Investigation of Solvent Effects on Spectroscopic and Photochemical Properties of Ruthenium (II) Polypyridyl Complexes

Abstract

Abstract. This study explores the influence of solvent environments on the spectroscopic and photochemical properties of ruthenium(II) polypyridyl complexes, with a focus on their application in sustainable hydrogen production and solar energy conversion. These complexes show great potential as photocatalysts for clean energy technologies; however, their efficiency and stability are highly dependent on the surrounding chemical environment. Using high performance liquid chromatography (HPLC) and UV-Vis spectroscopy, the research evaluates electronic transitions and photochemical behavior under continuous irradiation. Notably, the complex [(tbbpy)2Ru(tpphz) (Pt2)2] exhibited a significant metal-to- ligand charge transfer (MLCT) shift from 486 nm to 441 nm over 24 hours in polar solvents such as acetonitrile and methanol indicating solvent-induced ligand exchange and enhanced charge transfer. The inclusion of PtI, substantially improved photocatalytic performance, achieving a turnover number (TON) of 276. Measurement precision was confirmed by low standard deviations (±1.1 to ±1.5 nm) and relative standard deviation (RSD) values below 3%. These findings highlight the critical role of solvent polarity and ligand design in optimizing photocatalyst efficiency and stability for sustainable energy applications. While polar solvents enhance charge-transfer processes, they may compromise long-term stability. The study recommends the development of more robust ligands and the exploration of environmentally friendly solvents to advance photocatalytic technologies in line with environmental sustainability goals.