Optical properties of Graphene Quantum Dots

Himadri Sekhar Tripathi1,, Rajesh Mukherjee *2 , T.P. Sinha1 1Department of Physics, Bose Institute, 93/1, APC Road, Kolkata, India – 700009 2Department of Physics, , Bishnupur, Bankura, India –722122 *Corresponding author: [email protected]

ABSTRACT: Graphene quantum dots (GQDs) exhibit interesting chemical and physical properties due to the quantum confinement and edge effect. GQDs were prepared by simple pyrolysis of citric acid. Room temperature X-ray diffraction (XRD) pattern of the sample is carried out from 0 0 Bragg angle 2θ = 5 to 80 with the Rigaku Miniflex II diffractometer having Cu Kα radiation (λ = 0.1542 nm). The UV–Visible spectrum of the materials was collected using UV–Vis spectrophotometer (Shimadzu UV 2401Pc). The photoluminescence (PL) spectra of GQDs were taken by JASCO FP-8500.

INTRODUCTION: Semiconductor nanocrystal or quantum dots are Nano particles of ten of atoms but confined in a very small region. These are zero dimensional materials and are gaining attention to the researchers because of their interesting optical, electronic and opto-electronic properties compared to bulk. Quantum mechanical confinement plays a key role in determining the peculiar behaviour compared to bulk. GQDs exhibit interesting chemical and physical properties due to the quantum confinement and edge effect. As the number of carbon atoms in edge is more than in basal plane, GQDs are more reactive.

SYNTHESIS: Five grams of citric acid was heated and melted at 650C-700C temperature. This melted citric acid was converted into dark orange color within 25 – 30 min. Then this dark citric acid solution was kept at room temperature. 2 M solution of NaOH was added drop wise in the melted dense solution of citric acid at room temperature. PH of the solution was tested for several times. Finally, the GQDs are prepared at PH level 11. The temperature of the solution was increased slowly and was dried at temperature ~ 500C to get in powder form.

C X-ray diffraction peak at Bragg angle 2θ=18.420 corresponds to the inter layer H spacing 0.468 nm. Again another diffraction peak at 2θ=30.420, corresponding A the d spacing 0.293 nm. The inter layer spacing of GQDs is broader than graphite which suggests more oxygen containing functional group attached to R GQDs.

A 3 251 nm Bandgap of GQD C 440 nm 2000 460 nm

470 nm 10 T 2 (a.u)

480 nm

0.5 )

 66.82 nm h 100

E 

(

1000 R 80 1 0

2.7 3.6 4.5 Absorbance(a.u) I Absorbance (a.u) h (eV) 60 Z 0 40 0 A 500 600 700 200 300 400 500 600 700 800 900 Intensity (%) wavelength (nm) wavelength (nm) 20 T (a) (b) 0 0 50 100 150 I Size (nm) O The emission peaks in the UV-Visible spectra confirm that Dynamic light scattering (DLS) analysis N photoluminescence spectra are red shifted GQDs show optical absorption with the increase of excitation wavelength. shows that average size of the particles is in the visible region. found to be ~ 65 nm.

CONCLUSION: GQD can be synthesized by a simple process. Room temperature XRD data confirm the formation of the material. Optical property shows that the material can be a good candidates for optical applications. REFERENCES: 1. Rajesh Mukherjee. Quantum dots: Properties, Synthesis and Applications. Research & Reviews: Journal of Physics. 2020; 9(1): 1–4p. 2. Himadri Sekhar Tripathi, Rajesh Mukherjee, Moumin Rudra, Ranjan Sutradhar, R. A. Kumar, T. P. Sinha, AIP Conference Proceedings, 2019: 2162(1):020088 Molecular Dynamics simulation of human rennin Abhik Chatterjee, Biswajit Das, Uttam Kumar Mondal Insilico Chemical Laboratory, Department of Chemistry, Raiganj University,Raiganj-733134. [email protected]

Introduction: Renin is a hormone enzyme produced from the inactive protein prorenin. Renin initiates renin-angiotensin system (RAS) producing the angiotensin peptides that control blood pressure, cell growth, apoptosis and electrolyte balanced. Renin is highly specific aspartic proteinases and mainly produced by Juxtaglomerular cell in the kidney. The Secretion of renin from Juxtaglomrular cell is controlled by several mechanisms, including the sympathetic nervous system, salt and fluid balance, and blood pressure. It cleaves angiotensinogen to form the decapeptide angiotensin I. Then inactive decapeptide converted to active octapeptide angiotensin II by the angiotensin converting enzyme (ACE). Next the angiotensin II binds to the type 1 angiotensin II receptors (AT1). Stimulation of type 1 angiotensin II receptor increases arterial tone and also the secretion of aldosterone. Therefore angiotensin II plays a key role in blood pressure, fluid and electrolyte homeostasis. In this study MD simulation was performed to consider the flexibility of protein. The MD simulation was carried out using GROMACS software. The 2.00 A° resolution x-ray structure of Human renin (PDB code 3GW5) was used as a starting structure. The overall structural stability of the free protein during the simulation has been monitored using several parameters likes the radius of gyration (Rg), RMSF etc., were calculated over the course of the simulation. Methodology: The MD simulation was carried out using GROMACS. The 2.00 A° resolution x-ray structure of Human renin (PDB code 3GW5) was used as a starting structure. We have carried out MD simulation of free protein not the complex. The protein was solvated with SPC water molecules in a cubic box, having an edge length of 3.5 A°. The LINCS algorithm was employed to constrain all bond lengths. The simulation was conducted at a constant temperature (300K) and the Berendsen coupling method was used for coupling each component separately to a temperature bath. MD simulation was performed for 6 ns. Before running simulation, an energy minimization was performed by steepest descent (sd) method. After that the positional restraints were released and simulation is performed for 6ns with time step 2 fs. Finally the end of the simulation the respective trajectory files were examined with different tools of GROMACS. Results and Discussions: The overall structural stability of the free protein during the simulation has been monitored using several parameters likes the radius of gyration (Rg), RMSF and RMSD of individual residues were calculated over the course of the simulation.. The variation of radius of gyration (Rg) as a function of time is presented in Figure 2 and from this figure it is clear that the initial Rg value is 2.68172 and then Rg value decreases up to 437ps with Rg value 2.6126, after that Rg slightly increases up to 5261ps(2.69299). The overall plot of Rg during the simulation shows a periodical nature. The flexibility of different segments of the protein is also revealed by looking at the root mean-square fluctuation (RMSF) of each residue from its time-averaged position is presented in Figure3.. Among the secondary structure beta strand has higher fluctuation than alphahelix. There is ten Helix in both chains (A&B) within the protein in which Helix, H2 in chain B has highest fluctuations and Helix H10 in chain A has lowest fluctuations. Heilix H2, H4, H6 and H8, in chain A and H13, H14, H16, H17and H18 in chain B shows considerable fluctuations. Acknowledgement: Authors are thankful to Late Prof. Asim kumar Bothra. Figure 1. Protein 3GW5 Figure 2. Radius of gyration (Rg) as a function of time with respect to starting structure during the MD simulations. Figure 3. Root mean square fluctuations (RMSF) during the MD simulations. Dr. Amit Kumar Dutta, Assistant Professor,Department of Chemistry, Bangabasi Morning College

