Luminescence

Chemistry

Materials science

Photoswitch

Aggregation-induced emission

Benzothiophene

Thiophene

Stacking

Optoelectronics

Photochemistry

Fluorescence

Intermolecular force

Physics

Organic chemistry

Steric effects

Optics

Diarylethene

Intramolecular force

Molecule

Photochromism

Stereochemistry

Angewandte Chemie International Edition

Unprecedented dual aggregation-induced emission (AIE) behavior based on a steric-hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π-π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off-to-on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off-to-on fluorescent photoswitch is successfully established in super resolution imaging.

Unraveling Dual Aggregation‐Induced Emission Behavior in Steric‐Hindrance Photochromic System for Super Resolution Imaging