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Off-on-off fluorescent chemosensor for pH measurement with a terbium(iii) complex based on a tripodal salicylic-acid
Yan-Ling Yang1, Ya-Wen Wang, Dong-Zhu Duan
1State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China. pengyu@lzu.edu.cn.
Abstract:
New Tb(iii) and Eu(iii) complexes have been synthesized as potential pH probes using a tripodal substituted-salicylic ligand (H3). Among them, this carboxylate ligand is found to be a good sensitizer for Tb(iii) emission owing to the superior match of the triplet energy level of the ligand with the (5)D4 emitting level of Tb(iii). The resulting · complex exhibited high sensitivity in the physiological pH range with significant "off-on-off" fluorescence changes in aqueous solution. Furthermore, this unique rare-earth complex has been successfully used to monitor pH variations within HeLa cells and with filter papers.
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