Aggregation Induced Transition by Modulation of Substituent Groups on Rofecoxib Analogues and Multi‐Stimulus Response Properties.

Aggregation‐induced emission luminogens (AIEgens) have been widely investigated due to their promising applications in data storage, organic light‐emitting diodes, and deep tissue bioimaging as compared to conventional fluorophores. In this work, we have designed and synthesized two novel rofecoxib analogues functionalized with different terminal groups (−NH2, −Br) on the benzene ring B. Interestingly, the compound 2 a‐3 with −NH2 substituent shows aggregation‐caused quenching effect whereas the compound 1 b‐3 with −Br group displays aggregation‐induced emission (AIE) property which may be caused by the twisted conformation and restricted – stacking of 1 b‐3 according to the X‐ray single crystal diffraction analysis. These opposite results indicated that the terminal groups could have great influence on the photophysical properties of targets. Moreover, the compound 1 b‐3 exhibited multi‐stimuli response luminescence behaviors under various external stimuli including solvatochromism, mechanochromism and acidochromism. Furthermore, lipid droplets imaging investigation proved the compound 1 b‐3 was capable of achieving specific lipid droplets bioimaging. This work not only presents a better understanding of the structure‐fluorescent property relationship based on the scaffold of rofecoxib, but also provides a new avenue for spectral modulation and the development of new MSR materials. [ABSTRACT FROM AUTHOR]