Antibacterial activity of DPEphos-containing ruthenium-nitrosyl complexes

Abstract

The complex fac-[RuCl3(NO)(κ2-P,P′-DPEphos)] (1) was synthesized and characterized by 31P {1H} and 1H NMR, vibrational spectroscopy, ESI-MS and cyclic voltammetry. To support the formation of the fac-isomer, DFT level was used to optimize the structures of both fac- and mer-isomer and the energies were obtained. The optimized structure of the fac-isomer revealed an interaction between the diphenyl ether oxygen of the DPEphos ligand and the NO+. The frontiers orbitals of fac-isomer were used to support the electrochemical behavior of complex 1. Complex 1 and the complexes with general formula trans-(NO,OMe)-[RuCl(OMe)(NO)(κ2-P,P′-DPEphos)(L)]PF6, (L=pyridine – py (2), 4-methylpyridine – 4-Mepy (3), 1-methylimidazole – 1-Meim (4) and 1H–benzimidazole – 1H-Benzim (5)) were assayed as antibacterial agents against the strains of bacteria E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), S. aureus (ATCC 25932), S. epidermidis (ATCC 12228) and E. faecalis (ATCC 29212) using the method of Minimum Inhibitory Concentration (MIC). The best value was 4.0μg·mL−1 for the trans-(NO,OMe)-[RuCl(OMe)(NO)(κ2-P,P′-DPEphos)(1-Meim)]PF6 (4) against S. aureus, after 24 and 48h.