Soft Matter Anion Sensing Based on Lanthanide (Eu³⁺ and TB³⁺) Luminescent Hydrogels

Abstract

A novel design strategy has been applied to fabricate thermo-sensitive silica based lanthanide luminescent hydrogels (poly(N-isopropylacrylamide)), which possesses intense luminescence and exhibits host-guest interactions with anions. In detail, 2-(2-furyl)-4,5-imidazoledicarboxylic acid (a) was used as sensitizing ligand, which could not only transfer its energy to europium ion but also to terbium ion effectively. We observed that only HSO₄ ⁻ can give rise to fluorescence quenching to these target materials compared with CH₃COO⁻, F⁻, Cl⁻, Br⁻, and I⁻. We regarded that it was mainly due to the anion's acidity which resulted the turned-off process. More importantly, the emission intensities of the two hydrogels significantly enhanced at lower critical solution temperature (33°C). [Supplementary materials are available for this article. Go to the Publisher's online edition of Soft Materials for the following free supplemental resource(s): Supporting information.]

Keywords:

• Luminescence
• Optical materials
• Polymers

Acknowledgments

Zhan Zhou is thankful for the support from the Scientific Research Foundation of Graduate School of South China Normal University. Qianming Wang appreciates the National Natural Science Foundation of China (21002035).