Visible light-triggered acceptor-acceptor type dithienylethene with aggregation-induced emission for NIR photochromism in aqueous media

Photochromic dithienylethene (DTE) derivatives with aggregation-induced emission (AIE) performance are appealing for photoelectric functional materials and photopharmacology. However, they often have to be triggered by ultraviolet light to induce photoisomerization, severely limiting their potential applications in biological systems. Herein, a novel acceptor (A)-acceptor (A) type DTE derivative (CNSDTE) has been rationally designed and prepared, in which the cyanostilbene moieties as strong electron-withdrawing groups are incorporated into both sides of DTE skeleton. Its chemical structure is fully verified by 1H NMR, 13C NMR and HRMS. Upon alternating irradiation of visible and near-infrared light, CNSDTE shows excellent photochromic properties in toluene, chloroform and DMSO. Before irradiation with visible light, AIE properties and solid state luminescence behavior are observed. Furthermore, CNSDTE-loaded nanoparticles (CNSDTE NPs) are facilely fabricated by taking the amphiphilic Pluronic F127 as the encapsulating matrix. The as-prepared CNSDTE NPs display excellent photoswitching behavior in aqueous media. The experimental results of the excellent AIE properties and photoswitching behaviors in the various media is also confirmed by DFT calculations. In short, it may be employed in functional biomaterials as a novel visible light-triggered fluorescence switch with AIE features.