Interaction of The Silver(I) Ion With a Ligand of The Thiohydantoin Moiety

Abstract

As the threat of multi-drug resistant strains poses a serious global problem, the search for new antibacterial and antifungal therapeutics gains significant importance. Antimicrobial resistance has contributed to increases in morbidity, mortality and healthcare expense. The purpose of our study is to find new, potent antimicrobial agents which will combat this widespread health issue by discovering new compounds with potential activities. Silver and its complexes have a huge therapeutic potential due to their bioactivities. Numerous silver(I) complexes with nitrogen-, oxygen-, phosphorus- and sulphur-donor ligands have been synthesized and evaluated as potential antibacterial and antifungal agents. Hydantoins are a large family of structurally diverse drug-based compounds that exhibit a variety of different activities and they have found applications in many fields such as medicine, industry, agriculture etc. It is documented that the coordination of hydantoins with transition metals often leads to amplification of their biological activities. In this study, a reaction of AgNO3 with a 2-thiohydantoin derivative, 5-[2-(methylthio)ethyl]-3-(2-propen-1-yl)-2-thioxo-4-imidazolidinone was monitored by time dependent 1H NMR spectroscopy. All reactions were performed in acetone-d6 solutions at ambient temperature, by mixing equimolar amounts of the reactants. Silver has several modes of coordination and thiohydantoins have several possible donor atoms. 5-[2-(methylthio)ethyl]-3-(2-propen-1-yl)-2-thioxo-4-imidazolidinone has two coordination spots that we have turned our focus to, the thioether sulphur in the side chain and the NH proton in the thiohydantoin ring. No change in the integral values of the NH proton signal was detected in the time dependent 1H NMR spectroscopy, while the CH3-S proton signals have shifted from 2.08 to 2.16 ppm. This indicates that coordination, in fact, did occur to the side chain thioether sulphur. Additional efforts will have to be made towards obtaining monocrystals, so that the complex can be fully characterized. The results obtained from herein could contribute to a better insight into silver and hydantoin chemistry, the mechanisms of their interaction, and also might lead to the synthesis of silver complexes with potential antimicrobial activities.