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

An NMR crystallography study of the hemihydrate of 2′, 3′-O-isopropylidineguanosine (Gace) is presented, together with powder X-ray diffraction and thermogravimetric analysis. 1H double-quantum and 14N–1H HMQC spectra recorded at 850MHz and 75kHz MAS (using a JEOL 1mm probe) are presented together with a 1H–13C refocused INEPT spectrum recorded at 500MHz and 12.5kHz MAS using eDUMBO-122 1H homonuclear 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 13C and 1H chemical shifts for directly bonded CH and CH3 peaks. There are two Gace molecules in the asymmetric unit cell: differences in specific 1H chemical shifts are rationalised in terms of the strength of CH-π and intermolecular hydrogen bonding interactions.