O-Azophenylboronic Acid-Based Colorimetric Sensors for d-Fructose: O-Azophenylboronic Acids with Inserted Protic Solvent Are the Key Species for a Large Color Change

Yota Suzuki, Ayumi Ikeda, Keiji Ohno, Takashi Fujihara, Tomoaki Sugaya, Koji Ishihara*

*この研究の対応する著者

研究成果: Article査読

5 被引用数 (Scopus)

抄録

Many boronic acid-based chemosensors for saccharides have been developed; however, their detection mechanisms have seldom been studied. In this study, we synthesized 10 o-azophenylboronic acid derivatives (azoBs) and conducted a fundamental study on the reactivity and the sensing mechanism of azoBs, which undergoes a large color change, e.g., from red to yellow, upon a reaction with saccharides. Their pH-independent formation constants were determined by spectrophotometric titration and then converted to the conditional formation constant K′ at pH 7.4. A linear free energy relationship was established between log K′ and the pKa of azoB. 11B NMR measurements indicate that in aprotic solvents, azoB forms a trigonal planar structure, while in protic solvents, it forms a quasi-tetrahedral structure (azoB-ROH) with a protic solvent molecule (ROH) inserted between the boronic acid moiety and the azo group. In addition, UV-vis spectroscopic studies showed that the color change during the reaction between azoB and d-fructose in ROH was caused by the release of the ROH from azoB-ROH by d-fructose. Based on the findings in this study, we proposed a guideline for designing an azoB-based chemosensor that exhibits high reactivity toward saccharides and a sufficient color change to allow for the visual detection of saccharides.

本文言語English
ページ(範囲)9680-9693
ページ数14
ジャーナルJournal of Organic Chemistry
85
15
DOI
出版ステータスPublished - 2020 8月 7

ASJC Scopus subject areas

  • 有機化学

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