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

Dual-state emission (DSE) molecules bridge the gap between aggregation-caused quenching (ACQ) and aggregation-induced emission (ME), 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 degrees C, T-05 > 300 degrees C) renders them promising candidates for optoelectronic and biological applications.