths. With the increase of wavelength, absorbance increased and ultimately to its maximum. After it, absorption started decreasing with increase in wavelength. Following Table 5.31 represents the relevant data for wavelength and absorbance.
119
Results and Discussion Chapter 5
Table 5.31: Data showing absorbance against different wavelengths for Bis4ClI2CCo Sr. # Wavelength (nm) Absorbance 1 370 0.134 2 380 0.175 3 390 0.189 4 400 0.220 5 410 0.257 6 420 0.229 7 430 0.206 8 440 0.184
From the data given in the Table 5.31, a graph was plotted between wavelength and absorbance and λmax was determined. As shown in the graph, at very start curve was rising and reached to its maximum with absorbance 0.257 at wavelength 410nm and then falls to absorbance 0.184 at wavelength 440. So it is concluded that maximum absorbance for Bis4ClI2CCo was 0.257 at 410nm i.e. λmax = 410nm. (Graph 5.11)
Graph 5.11: Graph of wavelength vs absorbance for Bis4ClI2CCo
5.6.3.2.3.3 Estimation of Metal Ions in Bis4ClI2CCo: In order to estimate the amount of cobalt in Co-complexes abbreviated as
Bis4CH3I2CCo, Bis4ClI2CCo and Bis2NO2I2CCo, Atomic Absorption Spectrophotometry (AAS) was used. 120
Results and Discussion Chapter 5
Standard solutions of the complex Bis4ClI2CCo in chloroform were prepared ranging in concentrations 05-25ppm and AAS was used to note their absorbance. It was noted the absorbace increased with increase in concentration of Co-complex. Data regarding wavelength and corresponding absorbance is compiled in Table 5.32. Calibration curve was obtained in the light of Table 5.32.
Table 5.32: Calibration Data (Concentration of Co+2 Vs Absorption) for Bis4ClI2CCo Sr. # Conc. (ppm) Absorbance 1 05 0.109 2 10 0.139 3 15 0.161 4 20 0.199 5 25 0.225
The difference between estimated and calculated amounts was very less and insignificant, (Table 5.28, entry 2).
5.6.3.2.3.4 Determination of Metal to Ligands Ratio by AAS: Metal to ligand ratio in the Co-complex, Bis4ClI2CCo, was determined by using the technique known as Atomic Absorption Spectrophotometry (AAS). For this expected Cobalt metal to ligand ratio was calculated (Table 5.33). Then metal to ligand ratio was experimentally determined. For this standard solutions of the Co-complex Bis4ClI2CCo were prepared in chloroform, (detail given in section 5.5.3.2.3.3, Table 5.32) and absorbance was noted. Then absorbance of experiment solution was taken and amount of Cobalt in complex was estimated (Table 5.30, entry 2). Atomic mass of Co-metal = 58.93 g Molecular mass of ligand (4ClI2C) = 297.06 g
121
Results and Discussion Chapter 5
Table 5.33: Data for molecular mass for calculating metal to ligand ratio for Bis4ClI2CCo No. of Co No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 355.99 16.55% 2 1 2 653.05 9.02% 3 1 3 950.11 6.20% 4 1 4 1247.17 4.73%
Amount of Co-metal estimated from calibration graph = 10.18 ppm Total concentration of Co-metal = 10.18 × 10 = 101.8 ppm Experimental %age of Co-metal = 10.18% Theoretical %age of Co-metal (Table 5.33, entry 2) = 9.02% From the calibration graph, the amount of Co-metal is 10.18% which is very close to the calculated amounts of copper (Table 5.33, entry 2). This correlation convinced that metal to ligand ratio is 1:2. By this structure of Co-complex was confirmed.
5.6.3.2.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CCo: For the elucidation of structural parameters for the complex Bis4ClI2CCo, powder X- ray diffraction (PXRD) technique was used. For PXRD studies the complex was grinded. Grinding did not destroy the crystalline structure, it gave millions of very smaller crystals. The sample was placed in monochromator and diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. The spectrum obtained was studied to estimate the structure of metal complex.
122
Results and Discussion Chapter 5
Scan 5.23: PXRD spectrum of Bis4ClI2CCo
A number of peacks were selected from the diffraction pattern given in the PXRD spectrum and structural parameters were determined from these absorption bands. Miller indices were calculated; calculations are given in Table 5.34. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern had no correlation with reported patterns. This convinces that synthesized metal complex (Bis4ClI2CCo) was novel with its unique pattern. All the major peaks at positions 2θ/o 19.1310, 23.2379, 25.8136, 27.1514, 28.1211, 32.2149, 33.9568, 38.7229, 48.8687, 72.989 3have miller indices111, 200, 210, 211, 211, 220, 300, 221, 222, 331, 611 respectively which showed the characteristic pattern of complex.
123
Results and Discussion Chapter 5
Table 5.34: Calculation of Miller Indices by PXRD pattern for Bis4ClI2CCo
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin Integers 19.1310 9.5655 0.0276 1 2 3 3 111 23.2379 11.6189 0.0405 1.4674 2.9348 4.4022 4 200 25.8136 12.9068 0.0499 1.8080 3.6160 5.4240 5 210 27.1514 13.5757 0.0551 1.9963 3.9926 5.9889 6 211 28.1211 14.0605 0.0590 2.1377 4.2754 6.4131 6 211 32.2149 16.1074 0.0769 2.7862 5.5724 8.3586 8 220 300, 33.9568 16.9784 0.0853 3.0910 6.1820 9.2730 9 221 38.7229 19.3614 0.1099 3.9819 7.9638 11.9457 12 222 48.8687 24.4344 0.1711 6.1993 12.3986 18.5979 19 331 72.9893 36.4947 0.3537 12.8152 25.6304 38.4456 38 611 Grain size, dislocation line density and strain of cobalt complex (Bis4ClI2CCo) were calculated by using the formulae used in section 5.6.3.1.2.5. The results are tabulated in Table 5.35 given below;
Table 5.35: Data calculated for structural parameters for Bis4ClI2CCo Grain Dislocation FWHM d-spacing Intensity Strain (S) 2θ/0 size (D) Density (δ) [°2Th.] [Å] counts (lines-2cm-4) (nm) (lines/cm-2) 19.1310 0.3070 4.63930 31.86 4.5806 0.0477 0.0757 23.2379 0.2303 3.82785 11.05 6.1460 0.0265 0.0564 25.8136 0.2303 3.45146 8.98 6.1651 0.0263 0.0562 27.1514 0.2558 3.28436 14.28 5.5752 0.0322 0.0622 28.1211 0.2814 3.17327 42.41 5.0789 0.0387 0.0683 32.2149 0.3582 2.77876 100.00 4.0294 0.0616 0.0860 33.9568 0.3326 2.64010 49.43 4.3588 0.0526 0.0795 38.7229 0.2558 2.32542 25.45 5.7461 0.0303 0.0603 48.8687 0.3838 1.86374 47.57 3.9683 0.0635 0.0874 72.9893 0.2814 1.29624 9.29 6.1297 0.0266 0.0566
124
Results and Discussion Chapter 5
At high temperatures, there is a variation in grain size. This might be due the rearrangement of particles during growth of material particles. The variations in intensities assures the imperfections of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155].
o d-spacing(A ) FWHM(o2Th) Grain Size(nm) 2 6.5 0.40 Sigma(lines/cm ) 0.38 -2 -4 6.0 Strain(lines cm ) 0.36 5.5 0.34 0.32 5.0 0.30 0.28 4.5 0.26 0.24 4.0 0.22 3.5 0.20 0.18 (b)
Y Axis Title Y (a) 3.0 0.16
Material Parameters(a.u.) Material 0.14 2.5 0.12 0.10 2.0 0.08 1.5 0.06 0.04 1.0 0.02 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 X Axis Title 2Theta(o)
Graph 5.12: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o The graph based on these calculations (Graph 5.12) indicates the grain size in the o o range between 6.1651 nm at 2θ/ = 25.8136 to 3.9683 nm at 2θ/ = 48.8687.
5.6.3.2.3.6 Thermal Gravimetric Analysis of Bis4ClI2CCo: In order to find thermal stability of Bis4ClI2CCo TGA was used. Metal complex was investigated by heating at a rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Co-complex was observed with increase in temperature. Graph 5.13 shows the loss of weight of title complex. Loss of weight occurred in one stage from 75oC to 360oC and undergo 85.00% loss of weight. There is no loss in weight from 360oC to 600oC. Total loss in weight from 75oC to 360oC is 85.00%.
125
Results and Discussion Chapter 5
Graph 5.13: TGA of Bis4ClI2CCo
5.6.3.2.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)-2H- chromen-2-one]Cobalt(II): [Bis2NO2I2CCo]:
5.6.3.2.4.1 Infra-red Spectral Studies of Bis2NO2I2CCo: In order to confirm the presence of certain functional groups in the cobalt complex
Bis2NO2I2CCo, IR- spectrum was studied. Absorption bands in specified regions of spectrum confirmed the presence of particular functional groups in the complexes. An absorption band was found at 3481.48 cm-1 for sp3 C-H, an absorption band at1384.05 cm-1 indicated the presence of C-N bond. For CH=N, an absorption band was found at 1611.17 cm-1. Presence of an absorption band at 1727.62 cm-1 confirmed sp2 C=O and an absorption band at 1120.52 cm-1 convinced the presence of sp2 C-O. Presence of absorption bands at 455.17 cm-1 and 338.74 cm-1 confirmed the coordination of cobalt with ligand through nitrogen and oxygen respectively. These absorption bands were not found in the IR spectrum of ligand. Brief summary for IR spectrum is given in the table 5.9, entry 6. (Scan is given in appendix-1, Scan 5.24)
5.6.3.2.4.2 Estimation of λmax for Bis2NO2I2CCo:
After preparing 0.01ppm solution of Bis2NO2I2CCo in chloroform, its absorbance was noted at different wavelengths using uv-visible spectrometer. It was noted that with increase in wavelength, absorbance increased and then decreased after reaching a certain maximum. Wavelengths and absorbance noted is given in the Table 5.36.
126
Results and Discussion Chapter 5
Table 5.36: Data showing absorbance against different wavelengths for
Bis2NO2I2CCo Sr. # Wavelength (nm) Absorbance 1 380 1.119 2 385 1.335 3 390 1.652 4 395 1.875 5 400 1.993 6 405 2.179 7 410 2.302 8 415 2.210 9 420 2.012 10 425 1.863
To determine λmax for cobalt complex Bis2NO2I2CCo, a graph was plotted between wavelengths and absorbance; data collected in Table 5.36. Wavelength was taken along abscissa and absorbance was taken along Y-axis. Line of graph was going in upward direction with the increase in wavelength and corresponding absorbance.
Graph showed that the complex Bis2NO2I2CCo had maximum absorbance 2.210 at wavelength 415nm, see graph 5.14. It is concluded that Co-complex Bis2NO2I2CCo has λmax = 415nm.
Graph 5.14: Graph of wavelength vs absorbance for Bis2NO2I2CCo 127
Results and Discussion Chapter 5
5.6.3.2.4.3 Estimation of Metal Ions in Bis2NO2I2CCo: With the help of atomic absorption spectroscopy (AAS), amount of metal was estimated in the Co-Complex Bis2NO2I2CCo. For the determination of amount of metal ion, standard solutions were prepared in chloroform. Concentrations of standard solutions were ranging from 05-25ppm and then absorbance was noted by atomic absorption spectrophotometer (AAS). A calibration curve was drawn by plotting a graph between concentrations of solutions and their corresponding absorbance (Table 5.37).
Table 5.37: Calibration Data (Concentration of Co+2 Vs Absorption) for
Bis2NO2I2CCo Sr. # Conc. (ppm) Absorbance 1 05 0.101 2 10 0.126 3 15 0.159 4 20 0.189 5 25 0.204
+2 When the experimental and calculated amounts of Co in Bis2NO2I2CCo were compared, very small difference was found which was insignificant. Relevant data is given in Table 5.28, entry 3.
5.6.3.2.4.4 Determination of Metal to Ligands Ratio by AAS: With the help atomic absorption spectroscopy (AAS), metal to ligand ratio was estimated in cobalt complexes. Method involves the calculation of this ratio theoretically as done in Table 5.38. Then with the help of atomic absorption spectrophotometer (AAS), metal to ligand ratio was determined experimentally. Both calculated and experimental ratios were then compared to determine the ratio present in the complex. It remained very useful for determination of formula of newly synthesized Co-Complex Bis2NO2I2CCo.
128
Results and Discussion Chapter 5
For theoretical determination of metal to ligand ratio, the molecular mass and calculations are given in Table 5.38.
Atomic mass of Co-metal = 58.93 g
Molecular mass of ligand (2NO2I2C) = 308.08 g
Table 5.38: Data for molecular mass for calculating metal to ligand ratio for
Bis2NO2I2CCo Total No. of Co No. of %age of Metal Entry Molecular Ions Ligands (By mass) Mass (g/mole) 1 1 1 367.01 16.06% 2 1 2 675.09 8.73% 3 1 3 983.17 5.99% 4 1 4 1291.25 4.56%
Standard solutions of Bis2NO2I2CCo in chloroform were prepared with concentrations ranging from 05-25ppm and absorbance was noted with AAS (Table 5.37). From the data in Table 5.37, a calibration curve was drawn and amount of Co- metal was estimated in Bis2NO2I2CCo. Data regarding the amount of metal is given in Table 5.30, entry 3. Amount of Co-metal estimated from calibration graph = 9.79 ppm Total concentration of Co-metal = 9.79 × 10 = 97.9 ppm Experimental %age of Co-metal = 9.79% Theoretical %age of Co-metal (Table 5.38, entry 2) = 8.73% The amount of Co-metal estimated from graph is 9.79% which is associated with entry 2, Table 5.38. Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and this confirm the proposed structure of the complex.
129
Results and Discussion Chapter 5
5.6.3.2.4.5 Thermal Gravimetric Analysis of Bis2NO2I2CCo:
Thermal stability of Bis2NO2I2CCo was investigated by TG technique at a heating rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Co-complex was observed with increase in temperature. Graph 5.15 shows the loss of weight of title complex. First loss of weight occurred at 40oC to 120oC and undergo 15.18% loss of weight. Second loss of weight occurred from 120oC to 190oC and undergone 30.36% weight loss. In 3rd stage loss of weight occurred from 190oC to 350oC and loss in weight was 35.71%. There is no loss in weight from 350oC to 600oC. Total loss in weight from 40oC to 350oC is 81.25 %.
Graph 5.15: TGA of Bis2NO2I2CCo
5.6.3.3 Characterization of Copper Imine Complexes: Copper imine complexes have been synthesized by reaction the synthesized Schiff base ligands with CuSO4.5H2O at specific conditions. These Co-complexes were these characterized by following techniques.
5.6.3.3.1 Determination of Stability of Copper Imine Complexes: Specific amounts of Cu-Imine complexes were dissolved in chloroform to form solutions of specific concentrations. λmax was taken periodically for these solutions over a period of four weeks. There was no change in λmax as time passed. Constant values of λmax convinces that Cu-complexes are stable in solution form.
130
Results and Discussion Chapter 5
λmax of ligand and Cu-complexes solution in chloroform was determined when synthesized.
