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A Dual Colorimetric/Fluorescence System for Determining pH Based on the Nucleophilic Addition Reaction of an o ‐Hydroxymerocyanine Dye
Author(s) -
Yue Yongkang,
Huo Fangjun,
Lee Songyi,
Yin Caixia,
Yoon Juyoung,
Chao Jianbin,
Zhang Yongbin,
Cheng Fangqin
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201504395
Subject(s) - spiropyran , chemistry , fluorescence , nucleophile , deprotonation , photochemistry , merocyanine , protonation , amine gas treating , triarylmethane dye , ph indicator , nucleophilic addition , photochromism , organic chemistry , inorganic chemistry , ion , physics , quantum mechanics , catalysis
Owing to their ability to monitor pH in a precise and rapid manner, optical probes have widely been developed for biological and nonbiological applications. The strategies thus far employed to determine pH rely on two types of processes including reversible protonation of amine nitrogen atoms and deprotonation of phenols. We have developed a novel dual, colorimetric/fluorescence system for determining the pH of a solution. This system utilizes an o ‐hydroxymerocyanine dye that undergoes a nucleophilic addition reaction that subsequently causes reversible structural changes interconverting a merocyanine to a spirocyanine and a spirocyanine to a spiropyran. It was demonstrated that the dye can be employed to measure the pH of solutions in the 2.5–5.75 and 9.6–11.8 ranges with color changes from yellow to dark blue and then to lavender. Moreover, the fluorescence response associated with the spirocyanine–spiropyran transformation of the dye occurring in alkaline solutions provides a precise method.