P-Cymene Based Organometallic Ruthenium(II)-Arene Complexes with Benzaldehyde Derived Thiosemicarbazones: Synthesis, Characterization and Antimicrobial Activity

Abstract

Objective: Thiosemicarbazone (TSC) containing three new mononuclear ruthenium(II)-arene complexes were synthesized so as to contribute to the development of ruthenium complexes with pharmacologically attracted properties. Methods: Reactions of the ruthenium(II)-arene dimer [{RuCl(μ-Cl)(η6-p-cymene)}2] (1) with the respective TSC1-3 (1:2 molar ratio) in methanol resulted in p-cymene containing new conformationally rigid half-sandwich organometallic ruthenium(II)-arene complexes; [(η6-p-cymene)Ru(TSC1-κ3O,N,S)]Cl (I), [(η6-p-cymene)Ru(Cl)(TSC2-κ2N,S)]Cl (II), and [(η6-p-cymene)Ru(Cl)(TSC3-κ2N,S)]Cl (III). The molecular structures of complexes I, II and III were elucidated on the spectroscopic data obtained by the application of 1H NMR, Fourier transform infrared (FT-IR), UV-vis and elemental analysis techniques. In vitro antimicrobial activities of the synthesized three ruthenium(II)-arene complexes were evaluated using the disc diffusion method. Results: The spectroscopic data indicated that TSC1 was bounded to the metal as a tridentate ligand with its thione sulfur atom, phenolic oxygen atom and azomethine nitrogen atom in the complex I, while TSC2 and TSC3 were bounded to metal center as bidentate manner through their thione sulfur atom and imine nitrogen (C=N) atom in the complexes II and III, respectively. The obtained antimicrobial activity results showed that these complexes efficiently inhibit the growth of Gram-positive bacterial strains. Conclusion: The TSC1-3 containing ruthenium(II)-arene complexes were successfully synthesized and their molecular structures were also determined by the spectroscopic methods. All ruthenium(II)-arene complexes showed higher antibacterial activities against Gram-positive bacterial strains than the Gram-negative ones. Keywords: