Designed self-assembly of a bimolecular calix[4]resorcinarene capsule held together by hydrogen bonds

The X-ray crystallographic study of the macrocyclic tetrakis-N[N-2-hydroxyethyl-piperazino]calix[4]resorcinarene-3CH(3)CH(2)OH(.)H(2)O (3) reveals a self-assembled dimeric capsule-like complex held together by an array of intermolecular hydrogen bonds. Pairs of concave molecules associate directly in bowl-to-bowl fashion and enclose an accessible supramolecular cavity of 190 angstrom(3) hosting one water and three ethanol molecules. The supramolecular arrangement displays alternating layers of facing bowls and interlocking lower rim aliphatic moieties. The helical conformation of the 2-hydroxyethyl piperazinomethyl moieties displays chirality of a bimolecular capsule frozen in the solid state. 3 crystallises in the triclinic space group P-1 with two symmetry independent molecules in the asymmetric unit. Two enantiomeric capsules form a racemic pair in the unit cell. (c) 2005 Elsevier B.V. All rights reserved.