Recent Advances in Smart Sensing Based on Excited-State Intramolecular Proton-Transfer (ESIPT)-Inspired Emitters

The optical materials based on excited state intramolecular proton transfer (ESIPT) have garnered significant attention due to their unique photophysical properties and applications in sensors and imaging agents (probes). These materials exhibit an intrinsic four-level photocycle scheme through the enol (E)-keto (K) phototautomerization process, resulting in a large Stokes shift, environmental sensitivity, and potential for ratiometric sensing. This review primarily focuses on elucidating the luminescence mechanism and structure-property relationships of recent ESIPT molecules, as well as exploring the sensing applications of phosphorescent functional materials.