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Microwave Assisted Synthesis, Spectral and Antimicrobial Evaluation of Hydrazones and Their Metal Complexes

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Microwave Assisted Synthesis, Spectral and Antimicrobial Evaluation of Hydrazones and Their Metal Complexes Devendra Kumar et al. / Journal of Pharmacy Research 2012,5(2),830-834 Research Article Available online through ISSN: 0974-6943 http://jprsolutions.info Microwave assisted synthesis, spectral and antimicrobial evaluation of hydrazones and their metal complexes Devendra Kumar ,Shivani Singh,Neelam,Rubeena Akhtar Department of Chemistry, Institute of Basic Sciences,Dr. B. R. Ambedkar University, Khandari Campus, Agra-282002 Received on:19-12-2011; Revised on: 07-01-2012; Accepted on:28-01-2012 ABSTRACT Six new metal complexes of Co (II), Ni (II) and Cu (II) with bis-(furfuryl) adipic acid dihydrazone (FADH) and bis- (2-acetyl thiophene) adipic acid dihydrazone (2-ATADH) have been synthesized under microwave irradiation. The Microwave irradiation method was found remarkably successful and gave higher yield at less reaction time. All the synthesized compounds have been characterized by running their TLC for single spot, repeated melting point determinations, elemental analyses, IR, 1H-NMR and electronic spectral studies. The elemental analyses and spectral analysis results revealed their Metal: Ligand (1:1) stoichiometry. All the synthesized compounds have been screened in vitro for their antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and also for their antifungal activity against Aspergillus niger and Candida albicans. Key words: Synthesis, Microwave irradiation, Spectral, Antibacterial, Antifungal. INTRODUCTION Over the last few years, there has been growing interest in the synthesis of Synthesis of diethyl adipate: 14.6 g (0.1M) adipic acid was dissolved in organic compounds under green or sustainable chemistry such as micro- 20 ml absolute alcohol. To this solution, 3ml conc. H2SO4 was added. The wave irradiation because of increasing environmental consciousness. The reaction mixture was irradiated in a microwave at 400W for 4 min and feasibility of microwave assisted synthesis has been demonstrated in vari- transferred to a separating funnel containing 20 ml of distilled water and ous transformations like condensation [1], cycloaddition [2], alkylation [3] and shaken well. The upper pale yellow layer was separated out and treated in many other chemical reactions. The use of microwave irradiation has with excess of saturated solution of sodium bicarbonate to remove unreacted become an established tool in organic synthesis for achieving better selec- acid. It was distilled under reduced pressure to get the desired product. tivity, rate enhancement and reduction of thermal degradation byproducts [4]. Microwave Assisted Synthesis is rapidly becoming the method of choice Synthesis of adipic acid dihydrazide (AADH): 10.02 g (0.05M) diethyl in modern synthesis and discovery in chemistry laboratories. Microwave- adipate was dissolved in 25 ml absolute alcohol in a round bottom flask and assisted synthesis improves both throughput and turn-around time for chem- 4.95 ml (0.1M) hydrazine hydrate, dissolved in 15 ml absolute alcohol, was ists by offering the benefits of drastically reduced reaction times, increased mixed to it. This reaction mixture was irradiated in microwave oven at an yields, and purer products. In this type of synthesis we apply microwave emitted power of 400W for 6 min. The contents of the flask were cooled in radiation to carried out the chemical reactions. Microwave mediated reac- a freezing mixture. A white shiny product was obtained. It was filtered tion have emerged as a powerful technique to promote a variety of chemical washed with alcohol followed by ether and dried in a vacuum desiccator reactions. The microwave irradiation is used for carrying out chemical trans- over anhydrous CaCl . formation which is pollution free and eco-friendly. 2 Synthesis of dihydrazones: 0.348 g (0.002 M) adipic acid dihydrazide Hydrazones having azomethine linkage (>C=N-N) are well known for their (AADH) was dissolved in 15 ml of 30 % acetic acid. To this solution, wide spectrum biological applications such as anti-viral [5], anti-tuberculosis (0.004 M) of 0.33 ml furfuraldehyde for the synthesis of bis-(furfuryl) [6], anti-tumor [7], cardiovascular [8], antiplatelet [9], anti-convulsant [10], anti- adipic acid dihydrazone (FADH)/0.432 ml 2-acetyl thiophene for the syn- malarial [11], anti-depressant, pharmacological [12] activity. It has been ob- thesis of bis-(2-acetyl thiophene) adipic acid dihydrazone (2-ATADH), served that the biological activity[13] of hydrazones increases on complex- dissolved in 15 ml absolute alcohol was added with constant shaking. The ation with transition metal ions. A number of metal complexes of hydrazones resulting solutions were irradiated in a microwave oven at 360W for 4 min have been reported as tuberculositic [14], antitumor [15], antibacterial, antifun- and 6 min respectively. Coloured solid products were obtained which were gal [15] agents. These facts prompted us to synthesise some new hydrazones filtered, washed with alcohol followed by ether and then recrystallized and their metal complexes by adopting green chemistry approach. from a mixture of (1:1) DMF and alcohol. Finally, products were dried in a vacuum desiccator over anhydrous CaCl MATERIALS AND METHODS 2. The synthesis were carried out in a domestic microwave oven LG model Synthesis of Co (II), Ni (II), Cu (II) metal complexes of dihydrazones: MS-1927C. Melting points were taken in open capillaries and are uncor- 25 ml ethanolic solution (0.005M) of 0.302 g bis-(furfuryl) adipic acid rected. All the chemicals used were of AR grade and solvents were purified dihydrazone/ 0.432 ml 2-acetyl thiophene dihydrazone was mixed to 10 ml by suitable methods. aqueous solution (0.005M) of 0.124 g cobalt acetate tetrahydrate / 0.124 g nickel acetate tetrahydrate/ 0.099 gm copper acetate monohydrate sepa- rately in the round bottom flasks. These mixtures were irradiated at 450- *Corresponding author. 500 W in a microwave oven for 5- 7 min. On cooling the solutions, coloured Devendra Kumar precipitates were obtained which were filtered, washed with water fol- Department of Chemistry, lowed by alcohol. Finally, the products were dried in a vacuum desiccator Institute of Basic Sciences, over anhydrous CaCl . Dr. B. R. Ambedkar University, 2 Khandari Campus, Agra-282002 Antimicrobial activity Uttar Pradesh, India The antimicrobial activities were determined using disc diffusion method [17] Journal of Pharmacy Research Vol.5 Issue 2.February 2012 830-834 Devendra Kumar et al. / Journal of Pharmacy Research 2012,5(2),830-834 by measuring the zone of inhibition [18] in mm. All synthesized compounds The electronic spectrum of Ni(II) complexes exhibited three bands in the -1 3 were screened in vitro for their antibacterial activity against two bacteria region 12981-12624,14910-14335 and 24306-22444 cm assigned to A2g 2 3 3 3 3 (Staphylococcus aureus and Pseudomonas aeruginosa) at different concen- g T2g, A2gg T1g(F) and A2gg T1g (P) respectively which suggested trations of 50, 25,12.5,6.25mg/ml. The bacteria were subcultured in Mueller the octahedral geometry[19]. Hinton Agar medium. Antifungal activity [17] was tested against Candida albicans and Aspergillus niger at different concentration of 50, The electronic spectra of Cu (II) complex exhibited three bands in the 25,12.5,6.25mg/ml. The fungi were subcultured in Saboured’s Dextrose Agar regions 13105-12980, 16545-16225 and 25318-24340 cm-1 corresponding 2 2 2 2 medium. Ciprofloxin was used as a standard for antibacterial and Fluconazole to the transitions B1g g A1g g B2g and E1g respectively which suggest for anti-fungal screening. The complexes were dissolved in 10% DMSO octahedral geometry [20] for these complexes. Three bands may be due to which was found to be biologically inactive. The plates were incubated for John Teller Effect. 24 h at 37 oC for bacteria and 96 h at 28 oC for fungi. Each experiment was done in triplicate and the average mean inhibition zone have been reported. On the basis of IR, 1H-NMR and electronic spectral data it seems reason- The obtained results of zone of Inhibition in terms of mean inhibition zone able to assume the M (II) complexes have the following structure (Fig.1 & and graphical representation of microbial studies for the synthesized com- 2). plexes have been presented in Table.2 -10 respectively. RESULTS AND DISCUSSION Elemental analyses were carried out on Carlo Earba 1108 elemental ana- lyzer (Results have been presented in Table 1). Infrared spectra were recorded on Perkin Elmer spectrophotometer using KBr pellets in the range 4000-400 cm-1. 1H-NMR spectra were recorded on a Bruker DRX- spec- trometer at 300 MHz using TMS as internal standard and DMSO-d6 and CDCl3 as solvents. Chemical shifts (d) were expressed in ppm downfield from internal standard TMS. Electronic spectra of metal complexes were recorded in DMSO solvent on Shimadzu UV 1800 Spectrophotometer. The IR and 1H-NMR spectral data: Adipic acid dihydrazide -1 Fig.1: Metal complexes of bis-( furfuryl) adipic acid dihydrazone IR (KBr, umax in cm ): 3289.3(NH2), 3176.6 (NH), 3020.7 (CH), 1661.4 (CO), 1532.0 (CH bending), 1216.7 (C-N), 1033.6 (N-N). 1H NMR (300 MHz, DMSO, d ppm) 2.500 (2H, s, NH2), 8.908 (1H, s, -CONH), 2.353- 2.307 (2H, t, -CH2CO), 1.193-1.145(2H, m, -CH2). Bis - (furfuryl) adipic acid dihydrazone -1 IR (KBr,umax in cm ): 3177.2(NH), 2936.3(CH), 1665.6 (CO), 1591.2(C=N), 1446.6(Furan ring), 1217.6(C-N), 1020.0(N-N). 1H NMR (300 MHz, DMSO, d ppm) 7.855 (1H,s, -CONH), 2.500-2.184(2H,t, - CH2CO), 1.602-1.581(2H,t, -CH2), 6.859-6.819(3H,m, furyl ring), 7.768 (1H,s, azomethine proton). Bis-(2-acetyl thiophene) adipic acid dihydrazone -1 IR (KBr, umax in cm ): 3178.2(-NH), 3020(CH), 1663.3(CO), 1590.0(C=N), 1 1216.6(CN), 1051.8(N-N), 669.9(C-S).
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