The Tri(imidazole)‐Derivative Moiety: A New Category of Electron Acceptors for the Design of Crystalline Hybrid Photochromic Materials

The intermarriage of neutral and tripodal imidazole ligand, tris(4‐(1 H ‐imidazol‐1‐yl)phenyl)amine (TIPA), with zinc phosphite yields two hybrid phosphites, [Zn 2 (HPO 3 ) 2 (TIPA)]⋅2 H 2 O ( 1 ) and [Zn 3 (HPO 3 ) 3 (TIPA)]⋅6 H 2 O ( 2 ). Compound 1 has a hybrid sheet with neutral zinc‐phosphite chains as supramolecular building blocks (SBBs), whereas 2 exhibits a 3D hybrid architecture with other neutral zincophosphite chains as supramolecular building blocks. The structural discrepancy between 1 and 2 is mainly due to the distinct linkage modes between organic TIPA ligands and inorganic zincophosphite chains. Interestingly, compounds  1 and 2 feature fast photochromism in response to UV light irradiation under ambient conditions. The discrepancy of photochromic performance between 1 and 2 is mainly due to the different geometrical configuration of the TIPA ligand. Different to majority of reported hybrid photochromic compounds driven by photochromic active units, the photochromism in 1 and 2 is derived from the electron transfer (ET) between phosphite and non‐photochromic triimidazole‐derivative ligand TIPA. Compared with the widely explored nonphotochromic polypyridine‐derivative as electron acceptors (EAs), our work provides a new EA model for the design of hybrid photochromic materials based on the ligand‐to‐ligand ET mechanism. A multiple anti‐counterfeiting application based on 1 and 2 was investigated.