A new approach for the design of inclusion compounds

Abstract

A new strategy for the design of inclusion compounds is described. The approach is based on the analogy between the hydrogen-bonded hexamer unit present in the clathrates of phenol, quinol, Dianin's compound, and other hydroxyaromatic hosts, and a hexasubstituted benzene. Suitable hexasubstituted benzenes have been prepared, and on recrystallisation from various solvents, a wide range of inclusion behaviour has been found for compounds (I), (III), (VIII)–(XIII), (XV), and (XVIII)–(XX), In addition, several of these hosts, for example, (III), (VIII), (IX), and (XIII), exhibit remarkable guest selectivity properties when recrystallised from solvent mixtures. A detailed X-ray study of the carbon tetrachloride adduct of hexakisphenylthiobenzene (I) has been carried out. The crystals are trigonal, space group R, with a= 14.263; c= 20.717 A, and three host and six guest molecules in the hexagonal unit cell. A true clathrate structure is found and two CCl4 guest molecules fit snugly into a cavity of effective length ca. 17 A, a C–Cl bond of each guest being collinear with the c axis of the crystal.