Effect of the Thermal Decomposition and In Vitro Antimicrobial Activity of Mixed Ligand Copper(II) Complexes

Abstract

The author aimed to determine the activation energy for the thermal decomposition on mixed ligand copper(II) complexes of the type [Cu(Ln)(CQ)(H2O)2].xH2O (where L1 = 2-bromo-7-hydroxy-10,11-dihydroindeno[5,4-c]chromen-6(9H)-one, L2 = 2-bromo-7-hydroxy-9,10,11,12-tetrahydro-6H-naphtho[2,1-c]chromen-6-one, L3 = 5-bromo-14-hydroxy-7,8-dihydro-1H-phenanthro[2,1-c] chromen-1-one, and x = 4, 5, 3) were studied at room temperature. All the compounds have been characterized by elemental analysis, magnetic susceptibility, FT-IR, 1H-NMR, 13C-NMR, electronic spectra and FAB-mass spectrometry. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry. TGA and DSC determined thermal stability, order of kinetics, heat capacity, and activation energy of thermal degradation for these complexes. Order of stability of complexes was found to be [Cu(L1)(CQ)(H2O)2].4H2O > [Cu(L2)(CQ)(H2O)2].5H2O > [Cu(L3)(CQ)(H2O)2].3H2O. The ligands, metal salts, complexes, control, and standard drug were tested for their in vitro antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, and Bacillus substilis. The metal complexes exhibit good activity against bacterial strains compared with parental compounds and moderate compared with the standard drug (Clioquinol).