Five novel copper(II) complexes have been synthesized using Schiff base ligands, synthesized by the condensation reaction of anthranilic acid and Knoevenagel b-ketoanilide condensates (obtained by the condensation of acetoacetanilide and substituted benzaldehydes). The ligands and copper(II) complexes have been characterized on the basis of Microanalytical, Mass, UV-Vis., IR, 1 H NMR, ESR, XRD and CV spectral studies, as well as magnetic susceptibility and conductivity data. On the basis of spectral studies, a square-planar geometry has been proposed for the copper(II) complexes. From the XRD data, the CuL 1 complex has the crystallite size of 50 nm respectively. The in vitro antimicrobial activity of the compounds is tested against the bacteria Escherichia coli, Salmonella typhi, Staphylococcus aureus, Klebsiella pneumoniae and Pseudonomas aeruginosa and fungi Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by well diffusion method. The complexes show stronger antimicrobial activity than the free ligands. They represent a novel class of metal-based antimicrobial agents which provide opportunities for a large number of synthetic variations for modulation of the activities.

New neutral Schiff base tridentate ligand transition metal complexes of the composition, ML 2, where M= Cu(II), Ni(II), Co(II) and Zn(II); L= ligands derived from semicarbazide hydrochloride and 2,4pentanedione/methyl acetoacetate/acetoacetanilide, were synthesized and characterized by elemental analyses, magnetic susceptibility, IR, UV-Vis., 1 H-NMR, 13 C-NMR, CV, ESR, and FAB-mass spectral techniques. Electronic absorption spectra of the complexes indicate an octahedral geometry around the metal ion. The magnetic susceptibility measurements and low conductance data provide evidence for the monomeric and neutral natures of the complexes respectively. The electrochemical behaviour, the anodic and cathodic potential and the number of electron transfer were calculated using cyclic voltammogram. The X-band ESR spectrum of copper complex in DMSO at 300 K and 77 K was recorded and its salient features are reported. The antimicrobial activities of the ligands and their complexes have been studied by screening the compounds against the bacteria E. coli, P.aeruginosa, P.mirabilis, S. typhi, and B.subtilis and also the fungi C.albicans and R. stolonifer and results have been compared with the standard drug, amphicillin. The data indicate that most of the metal complexes have higher antimicrobial activity than the free ligands and the standard. The DNA cleavage experiments, performed using gel electrophoresis with the corresponding metal complexes in the presence of H 2 O 2 showed all the complexes afford a pronounced discernible DNA cleavage evidenced by the disappearance of Form I (supercoiled) of plasmid and the production of Form III (linear).

A new series of 14 membered tetraazamacrocyclic complexes of type [ML]X 2 , where M=Ni(II), Co(II), Cu(II), Zn(II), Hg(II), VO(IV), Cd(II) and Mn(II); X 2 = 2Cl-; SO 4 2-, have been synthesized by incorporating an N 4 donor site via. the template condensation of o-phenylenediamine, formaldehyde, p-anisidine and metal salt. The structural features of the complexes have been confirmed by spectral and analytical data. From the data, a square-planar geometry around the central metal ion has been suggested except VO(IV) complex which has square-pyramidal geometry. The antimicrobial screening data show good results. From the nuclease activity of the above metal complexes, it is inferred that only the copper and nickel complexes cleave DNA through redox chemistry.