The above solution was kept for four weeks and its λmax was periodically noted
as following and a graph of λmax was plotted against time. a) After every 3 hours for first 24 hours. b) After 24 hours for first week. c) After 48 hours for rest of the 3 weeks. During the above mentioned periods, freshly prepared solutions of Cu-complexes were also run for λmax. No change in λmax value confirmed that these Cu-complexes were stable in solid state.
5.6.3.3.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)-2H-chromen-2- one]Copper(II) [Bis4CH3I2CCu]:
5.6.3.3.2.1 Infra-red Spectral Studies of Bis4CH3I2CCu: In order to estimate the presence of certain functional groups in Cu-complex
Bis4CH3I2CCu, its IR spectrum was taken. In IR spectrum there was an absorption band at 2922.62 cm-1 standing for sp3 C-H. C-N bond was confirmed by the absorption band present at 1297.08 cm-1. An absorption band present at 1678.11 cm-1 revealed the presence of CH=N. Absorption bands at 1739.77 cm-1 and 1166.37 cm-1 confirmed the presence of sp2 C=O and sp2 C-O respectively. And important absorption bands which confirmed the newly formed copper nitrogen (Cu-N) and Cu- O bonds were found at 437.32 cm-1 and 353.54 cm-1 respectively. When compared, these absorption bands were absent in the IR spectrum of imine ligand. These newly formed copper nitrogen and cooper oxygen bonds convinced the formation of Cu- complex. Brief summary for IR spectrum is given in the table 5.9, entry 7. (Scan is given in appendix-1, Scan 5.25).
131
Results and Discussion Chapter 5
5.6.3.3.2.2 Estimation of λmax for Bis4CH3I2CCu:
Each complex has different capability to absorb radiations. In order to estimate λmax for Copper complexes, their 0.01 ppm concentrations were carefully prepared in chloroform. Absorbance was noted using uv-visible spectrophotometer against different wavelengths. By the increase in wavelength, absorbance increased to its maximum and λmax was noted. Data collected from uv-visible spectrometer is given in Table 5.39 below.
Table 5.39: Data showing absorbance against different wavelengths for
Bis4CH3I2CCu Sr. # Wavelength (nm) Absorbance 1 320 2.10 2 330 2.53 3 340 2.61 4 350 2.82 5 360 2.60 6 370 2.01 7 380 1.64 8 390 1.13 9 400 0.92
By drawing a graph between wavelength and absorbance, λmax for Bis4CH3I2CCu was determined. As usual, curve was rising which showed the regular increase of absorbance with increase in wavelength. Curve reached a maximum 2.82 and then moved in downward direction as absorbance was decreasing with increase in wavelength. Absorption band of curve showed the maximum absorption of light, corresponding wavelength 350 was determined and reported. Hence λmax noted for
Bis4CH3I2CCu is 350nm i.e. λmax = 350nm. Find detail in graph 5.16.
132
Results and Discussion Chapter 5
Graph 5.16: Graph of wavelength vs absorbance for Bis4CH3I2CCu
5.6.3.3.2.3 Estimation of Metal Ion in Bis4CH3I2CCu: Atomic absorption spectroscopy (AAS) was used to determine the amount of copper metal in all of its synthesized copper imine complexes (Bis4CH3I2CCu, Bis4ClI2CCu and Bis2NO2I2CCu). For the determination of copper metal, standard solutions in chloroform were prepared. The concentrations of standard solutions raged from 05- 25ppm and absorbance was noted by AAS. Data collected from AAS is tabulated in Table 5.40 and calibration curve was obtained. The amount of copper in experimental sample was determined using this calibration curve.
Table 5.40: Calibration Data (Concentration of Cu+2 Vs Absorption) for
Bis4CH3I2CCu Sr. # Conc. (ppm) Absorbance 1 05 1.101 2 10 1.296 3 15 1.563 4 20 1.791 5 25 1.945 Experimentally found amount of copper metal was compared with the calculated value. The difference found was very small and insignificant. This confirms the expected structure of Bis4CH3I2CCu. (Table 5.41, entry 1)
133
Results and Discussion Chapter 5
Table 5.41: Data of Cu+2 ions concentrations in Cu-complexes Calculated Amount of Metal Difference Entry amount of metal metal estimated by Complexes (ppm) (ppm) AAS (ppm)
1 Bis4CH3I2CCu 10.19 11.32 1.13 2 Bis4ClI2CCu 9.58 10.74 1.16
3 Bis2NO2I2CCu 9.27 10.16 0.71
5.6.3.3.2.4 Determination of Metal to Ligands Ratio by AAS: One of the important aspect was to find the number of ligands attached to the metal (copper), for this atomic absorption spectroscopy (AAS) was used. This involves two steps; first determination of metal to ligand ratio theoretically (Table 5.42) and secondly experimental determination of metal to ligand ratio. Both of these ratios were then compared to estimate the metal to ligand ratio in the copper complex
Bis4CH3I2CCu. It confirmed the structure of this complex. Table 5.42 shows the calculations of molecular masses and calculated metal to ligand ratios. Atomic mass of Cu-metal = 62.93 g
Molecular mass of ligand (4CH3I2C) = 277.11 g
Table 5.42: Data for molecular mass for calculating metal to ligand ratio for
Bis4CH3I2CCu No. of Cu No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 340.04 18.51% 2 1 2 617.15 10.19% 3 1 3 894.26 7.04% 4 1 4 1171.37 5.37%
To determine the copper to ligand ratio experimentally, standard solutions of Cu- complex Bis4CH3I2CCu in chloroform were prepared. The concentrations of these 134
Results and Discussion Chapter 5
solutions ranged from 05-25ppm. And absorptions were noted by AAS (Table 5.40); and a calibration curve was drawn in the light of this data. By this calibration curve, the amount of Cu-metal was estimated in the corresponding Cu-complexes (Table 5.43, entry 1).
Table 5.43: Estimated amounts of Copper in Cu-complexes by AAS Amount of Cu- Entry Cu-Complexes metal (ppm)
1 Bis4CH3I2CCu 11.32 2 Bis4ClI2CCu 10.74
3 Bis2NO2I2CCu 10.16
Amount of Cu-metal estimated from calibration graph = 11.32ppm Total concentration of Cu-metal = 11.32 × 10 = 101.4ppm Experimental %age of Cu-metal = 11.32% Calculated %age of Cu-metal (Table 5.42, entry 2) = 10.19% The amount of Cu-metal estimated from graph is 11.32% which is associated with entry 2 in Table 5.42. Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and this confirmed the proposed structure of the complex.
5.6.3.3.2.5 Thermal Gravimetric Analysis of Bis4CH3I2CCu:
Thermal stability of Bis4CH3I2CCu was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Cu-complex was observed with increase in temperature. Graph 5.17 shows the loss of weight of title complex. First loss of weight occurred at 95oC to 260oC and undergo 52.94% loss of weight. Second loss of weight occurred from 260oC to 460oC and undergone 27.06% weight loss. There is no loss in weight from 460oC to 600oC. Total loss in weight from 95oC to 460oC is 80.00%.
135
Results and Discussion Chapter 5
Graph 5.17: TGA of Bis4CH3I2CCu
5.6.3.3.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl)-2H- chromen-2-one]Copper(II): [Bis4ClI2CCu]:
5.6.3.3.3.1 Infra-red Spectral Studies of Bis4ClI2CCu: In the IR spectrum of Cu-complex Bis4ClI2CCu, absorption bands were found in particular regions for specific functional groups present in the complex. An absorption band was found at 3233.40 cm-1 for sp3 C-H; an absorption band at 1296.81 cm-1 confirmed the presence of C-N bond. For CH=N, an absorption band was found at 1678.11 cm-1. An absorption band at 3440.48 cm-1 confirmed the presence of C-Cl group. Presence of absorption bands at 1739.29 cm-1 and 1163.05 cm-1 confirmed the presence of sp2 C=O and sp2 C-O respectively. An absorption band at 438.74 cm-1 confirmed the formation of copper nitrogen bond (Cu-N) and newly formed Cu-O bond was confirmed by the band at 344.65 cm-1. This confirmed the formation of Cu- complex with the imine ligand (4ClI2C). Brief summary for IR spectrum is given in the table 5.9, entry 8. (Scan is given in appendix-1, Scan 5.26)
5.6.3.3.3.2 Estimation of λmax for Bis4ClI2CCu:
In order to estimate λmax for Copper complexes, after preparing the 0.01 ppm concentration of Bis4ClI2CCu, it was taken into the cell and absorbance against different wavelengths was measured by using uv-visible light. Same solvent chloroform was taken into the other cell as blank. As the wavelength was increased,
136
Results and Discussion Chapter 5
the absorbance increased until it reached to a maximum 2.34 and λmax was noted. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the Table 5.44 below.
Table 5.44: Data showing absorbance against different wavelengths for Bis4ClI2CCu Sr. # Wavelength (nm) Absorbance 1 320 1.40 2 325 1.60 3 330 1.92 4 335 2.10 5 340 2.34 6 345 1.90 7 350 1.74 8 355 1.51 9 360 1.34 10 365 1.25
When graph was plotted, curve was going in upward direction showing that absorbance was increasing with increase in wavelength. It was noted that complex Bis4ClI2CCu had maximum absorbance at 2.34 at wavelength 340nm which can be observed in graph 5.18 below. After then curve moved in downward direction representing the decrease in absorbance of uv-visible light with increase in wavelength. Hence λmax for Copper complex Bis4ClI2CCu was 340nm.
137
Results and Discussion Chapter 5
Graph 5.18: Graph of wavelength vs absorbance for Bis4ClI2CCu
5.6.3.3.3.3 Estimation of Metal Ion in Bis4ClI2CCu: In order to determine the amount of metal in the synthesized copper complexes, atomic absorption spectroscopy was used. Standard solutions with concentrations 05- 25ppm were prepared in chloroform and absorbance was noted by atomic absorption spectrophotometer (AAS). Data tabulated in Table 5.45. In the light of this data, a calibration curve was drawn and amount of copper in complex was estimated. Find data in Table 5.45.
Table 5.45: Calibration Data (Concentration of Cu+2 Vs Absorption) for Bis4ClI2CCu Sr. # Conc. (ppm) Absorbance 1 05 1.121 2 10 1.399 3 15 1.683 4 20 1.886 5 25 2.098
Experimentally found amount of copper metal was compared with the calculated value. The difference found was very small and insignificant. This confirmed the expected structure of Bis4ClI2CCu. (Table 5.41, entry 2)
138
Results and Discussion Chapter 5
5.6.3.3.3.4 Determination of Metal to Ligands Ratio by AAS: Atomic absorption spectroscopy was used to determine the number of ligands attached to copper metal. First, theoretically metal to ligand ratio is calculated as showed in Table 5.46 and then this ratio is determined experimentally. By the comparison of both ratios, metal to ligand ratio is estimated in copper complex Bis4ClI2CCu. It confirms the structure of this complex. Calculated molecular masses and metal to ligands ratios are given in the following Table 5.46. Atomic mass of Cu-metal = 62.93 g Molecular mass of ligand (4ClI2C) = 297.06 g
Table 5.46: Data for molecular mass for calculating metal to ligand ratio for Bis4ClI2CCu No. of Cu No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 359.99 17.48% 2 1 2 657.05 9.58% 3 1 3 954.11 6.59% 4 1 4 1251.17 5.03% To determine the copper to ligand ratio experimentally, standard solutions of Cu- complex Bis4ClI2CCu in chloroform were prepared. The concentrations of these solutions ranged from 05-25ppm. And absorptions were noted by AAS (Table 5.45); and a calibration curve was drawn in the light of this data. By this calibration curve, the amount of Cu-metal was estimated in the corresponding Cu-complexes (Table 5.43, entry 2). Amount of Cu-metal estimated from calibration graph = 10.74 ppm Total concentration of Cu-metal = 10.74 × 10 = 107.4 ppm Experimental %age of Cu-metal = 10.74% Theoretical %age of Cu-metal (Table 5.46, entry 2) = 9.58%
139
Results and Discussion Chapter 5
Estimated amount of Cu-metal from calibration graph was 10.74% which is comparable with calculated amount of copper (Table 5.46, entry 2). This correlation between two %ages confirmed the expected structure of complex.
5.6.3.3.3.5 Thermal Gravimetric Analysis of Bis4ClI2CCu:
Thermal stability of Bis4CH3I2CCu was investigated by TG technique at a heating rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Cu-complex was observed with increase in temperature. Graph 5.19 shows the loss of weight of title complex. For this copper complex, loss of weight occurred in one step from 80oC to 300oC and undergo 81.43% loss of weight. There is no loss in weight from 300oC to 600oC. Total loss in weight from 80oC to 300oC is 81.43%.
Graph 5.19: TGA of Bis4ClI2CCu 5.6.3.3.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)-2H- chromen-2-one]Copper(II): [Bis2NO2I2CCu]:
5.6.3.3.4.1 Infra-red Spectral Studies of Bis2NO2I2CCu: In order to confirm the presence of certain functional groups in the copper complex
Bis2NO2I2CCu, IR- spectrum was studied. Absorption bands in specified regions of spectrum confirmed the presence of particular functional groups in the complexes. An absorption band was found at 3223.17 cm-1 for sp3 C-H, an absorption band at 1218.22 cm-1 indicated the presence of C-N bond. For CH=N, an absorption band was found at 1635.66 cm-1. Presence of an absorption band at 1711.11 cm-1 confirmed sp2
140
Results and Discussion Chapter 5
C=O and an absorption band at 1218.22 cm-1 convinced the presence of sp2 C-O. An absorption band was found at 445.29 cm-1 which confirmed the formation of copper nitrogen bond (Cu-N) and at band at 340.73 cm-1 confirmed Cu-O bond. These absorption bands were not found in the IR spectrum of ligand. These new absorption bands convinced the coordination of copper with nitrogen and oxygen of imine ligand. Brief summary for IR spectrum is given in the table 5.9, entry 9. (Scan is given in appendix-1, Scan 5.27)
5.6.3.3.4.2 Estimation of λmax for Bis2NO2I2CCu:
0.01ppm solution of Bis2NO2I2CCu was prepared and its absorbance was measured against different wavelengths by uv-visible spectrophotometer. For Bis2NO2I2CCu, pattern of absorbance against the increase in wavelength was repeated as in other metal complexes. Absorbance increased with increased wavelength and increased to the maximum 2.853 corresponding to wavelength 395nm i.e. λmax = 395nm. As wavelength was further increased, corresponding absorbance started decreasing. Data is given in the Table 5.47 below.
Table 5.47: Data showing absorbance against different wavelengths for
Bis2NO2I2CCu Sr. # Wavelength (nm) Absorbance 1 365 1.431 2 370 1.603 3 375 1.897 4 380 2.110 5 385 2.364 6 390 2.621 7 395 2.853 8 400 2.716 9 405 2.409 10 410 2.147
141
Results and Discussion Chapter 5
For the determination of λmax for Bis2NO2I2CCu, a graph was plotted between wavelength and absorbance (values given in Table 5.47). Graph started with wavelength 365nm and absorbance 1.431; as wavelength was increased the respective absorbance of the solution increased and curve was going in upward direction. At 395nm, absorbance of uv-visible light was maximum 2.853; after it absorbance decreased with increase in wavelength (Graph 5.20). So the λmax for Bis2NO2I2CCu was found to be 395nm i.e. λmax = 395nm.