Substitution of A by T

Mutation is define as a change in nucleotide sequence of DNA (Thalassemia) Premature termination (during synthesis) of protein, functional activity may be destroyed. Some Viral vectors (carrier )(a modified Virus)) are used in gene therapy to deliver genetic material into cells, to restore the function of the protein., as vaccines, and for cancer therapy

Virus has been modified in a laboratory so they can't cause disease when used in people for gene therapy, as vaccines

Adenovirus vectors (most commonly employed vector, target and destroy cancer cells while leaving normal cells unharmed. Anti-leishmanial activities of palladium(II) and platinum(II) complexes of glyoxalbis(N-aryl)osazone ligand Dr. Amit Saha Roy Assistant Professor, New Alipore College, Kolkata-53 E-mail: [email protected]

NHPhH2 NH(ClPh)H2 NHPhH2 Abstract: These work report the synthesis and characterisation of four Pd(II) and Pt(II) complexes [Pd(L )Cl2] (1), [Pd(L )Cl2] (2), [Pt(L )Cl2] (3) and NH(ClPh) [Pt(L H2)Cl2] (4) containing osazone ligands including single crystal X-ray diffraction of 2 and 4. All the complexes 1-4 were characterized by different spectral study (IR, UV-vis, NMR, and Mass). Complexes 3 and 4 can be reversibly reduced and the electro-generated anions [3]•‒ and [4]•‒ show EPR parameters indicative for the localization of the unpaired electron on the osazone ligand. DFT calculations support this. Cell viability experiments (MTT assay) show that the complexes are potent anti-leishmaniasis agents while their anti-bacterial and anti-fungal activities are low.

In cyclic voltammetry 3 and 4 display quasi-reversible (ipc/ipa ≈ 1.2) waves at –1.28 (0.22) and –1.11 (0.21) V whereas the anodic waves of both 3 and 4 are NH(ClPh) • irreversible and appear at +0.97 and +0.75 V, respectively (L H2 = osazone anion radical).

(3) (4) Fig. 2 Cyclic voltammograms NHPh of [Pt(L H2)Cl2](3)and NH(ClPh) [Pt(L H2)Cl2] (4) (scan rate:100) in CH2Cl2 NHPh NHPh Fig. 1 Molecular geometries of cis-[Pd(L H2)Cl2] (2 )and cis-[Pt(L H2)Cl2] (4) solvent at 298K.

EPR spectra of the electro-generated [3] and [4]  (a) (b) Fig.4 Spin density plot of (a) [3] and (b) [4] ions were recorded in CH2Cl2 solution at 298 K.

Fig. 5 Spectroelectrochemical (a) (b) (a) (b) measurements of 3 and 4 showing the change in electronic spectra of electrochemically generated (a) [3]– and (b) [4]– ions in

CH2Cl2 at 298 K.   Fig. 3 X-band EPR spectra of (a) [3] and (b) [4] in CH2Cl2 solutions at 298 K. (black = experimental, red = simulated).

The anti-leishmanial activity in terms of killing of both the pathogenic and non-pathogenic strains of Leishmaniadonavani was recorded in this investigation. Both the compounds showed excellent anti-leishmanial effect at a dose of 15 µg/ml after 72 hrs of exposure. After the exposure to platinum and palladium complexes, the killing of the Leismania promastigote was higher with 3 for non-pathogenic strain (UR-6) while pathogenic strain (AG 83) appeared to be slightly less sensitive. However the dose of the platinum complexes used here was very much comparable to that of standard drug, SAG and hence it has tremendous potentiality as an anti- leishmanial therapeutic agent. When the complexes 1 and 3 were compared for their killing efficiency, 3 appeared to be more effective than 1.

Fig. 6 Cell viability with different concentration (0-100µM). Raw 264.7 cells were Fig. 7 Cell viability with different concentration against leishmania promastigote treated with all of these 6 compounds for upto 72 hrs and cell viability was assayed. with incubation time 24 h.

Conclusion: This work reported synthesized and well characterize platinum and palladium complexes of glyoxalbis(N-aryl)osazone ligand Ref: New J. which shows promising properties to act as antileshmanial agents. This particular work diversifies the applicability of osazones beyond its well Chem., 2019, established redox-active behaviors and opens up the new opportunity to explore the biological activities including the anticancer activity. 43, 9891-9901 . Crossover from Antiferro- to Ferromagnetic Exchange Coupling in a New Family of Bis-(µ- Phenoxido)dicopper(II) Complexes: A Comprehensive Magneto-Structural Correlation by Experimental and Theoretical Study Dr. Dhrubajyoti Mondal Department of Chemistry, Government General Degree College, Mangalkote (GGDCM), Purba Bardhaman, West Bengal 713132, India E-mail: [email protected]

Introduction Magenetic Properties Magnetic Materials in Technology: Magnetic materials are very important in modern technology Temperature dependence of T for compounds 1 – 5 measured under a 1000 Oe dc field. Solid lines Structural and Magnetic Fit Parameters for and industry and have been used in many everyday applications such as electric motors, sensors, Complexes 1 – 5. generators, hard disk media, and spintronic memories. correspond to the fit using the Bleaney-Blowers equation. Comp Average Cu···Cu J (cm1) g Molecular Magnetism and Bioinorganic Chemistry: Dinuclear copper(II) complexes with a Cu2O2 lexes Cu-O-Cu Distance core generated by the bridging hydroxido, alkoxido, and phenoxido ligands have received wide Angle (º) (Å) interest in contemporary coordination chemistry because of their relevance to bioinorganic 1 98.63 2.9822(16) 395.1 ± 0.6 2.237 ± 0.005 chemistry, as well as in molecular magnetism. 2 97.92 2.9927(4) 259.4 ± 0.8 1.784 ± 0.006 3 94.39 2.8730(2) 185.4 ± 0.4 2.242 ± 0.002 Antiferromagnetic vs ferromagnetic coupling: 4 86.95 2.7205(4) +46 ± 2 2.122 ± 0.004 5 83.27 2.6327(6) +53.2 ± 0.4 2.039 ± 0.0009 Field dependence of the magnetization at 1.8 K for compounds 4 and 5. The solid lines correspond to the fit with a Brillouin function.

