Enhancement of the excited-state intramolecular proton transfer process to produce all-powerful DSE molecules for bridging the gap between ACQ and AIE

Abstract Dual-state emission (DSE) molecules bridge the gap between aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE), allowing detailed exploration of the mechanisms of molecular luminescence and facilitating practical application of luminescent molecules. In this study, imidazolo[5,4- b ]thieno[3,2- e ]pyridine DSE molecules were designed by a strategy in which the excited-state intramolecular proton transfer (ESIPT) was enhanced to restrict the twisted intramolecular charge-transfer (TICT) of nonradiative de-excitation processes and the self-assembly is finely controlled. ITP3 and ITP4 , as typical examples, are all-powerful DSE molecules with fluorescence quantum yields of 41–83% and 53–92%, respectively. Additionally, their good thermal stability ( T m  > 200 °C, T 05  > 300 °C) renders them promising candidates for optoelectronic and biological applications.