Poly(γ-glutamic acid) Hydrogels with Water-Sensitive Luminescence Derived from Aggregation-Induced Emission of o-Carborane

We demonstrate the synthesis cola novel diglycidyl compound exhibiting aggregation-induced emission (AI E) derived from o-carborane, and employed it as a cross-linking reagent to prepare translucent hydrogels consisting of poly(gamma-glutamic acid). Swelling ratio of the obtained hydrogels depended on the cross-linking density. Higher cross-linking density of the obtained hydrogels led to stronger emission in the swollen state, and finally the absolute quantum yield reached 0.10, which is directed to that of cross-linker with AI E in water dispersion (Phi(F) = 0.19). The luminescence character of lower cross-linked hydrogels was drastically influenced by the gel-shrinkage from the change of ionic strength. Furthermore, these hydrogels showed effective reversible fluorescence switching between the swollen and dried states.