A Volumetric Analysis of the H NMR Chemical Shielding in Supramolecular Systems.

The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host-guest complexes. Its theoretical counterpart, that is, the H NMR chemical shielding affected by the solvent (H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.