Graph 5.20: Graph of wavelength vs absorbance for Bis2NO2I2CCu
5.6.3.3.4.3 Estimation of Metal Ion in Bis2NO2I2CCu: Atomic absorption spectroscopy (AAS) was used for the determination of amount of copper metal in all synthesized copper imine complexes (Bis4CH3I2CCu,
Bis4ClI2CCu and Bis2NO2I2CCu). Standard solutions with concentrations ranging from 05-25ppm were prepared and absorbance was noted by atomic absorption spectrophotometer (AAS). Data is given in Table 5.48; at the basis of this data a calibration curve was drawn.
142
Results and Discussion Chapter 5
Table 5.48: Calibration Data (Concentration of Cu+2 Vs Absorption) for
Bis2NO2I2CCu Sr. # Conc. (ppm) Absorbance 1 05 1.098 2 10 1.276 3 15 1.510 4 20 1.735 5 25 1.996
The difference between estimated and calculated amounts was very less and insignificant, data is given in Table 5.41, entry 3. This confirmed the expected structure Bis2NO2I2CCu.
5.6.3.3.4.4 Determination of Metal to Ligands Ratio by AAS: In order to estimate the metal to ligand ratio AAS was used. For the copper complex
Bis2NO2I2CCu, metal to ligand ratio was theoretically calculated (Table 5.49) and experimentally determined ratios were compared with these ratios. Calculated and experimental ratios were found much closed to eachother which confirmed the structure of newly formed metal complex (Bis2NO2I2CCu). Table 5.49 shows the calculations of molecular masses and calculated metal to ligand ratios. Atomic mass of Cu-metal = 62.93 g
Molecular mass of ligand (2NO2I2C) = 308.08 g Table 5.49: Data for molecular mass for calculating metal to ligand ratio for
Bis2NO2I2CCu No. of Cu No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 371.01 16.96% 2 1 2 679.09 9.27% 3 1 3 987.17 6.37% 4 1 4 1295.25 4.86%
143
Results and Discussion Chapter 5
To determine the copper to ligand ratio experimentally, standard solutions of Cu- complex Bis2NO2I2CCu in chloroform were prepared. The concentrations of these solutions ranged from 05-25ppm. And absorptions were noted by AAS (Table 5.48); and a calibration curve was drawn in the light of this data. By this calibration curve, the amount of Cu-metal was estimated in the corresponding Cu-complexes (Table 5.43, entry 3). Amount of Cu-metal estimated from calibration graph = 10.16 ppm Total concentration of Cu-metal = 10.16 × 10 = 101.6 ppm Experimental %age of Cu-metal = 10.16% Theoretically calculated %age of Cu-metal (Table 5.49, entry 2) = 9.27% The amount of Cu-metal estimated from calibration graph is10.16% which is associated with entry 2, Table 5.49. Correlation between calculated and experimental values convinced that the metal to ligand ratio is 1:2 and this confirmed the proposed structure of the complex.
5.6.3.3.4.5 Powder X-ray Diffraction Analysis of Bis2NO2I2CCu:
In order to determine the structural parameters of Cu-complex, Bis2NO2I2CCu, PXRD was done. For this, it was first ground and X-ray powder diffractometer was used. Diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. Structure of metal complex Bis2NO2I2CCu was estimated from the spectrum obtained.
144
Results and Discussion Chapter 5
Scan 5.28: PXRD spectrum of Bis2NO2I2CCu From the diffraction pattern obtained in PXRD spectrum, a number of absorption bands were selected for the determination of structural parameters of Bis2NO2I2CCu. Table 5.50 shows the calculations of miller indices from the selected absorption bands. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern have no correlation with reported patterns. This convinces that synthesized metal complex (Bis2NO2I2CCu) was novel with its unique pattern.
145
Results and Discussion Chapter 5
Table 5.50: Calculation of Miller Indices by PXRD pattern for Bis2NO2I2CCu
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin Integers 10.0828 5.0414 0.0077 1 2 3 3 111 10.2565 5.1283 0.0080 1.0376 2.0753 3.1129 3 111 10.6899 5.3450 0.0087 1.1269 2.2538 3.3807 3 111 16.2240 8.1120 0.0199 2.5859 5.1719 7.7578 8 220 300, 17.3028 8.6514 0.0226 2.9386 5.8771 8.8157 9 221 18.3428 9.1714 0.0254 3.2993 6.5986 9.8979 10 310 18.8142 9.4071 0.0267 3.4695 6.9390 10.4086 10 310 20.8046 10.4023 0.0326 4.2340 8.4680 12.7019 13 320 24.0525 12.0263 0.0434 5.6382 11.2763 16.9145 17 322 25.1809 12.5905 0.0475 6.1708 12.3417 18.5125 19 331 27.0094 13.5047 0.0545 7.0823 14.1647 21.2470 21 421 29.3365 14.6683 0.0641 8.3274 16.6549 24.9823 25 500 31.6795 15.8398 0.0745 9.6754 19.3508 29.0262 29 520 35.0537 17.5269 0.0907 11.7783 23.5566 35.3349 35 531 37.1843 18.5922 0.1017 13.2016 26.4032 39.6048 40 620 44.7886 22.3943 0.1451 18.8499 37.6999 56.5498 57 722
Grain size, dislocation line density and strain of copper complex (Bis2NO2I2CCu) were calculated by using the formulae used in section 5.6.3.1.2.5. The results are tabulated in Table 5.51 given below;
146
Results and Discussion Chapter 5
Table 5.51: Data calculated for structural parameters for Bis2NO2I2CCu
Grain Dislocation FWHM d-spacing Intensity Strain (S) 2θ/0 size (D) Density (δ) [°2Th.] [Å] counts (lines-2cm-4) (nm) (lines/cm-2) 10.0828 0.0512 8.77306 25.14 27.1871 0.0014 0.0127 10.2565 0.0768 8.62488 100.00 18.1484 0.0030 0.0191 10.6899 0.2558 8.27613 62.12 5.4438 0.0337 0.0678 16.2240 0.3326 5.46342 37.03 4.2106 0.0564 0.0823 17.3028 0.2814 5.12515 14.34 4.9840 0.0403 0.0695 18.3428 0.3070 4.83684 17.96 4.5745 0.0478 0.0758 18.8142 0.3326 4.71671 85.53 4.2260 0.0560 0.0820 20.8046 0.3582 4.26972 12.93 3.9357 0.0646 0.0881 24.0525 0.3582 3.70002 75.03 3.9582 0.0638 0.0876 25.1809 0.2814 3.53673 17.87 5.0493 0.0392 0.0687 27.0094 0.2814 3.30130 41.69 5.0678 0.0389 0.0684 29.3365 0.4093 3.04451 25.83 3.5014 0.0816 0.0990 31.6795 0.3326 2.82448 48.02 4.3329 0.0532 0.0800 35.0537 0.3326 2.55995 25.14 4.3712 0.0523 0.0793 37.1843 0.2814 2.41802 25.22 5.1989 0.0370 0.0667 44.7886 0.5117 2.02357 20.19 1.4996 0.4447 0.2316
Variation in grain size might be due to the rearrangement of particles during growth of material particles at higher temperatures. The variations in intensities convinces about the inadequacies of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155].
147
Results and Discussion Chapter 5
FWHM(o2Th) 30 0.45 Sigma(lines/cm-2) -2 -4 o 0.40 Strain(lines cm ) 25 d-spacing(A ) Grain Size(nm) 0.35
20 0.30
0.25 15 (a) 0.20 (b) 10 0.15
Material Parameters(a.u.) Material
Material Parameters(a.u.) Material 0.10 5 0.05
0 0.00
5 10 15 20 25 30 35 40 45 50 10 15 20 25 30 35 2Theta(o) 2Theta(o)
Graph 5.21: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
The graph based on these calculations (Graph 5.21) indicates the grain size in the o o range between 27.1871nm at 2θ/ = 10.0828 to 1.4996nm at 2θ/ = 44.7886.
5.6.3.3.4.6 Thermal Gravimetric Analysis of Bis2NO2I2CCu:
Thermal stability of Bis2NO2I2CCu was investigated by TG technique at a heating rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Cu-complex was observed with increase in temperature. Graph 5.22 shows the loss of weight of title complex. First loss of weight occurred at 50oC to 160oC and undergo 27.14% loss of weight. Second loss of weight occurred from 160oC to 230oC and undergone 15.71% weight loss. In 3rd stage loss of weight occurred from 230oC to 440oC and loss in weight was 40.00%. There is no loss in weight from 440oC to 600oC. Total loss in weight from 50oC to 440oC is 82.86%.
148
Results and Discussion Chapter 5
Graph 5.22: TGA of Bis2NO2I2CCu
5.6.3.4 Characterization of Zinc Imine Complexes:
Schiff base ligands were reacted with Zn(CH3COO)2.H2Oto form Zinc complexes which were abbreviated as Bis4CH3I2CZn, Bis4ClI2CZn and Bis2NO2I2CZn. The synthesized complexes were analyzed by uv-visible spectrophotometry and respective
λmax was determined. Detail is given below for each synthesized complex.
5.6.3.4.1 Determination of Stability of Zinc Imine Complexes:
Specific amounts of Zn-Imine complexes (Bis4CH3I2CZn, Bis4ClI2CZn and
Bis2NO2I2CZn) were dissolved in chloroform to form solutions of specific concentrations. λmax was taken periodically for these solutions over a period of four weeks. There was no change in λmax as time passed. Constant values of λmax convinces that Zn-complexes are stable in solution form.
λmax of ligand and Zn-complexes solution in chloroform was determined when synthesized.
The above solution was kept for four weeks and its λmax was periodically noted
as following and a graph of λmax was plotted against time. a) After every 3 hours for first 24 hours. b) After 24 hours for first week. c) After 48 hours for rest of the 3 weeks.
149
Results and Discussion Chapter 5
During the above mentioned periods, freshly prepared solutions of Zn-complexes were also run for λmax. No change in λmax value confirmed that these Zn-complexes were stable in solid state.
5.6.3.4.2 Characterization of Bis[(E)-3-(1-(p-tolylimino)ethyl)-2H-chromen-2- one]Zinc(II) [Bis4CH3I2CZn]:
5.6.3.4.2.1 Infra-red Spectral Studies of Bis4CH3I2CZn:
In order to confirm the presence of functional groups in the complex Bis4CH3I2CZn, IR spectrum was studied. Presence of absorption bands for different functional groups assured the formation Zinc complex. An absorption band was found at 3345.15 cm-1 for sp3 C-H and an absorption band at 1301.69 cm-1 confirmed the presence of C-N bond. For CH=N, there was an absorption band at 1663.85 cm-1. Presence of an absorption band at 1736.42 cm-1 confirmed sp2 C=O. Similarly the absorption band at 1175.17 cm-1 confirmed the presence of sp2 C-O. Absorption bands at 458.42 cm-1 and 339.91 cm-1 confirmed the formation of zinc nitrogen (Zn-N) and zinc oxygen (Zn-O) bonds. This confirmed the formation of zinc complex Bis4CH3I2CZn with this imine ligand 4CH3I2C. Brief summary for IR spectrum is given in the table 5.9, entry 10. (Scan is given in appendix-1, Scan 5.29)
5.6.3.4.2.2 Estimation of λmax for Bis4CH3I2CZn:
First 0.01ppm solution of Bis4CH3I2CZn was prepared in chloroform. Then by using uv-visible spectrometer absorbance was noted at different wavelengths. With the increase of wavelength, absorbance increased and ultimately to its maximum. After it, absorption started decreasing with increase in wavelength. Following Table 5.52 represents the relevant data for wavelength and absorbance.
150
Results and Discussion Chapter 5
Table 5.52: Data showing absorbance against different wavelengths for
Bis4CH3I2CZn Sr. # Wavelength (nm) Absorbance 1 380 0.119 2 385 0.136 3 390 0.169 4 395 0.184 5 400 0.204 6 405 0.239 7 410 0.266 8 415 0.294 9 420 0.343 10 425 0.379 11 430 0.321 12 435 0.280 13 440 0.257
From the data given in the Table 5.52, a graph was plotted between wavelength and absorbance and λmax was determined. The graph gave a curve in each case which can be divided into three parts. First part show ascending of curve which then becomes straight for a few points is the second part and third part of the curve was descending of absorbance with the increase of wavelength. As described, at very start curve was rising and reached to its maximum with absorbance 0.379 at wavelength 425nm and then falls to absorbance 0.257 at wavelength 440. So it is concluded that maximum absorbance for Bis4CH3I2CZn was 0.379 at 425nm i.e. λmax = 425nm. (Graph 5.23)
151
Results and Discussion Chapter 5
Graph 5.23: Graph of wavelength vs absorbance for Bis4CH3I2CZn
5.6.3.4.2.3 Estimation of Metal Ions in Bis4CH3I2CZn: In order to estimate the amount of Zi-ions in Zinc-complexes abbreviated as
Bis4CH3I2CZn, Bis4ClI2CZn and Bis2NO2I2CZn, Atomic Absorption Spectrophotometry (AAS) was used. Standard solutions of the complex
Bis4CH3I2CZn in chloroform were prepared ranging in concentrations 05-25ppm and AAS was used to note their absorbance. It was noted the absorbace increased with increase in concentration of Co-complex. Data regarding wavelength and corresponding absorbance is compiled in Table 5.53. Calibration curve was obtained in the light of this data.
Table 5.53: Calibration Data (Concentration of Zn+2 Vs Absorption) for
Bis4CH3I2CZn Sr. # Conc. (ppm) Absorbance 1 05 0.096 2 10 0.126 3 15 0.153 4 20 0.171 5 25 0.196
152
Results and Discussion Chapter 5
The difference between estimated and calculated amounts of zinc was very less and insignificant, data is given in Table 5.54 entry 1.
Table 5.54: Data of Zn+2 ions concentrations in Zn-complexes Calculated Amount of Metal Difference Entry amount of metal metal estimated by Complexes (ppm) (ppm) AAS (ppm)
1 Bis4CH3I2CZn 10.34 11.42 1.08 2 Bis4ClI2CZn 9.72 10.69 0.97
3 Bis2NO2I2CZn 9.40 10.51 1.11
5.6.3.4.2.4 Determination of Metal to Ligands Ratio by AAS: One of the important aspect was to find the number of ligands attached to the Zn+2, for this atomic absorption spectroscopy (AAS) was used. This involves two steps; first determination of metal to ligand ratio theoretically (Table 5.55) and secondly experimental determination of metal to ligand ratio. Both of these ratios were then compared to estimate the metal to ligand ratio in the zinc complex Bis4CH3I2CZn. It confirmed the structure of this complex. Table 5.55 shows the calculations of molecular masses and calculated metal to ligand ratios. Atomic mass of Zn-metal = 63.93 g
Molecular mass of ligand (4CH3I2C) = 277.11 g
Table 5.55: Data for molecular mass for calculating metal to ligand ratio for
Bis4CH3I2CZn No. of Zn No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 341.04 18.75% 2 1 2 618.15 10.34% 3 1 3 895.26 7.14% 4 1 4 1172.37 5.45%
153
Results and Discussion Chapter 5
To determine the zinc to ligand ratio experimentally, standard solutions of Zn- complex Bis4CH3I2CZn in chloroform were prepared. The concentrations of these solutions ranged from 05-25ppm. And absorptions were noted by AAS (Table 5.53); and a calibration curve was drawn in the light of this data. By this calibration curve, the amount of Zn-metal was estimated in the corresponding Zn-complexes (Table 5.56, entry 1).
