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Chemical and photophysical mechanism of fluorescence enhancement of 3‐quinolineboronic acid upon change of pH and binding with carbohydrates
Author(s) -
Shen Qian Jin,
Jin Wei Jun
Publication year - 2010
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.1258
Subject(s) - fluorescence , chemistry , protonation , boronic acid , quinoline , photochemistry , excited state , combinatorial chemistry , organic chemistry , ion , physics , quantum mechanics , nuclear physics
The free 3‐quinolineboronic acid (3‐QBA) with the lowest (n– π *) excited singlet is non‐ or weakly fluorescent while protonated 3‐QBA has the lowest ( π – π *) excited singlet state and is highly fluorescent. The hybridization of boronic atom or charge transfer from aromatic ring to boronic acid group plays a secondary role in affecting fluorescence intensity. Binding with carbohydrate at a proper acidity, the hybridization of boron atom changes from sp 2 to sp 3 and the nitrogen atom in the quinoline ring is partially protonated, resulting in large enhancement of fluorescence. Meanwhile, the fluorescent lifetime of 3‐QBA produces obvious change by binding with carbohydrates. Quinoline boronic acid is an important water‐soluble fluorescence sensor for carbohydrate recognition. Both the remarkable changes in intensity and lifetime of 3‐QBA can act as working parameters in recognition of carbohydrates at physiological pH. Copyright © 2010 John Wiley & Sons, Ltd.