<p>Three new neutral complexes of copper(II) containing chalcone ligands derived from 2'-hydoxyacetophenone and 4-substituted benzaldehydes were synthesized. Complexes were prepared by solution synthesis and characterized by spectroscopy. The catalytic activity of complexes was examined in the reaction of 3,5-di-tertbutylcatehcol (DTBC) oxidation. The kinetics of DTBC catalytic oxidation by copper(II) complexes (1 &ndash; 3) was investigated spectrophotometrically under pseudo-first-order conditions. Catalytic parameters, the maximum reaction rate (vmax), Michaelis-Menten constant (KM), catalytic efficiency, catalytic reaction rate constant (kcat), turnover number (TON), and turnover frequencies (TOF) for complexes 1 &ndash; 3 in DTBC oxidation were collected. The studied complexes 1 and 2 were found to have moderate catalytic activity, while complex 3 does not show catalytic properties.</p>

Two copper(II) complexes of 4-chloro- and 4-dimethylaminobenzaldehyde nicotinic acid hydrazones were prepared and characterized by elemental analysis, mass spectrometry, infrared and electron spectroscopy and conductometry. These rare examples of bis(hydrazonato)copper(II) complexes are neutral complex species with copper(II) center coordinated with two monoanionic bidentate O,N-donor hydrazone ligands coordinated in enol-imine form. The interaction of hydrazone ligands and corresponding copper(II) complexes with CT DNA and BSA was investigated. Copper(II) complexes are slightly effective in binding the DNA than pristine hydrazones. The results indicate groove binding or moderate intercalation which are not significantly affected by the nature of substituent at hydrazone ligands. On contrary, affinities of two copper(II) complexes toward BSA significantly differs and depends on the nature of the substituent, however in absence of thermodynamic data difference in nature of binding forces cannot be excluded. The complex bearing electron-withdrawing 4-chloro substituent has larger affinity toward BSA compared to 4-dimethyamino analogue. These findings were theoretically supported by molecular docking study.

: 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.

Spectrophotometric determination of ruthenium using 1,10-phenanthroline was modified and used for quantification of the ruthenium content in complexes. Complexes were decomposed by using aqua regia and a full recovery of ruthenium from thus obtained solutions was observed at pH 6 after three hours of heating at 90 °C with a hundredfold excess of phenanthroline. The modified procedure has several important advantages compared to the originally reported procedure. It is faster and more accessible for laboratory practice since it does not require tedious RuO4 distillation. Also it has much wider linearity range (20 μg L−1 to 12 mg L−1 compared to 162 μg L−1 to 1.62 mg L−1) and lower limit of quantification (30.4 μg L−1 compared to 100 μg L−1). Moreover, recoveries of ruthenium are practically quantitative and the single standard addition method, instead of the calibration curve method, can be successfully used for accurate analysis.

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.

ABSTRACT Here is the report on the interaction of ruthenium(III) species with DNA in aqueous solution at pH 7.42 by Fourier transformed infrared difference spectroscopy. Under the physiological pH and molar ratio [Ruthenium]/[DNA] = 1/80–1/20 direct binding to guanine-N7, adenine-N7, and surprising binding to exocyclic thymine-O2 was found. At low metal concentration no significant shift of the absorption bands was observed, only nonspecific electrostatic binding of ruthenium(III) with negatively charged phosphate groups occurred. The increase of ruthenium(III) concentration caused DNA double helix destabilization and direct binding of the metal cation to guanine-N7 and thymine-O2. At higher ruthenium(III) concentrations denaturation of the DNA helix is evident with no apparent binding of ruthenium(III) to adenine and cytosine. Helix opening allows migration of ruthenium(III) ions from phosphate to available nucleobases (guanine and thymine). No alteration of the sugar phosphate geometry was observed thus confirming that DNA remains in B conformation.