Interconversion of copper(II) to copper(I):: synthesis, characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)(2)]Cl-2 and [Cu(biq)(2)]BF4 (.) biq (biq = 2,2'-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)(2)]BF4 (.) biq, from [ Cu( biq) 2] Cl2 has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and H-1- and C-13-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)(2)]BF4 (.) biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from T-d, and displays many supramolecular motifs incorporating both hydrophobic (aryl (.) (.) (.) aryl) and hydrophilic (C - H (.) (.) (.) F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)(2)]BF4 (.) biq was slightly better than that observed for [Cu(biq)(2)]Cl-2 against both bacteria and fungi.