Table 5.56: Estimated amounts of Zn-metal in Zn-complexes by AAS Amount of Zn- Entry Zn-Complexes metal (ppm)
1 Bis4CH3I2CZn 11.42 2 Bis4ClI2CZn 10.69
3 Bis2NO2I2CZn 10.51
Amount of Zn-metal estimated from calibration graph = 11.42 ppm Total concentration of Zn-metal = 11.42 × 10 = 114.2 ppm Experimental %age of Zn-metal = 11.42% Theoretically calculated %age of Zn-metal (Table 5.55, entry 2) = 10.34% As the theoretically calculated (Table 5.55, entry 2) and experimentally determined amounts of Zn-metal are comparable, so metal to ligand ratio is 1:2. Hence the expected structure of complex is confirmed.
5.6.3.4.2.5 Powder X-ray Diffraction Analysis of Bis4CH3I2CZn:
For the elucidation of structural parameters for the complex Bis4CH3I2CZn, powder X-ray diffraction (PXRD) technique was used. For PXRD studies, the complex
Bis4CH3I2CZn was grinded. Actually grinding did not destroy the crystalline structure, it gave millions of very smaller crystals. The sample was then placed in monochromator and diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. The spectrum obtained was studied to estimate the structure of Zn-complex.
154
Results and Discussion Chapter 5
Counts ChE-0000265 (C-3.1) 10000
5000
0 20 30 40 50 60 70 80 Position [°2Theta] (Copper (Cu))
Scan 5.30: PXRD spectrum of Bis4CH3I2CZn
Table 5.57: Claculation of Miller Indices through PXRD pattern for Bis4CH3I2CZn
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin ntegers 15.7816 7.8908 0.01884 1 2 3 3 111 18.7288 9.3644 0.02647 1.4049 2.8098 4.2147 4 200 21.7286 10.8643 0.03552 1.8853 3.7706 5.6559 6 211 26.5731 13.2865 0.05281 2.8030 5.6060 8.4090 8 220 28.8529 14.4264 0.06206 3.2940 6.5880 9.8820 10 310 33.2222 16.6111 0.08172 4.3375 8.6750 13.0125 13 320 42.1027 21.0513 0.12902 6.8481 13.6962 20.5443 20 420 60.1391 30.0695 0.25105 13.3253 26.6506 39.9759 40 620
The miller indices for the 8 selected peaks were calculated as shown above in the Table 5.57. The calculated patterns were compared with reported patterns (present in the library) by peak search method and the difference in pattern showed the novelty of the complex. The miller indices relevant to the major peaks are 111, 200, 211, 220, 310, 320, 420 and 620respectively which are the characteristic of the pattern.
155
Results and Discussion Chapter 5
The structural parameters including grain size, dislocation line density and strain of the complex were calculated and shown below in the Table 5.58.
Table 5.58: Data calculated for structural parameters for Bis4CH3I2CZn Grain Dislocation FWHM Intensity d-spacing Strain (S) 2θ/0 size (D) Density (δ) [°2Th.] counts [Å] (lines-2cm-4) (nm) (lines/cm-2) 15.7816 0.1279 17.52 5.61557 11.2662 0.0078 0.0307 18.7288 0.1023 100.00 4.73802 14.3119 0.0048 0.0242 21.7286 0.2303 22.72 4.09021 6.4812 0.0238 0.0534 26.5731 0.1791 48.10 3.35450 8.6561 0.0133 0.0400 28.8529 0.1796 67.69 3.16425 8.8146 0.0128 0.0393 33.2222 0.2558 17.72 2.69677 6.4794 0.0238 0.0534 42.1027 0.2047 2.57 2.18531 9.1297 0.0119 0.0379 60.1391 0.5117 4.67 1.56225 5.4423 0.0337 0.0636
For Bis4CH3I2CZn, the grain size was found to be in the range of 14.3119 nm to 5.4423 nm at 2θ/0 = 18.7288 to 60.1391 (Graph 5.24). In the spectrum peaks of various widths were seen because broadening of the peak is directly proportional to the crystallite size. Crystallite size varied due to the rearrangement of particles in instrument conditions. The variation in intensities, d-spacing, dislocation density and strain are shown below in the graph 5.24.
156
Results and Discussion Chapter 5
15 o d-spacing (A ) o 14 Grain size (nm) 0.5 FWHM( 2Th) -2 13 Sigma(lines/cm ) -2 -4 12 Strain(lines cm ) (a) 0.4 11 10
9 0.3 8 7 (b) 6 0.2
Material Parameters(a.u.) Material 5 Parameters(a.u.) Material 4 0.1 3 2 1 0.0 10 20 30 40 50 60 10 20 30 40 50 60 2Theta(o) 2Theta(o)
Graph 5.24: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
5.6.3.4.2.6 Thermal Gravimetric Analysis of Bis4CH3I2CZn:
Thermal stability of Bis4CH3I2CZn was investigated by TG technique at a heating rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Zn-complex was observed with increase in temperature. Graph 5.25 shows the loss of weight of title complex. First loss of weight occurred at 25oC to 320oC and undergo 54.65% loss of weight. Second loss of weight occurred from 320oC to 425oC and undergone 25.00% weight loss. There is no loss in weight from 425oC to 600oC. Total loss in weight from 25oC to 425oC is 79.65%.
Graph 5.25: TGA of Bis4CH3I2CZn
157
Results and Discussion Chapter 5
5.6.3.4.3 Characterization of Bis[(E)-3-(1-((4-chlorophenyl)imino)ethyl)-2H- chromen-2-one]Zinc(II) [Bis4ClI2CZn]:
5.6.3.4.3.1 Infra-red Spectral Studies of Bis4ClI2CZn: In the IR spectrum of Zn-complex Bis4ClI2CZn, absorption bands were found in particular regions for specific functional groups present in the complex. An absorption band was found at 3038.04 cm-1 for sp3 C-H; an absorption band at 1323.78 cm-1 confirmed the presence of C-N bond. For CH=N, an absorption band was found at 1600.00 cm-1. Similarly, presence of absorption band at 3460.98 cm-1 assured the presence of C-Cl group. Presence of absorption bands at 1739.44 cm-1 and 1194.81 cm-1 confirmed the presence of sp2 C=O and sp2 C-O respectively. Similarly absorption bands at 453.28 cm-1 and 341.54 cm-1 confirmed the coordination of zinc with ligand through nitrogen (Zn-N) and oxygen (Zn-O) respectively. This confirmed the formation of Zn-complex with the imine ligand (4ClI2C). Brief summary for IR spectrum is given in the table 5.9, entry 11. (Scan is given in appendix-1, Scan 5.31)
5.6.3.4.3.2 Estimation of λmax for Bis4ClI2CZn: All Zn-complexes gave bands in the UV-Visible region, in the range of 340-485nm. For Bis4ClI2CZn, pattern of absorbance against the increase in wavelength was repeated as in other metal complexes. The graph of wavelength vs absorbance gave curve which can be divided into three parts. First part show ascending of curve which then becomes straight for a few points is the second part and third part of the curve was descending of absorbance with the increase of wavelength (Table 5.59).
158
Results and Discussion Chapter 5
Table 5.59: Data showing absorbance against different wavelengths for Bis4ClI2CZn Sr. # Wavelength (nm) Absorbance 1 380 0.123 2 385 0.141 3 390 0.177 4 395 0.192 5 400 0.211 6 405 0.247 7 410 0.279 8 415 0.301 9 420 0.357 10 425 0.387 11 430 0.311 12 435 0.287 13 440 0.264
Absorbance increased with increased wavelength and increased to the maximum
0.387 corresponding to wavelength 425nm i.e. λmax = 425nm. As wavelength was further increased, corresponding absorbance started decreasing. The λmax was confirmed by repeatedly determining the λmax for several days using fresh sample solution each time. (Graph 5.26).
159
Results and Discussion Chapter 5
Graph 5.26: Graph of wavelength vs absorbance for Bis4ClI2CZn
5.6.3.4.3.3 Estimation of Metal Ions in Bis4ClI2CZn: In order to estimate the amount of Zn-ions in Zinc-complexes abbreviated as
Bis4CH3I2CZn, Bis4ClI2CZn and Bis2NO2I2CZn, Atomic Absorption Spectrophotometry (AAS) was used. Standard solutions of the complex Bis4ClI2CZn in chloroform were prepared ranging in concentrations 05-25ppm and AAS was used to note their absorbance. It was noted the absorbace increased with increase in concentration of Zn-complex. Data regarding wavelength and corresponding absorbance is compiled in Table 5.60. Calibration curve was obtained in the light of this data.
Table 5.60: Calibration Data (Concentration of Zn+2 Vs Absorption) for Bis4ClI2CZn Sr. # Conc. (ppm) Absorbance 1 05 0.109 2 10 0.135 3 15 0.159 4 20 0.176 5 25 0.192
160
Results and Discussion Chapter 5
Experimentally found amount of Zn-metal was compared with the calculated value. The difference found was very small and insignificant. This confirmed the expected structure of Bis4ClI2CZn. (Table 5.54, entry 2)
5.6.3.4.3.4 Determination of Metal to Ligands Ratio by AAS: In order to estimate the zinc to ligand ratio AAS was used. For the Zn-complex Bis4ClI2CZn, metal to ligand ratio was theoretically calculated (Table 5.61) and experimentally determined ratios were compared with these ratios. Calculated and experimental ratios were found much closed to eachother which confirmed the structure of newly formed metal complex Bis4ClI2CZn. Calculated molecular masses and metal to ligands ratios are given in the following Table 5.61 Atomic mass of Zn-metal = 63.93 g Molecular mass of ligand (4ClI2C) = 297.06 g
Table 5.61: Data for molecular mass for calculating metal to ligand ratio for Bis4ClI2CZn No. of Zn No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 360.99 17.71% 2 1 2 658.05 9.72% 3 1 3 955.11 6.69% 4 1 4 1252.17 5.11%
Standard solutions of the Zn-complex Bis4ClI2CZn in chloroform with concentrations ranging from 05-25ppm were prepared and their respective absorptions were noted (Table 5.60) and a calibration curve was drawn. By this calibration curve, the amount of Zn-metal was estimated in the corresponding Zn-complexes (Table 5.56, entry 2). Amount of Zn-metal estimated from calibration graph = 10.69 ppm Total concentration of Zn-metal = 10.69 × 10 = 106.9 ppm
161
Results and Discussion Chapter 5
Experimental %age of Zn-metal = 10.69% Calculated %age of Zn-metal (Table 5.61, entry 2) = 9.72% The amount of Zn-metal estimated from graph is 10.69% which is associated with entry 2 in table5.64. Correlation between these two values convinces that the metal to ligand ratio is 1:2 and this confirm the proposed structure of the complex.
5.6.3.4.3.5 Powder X-ray Diffraction Analysis of Bis4ClI2CZn: For the elucidation of structural parameters for the complex Bis4ClI2CZn, powder X- ray diffraction (PXRD) technique was used. For PXRD studies the complex was grinded. Grinding did not destroy the crystalline structure, it gave millions of very smaller crystals. The sample was placed in monochromator and diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. The spectrum obtained was studied to estimate the structure of Zn-complex Bis4ClI2CZn.
Scan 5.32: PXRD spectrum of Bis4ClI2CZn A number of peacks were selected from the diffraction pattern given in the PXRD spectrum and structural parameters were determined from these absorption bands. Miller indices were calculated; calculations are given in Table 5.62. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern had no correlation with reported patterns. This convinces that synthesized metal complex Bis4ClI2CZn was novel with its unique pattern. 162
Results and Discussion Chapter 5
Table 5.62: Calculation of Miller Indices by PXRD pattern for Bis4ClI2CZn
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin Integers 10.7855 5.3927 0.0071 1 2 3 3 111 15.7522 7.8761 0.0152 2.1273 4.2545 6.3818 6 211 17.8222 8.9111 0.0195 2.7192 5.4384 8.1576 8 220 300, 18.2044 9.1022 0.0203 2.8368 5.6725 8.5088 9 221 300, 18.8611 9.4305 0.0218 3.0431 6.0862 9.1293 9 221 21.0039 10.5019 0.0269 3.7671 7.5343 11.3015 11 311 21.4200 10.7100 0.0280 3.9164 7.8329 11.7494 12 222 22.6956 11.3478 0.0314 4.3917 8.7835 13.1752 13 320 23.2436 11.6218 0.0329 4.6040 9.2080 13.8120 14 321 25.9301 12.9650 0.0409 5.7041 11.4283 17.1425 17 322 26.9771 13.4885 0.0442 6.1779 12.3558 18.5337 19 331 27.4145 13.7072 0.0456 6.3767 12.7534 19.1301 19 331 30.6607 15.3303 0.0568 7.9453 15.8906 23.8359 24 422 32.7477 16.3738 0.0647 9.0390 18.0780 27.1171 27 511
Grain size, dislocation line density and strain of zinc complex (Bis4ClI2CZn) were calculated by using the formulae used in section 5.6.3.1.2.5. The results are tabulated in Table 5.63 given below;
163
Results and Discussion Chapter 5
Table 5.63: Data calculated for structural parameters for Bis4ClI2CZn
Grain Dislocation FWHM d-spacing Intensity Strain (S) 2θ/0 size (D) Density (δ) [°2Th.] [Å] counts (lines-2cm-4) (nm) (lines/cm-2) 10.7855 0.1181 8.20301 39.94 11.7925 0.0072 0.0294 15.7522 0.1771 5.62600 20.35 7.9050 0.0160 0.0439 17.8222 0.1181 4.97694 34.21 11.8812 0.0071 0.0292 18.2044 0.1476 4.87329 32.14 9.5164 0.0110 0.0364 18.8611 0.1476 4.70509 52.77 9.5229 0.0110 0.0364 21.0039 0.2066 4.22966 22.30 6.8269 0.0215 0.0508 21.4200 0.1771 4.14843 21.80 7.9686 0.0157 0.0435 22.6956 0.1476 3.91808 25.46 9.5822 0.0109 0.0362 23.2436 0.1476 3.82693 34.14 9.5888 0.0109 0.0361 25.9301 0.1181 3.43621 23.21 12.0569 0.0069 0.0287 26.9771 0.1771 3.30518 68.82 8.0519 0.0154 0.0431 27.4145 0.2066 3.25343 100.00 6.9085 0.0209 0.0502 30.6607 0.1181 2.91597 18.25 12.1733 0.0067 0.0285 31.9214 0.2362 2.80363 14.48 6.1054 0.0268 0.0568 32.7477 0.2066 2.73476 18.14 6.9957 0.0204 0.0495
At high temperatures, there is a variation in grain size. This might be due the rearrangement of particles during growth of material particles. The variations in intensities assures the imperfections of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155].
164
Results and Discussion Chapter 5
o d-spacing (Å) FWHM( 2Th) -2 13 Grain size (nm) 0.24 Sigma(lines/cm ) Strain(lines-2cm-4) 12 0.22
11 0.20
10 0.18 0.16 9 0.14 8 0.12 7 0.10 6 0.08 Material Parameters(a.u.) Material (b)
Material Parameters Material (a.u.) 5 0.06 4 (a) 0.04 3 0.02
2 0.00 10 15 20 25 30 35 10 15 20 25 30 35 o 2Theta(0) 2Theta( )
Graph 5.27: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
The graph based on these calculations (Graph 5.27) indicates the grain size in the o o range between 12.1733nm at 2θ/ = 30.6607 to 6.1054nm at 2θ/ = 31.9214.
