: Complexes of general formula [ Ru(bpy) 2 (L) ]CF 3 SO 3 , where bpy = 2,2′ - bipyridine, and L = Schiff bases derived from salicylaldehyde and amino acids (glycine ( 1a), cysteine (1b), methionine (1c ) and phenylalanine ( 1d )) were synthesized. Characterization based on elemental analysis, Ru content, mass, infrared and electronic spectra confirmed RuN 5 O coordination unlike 1b where coordination occurred via azomethine nitrogen and cysteine sulfur. Cyclic voltammograms, except 1b, showed several quasi- reversible redox pairs in the positive potential range, the first located at about 0.5 V, corresponding to similar heteroleptic Ru(II) bipyridyl complexes. Biological activity was tested by interactions with DNA and BSA. DNA binding constants of order 10 3 M − 1 , suggest groove binding due to bpy ligand and hydrogen bonding of the OH and CO groups from the imine moiety. In vitro BSA protein inhibition assay performed by spectrofluorimetry showed Complex : BSA binding in 1 : 1 ratio with K b of 10 4 M − 1 order. Cytotoxicity studies by MTT assay for 72 h of drug action revealed activity of 1a and 1d against breast cancer MCF- 7 cells with IC 50 values 32 ± 8 and 26 ± 1µM, respectively.

Four new heteroleptic copper(II) complexes having chalcone or flavonol ligands and Schiff base (N-phenyl-5-chlorosalicylideneimine) as co-ligand were prepared, chemically and structurally characterized and investigated as functional biomimetic catecholase models. The complexes were prepared by the solution synthesis and crystal and molecular structures were determined by X-ray diffraction. Complexes were chemically characterized by elemental analysis, infrared and electronic absorption spectroscopy as well as by electrochemical measurements. Copper(II) chalcone complexes, with square-pyramidal CuO4N core, are binuclear, featuring phenolate oxygen from the Schiff base as a bridging atom, while copper(II) flavonol complexes are mononuclear, and reveal a square planar CuO3N coordination core. Catalytic activity of the complexes in 3, 5-di-tert-butylcatechol oxidation was confirmed by spectrophotometric and electrochemical measurements. Kinetic measurements revealed that the binuclear (chalcone-containing) complexes have enhanced catalytic activity as compared to the mononuclear Cu(II) flavonol complexes. Relatively high kcat values (300 – 750 h–1) confirmed their respectable biomimetic catecholase-like activity.