Spectral, XRD, SEM and biological activities of transition metal complexes of polydentate ligands containing thiazole moiety

Metal complexes of o-vanillidene-2-aminobenzothiazole have been prepared and characterized by elemental and spectral (vibrational, electronic, H-1 NMR and EPR) data as well as magnetic susceptibility measurements and thermo gravimetric analysis (TG/DTA). The low molar conductance values reveal the non-electrolytic nature of these complexes. The elemental analysis suggests that the stoichiometry to be 1:2 (metal:ligand). Magnetic susceptibility data coupled with electronic spectra suggest that two ligands coordinate to each metal atom by phenolic oxygen and imino nitrogen to form high spin octahedral complex with Co(II), Mn(II) and Ni(II). The fifth and sixth position of metal ion is satisfied with water molecules. The thermal behaviour (TG/DTA) of the synthesised complexes shows that the complexes loss water molecules in the first step followed by decomposition of the ligand. Spin Hamiltonian parameters predict a distorted tetrahedral geometry for the copper complex. XRD and SEM analysis provide the crystalline nature and the morphology of the metal complexes. The in vitro biological activity of the metal chelates is tested against the Gram positive bacteria (Bacillus amyloliquifacians) and gram negative bacteria (Pseudomonas species), fungus (Aspergillus niger) and yeast (Sacchromyces cereviaceae). Most of the metal chelates exhibited higher biological activities. (c) 2008 Elsevier B.V. All rights reserved.