Many structurally characterized bis(µ-phenoxido) dicopper(II) complexes are known, except of  Antiferromagnetic: 1, 2 , 3 (S = 0) few examples, the copper(II) ions in dimers are almost exclusively antiferromagnetically coupled.  Ferromagnetic: 4 , 5 (S = 1) Synthetic Scheme and Characterization  χT values (RT) : 0.39 (1), 0.49 (2), 0.70 (3), 0.84 (4), and 0.81 (5) cm3 mol−1 K Ligands R1 R2 R3 R1,R2,R3 (H2L )  Linear Correlations of Cu−O−Cu angle Me,Me,Me H2L Me Me Me and coupling constant. Crossover occurs Me,Me,Et for Cu−O−Cu angle at 87°. H2L Me Me Et i-Pr,i-Pr,i-Pr H2L i-Pr i-Pr i-Pr t-Bu,Me,i-Pr H2L t-Bu Me i-Pr Theoretical Calculations and Magneto−Structural Correlations t-Bu,t-Bu,i-Pr H2L t-Bu t-Bu i-Pr Calculated and Experimentally Determined Correlation of experimentally and theoretically Scheme 1. Synthesis of iminodiphenol ligands Exchange Coupling Constants [J, cm–1] determined exchange coupling constant J with Uv-Vis spectra of Complexes 1 to 5 Cu−O−Cu angle in 1−5. Blue squares: Complexes calc. exp. experimental data; red circles: theoretical data. 1 –323 395.1 ± 0.6 2 –249 259.4 ± 0.8 3 –190 185.4 ± 0.4 4 +22.3 +46 ± 2 5 +28.6 +53.2± 0.4 Correlation of calculated exchange coupling constant J and Cu−O−Cu−O torsion angle with Crossover point = 87 ° Cu−O−Cu angle in 1−5.

Crystal Structure of Complex 1

 Both Cu−O−Cu angle and Cu−O−Cu−O torsion angle correlate with J .  A switch from antiferromagnetic to ferromagnetic regime in our series occur at the Cu···Cu distance of 2.71 Å and at Cu−O−Cu−O torsion angle of 42°

Scheme 2. Synthetic scheme for bis(µ-phenoxido)dicopper(II) complexes 1 – 5. Spin density map for 1; a broken Spin density map for 4; a Crystal Structure of Complex 2 Crystal Structure of Complex 3 symmetry state is obtained triplate state is obtained

Spin density maps for 1 (left) and 5 (right) revealing more coplanar and more orthogonal arrangement of magnetic orbitals, respectively

 The antiferromagnetic coupling between two copper d(x2 - y2) type orbitals in 1−3 is promoted by superexchange interactions through in-plane p-orbitals of bridging oxygen atoms.  In complexes 4 and 5 antiferromagnetic pathway by superexchange via bridging oxygen becomes significantly diminished as the dihedral angle between the two NOCuOO planes attains 90°. Conclusion Crystal Structure of Complex 4 Crystal Structure of Complex 5 Cu-O-Cu Bond Angle, Cu···Cu Distance and Hinge  Synthesis and systematic variation of exchange coupling constant (J) in a series of bis-(μ- 1 – 5 Distortion of the Cu2O2 Framework in the Complexes phenoxido)-dicopper(II) complexes 1 – 5 are studied. Complexes Cu1- Cu1-O3- Average Cu···Cu Phen Cu–O– −1 −1 O2-Cu2 Cu2 Cu-O-Cu Distance yl Cu–O  Variation of Spin coupling Constant (J): −395 cm to +53.2 cm Angle Angle Angle (º) (Å) conf. Torsion (º) (º) (º)  Variation of Cu−O−Cu bond angle: 98.6 − 83.3°; Crossover point: 87° 1 98.63 98.63 98.63 2.9822 Syn 25.98 2 97.17 98.67 97.92 2.9927 Syn 26.48  Variation of Cu−O−Cu−O torsion angle: 26.0 − 46.5°; Crossover point: 42° 3 94.88 93.91 94.39 2.8660 Syn 32.25 4 86.89 87.01 86.95 2.7205 Syn 41.75  Variation of Cu···Cu separation: 2.982 − 2.633 Å; Crossover point: 2.71 Å 5 82.88 83.66 83.27 2.6327 Syn 46.49  Complex 5 has the lowest Cu···Cu separation (2.633 Å) and smallest Cu−O−Cu bond angle (83.3°), and a large ferromagnetic coupling constant (+53.2 cm−1) among reported complexes.

Publications: (1) ACS Omega 2019, 4, 10558 (2) Inorg.Chem. 2018, 57, 1004 (3) Inorg. Chem. 2017, 56, 9448 (4) Inorganica Chimica Acta 2017, 465, 70 (5) Chem. -Eur. J. 2018, 24, 10721 Synthesis of Stereoselective Fluorinated Dienamide Derivative Using Fluoro-Julia Olefination Reaction1

