Extended cavitands of nanoscale dimensions

Abstract

New tetrabenzimidazole cavitands with upper rims extended by aromatic groups have been prepared and their X-ray structures were analyzed. The reversible encapsulation of a series of n-alkylammonium guests was studied by NMR spectroscopy and mass spectrometry. These guests showed different binding modes and unique interactions with the hydrophobic cavity. The trimethylammonium guests bearing n-butyl to n-hexyl substituents stabilize the C4v conformation of the cavitand by additional CH⋯π interactions with the aromatic upper part. The longest n-hexylammonium salt adopts a minimal gauche conformation to fit in the cavity. Show more