Two-dimensional H-1-C-13 MAS-J-HMQC solid-state NMR spectra of the two anomeric forms of maltose at natural abundance are presented. The experimental H-1 chemical shifts of the CH and CH2 protons are assigned using first-principles chemical shift calculations that employ a plane-wave pseudo-potential approach. Further calculations show that the calculated change in the 1H chemical shift when comparing the full crystal and an isolated molecule is a quantitative measure of intermolecular C-(HO)-O-... weak hydrogen bonding. Notably, a clear correlation between a large chemical shift change (up to 2 ppm) and both a short (HO)-O-... distance (< 2.7 angstrom) and a CHO bond angle greater than 1301 is observed, thus showing that directionality is important in C-(HO)-O-... hydrogen bonding.
An investigation of weak CH center dot center dot center dot O hydrogen bonds in maltose anomers by a combination of calculation and experimental solid-state NMR spectroscopy / Yates, Jr; Pham, Tn; Pickard, Cj; Mauri, F; Amado, Am; Gil, Am; Brown, Sp. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - 127:29(2005), pp. 10216-10220. [10.1021/ja051019a]
An investigation of weak CH center dot center dot center dot O hydrogen bonds in maltose anomers by a combination of calculation and experimental solid-state NMR spectroscopy
Mauri, F;
2005
Abstract
Two-dimensional H-1-C-13 MAS-J-HMQC solid-state NMR spectra of the two anomeric forms of maltose at natural abundance are presented. The experimental H-1 chemical shifts of the CH and CH2 protons are assigned using first-principles chemical shift calculations that employ a plane-wave pseudo-potential approach. Further calculations show that the calculated change in the 1H chemical shift when comparing the full crystal and an isolated molecule is a quantitative measure of intermolecular C-(HO)-O-... weak hydrogen bonding. Notably, a clear correlation between a large chemical shift change (up to 2 ppm) and both a short (HO)-O-... distance (< 2.7 angstrom) and a CHO bond angle greater than 1301 is observed, thus showing that directionality is important in C-(HO)-O-... hydrogen bonding.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.