Three polymorphs of one luminogen: how the molecular packing affects the RTP and AIE properties?

Polymorphism of organicmolecules has received special attention, since the significantly different photophysical properties can provide important information to build a bridge between the micro- and macro-world. Here, we report three crystalline polymorphs of CzS-CN, which display much different properties of room temperature phosphorescence (RTP) and aggregation-induced emission (AIE). Due to their different molecular packings, the RTP lifetimes change from 266 ms to 41 ms, and then to 32 ms, accompanied by different photoluminescence quantum yields of crystals from 22.6% and 17.8% to 6.9%. Careful analyses of these crystal structures demonstrate that the properties are highly related to the packing mode and molecular configuration,regardless of the same chemical structure, thus disclosing some important clues to understand the structure-packing-property relationship of RTP and AIE performances.