Antibacterial activity of DPEphos-containing ruthenium-nitrosyl complexes

Abstract The complex fac -[RuCl 3 (NO)(κ 2 -P,P′-DPEphos)] (1) was synthesized and characterized by 31 P { 1 H} and 1 H 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)(κ 2 -P,P′-DPEphos)(L)]PF 6 , (L = pyridine – py (2), 4-methylpyridine – 4-Mepy (3), 1-methylimidazole – 1-Meim (4) and 1 H –benzimidazole – 1 H -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 4.0 μg·mL −1 for the trans -(NO,OMe)-[RuCl(OMe)(NO)(κ 2 -P,P′-DPEphos)(1-Meim)]PF 6 (4) against S . aureus , after 24 and 48 h.