Multicomponent reaction-based discovery of pyrimido[2,1-b][1,3]benzothiazole (PBT) as a novel core for full-color-tunable AIEgens

Abstract

The Hf(OTf)₄-catalyzed three-component reaction (3CR) was employed as a powerful tool for facile access to a library of 23 pyrimido[2,1-b][1,3]benzothiazole (PBT)-based AIEgens with full-color tunability, solid-state fluorescence quantum yields of up to 86.8%, and high crystallizability. As atypical propeller-shaped molecules, PBT AIEgens were experimentally determined to dissipate the energy of the excited state via the rotation of the exocyclic carbonyl (ester/ketone) rather than the commonly known phenyl group. Theoretical calculations and crystallographic analysis of PBT AIEgens provide insights into their unique structure–property relationships and AIE mechanism from orbital and molecular aspects, respectively.