The influence of π–π stacking on the room temperature phosphorescence of phenothiazine 5,5-dioxide derivatives

Abstract

The control of molecular packing in the aggregated state at the molecular design stage is significant but challenging. Herein, a strategy is provided to regulate the molecular packing as well as corresponding room temperature phosphorescence (RTP) performance. By changing the substituent, we designed five phenothiazine 5,5-dioxide derivatives to reveal their different RTP properties and inherent mechanism. Through careful analyses of experimental results, coupled with theoretical calculations, it is found that efficient intermolecular π–π interaction favors the long phosphorescence lifetime. Furthermore, polymorphisms with distinct intermolecular π–π interactions and RTP effects were obtained for compound PTZO-Cl, once again certifying the key role of strong π–π stacking in the persistent RTP effect. Also, these compounds with different RTP lifetimes were successfully utilized in silk-screen printing and multiple anti-counterfeiting.