Synthesis and characterization of cobalt (II), nickel (II), copper (II) and zinc (II) complexes derived from two Schiff base ligands: Spectroscopic, thermal, magnetic moment, electrochemical and antimicrobial studies

Two azo group-containing Schiff base ligands, namely 4-((2,4-dichlorophenyl) diazenyl)-2-(3-hydroxypropylimino) methyl) phenol (L-1) and 2-((3-hydroxypropylimino) methyl)-4-(thiazol-2 yldiazenyl) phenol (L-2) were prepared. The synthesis and characterization of Co(II), Ni(II), Cu(II), and Zn(II) complexes of the ligands (L-1) and (L-2) have been described. Elemental analyses, magnetic moment, mass spectrometry, H-1 NMR, C-13 NMR, electronic and infrared data suggest a mono-nuclear structure for all compounds. All these complexes have a general formula of type [M(L)(2)] (M = Co, Ni, Cu and Zn). The complexes are powders, insoluble in regular organic solvents but soluble in DMSO. Their probable structures have been estimated as per the basis of their spectroscopic data. The lagans show bidentate behavior in the complexes. The coordination occurs through azomethine nitrogen atom and an oxygen atom of the OH group. The infrared spectra of all complexes within the region of 540-500 cm (1) and 470-420 cm (1) can be assigned to M-O and M-N modes, respectively. The ligands (L-1 and L-2) and the synthesized complexes were tested for their antimicrobial activity against clinical isolates of Escherichia coli (the Gram-negative bacteria), Staphylococcus aureus (the Gram-positive bacteria) and Candida albicans (the fungus) using Kirby-Bauer and Micro plate dilution methods. (C) 2017 Elsevier B.V. All rights reserved.