Multimolecular Weak-Force Tectons and Their Alternative Clathrate Forms

Abstract

diquinoline 8 forms clathrate compounds on crystallization from benzene, acetone, or diethyl ether. Their crystal structures are analyzed in crystal engineering terms. Molecules of 8 form robust dimers, containing swivel angles around 110°, and assembled through a combination of seven intermolecular attractions. Two enantiomeric dimers assemble around an inversion center by means of eight further attractions. A cyclic R 2 2 (8) motif utilizing −CBr−H•••N weak hydrogen bonds is the key construction element used in both the intra-and interdimer assembly. These resulting tetramers are multimolecular tectons that generate the host lattice on propagation. In contrast to the usual unimolecular model, each multimolecular tecton is constructed from 4 molecules and 22 intermolecular attractions. All three clathrates involve crystallographically independent molecules, and the latter two crystals each employ two isomeric multimolecular tectons. The diethyl ether crystal contains a further independent host molecule that shores up its guest-containing substructure.