An investigation of weak CH...O hydrogen bonds in maltose anomers by a combination of calculation and experimental solid-state NMR spectroscopy.
Two-dimensional (1)H-(13)C MAS-J-HMQC solid-state NMR spectra of the two anomeric forms of maltose at natural abundance are presented. The experimental (1)H chemical shifts of the CH and CH(2) protons are assigned using first-principles chemical shift calculations that employ a plane-wave pseudopotential approach. Further calculations show that the calculated change in the (1)H chemical shift when comparing the full crystal and an isolated molecule is a quantitative measure of intermolecular C-H...O weak hydrogen bonding. Notably, a clear correlation between a large chemical shift change (up to 2 ppm) and both a short H...O distance (<2.7 A) and a CHO bond angle greater than 130 degrees is observed, thus showing that directionality is important in C-H...O hydrogen bonding.
Yates
Jonathan R
JR
TCM Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UK.
Pham
Tran N
TN
Pickard
Chris J
CJ
Mauri
Francesco
F
Amado
Ana M
AM
Gil
Ana M
AM
Brown
Steven P
SP
D002236:Carbohydrate Conformation; D002247:Carbon Isotopes; D006860:Hydrogen Bonding; D008320:Maltose / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011522:Protons
D002247:Carbon Isotopes; D011522:Protons; D008320:Maltose