(13)C CP MAS NMR and crystal structure of methyl glycopyranosides.
The X-ray diffraction analysis, (13)C CP MAS NMR spectra and powder X-ray diffraction patterns were obtained for selected methyl glycosides: alpha- and beta-d-lyxopyranosides (1, 2), alpha- and beta-l-arabinopyranosides (3, 4), alpha- and beta-d-xylopyranosides (5, 6) and beta-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.
Paradowska
Katarzyna
K
Department of Physical Chemistry, Medical University of Warsaw, Banacha 1, PL-02097 Warsaw, Poland.
Gubica
Tomasz
T
Temeriusz
Andrzej
A
Cyrański
Michał K
MK
Wawer
Iwona
I
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002627:Chemistry, Physical / Q000379:methods; D018360:Crystallography, X-Ray / Q000379:methods*; D005960:Glucosides / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry; D014961:X-Ray Diffraction
D005960:Glucosides; D010100:Oxygen