Spiro-Functionalized Diphenylethenes: Suppression of a Reversible Photocyclization Contributes to the Aggregation-Induced Emission Effect

Abstract

Many aggregation-induced emission (AIE) materials are featured by the diphenylethene (DPE) moiety which exhibits rich photophysical and photochemical activities. The understanding of these activities behind AIE is essential to guide the design of fluorescent materials with improved performance. Herein by fusing a flexible DPE with a rigid spiro scaffold, we report a class of novel deep-blue material with solid-state fluorescent quantum yield (ΦF) up to 99.8%. Along with the AIE phenomenon, we identified a reversible photocyclization (PC) on DPE with visible chromism, which is, on the contrary, popularized in solutions but blocked by aggregation. We studied the steric and electronic effects of structural perturbation and concluded that the PC is a key process behind the RIMs (restriction of intramolecular motions) mechanism for these materials. Mitigation of the PC leads to enhanced fluorescence in solutions and loss of the AIE characteristics.

Crosstalk‐Free Patterning of Cooperative‐Thermoresponse Images by the Synergy of the AIEgen with the Liquid Crystal

“…The rapid photocyclization of the AIEgen (TPE‐4CN) upon UV irradiation within the LC promises the facile fluorescent patterning. Despite the extensive study on the photocyclization of TPE derivatives, it still remains challenging to achieve a high conversion owing to the intrinsic competition between the photocyclization and fluorescence emission when excited . Distinctively, a high conversion up to 97 % is achieved during the photocyclization of the AIEgen in the LC (Supporting Information, Figures S23 and S24), upon exposure to UV irradiation (wavelength: 365 nm, intensity: 90 mW cm −2 , duration: 30 min).…”

Photo‐Responsive Fluorescent Materials with Aggregation‐Induced Emission Characteristics

“…[71][72][73][74][75][76][77][78] Some photo-responsive fluorescent materials with AIE properties based on photocyclization reactions have been reported, and show excellent performance in advanced nanotechnological, biomedical, and photo-physicochemical applications. [79][80][81][82][83][84][85][86][87][88] In a recent example, by introducing rigid spiro scaffolds into diphenylethene moieties, Tang et al synthesized a kind of novel AIEgens (SIPs) with deep-blue emission, which exhibited state-dependent photocyclization behaviors and fluorescence properties. [82] The photocyclization processes and AIE properties are shown in Figure 3A.…”

Unusual light-driven amplification through unexpected regioselective photogeneration of five-membered azaheterocyclic AIEgen

“…[31][32][33][34][35][36] Though the resulting cyclic products were successfully employed in various fields including super-resolution imaging, organic optoelectronic devices and self-assemble materials, yet N-containing fused five-membered heterocycle with AIE feature is rarely reported. [37][38][39][40][41][42][43][44][45] Thus, generating AIE-based compounds with fused five-membered azaheterocycles via an efficient and facile photoreaction is not only exceedingly challenging but also exceptionally appealing. In this contribution, we obtained an unexpected fivemembered azaheterocyclic AIEgen, namely c 5 -TPBQ with multiple functions via a clean, efficient and regioselective photoreaction.…”