SUPRAMOLECULAR DESIGN AND SYNTHESIS. THE CONTROL OF SYMMETRY AND INTERMOLECULAR SPACING. Joseph W. Lauher, Frank W. Fowler, Brian Dinkelmeyer, John Kane, Ruey-Fen Liao, Eric Matwey, Tam Nguyen, Caroline Schauer, and Leticia Toledo. Department of Chemistry, State University of New York, Stony Brook, NY 11794.

A library of molecular functionalities has been developed that allows us to systematically prepare molecular crystals with designed supramolecular structures with control of symmetry and intermolecular spacing. Each functionality leads to a hydrogen bonded network with a characteristic intermolecular spacing: ureas (4.6 ~), oxalamides (5.0 ~) and vinylogous ureas (6.7 ~). With a proper selection and combination of additional substituents specific supramolecular structures can be constructed in one dimension ((-networks), two dimensions ((-networks) or three dimensions ((-networks).

Consider, for example, symmetrical ureas and oxalamides synthesized from the 3- and 4-amino-methylpyridines. Employing co-crystallization methodology we can use these molecules as hosts to build supramolecular structures with a wide variety of carboxylic acid and alcohol guests. Conversely we can reverse the substituents and use ureas or oxalamides with carboxylic acid or phenol substituents as the hosts to align and space various pyridyl guests.

This host-guest/co-crystallization technique is now being applied to various real problems in supramolecular chemistry. Significantly we have designed and synthesized layered supramolecular structures containing various diacetylenes that exhibit structural parameters in accordance with those needed for a topochemical polymerization reaction. Similarly some of the same host molecules have been used to space various transition metals at designated positions within a crystal. Extensions of the methodology to new functionalities and new problems are underway.