Predicting quadrupole relaxation enhancement peaks in proton R1-NMRD profiles in solid Bi-aryl compounds from NQR parameters

We propose a simple method to calculate and predict quadrupole relaxation enhancement (QRE)
features in the spin-lattice nuclear magnetic relaxation dispersion (R1-NMRD) profile of protons (1H)
in solids. The only requirement is the knowledge of the nuclear quadrupole resonance (NQR) parameters
of the quadrupole nuclei in a molecule. These NQR parameters – the quadrupole coupling
constant Qcc and the asymmetry parameter η – can be determined by NQR spectroscopy or using
quantum chemistry calculations. As there is an increasing interest in using molecules producing
high field QRE features as, e.g. for contrast enhancing agents in magnetic resonance imaging, the
experimental efforts of seeking for suitable compounds can be reduced by pre-selecting molecules
via calculations. Also, the method can be used to extract NQR parameter, and thus structural information,
from R1-NMRD profiles showing QRE features. In this article, we describe the calculation
procedure and present examples of comparing the result to experimental R1-NMRD data of two
different solid 209Bi-aryl compounds.