ORGN 378

Polymorphism is a phenomenon of great contemporary interest in supramolecular chemistry.  Closely related to polymorphism are the occurrence of multiple crystalline inclusion complexes from a single inclusion host and various small molecule guests (i.e., pseudopolymorphism).  Such complexes can be regarded as prototypes of microporous organic solids.  1,3,5-Triaroylbenzene derivatives comprise a growing family of compounds that exhibit both polymorphism and pseudopolymorphism.  Triaroylbenzenes are easily prepared from aryl ethynyl ketones via an amine-catalyzed cyclotrimerization reaction.  Crystallization of relatively simple triaroylbenzenes results in formation of discrete supramolecular networks frequently propagated by weak solid-state hydrogen bonding.  An interesting example of this behavior is encountered in the solid-state structures of the tris(nitrile) 1.  In the absence of included guest (solvent) molecules, 1 crystallizes in dimorphic forms whereas in the presence of suitable guests isostructural clay-like inclusion complexes are obtained.  The structural features of inclusion complexes and polymorphs prepared from other triaroylbenzene derivatives will also be presented.