8: Solid-state NMR Techniques for the Study of Intermolecular Interactions

The local nature of the magnetic interaction probed by NMR allows structural information to be obtained on intermolecular interactions and also in solids characterized by a low crystallinity, where single crystal diffraction methods fail. There are indeed several cases where NMR has been crucial in determining the weak interaction networks that characterize specific self-assembled crystal structures; the specialized literature often refers to such studies as “NMR crystallography”. Among all the NMR parameters chemical shift, chemical shielding tensors, dipolar interaction, spin diffusion, and nuclear quadrupole coupling are the most important. The continuous development of stronger magnets, more sensitive probes operating at higher MAS rates, new pulse sequences and improved computational tools has led to dramatic progress in the NMR discipline for the study of intermolecular interactions, mainly in the field of hydrogen and halogen bonds. Recent results on this subject are presented within the context of their potential applications in crystal engineering and supramolecular chemistry.