Synthesis, Physico-chemical and Biological Properties of Some Mixed Ligand Complexes of Trivalent Lanthanides with 4[N-4×-Dimethylamino-Benzalidene)amino] antipyrineThiosemicarbazone and Pyridine

In the present studies, some seven and ten coordinated complexes of trivalent lanthanides derived from 4[N-(4’-dimethylaminobenzalidene)amino]antipyrinethiosemicarbazone (DMBAAPTS) and pyridine are reported with the general composition LnX3.n(DMABAAPTS).Py (Ln = La, Pr, Nd, Sm, Gd, Dy, Dy or Ho : X = NO3 , n =1, X = NCS or ClO4, n = 2, Py = pyridine). All the complexes were characterized by elemental analysis, molar mass, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. The infrared studies suggest that the DMBAAPTS behaves as a neutral tridentate (N,N,S) while pyridine is coordinated to central metal ion via its lone N-atom. Perchlorate ions are not coordinated in coordination sphere; nitrates are bicovalently bonded, while isothiocyanate is coordinated through a strong N-atom. From electronic spectral data, nephelauxetic effect (â), covalence factor (b1/2), Sinha parameter (ä%) and the covalence angular overlap parameter (ç) have been calculated. Antibacterial and antifungal activities of the thiosemicarbazone and its Ln(III) complexes have been evaluated. Thermal stabilities of these complexes were also studied by TGA.