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

Abstract The complexes [Cu(biq)2]Cl2 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 1H- and 13C-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 Td, 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]Cl2 against both bacteria and fungi. Keywords: Copper complexesInterconversion(aryl···aryl) and (C–H···F) intermolecular interactionsBiological activity Acknowledgement Financial support from the Deanship of Graduate Studies at Al al-Bayt University is greatly appreciated.