Coordination-driven fast self-assembly of a charge-transfer hydrogel with reversible photochromism.

Utilizing metal-ligand binding as the driving force, a unique photochromic hydrogel cross-linked by metal ions and π-acidic naphthalene bisimide dyes was obtained by simply mixing a two-phase solution. The mechanism of the coordination-driven self-assembly is elucidated by the morphological, XRD, FT-IR, ESR, UV-Vis and TGA studies and the controlled experiments.