Luminescent dual-network hydrogels based on terpyridine-Eu(III) supramolecular coordination: Fluorene as antenna

Abstract

The synthesis of a series of side-chain π-conjugated fluorene and terpyridine-functionalized hydrophilic poly(acrylamide) hydrogels via radical random copolymerization was reported. Based on the coordination of terpyridines and europium (III) ions, the dual-network hydrogels containing chemical covalent cross-linking bonds and metallo-supramolecular cross-linking bonds were prepared. Their structures and properties were studied systematically via NMR, IR, SEM, UV–vis absorption spectra, photoluminescence spectra and rheological. The photophysical properties showed that there was Förster energy transfer from conjugated chromophores (emission wavelength at 359–435 nm) to the europium emitter. The water content and the ratio of the energy donor and acceptor in the hydrogels make important influences on the energy transfer and then the emission color of the resulting dual-network hydrogel can be regulated from blue to red via controlling the degree of the energy transfer. Meanwhile, the dual-network hydrogels exhibited small and uniform pore structure and good mechanical properties with large storage and loss moduli.