5.6.3.4.3.6 Thermal Gravimetric Analysis of Bis4ClI2CZn: Thermal stability of Bis4ClI2CZn was investigated by TG technique at a heating rate of 20oC/min under nitrogen over a range of 0oC to 600oC. In TGA studies, weight loss of the Zn-complex was observed with increase in temperature. Graph 5.28 shows the loss of weight of title complex. In this case, like Bis4ClI2CCu, Bis4ClI2CCo and Bis4ClI2CNi, loss of weight occurred in single step from 80oC to 350oC and undergo 78.87% loss of weight. There is no loss in weight from 350oC to 600oC. Total loss in weight from 80oC to 350oC is 78.87%.
Graph 5.28: TGA of Bis4ClI2CZn 165
Results and Discussion Chapter 5
5.6.3.4.4 Characterization of Bis[(E)-3-(1-((2-nitrophenyl)imino)ethyl)-2H- chromen-2-one]Zinc(II) [Bis2NO2I2CZn]:
5.6.3.4.4.1 Infra-red Spectral Studies of Bis2NO2I2CZn: In order to confirm the presence of certain functional groups in the zinc complex
Bis2NO2I2CZn, IR- spectrum was studied. Absorption bands in specified regions of spectrum confirmed the presence of particular functional groups in this complex. An absorption band was found at 3036.59 cm-1 for sp3 C-H, an absorption band at 1297.83 cm-1 indicated the presence of C-N bond. For CH=N, an absorption band was found at 1690.03 cm-1. Presence of an absorption band at 1740.00 cm-1 confirmed sp2 C=O and an absorption band at 1209.06 cm-1 convinced the presence of sp2 C-O. An absorption band was found at 443.59 cm-1 which confirmed the formation of zinc nitrogen bond (Zn-N) and Zn-O bond was confirmed by the band at 343.05 cm-1.
These absorption bands were not found in the IR spectrum of ligand (2NO2I2C). These new absorption bands convinced the formation of bond of zinc with nitrogen and oxygen of imine ligand (2NO2I2C). Brief summary for IR spectrum is given in the table 5.9, entry 12. (Scan is given in appendix-1, Scan 5.33)
5.6.3.4.4.2 Estimation of λmax for Bis2NO2I2CZn:
After preparing 0.01ppm solution of Bis2NO2I2CZn in chloroform, its absorbance was noted at different wavelengths using uv-visible spectrometer. It was noted that with increase in wavelength, absorbance increased and then decreased after reaching a certain maximum. Wavelengths and absorbance noted is tabulated in the Table 5.64.
166
Results and Discussion Chapter 5
Table 5.64: Data showing absorbance against different wavelengths for
Bis2NO2I2CZn Sr. # Wavelength (nm) Absorbance 1 420 0.221 2 430 0.239 3 440 0.261 4 450 0.281 5 460 0.302 6 470 0.339 7 480 0.361 8 485 0.378 9 490 0.359 10 500 0.321 11 510 0.299
From the data given in the Table 5.64, a graph was plotted between wavelength and absorbance and λmax was determined. The graph gave a curve in each case which can be divided into three parts. First part show ascending of curve which then becomes straight for a few points is the second part and third part of the curve was descending of absorbance with the increase of wavelength. As described, at very start curve was rising and reached to its maximum with absorbance 0.378 at wavelength 485nm and then falls to absorbance 0.299 at wavelength 510nm. So it was concluded that maximum absorbance for Bis2NO2I2CZn was 0.378 at 485nm i.e. λmax = 485nm. (Graph 5.29)
167
Results and Discussion Chapter 5
Graph 5.29: Graph of wavelength vs absorbance for Bis2NO2I2CZn
5.6.3.4.4.3 Estimation of Metal Ions in Bis2NO2I2CZn: With the help of atomic absorption spectroscopy (AAS), amount of metal was estimated in the Zinc Complex abbreviated as Bis2NO2I2CZn. For the determination of amount of Zn+2, standard solutions were prepared in chloroform. Concentrations of standard solutions were ranging from 05-25ppm and then absorbance was noted by atomic absorption spectrophotometer (AAS). A calibration curve was drawn by plotting a graph between concentrations of solutions and their corresponding absorbance. Data is given in Table 5.65.
Table 5.65: Calibration Data (Concentration of Zn+2 Vs Absorption) for
Bis2NO2I2CZn Sr. # Conc. (ppm) Absorbance 1 05 0.117 2 10 0.139 3 15 0.163 4 20 0.186 5 25 0.206
+2 When the experimental and calculated amounts of Zn in Bis2NO2I2CZn were compared, very small difference was found which was insignificant. Relevant data is given in Table 5.54, entry 3.
168
Results and Discussion Chapter 5
5.6.3.4.4.4 Determination of Metal to Ligands Ratio by AAS:
Like other Zn-complexes, zinc to ligand ratio for Bis2NO2I2CZn was determined by AAS to estimate it structure. Method involved the calculation of this ratio theoretically as done in Table 5.66. Then with the help of atomic absorption spectrophotometer (AAS), metal to ligand ratio was determined experimentally. Both calculated and experimental ratios were then compared to determine the ratio present in the complex. It remained very useful for determination of formula of newly synthesized Zn-Complex Bis2NO2I2CZn. For theoretical determination of metal to ligand ratio, the molecular mass and calculations are given in Table 5.66.
Atomic mass of Zn-metal = 63.93 g
Molecular mass of ligand (2NO2I2C) = 308.08 g
Table 5.66: Data for molecular mass for calculating metal to ligand ratio for
Bis2NO2I2CZn No. of Zn No. of Total Molecular %age of Metal Entry Ions Ligands Mass (g/mole) (By mass) 1 1 1 372.01 20.75% 2 1 2 680.09 9.40% 3 1 3 988.17 6.47% 4 1 4 1296.25 4.93%
Standard solutions of Bis2NO2I2Zn in chloroform were prepared in chloroform with concentrations ranging from 05-25ppm and absorbance was noted with AAS (Table 5.65). From the data in Table 5.65, a calibration curve was drawn and amount of zinc ion was estimated in Bis2NO2I2CZn. Data regarding the amount of Zinc is given in Table 5.56, entry 3. Amount of Zn-metal estimated from calibration graph = 10.51 ppm Total concentration of Zn-metal = 10.51 × 10 = 105.1 ppm Experimental %age of Zn-metal = 10.51%
169
Results and Discussion Chapter 5
Theoretical %age of Zn-metal (Table 5.66, entry 2) = 9.40% The amount of Zn-metal estimated from calibration graph is 10.51% which is very close to theoretically calculated %age (Table 5.66, entry 2). Correlation between calculated and experimental values convinces that the metal to ligand ratio is 1:2 and this confirm the proposed structure of the complex.
5.6.3.4.4.5 Powder X-ray Diffraction Analysis of Bis2NO2I2CZn:
In order to determine the structural parameters of Zn-complex, Bis2NO2I2CZn, PXRD was done. For this, it was first grinded and X-ray powder diffractometer was used. Diffractometer was run under 45kV/40 mA x-ray, 2θ/0 scanning mode, fixed monochromator with a range from 2θ/0 = 15 to 90 with a step of 0.02 degree for a period of 30 minute. Structure of metal complex Bis2NO2I2CZn was estimated from the spectrum obtained.
Counts ChE-0000266 (C-12)
15000
10000
5000
0 20 30 40 50 60 70 80 Position [°2Theta] (Copper (Cu))
Scan 5.34: PXRD spectrum of Bis2NO2I2CZn A number of peacks were selected from the diffraction pattern given in the PXRD spectrum and structural parameters were determined from these absorption bands. Miller indices were calculated; calculations are given in Table 5.67. The pattern obtained was compared with reported patterns in literature by peak search method and it was found that the experimental pattern had no correlation with reported patterns.
170
Results and Discussion Chapter 5
This convinces that synthesized metal complex Bis2NO2I2CZn was novel with its unique pattern.
Table 5.67: Calculation of Miller Indices by PXRD pattern for Bis2NO2I2CZn
2 2 2 0 0 2 1x Sin θ 2x Sin θ 3x Sin θ Whole 2θ/ θ/ Sin θ 2 2 2 hkl Sin θmin Sin θmin Sin θmin integers 17.7590 8.8795 0.02382 1 2 3 3 111
23.3239 11.6619 0.04085 1.7149 3.4298 5.1447 5 210
25.4560 12.7280 0.04854 2.0377 4.0754 6.1131 6 211
30.9596 15.4798 0.07123 2.9903 5.9806 8.9709 9 221
39.3297 19.6648 0.11324 4.7539 9.5078 14.2617 14 321
45.0137 22.5068 0.14653 6.1515 12.3030 18.4545 18 411
58.1540 29.0770 0.23618 9.9151 19.8302 29.7453 30 521
63.2609 31.6304 0.27503 11.5461 23.0922 34.6383 35 531
Grain size, dislocation line density and strain of zinc complex (Bis2NO2I2CZn) were calculated by using the formulae used in section 5.6.3.1.2.5. The results are tabulated in Table 5.68 given below,
171
Results and Discussion Chapter 5
Table 5.68: Data calculated for structural parameters for Bis2NO2I2CZn
d- Grain Dislocation FWHM Intensity Strain (S) 2θ/0 spacing size (D) Density (δ) [°2Th.] counts (lines-2cm-4) [Å] (nm) (lines/cm-2) 17.7590 0.1279 22.94 4.99451 11.3837 0.0070 0.0304
23.3239 0.1279 28.32 3.81393 11.8103 0.0071 0.0293
25.4560 0.1279 16.30 3.49913 12.0150 0.0069 0.0288
30.9596 0.1535 19.96 2.88850 10.5360 0.0090 0.0329
39.3297 0.1796 67.69 3.16425 9.9822 0.0100 0.0347
45.0137 0.1791 7.29 1.99591 10.9521 0.0083 0.0316
58.1540 0.1023 4.02 1.61428 25.7243 0.0015 0.0134
63.2609 0.1535 2.26 1.47253 20.0947 0.0024 0.0172
At high temperatures, there is a variation in grain size. This might be due the rearrangement of particles during growth of material particles. The variations in intensities assures the imperfections of crystal, thermal stresses, non-uniform, lattice vibrations of atoms and texture effects [155].
0.19 0.18 o 25 d-spacing(A ) 0.17 Grain size(nm) 0.16 0.15 20 0.14 0.13 0.12 FWHM(2Theta) 0.11 -2 15 0.10 Sigma(lines/cm ) -2 -4 0.09 Strain(lines cm ) 0.08 10 0.07
Material Parameters(a.u) Material
Material Parameters(a.u) Material 0.06 0.05 0.04 5 0.03 0.02 0.01 0 0.00 10 20 30 40 50 60 70 20 30 40 50 60 70 Theta(o) Theta(o)
Graph 5.30: Graphical representation of material parameters [d-spacing and grain size (a) and FWHM and Sigma and Strain (b)] versus 2θ/o
172
Results and Discussion Chapter 5
The graph based on these calculations (Graph 5.30) indicates the grain size in the o o range between 25.7243nm at 2θ/ = 58.1540 to 9.9822nm at 2θ/ = 39.3297.
5.6.3.4.4.6 Thermal Gravimetric Analysis of Bis2NO2I2CZn:
Thermal stability of Bis2NO2I2CZn was investigated by TG technique at a heating rate of 20oC/min under inert environment (using nitrogen) over a range of 0oC to 600oC. In TGA studies, weight loss of the Zn-complex was observed with increase in temperature. Graph 5.31 shows the loss of weight of title complex. First loss of weight occurred at 65oC to 90oC and undergo 14.29 loss of weight. Second loss of weight occurred from 90oC to 250oC and undergone 35.71% weight loss; third loss in weight occurred from 250oC to 425oC and loss in weight was 36.61%. There is no loss in weight from 425oC to 600oC. Total loss in weight from 65oC to 425oC is 86.61%.
Graph 5.31: TGA of Bis2NO2I2CZn
5.7 Magnetic Properties of Prepared Metal Complexes: Vibrating sample magnetometer (VSM) were utilized to study the magnetism measurements of all metal (M = Ni, Co, Cu, Zn) complexes. All the metal complexes were found diamagnetic, this convinced that all the synthesized Schiff base acted as strong field ligands. Data is compiled in the Table 5.69
173
Results and Discussion Chapter 5
Table 5.69: Magnetic properties of prepared metal complexes Sr. # Metals’ Complexes Molecular Formula Magnetic Behavior
1 Bis4CH3I2CNi C36H30N2NiO4 Diamagnetic
2 Bis4ClI2CNi C34H24Cl2N2NiO4 Diamagnetic
3 Bis2NO2I2CNi C34H24N4NiO8 Diamagnetic
4 Bis4CH3I2CCo C36H30CoN2O4 Diamagnetic
5 Bis4ClI2CCo C34H24Cl2CoN2O4 Diamagnetic
6 Bis2NO2I2CCo C34H24CoN4O8 Diamagnetic
7 Bis4CH3I2CCu C36H30CuN2O4 Diamagnetic
8 Bis4ClI2CCu C34H24Cl2CuN2O4 Diamagnetic
9 Bis2NO2I2CCu C34H24CuN4O8 Diamagnetic
10 Bis4CH3I2CZn C36H30N2O4Zn Diamagnetic
11 Bis4ClI2CZn C34H24Cl2N2O4Zn Diamagnetic
12 Bis2NO2I2CZn C34H24N4O8Zn Diamagnetic
5.8 Study of Antibacterial Activity: Imine ligands and their transition metal complexes were investigated for bacterial activity separately against gram positive bacteria; MRSA, Bacillus subtilis, Staphylococcus aureus; and gram negative bacteria: Pseudomonas aeruginosa, Escherichia coli, and S. typhi.
5.8.1 Antibacterial Activity of Prepared Imine Ligands: The Schiff base ligands were screened for their antibacterial activities against different pathogenic bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, MRSA and S. typhi. The results are given in table 5.70.All the ligands were found active against different experimental pathogens.
Ligand 2NO2I2C was found very active against gram positive bacteria as it showed zones of inhibition with diameter of 10mm, 10mm, and 25mm for MRSA, Bacillus subtilis and S. aureus respectively. While this ligand 2NO2I2C was found passive against gram negative bacteria P. aeruginosa, E. coli and S. typhi. Ligand 4ClI2C was not active against MRSA, Bacillus subtilis and S. typhi. But it (4ClI2C) was found
174
Results and Discussion Chapter 5
exceptionally active against S. aureus, P. aeruginosa and E. coli with zines of inhibition 75mm, 10mm and 55mm respectively. Like ligand 4ClI2C, ligand 4CH3I2C was also inactive against gram positive bacteria MRSA and Bacillus subtilis. On the other hand, it (4CH3I2C) showed opposite behavior towards P. aeruginosa and E. coli while it was quite active against S. aureus with inhibition zone of 75mm and S. typhi with 25mm zone of inhibition.
Table 5.70: Antibacterial activity data of prepared Imine Ligands Diameter of Zone of Inhibition (mm) Synthesized Gram Positive Gram Negative Ligands Bacillus P. S. (50µg) MRSA S. aureus E.coli subtilis aeruginosa typhi 4ClI2C -- -- 75 10 55 --
2NO2I2C 10 10 25 -- -- -
4CH3I2C -- -- 75 -- -- 25 Note: Mean inhibition zones are measured in mm.
