The same molecule but a different molecular conformation results in a different room temperature phosphorescence in phenothiazine derivatives

Room temperature phosphorescence (RTP) luminogens have attracted much attention because of their wide range of applications in chemical sensors, bio-imaging, anti-counterfeiting technology, etc. However, these luminogens are still very scarce, especially those with a stimulus response effect, partly due to the unclear mechanism and the lack of design guidance. Here, in phenothiazine ( PTZ ) derivatives with different numbers of chlorine atoms, exciting conformation-dependent RTP emission was observed, that is, the luminogens with quasi-axial (ax) conformation showed an obvious RTP effect, while the quasi-equatorial (eq) ones did not. In particular, both conformers (ax and eq) were obtained for PTZ-3Cl in polymorphisms, demonstrating their mutual transformation under external stimulus with a unique stimulus-responsive RTP effect. An exciting conformation-dependent room temperature phosphorescence (RTP) was observed for phenothiazine derivatives, that is, the luminogens with quasi-axial (ax) conformation showed RTP effect while the quasi-equatorial (eq) ones did not.