Organoruthenium(II) compounds with pyridyl benzoxazole/benzthiazole moiety: studies on DNA/protein binding and enzyme mimetic activities

We report herein synthesis and characterization of four new organoruthenium(II) complexes of the type [RuH(CO)(PPh3)(2)(L-1,L-2)]Cl (1, 3) and [Ru(CO)(Cl)(2)(AsPh3)(L-1,L-2)] (2, 4) derived from the reaction of [RuHCl(CO)(EPh3)(3)] (E = P or As) with 2-(pyridine-2yl)benzoxazole (L-1) and 2-(pyridine-2yl)benzthiazole (L-2). Single-crystal X-ray diffraction data of 2 proved octahedral geometry of the complexes with a 1:1 ratio between the metal and the coordinated ligands. The binding affinities of 1-4 toward calf-thymus DNA (CT-DNA) and BSA were thoroughly studied by various spectroscopic techniques. Furthermore, the coordination compounds exhibit catecholase-like activities in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone and phosphatase-like activities in the hydrolysis of 4-nitrophenyl phosphate to 4-nitrophenolate ion. The kinetic parameters have been determined using Michaelis-Menten approach. The highest k(cat) values suggested that coordination compounds exhibit higher rates of catalytic efficacy.