All active ligands found were then screened against bacterial species and minimum inhibitory concentration (MIC) were determined. Ligand 2NO2I2C showed the same MIC for MRSA, Bacillus subtilis and S. aureus. 4ClI2C was found very dynamic against S. aureus and E. coli with MIC 10μg while for P. aeruginosa MIC was little higher 20 μg. Data given in Table 5.71 below. Ligand 4CH3I2C was active against only two bacterial species S. aureus and S. typhi with MIC 10 μg and 15 μg respectively.
Table 5.71: MIC of prepared Schiff Base Ligands Gram Positive Gram Negative Synthesized Bacillus S. P. S. Ligands MRSA E. coli subtilis aureus aeruginosa typhi 4ClI2C -- -- 10 μg 20 μg 10 μg --
2NO2I2C 20 μg 20 μg 20 μg ------
4CH3I2C -- -- 10 μg -- -- 15 μg Note: MIC values are μg/ml of Ligands 175
Results and Discussion Chapter 5
5.8.2 Antibacterial Activity of Schiff base Metal complexes: 5.8.2.1 Antibacterial activity of Ni(II) Complexes:
Nickel complexes Bis4CH3I2CNi, Bis4ClI2CNi and Bis2NO2I2CNi were formed with ligands 4ClI2C, 2NO2I2C and 4CH3I2C by the methods mentioned in section 3.4. Nickel complexes were then screened against gram positive and gram negative bacteria. Among these complexes, complex Bis2NO2I2CNi was found most active while Bis4ClI2CNi was found least active. Bis2NO2I2CNi showed maximum activity against MRSA, Bacillus, P. aeruginosa, E. coli and S. typhi with diameters of zones of inhibition 20mm, 20mm, 15mm, 40mm and 30mm while it was inactive against S. aureus. Complex Bis4CH3I2CNi showed activity against gram positive bacteria while remained inactive against the experimental gram negative bacteria. Zones of inhibition for complex Bis4CH3I2CNi against MRSA, Bacillus subtilis and S. aureus were found 30mm, 10mm and 10mm respectively. Nickel complex Bis4ClI2CNi was inactive against many of bacterial species. It remained passive against MRSA, S. aureus, P. aeruginosa and E. coli and was found active against only Bacillus subtilis and S. typhi with zones of inhibition of 115mm and 10mm.Data given in table 5.72.
Table 5.72: Antibacterial Activity of Ni(II) Complexes Diameter of Zone of Inhibition (mm) Nickel Gram Positive Gram Negative Complexes Bacillus S. P. (50µg) MRSA E. coli S. typhi subtilis aureus aeruginosa
Bis4CH3I2CNi 30 10 10 ------Bis4ClI2CNi -- 115 ------10
Bis2NO2I2CNi 20 20 -- 15 40 30 Note: Mean inhibition zones are measured in mm.
Complex Bis2NO2I2CNi was very effective against Bacillus subtilis with MIC 05μg while it showed little activity against MRSA with MIC 25μg as mentioned in table
5.73. MIC for P. aeruginosa, E. coli and S. typhi for complex Bis2NO2I2CNi were found 20μg, 10μg and 10μg respectively. For complex Bis4ClI2CNi, MIC against
Bacillus subtilis was 10μg. As the complex Bis4CH3I2CNi was found inactive against 176
Results and Discussion Chapter 5
experimental gram negative bacteria. For gram positive bacteria MRSA, Bacillus subtilis and S. aureus; MIC were 15μg, 25μg and 20μg. Among nickel complexes,
Bis2NO2I2CNi was found most active. See Table 5.73.
Table 5.73: MIC data of Ni(II) complexes Gram Positive Gram Negative Nickel Bacillus S. P. S. Complexes MRSA E.coli subtilis aureus aeruginosa typhi
Bis4CH3I2CNi 15 μg 25 μg 20 μg ------Bis4ClI2CNi -- 10 μg ------25 μg
Bis2NO2I2CNi 25 μg 05 μg -- 20 μg 10 μg 10 μg
5.8.2.2 Antibacterial activity of Co( II) Complexes Schiff base nickel( II) complexes when compared with complexes of cobalt( II), were found more dynamic against both gram positive and gram negative bacteria. These complexes were remained active against maximum of experimental bacterial species.
When complex Bis4CH3I2CCo was screened, it remained passive against gram positive bacteria MRSA and gram negative E. coli and found active against other experimental bacterial species. Zones of inhibition for Bacillus subtilis, S. aureus, P. aeruginosa and S. typhi for Bis4CH3I2CCo complex are respectively 30mm, 10mm, 15mm, 10mm. Bis4ClI2CCo was the only complex among cobalt(II) complexes which was active against MRSA. For Bacillus subtilis Bis4ClI2CCo had zone of inhibition of 20mm while Bis2NO2I2CCo found most inactive with 10mm zone of inhibition. Bis4ClI2CCo and Bis2NO2I2CCo showed activity against S. aureus with inhibition zone of 25mm and 15mm. When gram negative bacteria were screened for cobalt(II) complexes, Bis4CH3I2CCo and Bis2NO2I2CCo were found almost with equal activity but on the other hand Bis4ClI2CCo was only active against E. coli with
15mm. Diameters of zones of inhibition for complex Bis2NO2I2CCo against P. aeruginosa and S. typhi were found 10mm and 20mm respectively. Detail is given in table 5.74.
177
Results and Discussion Chapter 5
Table 5.74: Antibacterial Activity of Co(II) Complexes Diameter of Zone of Inhibition (mm) Cobalt Gram Positive Gram Negative Complexes Bacillus S. P. (50µg) MRSA E. coli S. typhi subtilis aureus aeruginosa
Bis4CH3I2CCo -- 30 10 15 -- 10 Bis4ClI2CCo 10 20 25 -- 15 --
Bis2NO2I2CCo -- 10 15 10 -- 20 Note: Mean inhibition zones are measured in mm.
Among the four bacterial strains MRSA Bacillus, S. aureus, P. aeruginosa and S. typhi, complex Bis4CH3I2CCo was most active against Bacillus subtilis with MIC 10μg and least effective against S. aureus and P. aeruginosa with MIC 20 μg for both. Bis4ClI2CCo was most active against MRSA with 10 μg and least against S. aureus with MIC 20 μg while its MIC was found 15 μg for both Bacillus subtilis and E. coli. Data given in table 5.75. .MIC of cobalt(II) complex against mentioned bacterial strains Bacillus subtilis, S. aureus, P. aeruginosa and S. typhi were 15 μg, 10 μg, 10 μg and 15 μg respectively.
Table 5.75: MIC data of Co(II) complexes Gram Positive Gram Negative Cobalt Bacillus S. P. S. Complexes MRSA E.coli subtilis aureus aeruginosa typhi
Bis4CH3I2CCo -- 10 μg 20 μg 20 μg -- 15 μg Bis4ClI2CCo 10 μg 15 μg 20 μg -- 15 μg --
Bis2NO2I2CCo -- 15 μg 10 μg 10 μg -- 15 μg
5.8.2.3 Antibacterial activity of Cu( II) Complexes Cu( II) complexes when screened were found less active in comparison to Co( II) complexes. These complexes were found inactive mostly against gram positive bacteria especially MRSA and Bacillus subtilis. Complex Bis4ClI2CCu was found active only against P. aeruginosa and E. coli with 30mm and 110mm while is
178
Results and Discussion Chapter 5
remained inactive against gram positive bacteria MRSA, bacillus subtilis, S. aureus and gram negative bacteria S. typhi. On the other hand, complex Bis4CH3I2CCu was active only against S. aureus with zone of inhibition of 20mm while it was quite active against gram negative bacteria P. aeruginosa, E. coli and S. typhi; their zone of inhibition are respectively 15mm, 95mm and 15mm. complex Bis2NO2I2CCu was active against some of gram positive and gram negative bacteria. For MRSA, S. aureus and E. coli the zones of inhibition were 20mm, 20mm and 15mm while it was totally inactive against Bacillus subtilis, P. aeruginosa and S. typhi. Regarding data is given in the table 5.76 below.
Table 5.76: Antibacterial Activity of Cu( II) Complexes Diameter of Zone of Inhibition (mm) Copper Gram Positive Gram Negative Complexes Bacillus S. P. (50µg) MRSA E. coli S. typhi subtilis aureus aeruginosa Bis4ClI2CCu ------30 110 --
Bis4CH3I2CCu -- -- 20 15 95 15
Bis2NO2I2CCu 20 -- 20 -- 10 -- Note: Mean inhibition zones are measured in mm.
MIC were calculated against both gram positive and gram negative bacteria. Complex Bis4ClI2CCu was found most effective against P. aeruginosa with 10 μg while for E. coli MIC was 15 μg. Complex Bis4CH3I2CCu was equally effective for both S. aureus and P. aeruginosa with MIC 15 μg while for E. coli and S. typhi MIC was 20
μg and 25 μg.For Bis2NO2I2CCu, MIC for MRSA, S. aureus and E. coli were 20 μg, 15 μg and 20 μg respectively. Among all the copper(II) metal complexes, Bis4ClI2CCu was found most active against P. aeruginosa with MIC 10 μg. Data is compiled in table 5.77.
179
Results and Discussion Chapter 5
Table 5.77: MIC data of Cu(II) complexes Gram Positive Gram Negative Copper Bacillus S. P. S. Complexes MRSA E.coli subtilis aureus aeruginosa typhi Bis4ClI2CCu ------10 μg 15 μg --
Bis4CH3I2CCu -- -- 15 μg 15 μg 20 μg 25 μg
Bis2NO2I2CCu 20 μg -- 15 μg -- 20 μg --
5.8.2.4 Antibacterial activity of Zn( II) Complexes: Zinc(II) complexes were also screened against mentioned bacterial strains. Complex Bis4ClI2CZn was very effective against E.coli with zone of inhibition 115mm. Similarly the zones of inhibition for S. aureus and P. aeruginosa were respectively
75mm and 15mm for complex Bis4ClI2CZn. Complex Bis4CH3I2CZn was more active against gram positive bacteria than gram negative bacteria. Zones of inhibition against gram positive bacteria MRSA, bacillus subtilis and S. aureus of
Bis4CH3I2CZn were 35mm, 25mm, 30mmand for gram negative bacteria S. typhi the zone of inhibition was 25mm. For Bis2NO2I2CZn, zones of inhibition for MRSA, Bacillus subtilis, P. aeruginosa, E. coli and S. typhi were 15mm, 20mm, 10mm, 15mm and 15mm while it was found inactive against S. aureus. Data is given in table 5.78.
Table 5.78: Antibacterial Activity of Zn(II) Complexes Diameter of Zone of Inhibition (mm) Zinc Gram Positive Gram Negative Complexes Bacillus S. P. (50µg) MRSA E. coli S. typhi subtilis aureus aeruginosa Bis4ClI2CZn -- -- 75 15 115 --
Bis4CH3I2CZn 35 25 30 -- -- 25
Bis2NO2I2CZn 15 20 -- 10 15 15 Note: Mean inhibition zones are measured in mm.
180
Results and Discussion Chapter 5
MIC for zinc(II) complexes were found. Complex Bis4ClI2CZn showed minimum MIC 10 μg against P. aeruginosa; and for S. aureus and E. coli; MIC were 15 μg and
20 μg. Complex Bis4CH3I2CZn was found equally effective for both MRSA and S. typhi with MIC 15 μg while its MIC values for Bacillus subtilis and S. aureus were 20
μg each. Bis2NO2I2CZn complex showed good activity against many bacterial strains. MIC for bacteria MRSA, P.aeruginosa and E. coli were found 10 μg while for Bacillus subtilis and S. typhi MIC were 20 μg and 15 μg respectively.
Table 5.79: MIC data of Zn(II) complexes Gram Positive Gram Negative Zinc Bacillus S. P. S. Complexes MRSA E.coli subtilis aureus aeruginosa typhi Bis4ClI2CZn -- -- 15 μg 10 μg 20 μg --
Bis4CH3I2CZn 15 μg 20 μg 20 μg -- -- 15 μg
Bis2NO2I2CZn 10 μg 20 μg -- 10 μg 10 μg 15 μg
When these 3d-metal complexes were compared among themselves for their antibacterial activities, Co(II) complexes showed promising activities against maximum gram positive bacterial strains while Cu(II) complexes were least active. Among Cu(II) and Zn(II) complexes, each found active against six gram negative strains while Ni(II) complexes were active against least number of bacterial strains. Metal complexes were found more active against bacteria than simple Schiff bases. This proved that metal chelation increased the antibacterial activities of complexes.
181
Results and Discussion Chapter 5
Conclusion
Present work involves the syntheses, spectroscopic and antibacterial studies of different aniline based imines and their complexes with 3d metals i.e. Nickel, Cobalt, Copper and Zinc. Aromatic ketone namely 3-acetyl-2H-chromen-2-one was prepared by reacting 2-hydroxybenzaldyhyde with ethyl acetoacetate (acacs) in the presence of piperidine; and it was used as starting material. It was then reacted with different anils; namely p-toluidine, p-chloro aniline and 2-nitro aniline; to synthesize Schiff base ligands abbreviated as 4CH3I2C, 4ClI2C and 2NO2I2C. 3d-transition metal complexes abbreviated as Bis4CH3I2CNi, Bis4ClI2CNi, Bis2NO2I2CNi,
Bis4CH3I2CCo, Bis4ClI2CCo, Bis2NO2I2CCo, Bis4CH3I2CCu, Bis4ClI2CCu,
Bis2NO2I2CCu, Bis4CH3I2CZn, Bis4ClI2CZn and Bis2NO2I2CZn were prepared by reacting with imine ligands by template method. Physical properties including colors, physical states, m.p/d,p, experimental yields and
λmax were noted. All imine ligands and respective metals’ complexes were characterized by using both physical and spectroscopic methods. Schiff base ligands were yellow, green and pink in colors and exhibited melting points from 125oC to 131oC while metals’ complexes were decomposed when heated. Their decomposition o o points were comparable ranging from 155 C to 240 C. λmax for each metal complex was noted by UV-visible spectrophotometry. IR spectra confirmed the structures of ligands/metals’ complexes with the presence of absorption bands in specific regions of their respective functional groups. Absorption bands at 1612-1603 cm-1 in IR spectra of ligands confirmed the formation of -HC=N bonds. Absorption bands for ν(C=O) were shifted to lower/higher wavenumbers in metals’ complexes when compared with ligands. New absorption bands at 460-435 cm-1 for metal to nitrogen (M-N) and 355-335 cm-1 for metal to oxygen (M-O) were seen in IR spectra of metals’ complexes. Both shifting of absorption bands and formation of new M-N and M-O bonds confirmed the formation of metal complexes. Amounts of carbon, hydrogen, nitrogen and metal (M) were determined by elemental analysis. Experimental and calculated %ages of elements were very close which also 182
Results and Discussion Chapter 5
confirmed the formation of expected ligands and metals’ complexes. Atomic absorption spectroscopy (AAS) confirmed the presence of metals and their quantitative estimations in complexes. Similarly, metals to ligands ratios were also determined by AAS. It confirmed that in all metal complexes, metals to imine ligands ratio was 1:2 i.e. M(Ligands)2. Thermal gravimetric analysis (TGA) results showed the thermal stabilities of these complexes. Miller indices (hkl) of synthesized complexes except Bis2NO2I2CNi, Bis4CH3I2CCo, Bis2NO2I2CCo, Bis4CH3I2CCu and Bis4ClI2CCu were determined by powder X-ray diffraction technique (PXRD); and were found polycrystalline solids. By VSM, the magnetic properties of these metal complexes were studied. All of the complexes did not show any magnetic properties and were found diamagnetic in character which proved that Schiff bases synthesized during current study acted as strong field ligands. Both synthesized Schiff base ligands and metals’ complexes were then investigated against different strains of gram positive and gram negative bacteria. They showed promising activities against bacteria. Coordination of metals with Schiff bases increased antibacterial activities of complexes than those of simple Schiff bases.
