Wenpeng Wei, Xu Zhao, Mengjia Li, Zejing Li, Zhenguang Wang, Yanyu Qi, Linfeng Cui, Bo Liu
Donor–acceptor fluorophores often suffer from low luminescent efficiency in either solution or solid states due to nonradiative decay and aggregation-caused quenching. This study reports the rational design of two novel fan-shaped fluorophores ( 1 and 2 ) that achieve ultrahigh photoluminescence in both phases (Φ DIO = 0.99 and Φ solid = 0.92). This dual-state emission is enabled by a strategic structure incorporating bulky carbazole/triphenylamine branches. These groups effectively restrict intramolecular motion in solution to suppress energy loss, while their steric hindrance prevents detrimental π–π stacking in aggregates, conferring distinct aggregation-induced emission characteristics. The compounds exhibit pronounced intramolecular charge transfer, enabling solvent polarity sensing and visual gasoline grade discrimination. Furthermore, self-assembled aggregates of molecule 2 function as an exceptional fluorescent sensor for benzene derivative vapors, demonstrating high sensitivity (detection limits down to 84 ppb for benzene), a rapid response (∼2.44 s), and excellent selectivity. This work provides a viable molecular design strategy for high-performance dual-phase emissive materials with significant potential in environmental sensing.