NMR crystallography of p-tert-butylcalix[4]arene host-guest complexes using 1H complexation-induced chemical shifts.

(1)H magic-angle spinning (MAS) NMR spectra of p-tert-butylcalix[4]arene inclusion compounds with toluene and pyridine show large complexation-induced shifts of the guest proton resonances arising from additional magnetic shielding caused by the aromatic rings of the cavities of the host calixarene lattice. In combination with ab initio calculations, these observations can be employed for NMR crystallography of host-guest complexes, providing important spatial information about the location of the guest molecules in the host cavities.