Ligand 4ClI2C showed activity against S. aureus, P. aeruginosa and E.coli; 2NO2I2C was found active against gram positive bacteria only and remained passive against gram negative bacteria while 4CH3I2C showed least activity among all ligands. It showed activity against S. aureus and S. typhi.
Among Ni-complexes Bis2NO2I2CNi showed maximum antibacterial activity against both type of bacterial strains while Bis4CH3I2CNi and Bis4ClI2CNi remained passive towards gram negative bacteria. Cobalt complexes were found mostly active against both types of bacterial strains. Among copper complexes Bis4ClI2CCu showed no activity against gram positive strains while other two Co-complexes were fairly active. Similarly among the Zinc complexes, Bis4ClI2CZn showed minimum antibacterial activity. Minimum inhibitory concentrations (MIC) for imine ligands and metals’ complexes were determined against each bacterial strain. Among ligands 4ClI2C and 4CH3I2C was found highly active with MIC 10μg and among all synthesized metals’ complexes
Bis2NO2I2CNi was most active with MIC 05μg.
183
Chapter 6
References
References Chapter 6
1. P. G. Cozzi, Chem. Soc. Rev, 2004, 33, 410. 2. M. Jerry, “Advanced Organic Chemistry reactions, mechanisms and structure” New York: John Wiley & Sons, inc., 3rd ed. 1985. 3. W. J. Middleton and H. D. Carlson, "Org. Synth." Coll. 1988, 6, 664. 4. Schiff, H.; Ann. Chem., 1864, 3 343. 5. Z. Li, K. R. Conser, E.N. Jacobsen, J. Am. Chem. Soc. 1993, 115, 5326. 6. Taramura K. Nakano J. and Iot S.; Chem. Abstr., 1979, 71, 114093. 7. Zhurin R. B., Rodichera D. L. and Chartorishi B. A.; Zh. Obsch. Khim., 1963, 33, 3360. 8. McCoy F. C. and Knaloy E. C.;Chem Abstr., 1967, 66, 4734. 9. Cyba, H. A.; Chem Abstr., 1968, 68, 6364. 10. Kimura T.; Chem Abstr., 1973, 79, 146264n. 11. Farabenfabrikon Bayer A. G.; Ger. 1., 1956, 108, 659. 12. Badische A. and Soda A. G.; Fabric Brit. 1, 1969, 122, 938. 13. Moraianoos J. J. and Aams S. P.; Adams U. S. Patent, 1976, 3, 960. 14. Costain W. and Terry W. H.; Chem Abstr., 1976, 85, 147255a. 15. Attia Y. A.; Chem Abstr., 1977, 87, 185326y . 16. Kozolv N. S., Pak U. D., Mashevsku V. V. And Khim Planksina; Pharm. Ah., 1973, 7, 15. 17. Cavalline, G., Massarani E., Nardi, D. F. Tenconi and Mauri L.; Chem Abstr., 1965, 62, 1590. 18. Das B., Patra M. and Mahapatra P. K.; J. Ind. Chem. Soc. 1983, 60, 772. 19. Goyal Sudha and Keemti Lal; J. Ind. Chem. Soc. 1989, 66, 477. 20. Chaudhari T. D. and Salensis S. S.; Bull. Hoffkins Inst., 1976, 4, 85. 21. Hodnett E. M. and Money P. D.; J. Med. Chem., 1970, 12, 786. 22. Gutmann A. D.; Chem Abstr., 1977, 87, 6192. 23. Profit E. and Hoegel E.; East Ger. Pat., 1973, 97; Chem Abstr., 1974, 80, 26913. 24. Torihara K.; Jap. Kokai, 948, 7357 (1973); Chem Abstr., 1973, 79, 146264. 25. Popp F. D.; J. Org. Chem., 1961, 26, 1566. 26. Pearson R. G.; J. Chem. Educ., 1968, 45, 581 and 643.
185
References Chapter 6
27. Huges M. N.; The inorganic Chemistry of Biological Process, John Wiley and Sons (London), 1978, 285. 28. Rosenburg B. Van Camp L., Teroski J. E. and Mansour V. H.; Nature, 1969, 222, 385. 29. Kirschner S. and Rutter D. E.; Sci J. 1970, 6, 62. 30. Schuster G., Heinisch L., Scnulze W., Ulbricht H. and Willitzer H.; Phytopathol, 1984, 97, 2. 31. Houji, M. A. Chen S. Niu Lini, Shang S., Li Shulani Zaho S., Quan Zhenlan; J. Electrochem. Soc., 2001, 5, 148. 32. Quan, Zhenlan, Chen, Shenhao, Li Shulan; Corros, Sci., 2011, 43, 1071. 33. Bilgic S., Calskan N.; J. Appl. Electrochem., 2001, 31, 79. 34. Kuznetsov Yu I. and Vagapov R. K.; Russian Academy of Sciences, Moscow. Port. Met., 2001, 37, 210. 35. Popov Yu V., Korchagina T. K. and Chicherina G. V.; Russ. J.Org. Chem., 2001, 37, 677. 36. Dandg N., Nguyen V. N., Tran T. V., Ngugen D. T. and Rham D. N.; Le Xuan Que. Tap Chi Hoa Hoc., 2000, 38, 48. 37. Mehtal N. K. and Agrawal V. S.; Int. Corros. Congr. Proc., 13th Paper, (1996). 38. Li S. L., Chen Shenhao, Lei S., Houyi Ma. and Yu Rui et al.; Corros. Sci., 1999, 41, 1273. 39. Li S. L., Ma H. Y. Lei, S. B. Et al.; Shandong University, Jinan 25011, Peop. Rep. China., 1998, 54, 947. 40. Hyde P. C. and Watkins D. M.; (Johnson, Malthey & Co. Ltd.), Belg., 875, 739 (et. Co. 7F) (1979); Brit. Appl., 1978, 78, 659. 41. Thakur K. N., Bhawal B. M. and Achla B.; J. Ind. Chem. Soc., 1980, 11, 1138. 42. Societe Pour I. E.; Develop, Chem. Abstr., 1969, 71, 37903. 43. Farrow W. M., Calvin H. and Schieler F. W.; J. Am. Pharm. Ass., 1954, 13, 370. 44. Tsukamoto T.; Chem Abstr., 1961, 55, 8796.
186
References Chapter 6
45. Narang K. K. and Gupta J. K.; Curr. Sci., (India), 1976, 45, 536, 744, J. Inorg. Nucl. Chem., 1976, 38, 589. 46. G.H. Olie, S. Olive, Springer, Berlin, 1984, 152. 47. H. Dugas, C. Penney, Bioorganic Chemistry, Springer, New York, 1981, 435. 48. K. Sancak, Mustafa. U. Yasemin, M. Yildirim, I. Degirmencioglu, Transition Metal Chemistry 2007, 32, 16. 49. M.N. Ibrahim, S.E. A. Sharif, E-Journal of Chemistry 2007, 4, 531. 50. M. D. Tsai, J. Biochem., 1978, 17, 3183. 51. F. A. Carey, “Organic Chemistry” 2nd ed., Mc Graw-Hil, 696, 1992. 52. G. Georgiev, Dokl. Bolg. Akad. Nauk., 1981, 34(2), 189. 53. A. E. Braunstan, ‘Definative review of transammination reactions”, “The Enzymes”, 3rd ed., 379, 1973. 54. Zumdahl, S. Steven. “Chemical Principles”, New York: Houghton Mifflin, 5th ed., 944-948, 2005. 55. N. Ahmad, C. Munir, “Chemistry of coordination compounds”, National Academy Of Higher Education, University Grant Commision, H-9 Islamabad, 13-14, 1986. 56. F. A. Cotton, G. Wilkinson and P. L. Gaus, “Basic Inorganic Chemistry”, 3rd ed., John Wiley, 171-172, 1995. 57. W. L. Masterton, E. J. Slowinski and C. L. Stanitski., “Chemical Principles”, 6th ed., Saunders College Publishing, 637-638, 1985. 58. D. J. Curran and S. Siggia, “The Chemistry Of Carbon-Nitrogen Double Bond”, ed. S. Patai, Interscience, 61, 1970. 59. M. Z. Iqbal, H. M. Farooq, M. Q. Zaman and W. A. Shan, J. Sc. Res., XXII, 73-77, 1993. 60. W. J. Middleton and H. D. Carlson, Hexafluoroacetone imine, Org. Synth. 1988, 6, 664. 61. (a) Bruice, P.Y., Organic Chemistry, 5th. edn., 2007, Pearson Education Inc.; (b) Thomas, C.W., Mak, Xiao-Li, Z., Encyclopedia of Inorganic Chemistry, 2nd edn., 2006, Wiley, New York.
187
References Chapter 6
62. Schiff, H., Ann. Chem., 1859, 131, 1-59; (b) Layer, W., Chem. Rev., 1963, 63, 489–510. 63. P.G Cozzi. Chemical Society Reviews, 2004, 33, 410-421. 64. A. Dijksman, I.W.C.E. Arends, R.H. Sheldon, Chem. Commun. 1999, 1591. 65. R.I. Kureshy, N.H. Khan, S.H.R. Abdi, S.T. Patel, P. Iyer, J. Mol. 1999, 150,175. 66. S. Lin, Y. Zhen, S.M.Wang, Y.M. Dai, J. Mol. Catal. A Chem 2000, 156, 113. 67. J.B. Berna, A.pazari, J.Org.Chem. 2000, 65, 2344. 68. W.Adam, W.A. Hermann, J.Org.Chem. 1994, 39, 8281. 69. G. Venkatachalam, N. Raja, D. Pandiarajan, R. Ramesh, Spectrochimica Acta Part A 2008, 71, 884. 70. R. Karvembu, K. Natarajan, Inorganic Chemistry Communications 2003, 6, 486. 71. T. D. Thangadurai, K. Natarajan, Transition Metal Chemistry 2000, 25, 347. 72. R. Ramesh, Inorganic Chemsitry Communications 2004, 7, 274. 73. R. Prabhakaran, R. Huang, K. Natarajan, Inorganica Chimica Acta 2006, 359, 1114. 74. V.B Sharma, S.L. Jain, B. Sain, Journal of Molecular Catalysis A: Chemical 2004, 212 (1-2), 55. 75. F. Hosseinpoor, H. Golchoubian, Tetrahedron Letters 2006, 47, 5195. 76. S.M. Islam, P. Mondal, K. Tuhina, A.S. Roy, D. Hossain, S. Mondal, Transition Metal Chemistry 2010, 35, 891. 77. T. Ohkuma, H. Ooka, S. Harshiguchi, T. Ikariya, R. Noyon, J. Am. Chem. Soc. 1995, 117, 2675. 78. V. Cadierno, P. Crochet, J. Diez, J. Garcia-Alvarez, S.E. Garcia-Garrido, S. Gaxcia-Granda, J. Gimeno, M.A. Rodriguez, J. Chem. Soc., Dalton Trans. 2003, 3240. 79. R. Noyon, T. Ohkuma, Angew. Chem. Int. Ed. 2001, 40, 40. 80. V. Arun, N. Sridevi, P.P. Robinson, S. Manju, K.K.M. Yusuff, Journal of Molecular Catalysis A: Chemical 2009, 304, 191.
188
References Chapter 6
81. G. Venkatachalam, R. Ramesh, Inorganic Chemistry Communications 2006, 9, 703. 82. S. Alexander, V. Udayakumar, V. Gayathri, Journal of Molecular Catalysis A: Chemical 2009, 314 (1-2), 21. 83. M.K. Dalal, R.N. Ram, Studies in Surface Science and Catalysis 130 D, 2000 3435. 84. R. Antony, G.L. Tembre, M. Ravindranathan, R.N. Ram, Journal of Applied Polymer Science 2003, 90, 370. 85. Y. Himeda, N. Onozawa-Komatsuzaki, H. Sugihara, H. Arakawa, K. Kasuga, Journal of Molecular Catalysis A: Chemical 2003, 19 , 95. 86. M. Costa, P. Pelagatti, C. Pelizzi, D. Rogolino. Journal of Molecular Catalysis A: Chemical 2002, 178, 21–26. 87. E.M. McGarrigle, D.G. Gilheany. Chemical Reviews, 2005, 105, 1563-1602. 88. S.H. Zhao, P.R. Ortiz, B.A. Keys, K.G. Davenport. Tetrahedron Letters, 1996, 37, 2725-2728. 89. I. Fernández, J.R. Pedro, R. Salud. Tetrahedron, 1996, 52, 12031-12038. 90. R.I. Kureshy, N.H. Khan, S.H.R. Abdi, S.T. Patel, P.K. Iyer, R.V. Jasra. Journal of Catalysis, 2002, 209, 99-104. 91. R.I. Kureshy, N.H. Khan, S.H.R. Abdi, P. Iyer. Journal of Molecular Catalysis A: Chemical, 1997, 124, 91-97. 92. R. Drozdzak, B. Allaert, N. Ledoux, I. Dragutan, V Dragutan, F. Verpoort. Coordination Chemistry Reviews 2005, 249, 3055–3074. 93. R. Souane, F. Isel, F. Peruch, P.J. Lutz. Comptes Rendus Chimie, 2002, 5, 43- 48. 94. D.P. Knight, A.J. Clarke, B.S. Kimberley, R.A. Jackson, S. Peter. Chemical Communication. 2002, 352-353. 95. K.P. balasubramanian, K. Parameswan, V. Chinnusamy, R. prabhakaran, K. Natarajan, Spectrochim. Acta Part A 2006, 65, 678. 96. S. Ren, R. Wang, K. Komatsu, P.Bonaz-Krause, Y. Zyrianov, C.E. McKenna, C.Csipke, Z.A. Tokes, E.J. Lien, J.Med. Chem. 2002, 45, 410. 97. A. Altundas, N. San, N. Colak H. Ogutcu J. Med Chem Res. 2010, 19, 576.
