4-Aryldithieno[3,2-b:2',3'-d]arsoles: effects of the As-substituent on the structure, photophysical properties, and stability.

Dithieno[3,2-b:2',3'-d]arsole (DTA) is one of the representative arsenic-containing conjugated units. In this work, the effects of the As-substituent on the structure, photophysical properties, and stability were investigated. Surprisingly, the As-substituent affected the structural relaxation and stability in the photo-excited state, while there was negligible effect in the ground state. Bulky substituents resulted in red-shifted emissions due to the relaxation of steric repulsion upon photo-excitation. In addition, the crystal structure highly affected the photo-degradation behaviors.