Coordination-driven strategy towards crystalline hybrid photochromic materials via the marriage of a non-photochromic extended dipyridine unit and zincophosphate

The coordinative linkage of supramolecular zincophosphate building units and an extended dipyridine unit, 1,4-di(pyridine-4-yl)benzene (bpyb), generates two hybrid photochromic frames. The structural and photochromic diversities were mainly attributable to the distinct coordination mode of bpyb in the resultant structure. Different from most of the reported photochromic materials driven by photochromically active units, the crystalline hybrid photochromic materials in this work are decorated by non-photochromic bpyb. The metal-assisted phosphate-to-bpyb charge transfer is responsible for the photochromism. Our work provides a new perspective to develop photochromic hybrid materials based on non-photochromic moieties.