Self-Catalyzed Hydroxyl-Yne Click Reaction: A Powerful Tool toward Red-Emitting Nontraditional Small Organic Luminogens

Nontraditional small organic luminogens (NTSOLs) without classic conjugated chromophores have attracted significant attention. However, the design and synthesis of NTSOLs with fluorescence in the red region remain significantly challenging. In this study, we established a self-catalyzed hydroxyl-yne click reaction for preparing long-wavelength and red-emitting NTSOLs. Owing to their perfect reaction selectivity, high efficiency, and excellent universality, a series of compounds with well-defined structures were obtained in high yields. Moreover, the obtained compounds showed concentration-enhanced and excitation-dependent emission characteristics. The compounds also exhibited dramatical chemical structure-dependent and aggregation-induced red-shifted fluorescence properties, based on which we successfully obtained red-emitting NTSOLs by simply adjusting chemical structure and concentration. Also, the compounds show good cell staining ability, which can be used in cell imaging.