STRUCTURAL AND BIOLOGICAL ASPECTS OF COPPER(II) COMPLEXES WITH 2-METHYL-3-AMINO-(3 H)-QUINAZOLIN-4-ONE

A series of new copper(II) complexes with 2-methyl-3-amino(3H)-quinazo lin-4-one (MAQ) and various anions (Cl-, Br-, ClO4-, NO3-, SCN-, and S O42-) was prepared. Their structures and properties were characterized by elemental analysis, IR, UV-Vis and ESR spectroscopy, molar conduct ivity, and magnetic moment measurements. The square-planar complex was only obtained in the presence of perchlorate anion, whereas the five coordinate species, which have a square-pyramidal structure, were obta ined for chloro and bromo complexes. In the case of hexa coordinate co mplexes, in which nitrate, sulphate, or thiocyanate is attached to a c opper(II) ion in a 1:2 (metal:ligand) ratio, a distorted octahedral ge ometry around copper(II) is proposed. The antimicrobial activity of th e free ligand and its copper(II) complexes clearly illustrates that th e compounds have both an antibacterial and antifungal potency against the organisms tested. In most cases, the complexes were found to be mo re active than the free ligand, but in some cases, an equal activity w as displayed. To further elucidate the biological activity of the comp lexes, their activities towards active oxygen species, such as H2O2 an d O-2(-), were investigated. A probable mechanism for the cytotoxic re action with the different organisms is proposed. (C) 1997 Elsevier Sci ence Inc.