Tb(3+)-containing supramolecular hydrogels: luminescence properties and reversible sol-gel transitions induced by external stimuli.

A dual-responsive green-light-emitting supramolecular metal hydrogel (G-gel) was prepared by the reaction of a simple hydrazide-functionalized benzimidazole ligand (L) with Tb(NO3)3. The green luminescence of gelator L is enhanced in the G-gel due to the coordination effect between L and Tb(3+). In addition, the G-gel shows different luminescence when in a semisolid state (gel) and in a solid state (xerogel). Remarkable reversible sol-gel transitions induced by temperature or pH were observed for this G-gel.