An arch-bridge-type fluorophore for bridging the gap between aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE)

Abstract

Solution and solid dual photoluminescence (PL) molecules fill the substantial gap between ACQ and AIE molecules to explore the mechanism of molecular luminescence in greater detail and to facilitate practical applications. A unique arch-bridge-like thiazolo[5,4-<i>b</i>]thieno[3,2-<i>e</i>]pyridine moiety is obtained as a stator after the rigidification of rotor 1 by intramolecular H-bonding of <i>ortho</i> -OH or -NH₂ to afford two classes of solid and solution dual PL molecules. As a typical example, <b>DF5</b> is dual PL active. Moreover, the large Stokes shift with high dual PL efficiency (<i>Φ</i>_F up to 51% in the solid state, 80% in DMF, 74% in DMSO, and 100% in water), together with the good thermal stability (<i>T</i>_m > 200 °C and <i>T</i>₀₅ > 200 °C), make it more practical for promising optoelectronic and biological applications.