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

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, 1H 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 (Kb), 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.

The characterized dinuclear and mononuclear cadmium(II) complexes with 5-bromo-salicylaldehyde may interact with calf-thymus DNA possibly via intercalation and can get bound and transferred by the albumins and released upon arrival at the targets as indicated the corresponding binding constants.Figure optionsDownload as PowerPoint slide