A combined deuterium NMR and quantum chemical investigation of inequivalent hydrogen bonds in organic solids

Deuterium magic angles pinning (MAS) NMR spectroscopy and quantum chemical calculations are used to investigate organic solids in which inequivalent hydrogen bonds are present. The use of H-2 MAS allows one to measure the chemical shift, delta, quadrupolar coupling constant, C-Q, and asymmetry in the quadrupolar interaction, eta(Q), for each type of hydrogen bond present in the system. Quantum chemical calculations of the magnetic shielding (sigma, which can be related to delta) and the electric field gradient (EFG, which can be related to C-Q) are compared to the experimental results and are discussed with respect to the relative strengths of the hydrogen bonds within each system. (C) 2012 Elsevier Inc. All rights reserved.