Structure and Selectivity of a Small Dimeric Encapsulating Assembly

Abstract
The binding selectivity of a dimeric molecular capsule in solution and its X‐ray crystal structure in the solid state are reported. The capsule is a self‐complementary bisglycoluril molecule, formed through a series of intermolecular hydrogen bonds. The dimeric host is capable of discriminating in CDCl3 solution between methane and ethane as guests, and direct evidence for the selectivity is presented from 1H NMR studies. The thermodynamic parameters for the encapsulation of methane, obtained from a VT 1H NMR (500 mHz) study, are presented.