کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
28999 44112 2008 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Structure effects on the photobehaviour of 2,2-diphenyl(2H)chromenes
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی بیو مهندسی (مهندسی زیستی)
پیش نمایش صفحه اول مقاله
Structure effects on the photobehaviour of 2,2-diphenyl(2H)chromenes
چکیده انگلیسی

The photochromic behaviour of a series of 2,2-diphenyl(2H)chromenes, bearing different substituents (methyl, thienyl, B(OH)2 and nitro groups), has been investigated. The photochromism of these molecules is described in terms of absorption spectra, photocolouration and photobleaching quantum yields, kinetics of thermal bleaching and competition between photochemical and photophysical relaxation. The quantum yield of UV photocolouration is generally fairly high (0.7–1.0), but decreases for compounds with thienyl and nitro substituents. The ring-open coloured form thermally rearranges to the closed uncoloured form, whereas visible photobleaching is substantially negligible (≤10−3). The thermal bleaching process is markedly affected by the substituents and, in the case of the nitro-derivatives, is characterised by a drastic decrease of activation entropy and enthalpy.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 200, Issues 2–3, 15 December 2008, Pages 287–293
نویسندگان
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