Presented by: Samir K. Mandal Department of Chemistry, , Bankura, India - 722173

INTRODUCTION RESULTS AND DISCUSSION The conjugated diene and polyene amide Required Julia-Kocienski reagent, 2- structural unit is found in many naturally occurring (benzo[d]thiazol-2-ylsulfonyl)-2-fluoro-N-methoxy- compounds that possess biological activity. These N-methylacetamide (1), was synthesized as Scheme 4 compounds have a variety of uses, ranging from reported3. Synthesis of the other key reactive medicinal purposes, to insecticides, as well as partner, 2-(benzo[d]thiazol-2-ylthio)acetaldehyde culinary flavoring agents. Some examples of (2), was initially attempted via dioxolane derivative Different aldehydes were tested under this conditions. dienamides are shown in Figure 1. Trichostatin A of 2 but attempts at deprotection of 2-[(1,3- Moderate to high 4Z selectivity was obtained with is an antifungal antibiotic, and as an inhibitor of dioxolan-2-yl)methylthio]benzo[d]thiazole under electron-rich aryl and heteroaryl aldehydes. The mammalian histone deacetylase, is a potential various conditions proved unsuccessful. Therefore, electron-deficient p-nitrobenzaldehyde gave product in anticancer agent. Pellitorine has insecticidal and synthesis via the dimethyl acetal was considered a good yield, but with poor 4Z selectivity. Reaction of 5 cytotoxic activities. Piperlonguminine has broad- (Scheme 2) with 3-phenylpropanal gave product in a moderate yield ranging therapeutic activities such as antibacterial, and with high 4Z selectivity. Isomeric ratios were antifungal, antitumor, anticoagulant, confirmed from 19F NMR spectra of all products. antimelanogenesis, and anti-inflammatory, to Isomerization of the (2Z,4Z)-isomer to the (2Z,4E)- name a few. Piperovatine exhibits local anesthetic isomer were carried out using several known protocols.. and antinflammatory activities. Due to their A convenient method for the isomerization using interesting biological activities, several analogs, catalytic I2 in CHCl3 at room temperature has been such as fluorinated Trichostatin A analog, have reported. Using this method, complete isomerization of Scheme 2 been synthesized as well2. (2Z,4E/Z)-isomers to (2Z,4E)-isomers was achieved (Scheme 5). With both desired building blocks in hand, the Julia- Kocienski reagent 1 and aldehyde 2, we tested reaction conditions for the olefination reaction. All condensation reactions were performed at −78 °C in the presence of LHMDS, and gave (Z)-4-(benzo[d]thiazol-2-ylthio)-2- fluoro-N-methoxy-N-methylbut-2-enamide (4) as the only stereoisomer (Scheme 3). In reactions herein, the molar ratio of sulfone 1, aldehyde 2, and LHMDS was Figure 1 critical for a good yield of 4. When aldehyde 2 was used Scheme 5 as a limiting reactant or in an equimolar amount, Herein, we report the synthesis of regiospecifically enamide 4 was obtained in low yield. On the other hand, CONCLUSIONS fluorinated dienamides, via sequential olefination of a with excess aldehyde 2 and LHMDS, a substantial yield This poster describes the synthesis of bifunctional Julia-Kocienski building block. improvement was observed. Thus, product 4 was stereoselective fluorinated dienamide derivative Condensation of 2-(benzo[d]thiazol-2-ylsulfonyl)-2- isolated in 76% yield when 2 molar equiv of 2 and 3 using Fluoro-Julia Olefination reaction. This fluoro-N-methoxy-N-methylacetamide (1) with a 2- molar equiv of LHMDS were used. intermediates are very useful for several (heteroarylthio)ethanal (2, heteroaryl = benzothiazolyl, pharmaceuticals to polymeric materials. Scheme 1) and subsequent oxidation would furnish a ACKNOWLEDGEMENT second-generation Julia-Kocienski reagent for This work was supported by NSF Grant CHE- dienamide synthesis. Retrosynthetic approach to 1058618 and a PSC CUNY award. Infrastructural conjugated dieneamides is outlined in Scheme 1. support was provided by NIH NCRR Grant 2G12RR03060-26A1 and by NIMHD Grant Scheme 3 8G12MD007603-27. REFERENCES For the second generation Julia-Kocienski reagent 5, 1. Chowdhury, M., Mandal, S. K., Banerjee, S. and Zajc, B. Molecules, 2014, 19, 4418. sulfide 4 was oxidized using H5IO6 in the presence of a 2. Charrier, C.; Roche, J.; Gesson, J.-P.; Bertrand, P. J. Chem. Sci. 2009, catalytic CrO3. Sulfone 5, obtained in 63% yield, was 121, 471. then used for the screening of reaction conditions for the 3. Ghosh, A.K.; Banerjee, S.; Sinha, S.; Kang, S.B.; Zajc, B. J. Org. Chem. 2009, 74, 3689–3697. olefination with 2-naphthaldehyde. Good yield and 4. Gaukroger, K.; Hadfield, J.A.; Hepworth, L.A.; Lawrence, N.J.; selectivity was observed using DBU as base in CH2Cl2, McGown, A.T. J. Org. Chem. 2001, 66, 8135–8138, and references Scheme 1 at 0 °C (Scheme 4). . therein. Hydrazine sensing event of two Ni(II)-complexes via indicator displacement approach Sudipta Dasa and Debasis Dasb

aRaina Swami Bholananda Vidyayatan, Purba Bardhaman, WB, India & bDepartment of Chemistry, The University of Burdwan, Golapbag, WB, India

Abstract Selectivity experiment

The use of metal complexes in molecular/ analyte recognition is an emerging research area. Two new promising X-ray crystallographically characterized mononuclear Ni(II)-complexes MC1, MC2 from different Schiff bases have been explored. MC1 and MC2 efficiently

detect molecular hydrazine (N2H4) in solution (20 mM HEPES buffer, methanol/water, 4/1, v/v). The hydrazine recognition event by MC1 and MC2 is based on indicator displacement approach (IDA). Detection limit for hydrazine in case of MC1 and MC2 are 3.6 nM and 1.2 nM, respectively. The associated displacement equilibrium constants for MC1 and MC2 are 4.18×105 and 1.66×105 M-1, respectively in same solvent system. The complexes, MC1 and MC2 exhibited excellent selectivity over several relevant amines including hydroxylamine. Thus, the two newly synthesized Ni(II)-complexes are Fluorescence intensity of MC1 (20 µM, λex = 375 nm) (left) and MC2 (20 µM, very simple, easy to synthesize, low cost and thus, may find λex=373 nm) (right) at 471 nm and 448 nm in presence of different significance in analytical field. ------2- anions/cations/molecules (100 µM): Anions F , Cl , ClO , ClO4 , Br , I , SO4 , 3------+ + + PO4 , NO3 , HAsO4 , CH3COO , SCN , NO2 and ASO2 ; Cations: Li , Na , K , Synthesis of metal complexes MC1 and MC2 Ca2+, Mg2+, Al3+, Cr3+, Mn2+, Co2+, Cu2+, Ni2+ and Zn2+ and molecules: ethylenediamine ((NH2CH2)2), dimethylamine (Me2NH), triethylamine (Et3N), diethylenetriamine (NH(CH2CH2NH2)2), ammonium hydroxide (NH4OH), pyridine (Py), aniline (C6H5NH2), cysteine (Cys) and hydroxylamine (NH2OH), in aqueous methanol (20 mM HEPES buffer, MeOH/ H2O, 4/1, v/v, pH 7.4), respectively

Fluorescence and absorption spectral changes of MC1 (20 µM) in presence of hydrazine (0.0001-3000 µM)

X-ray structure of the metal complexes

Fluorescence and absorption spectral changes of MC2 (20 µM) in presence of hydrazine (0.0001-3000 µM)

MC1 MC2

Plausible sensing mechanism: IDA

Detection limit for hydrazine-

MC1: 3.6 nM MC2: 1.6 nM Synthesis and application of an ionic molecule containing benzimidazole core Susanta Kumar Manna Department of Chemistry, Bidhannagar College, Kolkata 700064, India [email protected] In the last few decades ionic compound with N-alkylation such as berberine, quinazolinium cation, quinolizinium based alkaloid Nitidine (anti malaria), NK-109 (antitumor) have got special importance. The biological activities of such alkaloids range from anti-cancer to anti-fungal, anti-bacterial etc. Important bioactive scaffold a) b)

Synthesis of N-methylated polycyclic benzimidazole

Figure 1: b) Fluorescence titration of L- Fig. 1: a) Fluorescence titration of CH CN-H O 3 2 Fe3+complex by adding EDTA (0-20μM) in (8:2, v/v) mixture solution containing 5M sensor 3+ CH3CN-H2O (8:2, v/v) solution at 425 nm (L) with Fe (10M) at 425 nm (λex=360 nm) (λex=360 nm)

Effect of R99 on the formation of B.subtilis biofilm Control after 2 Hrs 6 Hrs 8 Hrs Cellular localization of R99 in RAW 264.7

150

100

50 survival Acknowledgements

Percentage of 0 control Concentration20 40 of R9960 (μg/ml80 ) Department of Chemistry, INDAS MAHAVIDYALAYA Bankura, West Bengal SYNTHESIS AND CHARACTERIZATION OF IRON(III) COMPLEXES INCORPORATING AZOSALPHEN LIGAND

