Cadmium(II) complexes of 5-bromo-salicylaldehyde and alpha-diimines: Synthesis, structure and interaction with calf-thymus DNA and albumins

Abstract

Five Cd(II) complexes, four dinuclear (1-4) and a mononuclear one (5), with the anion of 5-Br-salicylaldehyde (5-Br-salo(-)), were synthesized and characterized as [Cd(5-Br-salo)(2)(CH3OH)](2) (1), [Cd(5-Br-salo)(2) (bipy)](2) (2), [Cd(5-Br-salo)(2)(phen)](2) (3), [Cd(5-Br-salo)(neoc)(NO3)](2) (4) and [Cd(5-Br-salo)(2)(dpamH)] (5). The complexes were characterized by spectroscopy (IR, UV-vis, H-1 NMR), elemental analysis and molar conductivity measurements. The structures for three complexes (2, 3 and 5) were determined by X-ray crystallography providing different coordination modes of the 5-Br-salicylaldehydo ligand. The complexes bind to DNA mainly by intercalation, as concluded by the viscosity measurements and the EB-displacement studies from the EB-DNA complex and present high DNA-binding constants (K-b), as calculated by the Wolfe-Shimer equation and plots. The interaction of the complexes with serum albumins was studied by fluorescence emission spectroscopy and the determined binding constants exhibit relative high values. (C) 2016 Elsevier Ltd. All rights reserved.