189
References Chapter 6
98. M. Kumar, Orient J. Chem 2002, 18, 559. 99. A. K. Mishra, S. B. Mishra, N. Manav, D. Saluja, R. Chandra, N. K. Kaushika, Bioorganic & Medicinal Chemistry 2006, 14, 6333. 100. R. Prabhakaran, S.V. Renukadevi, R. Karvembu, R. Huang, J. Mautz, G. Huttner, R. Subashkumar, K. N, European Journal of Medicinal Chemistry 2007, 1. 101. K.N. Kumar, R. Ramesh, Spectrochimica Acta part A. 2004, 60, 2913. 102. F. Grums, P. Gurkah, Gunduz N, (FABAD) Farm Bilmer Derg, 1994, 19, 5. 103. M.D. Deshmukh, A.G. Doshi, Orient J Chem, 1995, 11, 86. 104. N. Raman, A. Sakthivel, K. Rajasekaran, Mycobiology 2007, 35, 150. 105. N. Raman, S. Parameswari, Mycobiology 2007, 35, 65. 106. L. R. Kelland, N. P. Farrell, The Pathway to Oral Therapy (Humana Press, Totowa) 2000, 299. 107. D.S. Sigman, D.R. Graham, V.D. Aurora, A.m. Stern, J. Biol. Chem. 1979, 254, 12269. 108. E. Wang, L. Qin, M. Fan, “Transient Absorption Spectra and Photochromic Mechanism of Schiff bases”, “Research On Chemical Intermediates” 1993, 19 (4), 299-306. 109. M. D. Cohen and S. Flavian, J. Chem. Soc., B, 1967, 321. 110. E. Hadijoudis, I. M. Mavridis, “Photochromism and Thermochromism of Schiff bases In Solid State”, Chem. Soc. Rev., 2004, 33, 579-588. 111. N. Ahmad, C. Munir, “Chemistry of coordination compounds”, National Academy Of Higher Education, University Grant Commision, H-9 Islamabad, 110, 1986. 112. F. Basolo and R. C. Johnson, “Coordination Chemistry; The Chemistry Of Metal Complexes”, W. A. Benjamin, inc., 130-131, 1964. 113. N. Ahmad, C. Munir, “Chemistry of coordination compounds”, National Academy Of Higher Education, University Grant Commision, H-9 Islamabad, 128, 1986. 114. J. E.Huheey “Inorganic Chemistry” 4th ed., 82-95, 2002.
190
References Chapter 6
115. N. N. Greenwood and A. Earnshow “Chemistry Of The Elements”, 1st ed., Pergamon Press, 1379, 1984. 116. L. G. Sillen and G. Martell, “Stability Constants” Chem. Soc., Suppl. 2nd ed. Pub. No. 25, 1971. 117. H. S. Maslem and T. N. Waters, Coord. Chem. Revs., 1975, 17, 137. 118. H. W. Joseph, Bull. John Hopkins Hosp., 1931, 499, 246. 119. R. J. Carrico and H. J. Deutsch, J. Biol. Chem., 1973, 245, 723. 120. B. L. Valee and W.E.C. Wacker, “The Proteins”, 2nd ed., Vol.5, Acad. Press, N.Y. 1974. 121. T. P. Grant and T. L. Combs, “Essays in Biochemistry” 1970, 6, 69. 122. R. P. Hausinger, “Nickel utilization by Microorganism”, Microbial Review, 1987, 51(1), 22-42. 123. Cracan, Valentin; Banerjee, Ruma, 2013. "Chapter 10 Cobalt and Corrinoid Transport and Biochemistry". In Banci, Lucia (Ed.).Metallomics and the Cell. Metal Ions in Life Sciences. 124. Voet, Judith G.; Voet, Donald, 1995. Biochemistry. New York: J. Wiley & Sons. p. 675. 125. Smith, David M.; Golding, Bernard T.; Radom, Leo. Journal of the American Chemical Society 1999, 121, (40): 9388. 126. Kobayashi, Michihiko; Shimizu, Sakayu. European Journal of Biochemistry 1999, 261 (1), 1–9. 127. El-ajaily, M.M., Maihub, A.A., Hudere S.S. & Ben Saber S. M. Asian Journal of Chemistry Society, 2006, 18(4), 2427- 2430. 128. Luria, Adams and Ting. Virology 1960, 12, 348. 129. Miller. 1972. Experiments in molecular genetics. Cold Spring Harbor Laboratory, Cold Spring Harbor,N.Y. 130. Ausubel, Brent, Kingston, Moore, Seidman, Smith and Struhl (ed.). 1994. Current protocols in molecularbiology, vol. 1. Greene Publishing Associates, Inc., Brooklyn, N.Y. 131. Tuite, J. Plant Pathological Methods, Fungi and Bacteria; Burgess Publishing Company: Minneapolis, MN, USA, 1969; p. 93.
191
References Chapter 6
132. National Committee for Clinical Laboratory Standards. NCCLS Approved Standard M27-A. Wayne: Pennsylvania, PA, USA, 1997. 133. K.N. Kumar, R. Ramesh, Spectrochimica Acta Part A. 2004, 60, 2913. 134. A. Altundas, N. Sari, N. Colak H. Ogutcu J. Med Chem Res. 2010, 19, 576. 135. L. D. Gebbharadt, J. G. Bachtold, Proc. Soc. Exptl. Biol. Med., 1955, 88, 103. 136. Klevens, Monina R., Morrison, Melissa A., Nadle, Joelle, et al. Journal of the American Medical Association 2007, 298.15: 1763-71. 137. Perez, A.R., A. Abanes-De Mello, K. Pogliano. Journal of Bacteriology. 2000 February; 182(4): 1096-1108. 138. Schaechter, M., J.L. Ingraham, F.C. Neidhardt. Microbe. (ASM Press, Washington, DC, 2006). 139. Cryz, S. J., Jr., E. Furer, L. S. Baron, K. F. Noon, F. A. Rubin, and D. J. Kopecko. 1989. 57:3863-3868. 140. Ashcroft, M. T., C. C. Nicholson, S. Balwant, J. M. Ritchie, E. Sobryan, and F. Williams. 1967, 2, 1056-1059. 141. Cvjetanovic, B., and K. Uemura. Bull. W.H.O. 1965, 32:29-36. 142. Hejfec, L. B., L. V. Salmin, M. Z. Lehtman, M. L. Kuzminova, A. V. Vasileva, L. A. Levinna, T. G. Bencianova, E. A. Pavola, and A. A. Antonova. Bull. W.H.O.1966, 34:321-329. 143. Levine, M. M., D. Hone, C. Tacket, C. Ferreccio, and S. Cryz. Microbiol. 1990, 141:807-816. 144. J. A. Wlamsby and S. A. Tyree, Inorg. Chem., 1963, 2, 312. 145. R. Barbieri, R. Caflne, S. C. Chanelra and R. H. Herber, J. Organometallic Chem., 1971, 32, 97. 146. J.E. Kovacie, Spectrochim Acta, A, 1967, 23, 183. 147. A.A. Soliman and W. Linert, Thermochimica Acta, 1999, 333, 67-75. 148. Angela kriza, Lucica viorica, Nicoleta cioatera., J. Serb. Chem. Soc, 2010, 75 (2), 229-249. 149. M. S. Iqbal, Ph.D Thesis, University of Strathelyde, U.K. 1982. 150. Figgis. B. N, Lewis. J., Prog. Inorg. Chem., 1954, 157, 37-67. 151. O.P. Sing and Tanden. J. Ind.Chem. Soc., 1979, 56(4), 331.
192
References Chapter 6
152. S. T. Chow, D. M. Jones and C. A. MacAuliffe, Inorg. Chim, Acta, 1977, 22, 1. 153. G. H. Rist, J. S. Hyde and T. Vangard, Proc. Natl. Acad Sci., 1977, 77, 1339. 154. M. Arif, S. Rehman, K. Masud and N. Arshad, Turk. J. Chem., 2001, 25, 73. 155. E. Mirica, G. Kowach, H. Du, Modified Structure Zone Model to Describe the Morphological Evolution of ZnO Thin Films Deposited by Reactive Sputtering, Crystal Growth & Design, 2004, 4, 157-159
193
Appendix-I (IR-Spectra)
IR-Spectra Appendix-I
Scan 5.1: IR spectrum of 3 – acetyl -2 H – chromen - 2 –one
Scan 5.4: IR-Spectrum of 4CH3I2C
195
IR-Spectra Appendix-I
Scan 5.8: IR-Spectrum of 4ClI2C
Scan 5.12: IR-Spectrum of 2NO2I2C
196
IR-Spectra Appendix-I
Scan 5.16: IR spectrum of Bis4CH3I2CNi
Scan 5.18: IR spectrum of Bis4ClI2CNi
197
IR-Spectra Appendix-I
Scan 5.21: IR spectrum of Bis4CH3I2CCo
Scan 5.22: IR spectrum of Bis4ClI2CCo
198
IR-Spectra Appendix-I
Scan 5.24: IR spectrum of Bis2NO2I2CCo
Scan 5.25: IR spectrum of Bis4CH3I2CCu
199
IR-Spectra Appendix-I
Scan 5.26: IR spectrum of Bis4ClI2CCu
Scan 5.27: IR spectrum of Bis2NO2I2CCu
200
IR-Spectra Appendix-I
Scan 5.29: IR spectrum of Bis4CH3I2CZn
Scan 5.31: IR spectrum of Bis4ClI2CZn
201
IR-Spectra Appendix-I
Scan 5.33: IR spectrum of Bis2NO2I2CZn
202
Appendix-II (NMR-Spectra)
NMR-Spectra Appendix-II
Scan 5.2: 1H NMR of 3 – acetyl -2 H – chromen - 2 -one
Scan 5.3: 13C NMR of 3 – acetyl -2 H – chromen - 2 -one
204
NMR-Spectra Appendix-II
1 Scan 5.5: H NMR of 4CH3I2C
13 Scan 5.6: C NMR of 4CH3I2C
205
NMR-Spectra Appendix-II
Scan 5.9: 1H NMR of 4ClI2C
Scan 5.10: 13C NMR of 4ClI2C
206
NMR-Spectra Appendix-II
1 Scan 5.13: H NMR of 2NO2I2C
13 Scan 5.14: C NMR of 2NO2I2C
207
Appendix-III (Publications)
Publications Appendix-III
1. HABIB HUSSAIN, SYEDA RUBINA GILANI, FARKHANDA JABEEN, ZULFIQAR ALI, HAJIRA REHMAN and IMDAD HUSSAIN; Synthesis and Antibacterial Activity of Zn(II) Schiff Base Complexes derived from 3-acetyl- 2H-chromen-2-one; Asian Journal of Chemistry; Vol. 27, No. 9 (2015), 3440- 3444
2. HABIB HUSSAIN, SYEDA RUBINA GILANI, ZULFIQAR ALI, HAJIRA REHMAN and IMDAD HUSSAIN; Synthesis and Characterization of Novel (E)-1-(Hexa-3,5-dien-1-yl)-4-methoxybenzene via Boronate Complex; Asian Journal of Chemistry; Vol. 26, No. 21 (2014), 7401-7403
3. HABIB HUSSAIN, SYEDA RUBINA GILANI, ZULFIQAR ALI and IMDAD HUSSAIN; Asymmetric Synthesis, Characterization and Stereoselectivity of Novel 1-{2-[(1R,2S)-2- (Chloromethyl)cyclopropyl]ethyl}-4-methoxybenzene via Boronate Complex; Asian Journal of Chemistry; Vol. 26, No. 8 (2014), 2437-2442
4. HABIB HUSSAIN, SYEDA RUBINA GILANI, ZULFIQAR ALI and IMDAD HUSSAIN; Effect of Increase in Steric Bulk of Aryl lithium on Stereoselectivity of Boronate Complexes; Asian Journal of Chemistry; Vol. 25, No. 17 (2013), 9965-9969
5. H. HUSSAIN, S. R. GILANI, Z. ALI and I. HUSSAIN; Synthesis and Characterization of Novel (E)-tert-butyl 7-(4-methoxyphenyl)-5-(4,4,5,5- tetramethyl-1,3,2-dioxaborolan-2-yl)hept-2-enoate and (E)-diethyl (6-(4- methoxyphenyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hex-1-en-1- yl)phosphonate; Application of Olefin Cross Metathesis; Pak. J. Chem. 3(4): 1-9, 2013
6. HABIB HUSSAIN, SYEDA RUBINA GILANI, ZULFIQAR ALI, HAJIRA REHMAN and IMDAD HUSSAIN; Syntheses of Imines, their Ni (II) Complexes and Study of Antibacterial Activity against various Bacterial Strains; Asian Journal of Chemistry; (Submitted)
209
Publications Appendix-III
7. ZULFIQAR ALI, SYEDA RUBINA GILANI, HABIB HUSSAIN, HAJIRA REHMAN and IMDAD HUSSAIN Synthesis, characterization and study of antibacterial activity of bis [3-acetyl-2H-chromene-2-one] silver (IV); Asian Journal of Chemistry; (Submitted)
8. ZULFIQAR ALI, MIRZA NAMAN KHALID, SYEDA RUBINA GILANI, HABIB HUSSAIN, HAJIRA REHMAN, IMDAD HUSSAIN AND AYESHA SADIQA; Synthesis and Antibacterial Activity of Coumarin and its Derivatives; Asian Journal of Chemistry; Vol. 27, No. 9 (2015), 3321-3324
9. ZULFIQAR ALI, SYEDA RUBINA GILANI, FARKHANDA JABEEN, HABIB HUSSAIN, HAJIRA REHMAN and IMDAD HUSSAIN; Investigation of Antibacterial Activity of Alanine and Phenylalanine Derived Weinreb Amides Against Different Bacterial Strains; Asian Journal of Chemistry; Vol. 26, No. 20 (2014), 7067-7068
10. ZULFIQAR ALI, SYEDA RUBINA GILANI, HABIB HUSSAIN and IMDAD HUSSAIN; Conversion of Alanine and Phenylalanine into Weinreb Amides by Using Different Protecting Groups; Asian Journal of Chemistry; Vol. 26, No. 20 (2014), 6733-6736
11. ZULFIQAR ALI, RUBINA GILANI, HABIB HUSSAIN, IMDAD HUSSAIN; Quantitative Determination of Deltamethrin in Milk, Blood and Urine of Domestic Animals; IOSR Journal of Applied Chemistry; Volume 5, Issue 1 (Jul. – Aug. 2013), PP 51-56
12. IMDAD HUSSAIN, RUBINA GILLANI, VICKIE MCKEE, MUHAMMET KOSE, ZULFIQAR ALI, HABIB HUSSAIN, ZILLE HUMA; Synthesis, Characterization and X-Ray Crystal Structure of a DiZinc(II) complex of a Pseudocalixarene macrocycle based on 2, 2-methylene-bis[(6-formyl)-4-tert- butylphenol] and 1, 3-diamino-2-propanol; Asian Journal of Chemistry; Vol. 27, No. 7 (2015), 2630-2634
210
Publications Appendix-III
13. IMDAD HUSSAIN, RUBINA GILLANI, VICKIE MCKEE, HABIB HUSSAIN and ZULFIQAR ALI; Synthesis, Characterization and X-Ray Crystal Structure of Macrocyclic Ligand Based on 2,2-Methylene-bis[(6- formyl)-4-tert-butylphenol] and 1,2-bis-(2-aminoethoxy)ethane; Asian Journal of Chemistry; Vol. 26, No. 18 (2014), 6202-6206
14. IMDAD HUSSAIN, RUBINA GILLANI, VICKIE MCKEE, HABIB HUSSAIN and ZULFIQAR ALI; Synthesis, Characterization and X-Ray Crystal Structure of Copper Complex with 18-Crown-6; Asian Journal of Chemistry; Vol. 26, No. 13 (2014), 3953-3957
15. IMDAD HUSSAIN, RUBINA GILLANI, ZILLE HUMA, MUHAMMET KOSE, HABIB HUSSAIN, ZULFIQAR ALI; Templated Self-Assembly and Crystal Structure of Methyl Pamoate and its Polynuclear Clusters With Nickel(II) and Barium(II); Asian Journal of Chemistry (Submitted 2015)
211