Synthesis, Structural Characterization and Antimicrobial Evaluation of Ruthenium Complexes with Heteroaromatic Carboxylic Acids

Abstract

The antibacterial and antibiofilm activities of two new ruthenium complexes against E. coli, S. aureus, P. aeruginosa PAO1 (laboratory strain) and P. aeruginosa LES B58 (clinical strain) were evaluated. Complexes, mer‐[RuIII(2‐bimc)3] ⋅ H2O (1) and cis‐[RuIVCl2(2,3‐pydcH)2] ⋅ 4H2O (2), were obtained using aromatic carboxylic acid ligands, namely, 1H‐benzimidazole‐2‐carboxylic acid (2‐bimcH) and pyridine‐2,3‐dicarboxylic acid (2,3‐pydcH2). Compounds were physicochemically characterized using X‐ray diffraction, Hirshfeld surface analysis, IR and UV/VIS spectroscopies, as well as magnetic and electrochemical measurements. Structural characterization revealed that Ru(III) and Ru(IV) ions in the complexes adopt a distorted octahedral geometry. The intermolecular classical and weak hydrogen bonds, and π⋅⋅⋅π contacts significantly contribute to structure stabilization, leading to the formation of a supramolecular assembly. Biological studies have shown that the Ru complexes inhibit the growth of bacteria and biofilm formation by the tested strains and the complexes seem to be a potential as antimicrobial agents.

Ruthenium(IV) Complexes as Potential Inhibitors of Bacterial Biofilm Formation

“…The activity of the chloride ruthenium complexes against the P. aeruginosa PAO1 biofilm, described in this paper, is higher than the activity of the chelate ruthenium complexes with Nheteroaromatic carboxylic acids and slightly lower than the activity of the benzimidazole-based ruthenium(IV) complex (these results have been published by our group most recently) [16,17]. Our results show that the ruthenium complexes have a high potential to inhibit biofilm formation.…”

“…The correlation tendency between the biological activity and the electrochemical evaluations of chloride ruthenium(IV) compounds (studied by our team so far) was carried out by CV/DPV yields interesting results. The electrochemical behaviour was similar in Ru(IV)/Ru(III) cases studied (E1/2 0.1-0.15 V) [17,20]. The correlation of the biological activity with half-wave potentials was made on the Ru(IV)/Ru(III) couple, reported as the stable formation of complexes.…”

“…The results of our study indicate that the higher half-wave potential, the lower the biological activity of the ruthenium(IV) complexes. In a previous paper, we have found out the inverse relationship between biological activity and redox potential among chelate complexes [17]. Also, Ruiz-Azuara and colleagues have observed correlation between biological activity and reduction potential [46].…”

“…Moreover, we have found out that chloride Ru(IV) complexes indicated higher biological activity than chloride/acetonitrile complexes. between biological activity and redox potential among chelate complexes [17]. Also, Ruiz-Azuara and colleagues have observed correlation between biological activity and reduction potential [46].…”

Tuning Anti-Biofilm Activity of Manganese(II) Complexes: Linking Biological Effectiveness of Heteroaromatic Complexes of Alcohol, Aldehyde, Ketone, and Carboxylic Acid with Structural Effects and Redox Activity

“…To this purpose, serial two-fold dilutions of the compounds ranging between 1 and 0.0625 mM were made. The details of the experiment were presented in our previous paper [ 64 ]. MIC values were recorded as the lowest concentration of the tested compound that completely inhibited bacterial growth, using the Infinite M200 PRO microplate reader (Tecan, Männedorf, Switzerland).…”