Manipulating Excited‐State Intramolecular Proton Transfer (ESIPT) Thermodynamics and Kinetics through Coordination Self‐assembly

Abstract Coordination self‐assembly offers a powerful yet mechanistically underexplored route to manipulate excited‐state intramolecular proton transfer (ESIPT). Herein, its profound impact is demonstrated by constructing a Cd 2+ ‐based coordination polymer ( LIFM‐110 ) that unlocks an ultrafast and efficient ESIPT process, starkly contrasting with the dual emission of its free ligand. We reveal a dual enhancement mechanism: i) suppression of an ESIPT‐inhibiting intermolecular proton migration pathway and ii) creation of a rigid framework, directed by coordination bonds and reinforced by multiple supramolecular interactions, which significantly strengthens the key intramolecular hydrogen bond. This pre‐organized environment provides a substantial thermodynamic driving force (ΔE = −0.29 eV) and a minimal kinetic barrier (E a = 0.01 eV), leading to an exceptionally fast proton transfer rate. The synergistically enhanced ESIPT results in exclusive keto emission with a high quantum yield and excellent multiphoton absorption. This work establishes coordination self‐assembly as a powerful and rational strategy for manipulating excited‐state reaction pathways, going beyond traditional synthesis to enable precise control over photophysical properties.