Uttam Das

Department of Chemistry, Kalyani Govt. Engg. College, Kalyani, Nadia, 741235 Email: [email protected]

Introduction Synthesis of Iron(III) complexes of azosalphen ligand Crystal data of Fe(III)-complex

Bond Distances Interests of research on azosalphen group of ligands incorporating Bond Angles transition metal have been developing in recent days due to their Cl1-Fe1-O1 108.28(6) Fe1-Cl1 2.2148(7) interesting catalytic and electron transfer properties. Several metallo Cl1-Fe1-O2 108.67(6) Fe1-O1 1.8673(18) proteins containing heme group in their active site have been identified as Cl1-Fe1-N1 102.66(5) Fe1-O2 1.8932(17) Cl1-Fe1-N2 102.98(5) good bio catalyst for oxygenation in living organism. The iron (III) complexes Fe1-N1 2.0862(17) incorporating azosalphen ligands are scarce in chemical literature. A new Fe1-N2 2.0955(19) Fe1-O1-C1 132.28(15) type of iron (III) complexes [Fe(L)Cl] incorporating the azosalphen ligand O1-C1 1.307(3) Fe1-O2-C15 130.38(16) (H2L) has been synthesized, where the complex contains a free phenolic-OH O2-C15 1.309(3) Fe1-N2-N3 130.88(14) Fe1-N1-C7 124.78(15) functional group. This free phenolic-OH functional group can be utilized to Yield = 72% O3-C2 1.360(3) anchor the complex on solid support to make a heterogeneous catalyst or to N1-C7 1.304(4) Fe1-N2-C13 113.97(14) Fe1-N1-C8 113.71(14) build an interesting hydrogen bonding network in suitable biological system. N1-C8 1.422(3) N2-C13 1.423(3) O1-Fe1-O2 92.39(7) N3-C14 1.381(3) O1-Fe1-N1 88.19(7) Single crystal X-ray diffraction studies of the single crystals of the N2-N3 1.276(3) O1-Fe1-N2 147.69(7) penta-coordinated Fe(III) complex revealed that hydrogen bonding network C1-C2 1.419(4) O2-Fe1-N1 146.73(7) was observed in its solid state through the free OH functional group. C1-C6 1.418(3) O2-Fe1-N2 85.11(7) Synthesis and characterization of the Fe(III) complex has been presented in C6-C7 1.418(4) N1-Fe1-N2 77.08(7) this poster. C8-C13 1.395(3) N3-N2-C13 114.61(18) C14-C15 1.414(4) N2-N3-C14 119.3(2)

1 4 7

Synthesis of pre-cursor ligands Spectral characterizations of Fe(III)-complex Pattern of H-bonding in the Fe(III)-complex

59.1

58

57 1 56 UV-Vis spectra of [Fe(L )Cl] in CH2Cl2 55 508.31 829.73 54 811.67 553.01

53 2920.93 581.74 886.46 625.49 52 977.04 663.03 569.21 872.64 695.93 51 636.19 1346.59 1023.03 536.82 1280.26 1168.17 1067.00 799.36 605.75 50 3482.87 1397.02 1156.47 1045.56 49 1607.56 1084.73 %T 1471.81 48 1454.88 1192.04 1578.55 1124.35 47 1141.26

46 1596.70 1317.09 1219.22 762.81 45 1231.52 738.48 1432.29 1252.21 44

43 1546.48

42

41

40 1372.54

38.9 R = H, CH3 , Cl 4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0 cm-1

IR spectra of [Fe(L1)Cl] in KBr disc 2 5 8

Synthesis of Synthesis of ligands Single Crystal XRD-data of [Fe(L1)Cl] CONCLUSION

Crystallographic Data

Empirical formula  A derivative of azosalphen ligands were C19 H13ClFeN3O3, H2O

Formula weight 438.62 synthesized and characterized by IR, UV and Crystal system Triclinic space group P1 (No. 1) NMR spectroscopy a/Å 9.6655(3)

b/Å 23.2437(7)

c/Å 8.7193(3) /deg 90 Perspective view of [Fe(L1)Cl] with atom numbering scheme  A new penta coordinated iron(III) complexes /deg 109.119(2) /deg 90 with free phenolic –OH functional group has  /Å 0.71073 Yield = 94% V /Å3 1850.84(10) been synthesized and characterized. F(000) 223

Z 1

T/K 273

D/mg/m-3 0.394  H-bonding network was observed and studied

Mu(MoKa) [ /mm ] 0.248

R1(all data) 0.0394 from the single crystal X-ray diffraction.

wR2[I > 2s(I)] 0.107

GOF 0.98

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Turn off and Turn on Approach of Au Nanocluster-CdTe QD Nanocomposite Probe for Detection of Hg2+ and F- ions

Dr. Bipattaran Paramanik Assistant Professor, Department of Chemistry New Alipore College, Block - L, New Alipore, Kolkata - 700 053

Motivation of Our Work Our Goal Synthesis of CdTe QDs Unique photo-physical properties of QDs. Excellent brightness, narrow and precise size tunable emission.

Exceptionally high photo and thermal stability. CdCl2 + GSH (Turbid Solution)

CdTe QDs could be synthesized in water, directly. Absorbance Less surface defects and fairly high QY of CdTe. An Optical Sensor for

Detection of Hazardous SPR is the characteristic of metal NPs. Cation and Anion 400 450 500 550 600 650 Nanocluster exhibits PL due to strong Wavelength (nm) a b c d e f g h quantum confinement. QY≈ 40 % No SPR, HOMO-LUMO transition Oxygen free due to low density of states. Under normal light condition for CdCl2

Each atom within the NC is important. a b c d e f g h 15min 1h 2h 2.5 h 4h 5h 6h 20h Rapid injection NormalizedIntensity PL of NaHTe Off /On approach at Ar atmosphere Under UV light

450 500 550 600 650 pH > 8 Wavelength (nm)

For composite formation  Interactions of amino acids dictate Synthesis of BSA Notes  BSA: 20 μL of 10 mg/mL the structure of a protein. Time resolved capped AuNC QD553: 20μL of 6.40 x 10-7 M Notes florescence decay  GSH-BSA interaction is the  CdTe was incubated interaction of amino acids.  pH < 11 AuNP is with BSA capped AuNC at Systems Average Life 0  H-bonding assist the  CdTe possess high life 10 mM HAuCl4 30 C for 2h. Time observed, no AuNC. composite formation.  Total volume was 2mL. time. CdTe QDs 5.9 ns BSA in water Stirring for 501 mg/mLmg/mL 2 min  pH ≈ 11 BSA acts as  GSH is a tri-peptide.  AuNC absorbs at the 1 (M) NaOH mild reducing agent. Composite 3.7 ns emission range of QDs.

