Improved antenna effect of terbium(III)-cored dendrimer complex and green-luminescent hydrogel by radical copolymerization

This study explored practical applications of the unique green fluorescence of terbium(III)-cored poly(benzyl ether) dendrimer complexes for luminescence polymeric materials. At first, to maximize the fluorescence ability, we examined the influence of the isomerism in the dendron skeleton, both at the focal point and the hyperbranch repeating unit. Next, a 4-vinylphenyl group was successfully introduced at the terminal of the dendron subunit for radical polymerization. A 3,4-dioxybenzoate moiety for the focal point of the dendron gave stronger fluorescence than the usual 3,5-isomer; however, the authentic 3,5-dioxybenzyl ether moiety appeared the best hyperbranch repeating unit for the fluorescence ability. The terminal vinyl groups enabled the copolymerization of the terbium(III)-cored dendrimer complex with N-isopropylacrylamide, resulting in a green-fluorescent, clear hydrogel. The hydrogel showed a gel phase transition at 33-35 degreesC to exhibit temperature-induced switching in the opacity.