Phenothiazine-Based Luminophores with AIE, Solvatochromism, and Mechanochromic Characteristics

Aggregation-induced emission (AIE) fluorescent molecules with unique photoelectric properties have received extensive attention due to the wide range of applications. In this work, two novel phenothiazine-based luminophores DPE-PTZ-Cl and DPE-PTZ-CF were designed based on the frontier molecular orbital (FMO) theory and construction strategy of AIEgens. As expected, both of the luminophores displayed typical AIE behavior and realized the spatial separation of FMOs, which was confirmed by the positive solvatochromism behavior. Their AIE properties could be attributed to the twisted three-dimensional (3D) conformation. Such a conformation resulted from "butterfly-like" phenothiazine and a multirotor structure of diphenylethylene. The spatial separation of FMOs originated from the push-pull electronic synergistic effect of the donor-acceptor (D-A) architecture. Interestingly, DPE-PTZ-Cl also showed a rare blue-shifted mechanochromic (MC) luminescence property. Single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD) experiments were carried out to reveal that the phase transformation between crystalline and amorphous states was responsible for the peculiar solid-state luminescence phenomenon.