Facile photocatalytic reactions in various conditions using quinolinium salts as photocatalysts

Abstract

Quinolinium salts, a class of N-heteroaromatic cationic compounds, have recently emerged as versatile organic photocatalysts due to their excellent photophysical properties, including long fluorescence lifetimes, high quantum yields, and strong oxidative capabilities. This review highlights recent advances in the application of quinolinium-based photocatalysts to a variety of photocatalytic transformations, such as hydrogen generation, hydrogen peroxide formation, photooxygenation, and oxidative C–C bond formation, with particular emphasis on their relevance to green chemistry. Notably, the simple quinolinium derivative QuPh⁺–NA has been most frequently employed as a photocatalyst, exhibiting high reactivity and stability under visible or UV light irradiation. We provide a comprehensive overview of quinolinium salt-based photocatalysis, covering their structural characteristics, synthetic strategies, and mechanistic insights. Finally, we outline future directions for their development and application in sustainable chemical synthesis.