کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4766377 | 1423900 | 2016 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Evidence against the Twisted Intramolecular Charge Transfer (TICT) model in 7-aminoflavylium derivatives
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
مهندسی شیمی (عمومی)
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چکیده انگلیسی
The julolidine substituent is however slightly more efficient to prevent the hydration of the flavylium cation than the non-rigid amines. In both compounds hydration takes place only at basic pH values through the attack of the hydroxyl in position 2 of the quinoidal base. The chalcone forms of the julolidine derivative are unstable and decompose after several hours. The rate of flavylium formation from trans-chalcone is slow but increases directly with the mole fraction of protonated trans-chalcone for 1Â <Â pHÂ <Â 3 and at higher proton concentrations it is proportional to [H3O+] suggesting the existence of proton catalysis for the isomerization in the chalcone form. This catalytic effect of the proton is also observed in the compound 4â²,7-dihydroxyflavylium, showing that it is a more general phenomenon not related to the protonation of the amine substituent and not reported so far.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Dyes and Pigments - Volume 135, December 2016, Pages 86-93
Journal: Dyes and Pigments - Volume 135, December 2016, Pages 86-93
نویسندگان
João Avó, Vesselin Petrov, Nuno BasÃlio, A. Jorge Parola, Fernando Pina,