An NMR crystallography study of the hemihydrate of 2′, 3′-O-isopropylidineguanosine

An NMR crystallography study of the hemihyclrate of 2', 3'-O-isopropylidineguanosine (Gace) is presented, together with powder X-ray diffraction and thermogravimetric analysis. H-1 double-quantum and N-14-H-1 HMQC spectra recorded at 850 MHz and 75 kHz MAS (using a jEOL 1 mm probe) are presented together with a H-1-C-13 refocused INEPT spectrum recorded at 500 MHz and 12.5 kHz MAS using eDUMBO-1(22) H-1 homo-nuclear decoupling. NMR chemical shieldings are calculated using the GIPAW (gauge-including projector augmented wave) method; good two-dimensional agreement between calculation and experiment is observed for C-13 and H-1 chemical shifts for directly bonded CH and CH3 peaks. There are two Gace molecules in the asymmetric unit cell: differences in specific H-1 chemical shifts are rationalised in terms of the strength of CH-pi and intermolecular hydrogen bonding interactions. (C) 2015 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:creativecommons.org/licenses/by/4.0).