Organic crystal engineering with piperazine-2,5-diones. 1. Crystal packingof piperazinediones derived from substituted 2-aminoindan-2-carboxylic acids

We have postulated that molecules engineered to participate in three chemic ally distinct and linearly independent intermolecular interactions will sel f-assemble in a predictable fashion. Six prototypes for molecules capable o f manifesting such interactions were synthesized from 2-amino-indan-2-carbo xylic acid, 2-amino-5,6-dimethylindan-2-carboxylic acid, and 2-amino-4,7-di methoxyindan-2-carboxylic acid. These piperazinediones were characterized i n solution by NMR spectroscopy and in the solid state by X-ray crystallogra phy. "Ladder-like" intermolecular amide-to-amide hydrogen bonding interacti ons were observed in each case, establishing tape structures parallel to on e crystallographic axis. Tape morphology varied depending on the arene subs titution pattern and was governed by the development of arene and/or van de r Waals contact interactions. (C) 1999 Elsevier Science Ltd. All rights res erved.