کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1385229 982437 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
13C CP MAS NMR and crystal structure of methyl glycopyranosides
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
13C CP MAS NMR and crystal structure of methyl glycopyranosides
چکیده انگلیسی

The X-ray diffraction analysis, 13C CP MAS NMR spectra and powder X-ray diffraction patterns were obtained for selected methyl glycosides: α- and β-d-lyxopyranosides (1, 2), α- and β-l-arabinopyranosides (3, 4), α- and β-d-xylopyranosides (5, 6) and β-d-ribopyranoside (7) and the results were confirmed by GIAO DFT calculations of shielding constants. In X-ray diffraction analysis of 1 and 2, a characteristic shortening and lengthening of selected bonds was observed in molecules of 1 due to anomeric effect and, in crystal lattice of 1 and 2, hydrogen bonds of different patterns were present. Also, an additional intramolecular hydrogen bond with the participation of ring oxygen atom was observed in 1. The observed differences in chemical shifts between solid state and solution come from conformational effects and formation of various intermolecular hydrogen bonds. The changes in chemical shifts originating from intermolecular hydrogen bonds were smaller in magnitude than conformational effects. Furthermore, the powder X-ray diffraction (PXRD) performed for 4, 5 and 7 revealed that 7 existed as a mixture of two polymorphs, and one of them probably consisted of two non-equivalent molecules.

The X-ray diffraction analysis, 13C CP MAS NMR spectra and powder X-ray diffraction patterns were obtained for selected methyl glycosides: α- and β-d-lyxopyranosides (1, 2), α- and β-l-arabinopyranosides (3, 4), α- and β-d-xylopyranosides (5, 6) and β-d-ribopyranoside (7), and the results were confirmed by GIAO DFT calculations of shielding constants. The powder X-ray diffraction (PXRD) performed for 4, 5 and 7 revealed that the sample of 7 existed as a mixture of two polymorphs, and one of them probably consisted of two non-equivalent molecules.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Research - Volume 343, Issue 13, 8 September 2008, Pages 2299–2307
نویسندگان
, , , , ,