Adjusting Organic Room-Temperature Phosphorescence with Orderly Stimulus-Responsive Molecular Motion in Crystals

Summary: The transfer of molecular machine technology into aggregated states is a key step for the realization of many potential applications. Here we report three organic luminescent agents, CzS-o-py, CzS-m-py, and CzS-p-py, that can adjust organic room-temperature phosphorescence (RTP) via orderly stimulus-responsive molecular motion in the crystal. Careful analysis of the single-crystal structure before and after ordered molecular motion, coupled with theoretical calculations, reveals the effective intermolecular charge transfer generated by the dense packing mode to be responsible for the RTP effect. Accordingly, a dual anti-counterfeiting application is successfully implemented, exploiting the RTP effect of the stimulus response. The introduction of molecular mechanical technology may provide a strategy for the molecular design, internal mechanism exploration, and practical application of RTP luminescent agents.