Aggregation-induced emission and reversible mechanoresponsive behavior of boryl substituted phenothiazine

A series of donor-acceptor (D-A) type luminophores, i.e., aminoboranes containing phenothiazyl substituents 4a, 4b, and 4c, were synthesized and characterized. These aminoborane derivatives showed good air/moisture stability and excellent optical performance. The results revealed that these compounds exhibited typical intramolecular charge-transfer (ICT) and aggregation-induced emission (AIE) behavior. Moreover, these luminophores displayed a significant stimuli-induced emission behavior and obvious chromism properties with high reversibility. Upon grinding, the emission spectrum of the ground sample 4c exhibited a significant 106 nm red-shift from 461 to 567 nm. Compared to the B-N-containing compound, the C-N-containing compound 4d did not show any evident AIE properties and MFC phenomenon; hence, interesting electronic, photophysical, luminescence, and chemical properties were only observed for 4a, 4b, and 4c. Comprehensive analysis of the crystal structure and theoretical calculations revealed that the remarkable MFC phenomenon originated due to the strongly twisted conjugated backbones and loose molecular packing. A series of donor-acceptor (D-A) type luminophores, i.e., aminoboranes containing phenothiazyl substituents 4a, 4b, and 4c, were synthesized and characterized.