An ab initio study of the relation between NMR chemical shifts and solid-state structures: hexabenzocoronene derivatives

The assignment of solid-state NMR spectra is studied by the use of model systems computed with ab initio methods. The investigated system is a hexabenzocoronene derivative, for which a T-like arrangement of dimer units is found in the solid-state structure. Here, a tetramer model is required to explain the intermolecular interactions influencing the spectrum, whereas a dimer model is found to be inadequate. For the tetramer model, agreement of the computed NMR spectrum with the experimental solid-state magic angle spinning MAS-NMR data is observed. This study implies that the combination of experimental NMR data with quantum chemical calculations can be employed as a useful tool in determining the structure of solid-state systems in general, especially where other experimental techniques, such as single crystal X-ray diffraction, fail.