Tunable Reversible Photochromic Ultralong Organic Phosphorescence via a Universal Phenylpyridine Noncovalent Assembly Strategy

ABSTRACT Supramolecular photochromic materials capable of reversible alteration in visual color and photoluminescence upon light stimulation represent a pivotal frontier in contemporary materials science. Herein, we present a facile yet universal supramolecular assembly strategy based on linear phenylpyridine derivatives and α‐cyclodextrin, enabling the simultaneous switchable modulation of photochromism and ultralong organic phosphorescence (UOP) in the solid state. Multivalent interactions, including host‐guest complexation and hydrogen bonding, synergistically construct a robust noncovalent network that not only stabilizes excited triplet states with a maximum phosphorescence lifetime of 0.96 s and quantum yield of 53.1%, but also promotes efficient photoinduced electron transfer for in situ generation of stable radicals governing reversible photochromism. Notably, the UOP can be dynamically regulated via a photoinduced radical‐mediated photochromic switch. Furthermore, precision engineering of aryl substituents or pyridine substitution sites on guest molecules enables tailorable phosphorescent performance and multicolor reversible photochromism. Owing to their dual photochromism and UOP characteristics, these supramolecular assemblies exhibit great promise for applications in multistage information encryption and time‐resolved photopatterning. This work provides a universal and green supramolecular strategy for constructing multifunctional photo‐responsive materials and opens new avenues for advanced photonic applications.