Quantum chemistry − guided design of luminescent Triphenylene − based co-crystals: Unveiling heavy atom for enhanced fluorescence lifetime

This study employed quantum chemical methods to predict and synthesize three luminescent cocrystals. Utilizing Triphenylene as the electron donor and 1,2,4,5-tetracyanobenzene (TCNB), 2,3,5,6-tetrafluoroterephthalonitrile (TFP), and 2,3,5,6-tetrachloroterephthalonitrile (TCP) as acceptors, the structures and internal interactions of these cocrystals were analyzed. The predominant interactions observed were charge transfer, hydrogen bonding, and π-π interactions. Notably, the Triphenylene-TCP cocrystal exhibited a significantly extended fluorescence lifetime compared to the other two. Further investigations, employing time-dependent density functional theory (TD-DFT) on Triphenylene-TCP, suggested that intersystem crossing (ISC) and reverse intersystem crossing (RISC) mechanisms contribute to the prolonged fluorescence lifetime. This study offers valuable insights into the design of supramolecular cocrystals to enhance the performance of organic fluorescent materials.