Modulating the electron-donating ability of aggregation-induced emission molecules for improved photo-responsive properties

Organic photoresponsive materials have gained broad research interest in materials science and have made significant progress in the past two decades. Developing multifunctional photoresponsive materials with high emission efficiency and fast response to fulfill the demand for practical applications remains desired but challenging. Herein, three novel photoresponsive compounds featuring aggregation-induced emission properties were synthesized, and their photoresponsive activities were regulated via optimizing electron-donating capacity. All compounds undergo Z/E isomerization under both white light irradiation and UV irradiation. Equipped with strong electron-donating ability, compound PBYN exhibits the fastest isomerization reaction with a photoconversion rate of 50% after continuous irradiation for 0.5 hours in comparison with DOPBYN and OPBYN. Meanwhile, only DOPBYN shows photodimerization in the solid state with a short center-to-center distance of 3.46 & ANGS;. Crystal packing analysis indicates that compounds OPBYN and PBYN possess relatively loosely packed modes because of their twisted structure, which dramatically hinders the photodimerization reaction. These results indicated that the optimization of electron-donating ability and molecular packing by oxidizing phenothiazine units is a promising strategy for constructing multifunctional photoresponsive materials.