Investigation on water soluble copper(II) mono-anionic glutamate complexes with planar aromatic ligands: synthesis, crystal structures, biomacromolecular interactions and radical scavenging activities

Abstract

Two water soluble copper(II) mono-anionic glutamatecomplexes -[Cu(phen)(glu)(H2O)]NO3·H2O (1) and [Cu(py-phen)(glu)(H2O)]NO3·H2O (2) - (phen: 1,10-phenanthroline, py-phen: pyrazino[2,3-f][1,10]phenanthroline, glu: glutamic acid), have been synthesized and characterized by CHN analysis, ESI-MS, FTIR and single-crystal X-ray diffraction techniques. Interaction of the complex with biomacromolecules {calf thymus DNA (CT-DNA) and bovine serum albumin (BSA)} has been investigated by electronic absorption and fluorescence spectroscopy methods. The experimental outcomes displays that the complexes 1 and 2 bind to CT-DNA by means of a moderate intercalation mode. Furthermore, the fluorescence quenching mechanism between BSA and the complexes 1 and 2 is a static quenching process. The Stern-Volmer constants, binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS) of BSA+ the complexes 1 and 2 systems were determined at different temperatures. The binding distance between BSA and the complexes 1 and 2 was calculated according to Förster non-radiation energy transfer theory (FRET). The effect of the complexes 1 and 2 on the conformation of BSA was also examined using synchronous, two dimensional (2D) and three dimensional (3D) fluorescence spectroscopy. Radical scavenging activity of the complexes 1 and 2 was determined in terms of IC50, using the DPPH and H2O2 method. In biomacromolecules interactions and radical activity studies, the complexes 1 and 2 were found to give good results.