 PL quenching of the QD553 370 C  35 sulfur constituent emission. Composite 2.7 ns Stirring  Shortening of the life + For 12 h in BSA.  Energy transfer from QDs to Hg2+ Au25 NC pH ≈ 11 AuNC. time in the composite

Composite 5.6 ns is due to energy transfer.  Amines and  Valleys at 208 nm and 223 nm are + attributed to alpha-helix of BSA. F- carboxylates gives extra  Blue shifting of 208 nm and  Hg2+ reduce the decay stability of NC. fattening of 223 nm . time of QDs in the 2+  Random coil formation. composite. Strong Hg sulfur 0 Absorbance  Heating> 40 C AuNP. PL Intensity PL interaction. Size of CdTe ~ 4 nm Size of AuNC ~ 1.7 nm

 F- enhances the life time  480-560 nm is due to Detachment of GSH a 10000 (a) GSH capped QDs. (a) GSH capped QDs. 10 of QDs in the composite. from QDs surface. 6 (a) BSA protein intra band sp-sp 6.0x10 (b) Composite (b) Composite 400 450 500 550 600 650 700 750 (b) BSA protected AuNC 8000 (c) Composite Wavelength (nm) and inter band d-sp Aggregation induced PL 4.0x106 6000 0 Enhancement of the life transition. 200 225 250 275 quenching of the QDs.

c - CD(mdeg) Counts Wavelength (nm) time in presence of F 4000 b 6 (a)  Large Stock shift. Intensity PL (a.u) 2.0x10 b almost equal to pure - -10 F detaches the QDs 2000 (b) Digital photographs a

of the AuNC CdTe. from the quencher 0.0 0 520 560 600 640 680 720 0 25 50 75 surface. Wavelength (nm) Time (ns)

Turn on approach for 128 % PL Turn off approach for - detection of F enhancement Application 74 % PL quenching detection of Hg2+ for for -7 - 8.47 x10 M F 6.56 x10-7 M Hg2+

6 2.5 2.0x10 2+ 1.0 Blank Pb 2- 6 CO 3+ 2+ 4x10 3 Ce Sr - NO 2+ 2+ 3 2.0 Co Zn 0.8 1.5x106 Blank 3+ 2+ - Fe Ca Br 3x106 2+ 2+ - Mg Cd 0.6 OAc 1.5 - 2+ 0 2+ ClO 6 Mn 0 4 1.0x10 Cu

- 2+ Salt I / I I I I / I Ni 6 0.4 2x10 - Detachment of Salt Induced mixture Cl 1.0 PL Intensity PL 2+ 2- Hg SO Quencher 4 5 Aggregation 5.0x10 PL Intensity PL (a.u) - 0.2 6 F 1x10 0.5 form QDs of QDs

Surface 0.0 0.0 2+ 3+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ Blank Ce3+ Co Fe Mg Mn Ni Pb Sr Zn Ca Cd2+ Cu Salt Hg 0 0.0 - - 2- - - 520 560 600 640 680 720 mixture F OAc CO Cl - Blank I - Br- SO 2- NO ClO 500 550 600 650 700 3 4 3 4 Wavelength (nm) Wavelength(nm)

6 4.5 2.0x10 1.00 LOD forLimit F - ion = 117 ofnM a 6 Limit of 8.0x10 a (Blank) (30 mic. lit) Conclusion b -7 detection 6 b (1.31x 10 M) 5.085 E-6 4.0 1.6x10 detection

6 - 117 nM 2+ 6.0x10 F Hg 0.75 9 nM

6 3.5 (a) A dual emissive composite has been designed. 1.2x10

h (7.10x 10-7 M)

0 0

4.0x106 I / I I 8.475 E-7 / I I 5 PL Intensity PL (5 mic. lit) 3.0 8.0x10

(b) Composite shows highly selective ON/OFF response towards Intensity PL 0.50

6 Blank 2.0x10 analytes. h 2.5 4.0x105 0.0 2+ (c) 74 % PL quenching in presence of Hg is due to salt induced 0.25 500 550 600 650 700 -6 -6 -6 -6 -6 1.0x10 2.0x10 3.0x10 4.0x10 5.0x10 -7 -7 -7 -7 aggregation mechanism. 540 600 660 720 0.0 2.0x10 4.0x10 6.0x10 8.0x10 Wavelength(nm) - Concentration of F ion 2+ Wavelength (nm) Concentration of Hg (M) (d) 128 % PL enhancement when F- is present in the system. 10000 (a) GSH Capped QDs References (a) GSH Capped QDs (b) Composite 10000 - (b) Composite (c) Composite +F 2+ - 2+ 8000 1. B. Paramanik, S. Bhattacharyya, (e) The LOD for Hg and F are 9 nM and 117 nM, respectively. (c) Composite + Hg 8000 A. Patra, Chem. Eur. J., 2013, 19, 5980. 6000 (f) Within the safety limit in drinking water, set by USEPA. 2. B. Paramanik, D. Bain, A. Patra, 6000

J. Phys. Chem. C, 2016, 120, 17127. Counts 4000

(a) Counts 3. D. Bain, S. Maity, B. Paramanik, A. 4000 (a) (c) Patra, ACS Sustainable. Chem. Eng., 2018, Acknowledgement 2000 6, 2334. 2000 (b) (b) 4. D. Bain, B. Paramanik, A. Patra, J. Phys. Prof. Amitava Patra for his encouragement. 0 (c) 0 25 50 75 Chem. C, 2017, 121, 4608. Principal and colleagues of New Alipore College for their support. 0 Time (ns) Department of Chemistry, Indas Mahavidyalaya, Bankura, WB. 0 25 50 75 Time (ns) binding INTERACTION OF A KETOCYANINE DYE WITH SERUM ALBUMINS Dr. Atanu Mahata, Assistant Professor Department of Chemistry Government General Degree College, Ranibandh

➢ To explore the potential usefulness of the 2-[3-(N-methyl-N-phenylamino)-2- IB OBJECTIVES I II B spectroscopic properties of the fluorophore for propenylidene] indanone (MPAPI) understanding the binding interaction with IA proteins. O CH ➢ To investigate the photophysical behavior of N 3 I II A MPAPI in serum albumins. IIA Site I Site I I Steady state absorption and fluorescence STUDY

0.4 0.4 HSA IIB (i) HSA BSA 0.3 (ix) 0.3 (i) An initial decrease followed by a slight increase in 0.2 0.2(ix) the absorbance along with a continuous blue shift 0.1

Absorbance 0.1 Absorbance 0.0 350 400 450 500 550 0.0 Wavelength (nm) 350 400 450 500 550 Wavelength (nm)

-3 -3 0.4 × 10 mol dm 0.27× 10-3 mol dm-3 ✓ Intensity increases with blue shift in the presence of proteins ✓ Lowering in polarity in the proteinous environments than that of pure buffer medium 0 mol dm-3

0 mol dm-3

Fl. Intensity (A.U.) Fl. Intensity (A.U.) 500 550 600 650 Wavelength (nm) 500 550 600 650 Wavelength (nm) Steady state anisotropy study DYE―PROTEIN BINDING 0.40 HSA 0.16

