Intra- and intermolecular H-bonds and π–π stacking driven organization of a triazine-based room temperature phosphorescent emitter

Excitation dependent, multiemissive single component organic materials are receiving evergrowing attention for various applications. In this regard, intermolecular interactions have been revealed to be efficacious in positively affecting photoluminescence features. Here, the photophysical properties of TT-2PyH+NO3- characterized by fluorescence and dual phosphorescence with ultralong contributions, are interpreted through DFT-TDDFT calculations and crystal structure analysis. The compound's locked molecular conformation through an intramolecular hydrogen bond is at the basis of suppression of the low energy fluorescence displayed by its parent neutral derivative. On the other side, pi-pi interactions are deemed responsible for the ultralong RTP features and the highly dense network of intermolecular hydrogen bonds provides a rigid molecular environment which efficiently restricts the non-radiative deactivation channels of triplet excitons.