Antibacterial, spectral and thermal aspects of some novel first transition metal-based heterochelates

A new ligand, 5-{[5-(pyridine-4-yl)-1,3,4-oxadiazole-2-ylthio]methyl}quinoline-8-ol (K), was synthesized by base-catalysed reaction of 5-chloromethyl-8-hydroxy quinoline (CMQ) and 5-(pyridine-4-yl)-1,3,4-oxadiazole-2-thiol. The obtained ligand K was characterized by 1H NMR, 13C NMR and IR spectroscopic techniques and reacted with transition metal salts to afford metal-containing heterochelates. The structures of the synthesized heterochelates were characterized using elemental analyses, infrared spectra, electronic spectra, magnetic measurements, FAB mass spectrum and thermogravimetric analyses. The kinetic parameters such as order of reaction (n) and the energy of activation (Ea) are reported using the Freeman–Carroll method. The pre-exponential factor (A), the activation entropy (ΔS#), the activation enthalpy (ΔH#) and the free energy of activation (ΔG#) were calculated. Heterochelates were also screened for their in vitro antibacterial activity against a range of Gram-positive (Bacillus substilis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Serratiamarcescens) organisms. Copyright © 2010 John Wiley & Sons, Ltd.