Oxovanadium(IV) complexes have been synthesized and characterized the general composition [VOL(A)], where H2L = salicylidene-o-aminothiophenol A1 = bis(benzylidene)ethylenediamine, A2 = bis(acetophenone)ethylenediamine, A3 = 2,2'-bipyridylamine, A4 = bis(benzylidene) - 1,8-diaminonaphthalene, A5 = thiophene-o-carboxaldeneaniline and A6 = thiophene-o-carboxaldene-p-anisidine. Spectral studies indicate that the oxovanadium(IV) complexes assume a six-coordinate octahedral geometry. The antibacterial activities of the complexes against Salmonella typhi, Escherichia coli and Serratia mercescens are higher as compared to the free ligands, vanadyl sulphate, and the control (DMSO) but of moderate activity as compared to the standard drug (tetracycline).

Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with the Schiff bases salicylidene-o-aminothiophenol (H2L) and thiophene-o-carboxaldeneaniline (SB) have been synthesized and characterized by elemental analyses, magnetic measurements, thermogravimetric analyses as well as infrared spectra and reflectance spectra. The nature of the bonding has been discussed on the basis of IR spectral data. Magnetic susceptibility measurements and electronic spectral data suggest a six-coordinated octahedral structure for these complexes. The complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic, while Zn(II) and Cd(II) are diamagnetic in nature. The complexes were tested for their antimicrobial activities against Salmonella typhi, Escherichia coli and Serratia marcescens using the "Disc Diffusion Method". The results are compared with the standard drug (tetracycline) and show moderate activity.

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Novel dimeric Cu(II) heterochelates were synthesized using 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-1,4-dihydro-quinoline-3-carboxylic acid (Cpf) and eight different neutral bidentate ligands. All ligands were characterized by elemental analyses, melting point and IR, 1 H NMR and 13 C NMR spectra, while heterochelates were characterized by elemental analyses, IR spectra, reflectance spectra, magnetic measurements and thermogravimetric analyses. The DNA interaction and cleavage behaviors of the ligands and corresponding heterochelates were studied by UV-vis absorption titration and gel electrophoresis technique, respectively. The results indicate that heterochelates show larger DNA interaction and cleavage affinity than the ligands. The antimicrobial activities of heterochelates, ligands, cupric nitrate and standard drugs against six bacteria and three fungi were tested.