) Higher degree of motional

0.35 r ( 0.12 5 -1 3 restriction on the probe in HSA

F 0.30 0.5 BSA For HSA, K = 1.87  10 mol dm

0.4 5 -1 3 than BSA indicating that the

F 

0.3 For BSA, K = 0.6  10 mol dm 0.08 1 / 0.25 1 / dye has a greater binding 0.2 MPAPI binds in a stronger way to BSA 0.1 affinity towards HSA than BSA 0 50 100 150 200 0.20 -1 3 -1 3 Anisotropy 0.04 HSA [BSA] × 10 (mol dm ) HSA than BSA 0 50 100 150 200 0.0 0.1 0.2 0.3 0.4 0.5 -1 3 -1 3 -3 -3 [HSA] × 10 (mol dm ) [SA] × 10 (mol dm )

EFFECT OF DENATURANT

BSA 1.0 1.0 HSA BSA + MPAPI HSA + MPAPI Addition of denaturants to the protein bound probe 0.8

0 0.8 0

F / F 0.6 Both BSA and HSA F / F 0.6 gain structural stability A consistent red shift along with a decrease in 0.4 upon binding fluorescence intensity with the dye 0.4 0 1 2 3 4 5 6 7 8 -3 0 1 2 3 4 5 6 7 8 [GuHCl] (mol dm ) -3 [GuHCl] (mol dm ) Liberation of the probe into bulk aqueous phase Time resolved study ❖  value in HSA >  Circular Dichroism Study HSA 1000 value in BSA 40 40 BSA 0 M 0 M Buffer ❖ The fluorophore ✓ Helicity increases Lamp resides in less polar 20 20 from 59% to 73% for 100 20 M 20 M

region in HSA than that BSA, 64% to 69% for

in BSA 0 0 HSA. Counts 10 ❖ Higher degree of ✓No significant motional restriction in -20 perturbation in the Ellipticity (mdeg) -20 Ellipticity(mdeg) secondary structure 0 5 10 15 20 HSA as compared to of the serum albumins Time (ns) BSA 200 220 240 200 220 240 Wavelength (nm) in the presence of dye Wavelength (nm) Fluorescence Resonance Energy Transfer

BSA HSA Conclusions:

MPAPI binds strongly with HSA than that of BSA

CD study suggests that the secondary structure of the protein Fl.Intensity

Fl.Intensity is perturbed, but not drastically, in the presence of dye. FRET study indicates that the dye resides closer to the Trp 350 400 450 500 550 Wavelength (nm) 350 400 450 500 550 residue in HSA environment than in BSA Wavelength (nm)

✓ FRET efficiency is 0.32 for HSA and 0.14 for BSA ✓ FRET in HSA suggests that the MPAPI resides close to the Trp moiety i.e. in the inner domain cleft region of HSA (near Trp-214) J. Photochem. Photobiol B: Biology., 2009, 96,136-143. One Day International Webinar on ‘Role of Chemistry in Recent Technology’ organized by Deptt. of Chemistry, Indus Mahavidyalaya, Indus. Bankura. 23rd Aug’2020 Synthesis, structure and catalytic efficacy of a nitrate bridged 1D copper(II) coordination polymer with a tridentate Schiff base Habibar Chowdhurya, Rajesh Berab and Chandan Adhikaryc aDepartment of Chemistry, Kabi Nazrul College, Murarai, Birbhum 731 219, West Bengal, India bDepartment of Chemistry, Dinabandhu Andrews College, Kolkata 700084, West Bengal, India cDepartment of Education, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal, India Email ID: [email protected] (H. Chowdhury) Abstract: Coordination polymers (CPs) and metal-organic frameworks (MOFs) through strong metal-ligand covalent bonds and multiple weak non-covalent forces have attracted great attention of many research groups in isolation of different advanced functional materials. Single-pot synthesis is an efficient synthetic approach using judiciously chosen metal ions, organic ligands and bridging units in pre-assigned molar ratios to isolate such target materials. A one-dimensional copper(II) coordination

polymer of [Cu(L)(μ-ONO2)]n (1) (HL = 4-methoxy-2-[1-(methylaminoethylimino)methyl]-phenol) with a bidentate bridging nitrate has been isolated and characterized by X- ray diffraction analysis and spectroscopic studies. X-ray single crystal structure analysis revealed that each copper (II) center in the asymmetric unit of complex 1 adopts a

distorted square pyramidal geometry with a CuN2O3 chromophore ligated through a tridentate Schiff base (L) with (NNO) donor sets and two O atoms of bridging nitrate ion. The adjacent copper atoms are connected by bridging nitrate (μ-ONO2) in bidentate fashion affording to a 1D coordination polymeric chain structure along crystallographic b-axis. In the polymeric framework, the Cu…Cu separation is 4.3749(4) Å. The catalytic efficacy of complex 1 was studied in a series of solvents for the epoxidation of cyclooctene using tert-butyl-hydroperoxide (TBHP) as an efficient oxidant under mild conditions. The catalytic reaction mixture has been analyzed by gas chromatography and it displayed that the yield of the epoxidation and its selectivity is maximum in acetonitrile medium. Keywords: ID CPs of Copper(II); Nitrate bridged; Tridentate Schiff base; X-ray structure; Catalytic efficacy

Result and Discussion: C. (i) Crystal structure of [Cu(L)(μ-ONO2)]n (1): C. (ii). Selected bond distances (Å) and bond angles (°) for 1 A. Preparatory method: Chemical formula C11H15N3O5Cu (i) Synthesis of Schiff base (HL): Formula weight 332.80 Bond distances 5-Methoxysalicyladedehyde (1 mmol) was refluxed (10 h) with N-methyl ethanediamine Crystal system Monoclinic Cu1-N1 1.9384(17) Cu1-O4_a 2.037(7) (1 mmol) in dehydrated alcohol (20 ml). Space group P 21/n Cu1-N2 2.0386(19) Cu1_b-O4 2.105(6)

