Cage-Confinement Induced Emission Enhancement
Rao Tao, Xin Zhao, Tianshu Zhao, Miaomiao Zhao, Ruiyang Li, Tianfu Yang, Lizhi Tang, Yinghua Jin, Wei Zhang, Li Qiu
Abstract
As a proof-of-concept study, Imi-cage and Phos-cage organic molecular cages (OMCs) containing the triphenylphosphine (TPP) moiety, a nonclassic AIE luminogen (AIEgen), have been designed to demonstrate the cage-confinement induced emission enhancement (CCIEE). Thanks to the confinement effect of OMCs, the rigid Imi-cage exhibits much higher photoluminescence (PL) quantum yield (ΦPL) than the open-shell Semicage and small molecule TPP in both solution and amorphous solid states. The emission of Phos-cage could be further enhanced in crystalline solid state with a remarkably high ΦPL of 97.6% (vs 3.47% of crystalline TPP) benefiting from AIE enabled by the highly ordered molecular packing. The novel strategy of CCIEE via confining an AIEgen into an OMC to achieve a significant emission enhancement will shed light on the development of solid-state highly fluorescent materials. The fluorescent nature of Imi-cage was further exploited for the ultrahighly sensitive detection of the explosive picric acid.