کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1231601 1495219 2015 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ionization and tautomerism of methyl fluorescein and related dyes
ترجمه فارسی عنوان
یونیزاسیون و تاتومریسم متیل فلورسین و رنگ های مربوطه
کلمات کلیدی
فلورسسین متیل اتر، طیف سنجی رزونانس مغناطیسی و هسته ای، دائمی تجزیه، توتومریزی، تجزیه و تحلیل ساختار اشعه ایکس
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
چکیده انگلیسی


• The molecular form of fluorescein methyl ether in water is a mixture of tautomers.
• The fractions of the zwitter-ion, quinonoid, and lactone are 11%, 6%, and 83%.
• In aqueous ethanol, the colorless molecular lactone predominates.
• The lactone structure of the monoanion in solution is unlikely.

The protolytic equilibrium of methyl ether of fluorescein is studied in water, aqueous ethanol, and in other solvents. The constants of the two-step dissociation are determined by spectrophotometry. In water, the fractions of the zwitterionic, quinonoid, and lactonic tautomes are correspondingly 11%, 6%, and 83%, as deduced from the UV–visible spectra. Corresponding study of the ionization of the methyl ether ester of fluorescein, fluorescein ethyl ester, and sulfonefluorescein allows testing the correction of the attribution of the microscopic dissociation constants of methoxy fluorescein. The results of nuclear magnetic resonance and infrared spectroscopy, as well as the X-ray analysis confirm the predomination of the lactonic structure of the molecular species in solid state and in DMSO. Contrary to it, the spectroscopic studies in both hydrogen-donor bond (HDB) and non-HBD solvents confirm that the presence of lactonic monoanion is atypical for the dye under study and, with high probability, also for the mother compound fluorescein.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 150, 5 November 2015, Pages 151–161
نویسندگان
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