Syntheses, Characterization and Antimicrobial Studies of Coordination Compounds of Schiff Base Possessing Semicarbazone Moiety

Abstract

Salicylaldehyde and o-hydroxyphenylsemicarbazide (OHPSC) react in 1:1 molar ratio in EtOH and produce the Schiff base, LH4 (1). On refluxing a MeOH solution of 1 with divalent Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Zr(OH)2(IV), MoO2(VI) and UO2(VI) ions in 1:1 molar ratio, produces the corresponding non-electrolytic (ΛM = 2.9-10.2 mho cm 2 mol -1 in DMSO) dimeric coordination compounds, H2O)]2 (9) and [UO2(LH2)(H2O)]2 (10) respectively. The various studies like elemental analyses, molar conductance, spectral (IR, reflectance, 1 H NMR), TGA and magnetic susceptibility measurements have been used for the characterization of the above synthesized coordination compounds. The Schiff base behaves as a dibasic pentadentate (ONONO donor) ligand and the comparative IR spectral studies of the Schiff base and its coordination compounds suggest the involvement of phenolic O (aldehydic moiety), azomethine N, carbonyl O, semicarbazidic N and phenolic O (aminophenolic moiety) atoms towards coordination. The molecular structures of the Schiff base and its coordination compounds have been optimized by molecular modelling calculations. The Schiff base and all the coordination compounds are good growth retarder for Gram-positive bacteria (S. aureus, B. subtilis), Gram-negative bacteria (E. coli, P. aeruginosa) and yeast (S. cerevisiae, C. albicans). A distorted octahedral structure has been suggested for the coordination compounds.