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

Abstract

We report herein synthesis and characterization of four new organoruthenium(II) complexes of the type [RuH(CO)(PPh₃)₂(L_1,2)]Cl (1, 3) and [Ru(CO)(Cl)₂(AsPh₃)(L_1,2)] (2, 4) derived from the reaction of [RuHCl(CO)(EPh₃)₃] (E = P or As) with 2-(pyridine-2yl)benzoxazole (L₁) and 2-(pyridine-2yl)benzthiazole (L₂). 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.

Keywords:

• Ruthenium(II) compound
• X-ray structure
• DNA/BSA binding
• enzyme kinetic studies

Acknowledgement

One of the authors (A.G.) thanks the Department of Science and Technology, Ministry of Science and Technology, Government of India, for a fellowship under the INSPIRE scheme (No. IF140098). The authors also thank UGC, India for financial assistance to Department of Chemistry, Periyar University, Salem under SAP (No. 540/20/DRS-I/2016(SAP-I)).