A Dinuclear Ruthenium(II) Schiff Base Complex with Dissimilar Coordination: Synthesis, Characterization, and Biological Activity

A dinuclear Schiff base Ru-II complex derived from 5-chlorosalicylaldehyde and 2-aminopyridine was synthesized. The structure of the compound was analyzed by mass spectrometry as well as IR, UV/Vis, and H-1 NMR spectroscopy, along with chemical analysis, as well as magnetic, cyclovoltammetric and conductivity measurements. Two Ru-II atoms are octahedrally coordinated by azomethine and pyridine nitrogen atoms from two tridentate monobasic Schiff bases and bridging phenol oxygen atoms. The formula of the complex is [Ru2L2Cl2(Et2NH)(H2O)] [L = N-(2-pyridyl)-5-chlorosalicylidene-imine and Et2NH = isodiethylamine]. The Ru-II atoms in the dinuclear neutral complex species have different coordination environments, RuN3O2Cl and RuN2O3Cl. Interaction with CT DNA showed moderate hydrophobic binding. The compound demonstrates strong activity against methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, and especially Enterococcus faecalis. Microbiological tests showed significant inhibition of growth and ability to kill pathogens, similar or even improved compared to reference antibiotics vancomycin.