The Impact of Molecular Packing on Organic Room Temperature Phosphorescence and Corresponding Stimulus Response Effect

Abstract Organic luminescent materials exhibiting persistent room temperature phosphorescence (RTP) have garnered considerable interest due to their versatile applications. However, the mechanism is still unclear, especially for the molecular structure‐molecular arrangement‐property relationship. Herein, six derivatives of phenothiazine 5,5‐dioxide are synthesized, revealing their distinct RTP properties and the associated underlying mechanisms. Careful analyses of their single crystal structures, combined with initial theoretical calculations, indicate that the persistent RTP effect is facilitated by effective intermolecular π–π interactions in the solid state led by folded conformation. Specifically, PTZO‐CF₃‐3F exhibits distinctive photo‐activated phosphorescence both in crystal and grinding state in response to the changes of molecular arrangement. Besides, a porous structure is found to be present in PTZO‐CF₃‐2F crystal, offering it great sensitivity to oxygen for both RTP intensity and lifetime. Accordingly, the visual oxygen warning device is fabricated successfully. Furthermore, PTZO‐CF₃‐3F with photo‐activated RTP effect in a grinding state is successfully utilized in the applications of anti‐counterfeiting and optical logic gates, expanding the scope of stimulus‐responsive phosphorescence materials for broader applications.