a (Å) 12.8738(10) 1.9026(15) O3-N3 1.276(2) Cu1-O1 b (Å) 7.8553(6) Cu1-O3 2.0531(15) O4-N3 1.242(2) c (Å) 13.0713(10) Cu1-O4 2.5817(16) O5-N3 1.215(2)  (°) 90 Bond angles N1-Cu1-N2 84.54(7) N2-Cu1-O4_a 86.94(7) (ii) Synthesis of [Cu(L)(μ-ONO2)]n (1):  (°) 93.6188(12) N1-Cu1-O1 94.14(7) O1-Cu1-O3 89.76(6) A nitrate bridged 1D chain copper(II) coordination polymer, [Cu(L)(μ-ONO2)]n (1) HL =  (°) 90 N1-Cu1-O3 172.11(7) O1-Cu1-O4 91.72(6) 4-methoxy-2-[1-(methylaminoethylimino)methyl]-phenol) has been isolated using a one- 3 V (Å ) 1319.23(18) pot reaction of a 1:1 molar ratio of Cu(NO ) .6H O and a Schiff base (HL) in methanol at N1-Cu1-O4 119.12(6) O1-Cu1-O4_a 90.05(7) 3 2 2 λ (Å) room temperature. 0.71073 N1-Cu1-O4_a 107.44(7) O3-Cu1-O4 53.81(6) -3  calcd (g cm ) Cu(NO3)2.6H2O + HL [Cu(L)(μ-ONO2)]n (1) 1.672 N2-Cu1-O1 176.19(7) O3-Cu1-O4_a 79.37(6) Z 4 N2-Cu1-O3 91.99(7) O4-Cu1-O4_a 133.12(6) B. Spectral analyses: Crystal size (mm3) 0.17 ×0.09×0.08 N2-Cu1-O4 92.04(7) Cu1-O4- 121.50(7) Temperature (K) 294(2) Cu1_b (i) IR spectrum: IR (KBr, cm-1):  (NO ) 1735, 1794. s 3  (mm-1) Symmetry code: (a) 1/2-x,-1/2+y,1/2-z; (b) 1/2-x,1/2+y,1/2-z. In IR spectra, the complex 1 shows a band at 1794 cm-l with a shoulder at 1735 cm-l due to 1.676 bidentate bridging nitrate . Also, the bands of weak intensity at 3062, 2945 and 2840 cm-1 are F(000) 684 assigned to the C-H stretching vibrations of aromatic rings, methylene and methoxy groups,  ranges (°) 2.15 to 25.25 respectively . h/k/l -14/15, -09/09, -15/15 Reflections collected 8498 (ii) CHN analysis: Independent reflections 2401 Anal. Calcd for C11H15N3O5Cu (1): C 39.7; H 4.5; N 12.6%. Found: C 40.2; H 4.1; N 13.0%. Data/restraints/parameters 2401/1/187 (iii) Conductance measurement: Goodness-of-fit on F2 1.066 -1 2 -1 D. (iv). Molecular and crystal structure for 1 M (MeCN, ohm cm mol ): 6, which shows that 1 behaves as non-electrolyte. Final R indices [I>2(I)] R = 0.0275 and wR = 0.0734 (iv) Electronic spectrum: Largest diff. peak and hole (eÅ-3) 0.333 and -0.186 3 -1 -1 4 4 UV-Vis in DMF [λmax, nm (εmax/dm mol cm )]: 266, 296 (1.20 × 10 ), 387 (1.15 × 10 ), 607 (2.30 × 102). X-ray structural analysis reveals that each Cu(II) center in In the UV-vis spectrum, a weak low-intensity absorption band at 600 nm is assignable to d-d asymmetric unit of 1 adopts a distorted square pyramidal transition, consistent with the square pyramidal (sp) geometry of the copper(II) centers. The geometry ( = 0.07) with a CuN2O3chromophore absorption band observed at 380 nm may be attributed to the ligand to copper(II) charge coordinated by two N atoms (N1, N2) and one O atom (O1) Fig. 1. the asymmetric unit in 1 transfer transition (LMCT). Additionally, two strong absorption bands in the region 265 and of the tridentate Schiff base ligand (L) and two O atoms 295 nm may be assigned to a ligand-based charge transfer transitions. (O3, O4) of the bridging nitrate (Fig. 1). The coordination sites of the basal plane are occupied by two N atoms (N1, (v) Magnetic moment and EPR study: N2) and one O atom of the Schiff base (L) and two O atoms

eff. (B.M.) = 1.78. EPR (solid state): g║ = 2.042; g┴ = 2.013, gav = 2.022. Room-temperature (O3, O4) of bridging nitrate acting as a bidentate ligand. solid-phase magnetic susceptibility measurement shows that the compound (1) has magnetic The Cu(II) center deviates 0.0314(2) Å from the moment close to the spin-only value 1.78 BM. The g and g values of the complex were N1/N2/O1/O3mean plane. The apical position is occupied calculated to be 2.18 and 2.08 with gav = 2.022. This is a typical axial spectrum in which copper by O atom [Cu1-O4_a: 2.4319(16) Å; symmetry code: a = (II) ion possessing either a square planar or a penta-coordinated geometry around it. ½-x, -1/2+y, ½-z] of the other bridging nitrate.

D. Catalytic Activity: The three Cu-O bond lengths are The catalytic activity of [Cu(L)(μ-ONO2)]n (1) was studied in the different, where Cu1-O1(ligand) epoxidation of cyclooctene with tert-BuOOH as an oxidant. [1.9026(15) Å] is smallest than (Fig.4). Cyclooctene was converted to cyclooctene epoxide in the other two Cu1-O3(nitrate) Fig. 2. Perspective view of molecular unit of 1 good yield with high selectivity in different solvents when [2.0531(15) Å] and Cu1- catalyzed by complex 1. 1 exhibits highest conversion 88%with O4(nitrate) [2.5817(16) Å]. 86% epoxide selectivityIn general, the efficiency of catalyst Complex 1 is an example of followed the order: coordination polymer containing acetonitrile>chloroform>dichloromethane>methanol. The a bidentate bridging nitrate. The optimum polarity of the acetonitrile that is suitable to dissolve adjacent copper atoms are both tert-BuOOH and cyclooctene might be facilitating the highest connected by a bidentate catalytic activity. The conversion of cyclooctene was only 4% in bridging nitrate with μ-ONO2 the absence of the catalyst. The Cu(NO3)2 salt, although achieved bridging mode affording to a 1D a conversion of 66%, but selectivity was lower (53%). The results polymeric chain structure (Fig. of epoxidation reactions of cyclooctene using tert-BuOOH as 3). The Cu1-O4-Cu1_b bridging oxidant over copper(II)-Schiff base complexes under angle is 121.49(6)°. In the homogeneous conditions. Here, the coordination environment polymeric framework the around copper(II) is easily accessible for an external ligand. As a Cu…Cu separation is 4.3749(4) result, tert-BuOOH gets enough space to bind copper in the Fig. 4. Probable mechanism of catalytic cycle Å. Fig. 3. Crystal packing views of 1 showing a intermediate stages of the catalytic cycle. for olefinic epoxidation catalyzed by complex 1 polymeric chain extending along b axis. E. Research Highlights: ►A one neutral nitrate bridged coordination polymer 1 of copper(II) containing a tridentate Schiff base has been isolated and characterized by X-ray crystallographic study. ► Structural analysis revealed that each copper(II) center with a distorted square pyramidal geometry with a CuN2O3 chromophore in 1. ► The adjacent copper atoms are connected by a bidentate μ-NO3 bridged to form a one-dimensional coordination polymeric structure. ► The complex 1 displayed moderate catalytic efficacy in homogeneous cyclooctene epoxidation. It also revealed highest selectivity in acetonitrile medium.