Mixed ligand complexes of cobalt(III) and iron(III) containing N2O2-chelating Schiff base: Synthesis, characterisation, antimicrobial activity, antioxidant and DFT study

Six mixed ligand complexes, namely, [Co(acac)L-1] (1), [Fe(acac)L-1] (2), [Co(acac)L-2] (3), [Fe(acac)L-2] (4), [Co(acac)L3] (5), and [Fe(acac)L3] (6) (H2L1 = NN/-bis(salicylidene)-trans 1,2 diaminocyclohexane, H2L2 = NN/-bis(salicylidene)-1,2 phenylenediamine, H2L3 = NINt-bis(salicylidene)-4-methyl-1,2-phenylenediamine) were synthesised and characterized using elemental analysis, IR spectra, UV Vis spectra, mass spectra, magnetic susceptibility measurements, H-1 and C-13 NMR spectroscopy, thermogravimetric analysis. The molar conductance measurement confirmed the non-electrolytic nature of the complexes in DMF solution. Antioxidant activity of the complexes was studied using the 2, 2-dipheny1-1picrylhydrazyl (DPPH) scavenging method. Biological studies of the complexes have been carried out in vitro for antimicrobial activity against some selected gram-positive and gram-negative bacteria. DFT calculations were performed using GAUSSIAN 09 program to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the complexes. (C) 2015 Published by Elsevier B.V.