Photo‐excited intramolecular charge transfer and excited state intramolecular proton transfer behaviors for HPIBT system: A theoretical investigation.

Given facile synthetic route and excellent photo stability, excited state intramolecular proton transfer (ESIPT)‐active luminous materials have gained more and more attention. Here, we focus on photo‐induced excitation process and the ESIPT reaction process for the novel 5‐benzothiazol‐2‐yl‐6‐hydroxy‐2‐methyl‐isoindole‐1,3‐dione (HPIBT) molecule. On the level of chemical geometries and infrared spectra, we verify that O─H⋯N of HPIBT should be enhanced. We find that a proton is likely to be attracted by enhanced electronic densities around N, that is, charge transfer impetus ESIPT trend. Combing potential energy curves and searching for transition state, we clarify the ultrafast ESIPT mechanism of HPIBT due to a low barrier, which legitimately explains previous experimental characteristics. [ABSTRACT FROM AUTHOR]