کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
29135 44124 2008 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Structure and fluorescent properties of merocyanines based on N,N-diethylthiobarbituric acid
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی بیو مهندسی (مهندسی زیستی)
پیش نمایش صفحه اول مقاله
Structure and fluorescent properties of merocyanines based on N,N-diethylthiobarbituric acid
چکیده انگلیسی

Fluorescent properties of a series of positively and negatively solvatochromic merocyanines based on N,N-diethylthiobarbituric acid containing heterocycles of various electron-donating properties are explored in solvents of various polarity. It is shown, that their solvatofluorochromic range is less than the solvatochromic range. A lengthening of the polymethine chain causes a growth of the vinylene shifts, a decrease of the deviations and a narrowing of the fluorescent spectral bands, as opposed to the absorption ones. The transition to the higher vinylogues is also accompanied by a decrease of the Stokes shifts and an increase of the fluorescent quantum yields. However, a growth of the latter for merocyanines absorbing light in the near-IR range is levelled by an amplification of internal conversion. An absence of a mirror symmetry of the absorption and fluorescence spectra has been revealed. The quantum-chemical analysis of an electronic structure of the merocyanines by the semi-empirical method AM1 is also carried out. The transitions between their ideal electronic states – non-polar polyene, polymethine and dipolar polyene – are investigated. It is shown, that the electronic structure of the fluorescent state of merocyanines approaches the cyanine limit at polymethine chain lengthening.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 197, Issue 1, 10 June 2008, Pages 40–49
نویسندگان
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