Design of molecular solids: utility of the hydroxyl functionality as a predictable design element

Abstract

In order to design a new molecular solid one needs a library of functional groups that will self assemble into predictable structural patterns. To test the utility of the hydroxyl group for this purpose, a series of ureas and oxalamides with side-arm substituents containing the hydroxyl functionality were prepared. X-Ray crystallographic analysis of five such compounds revealed a variety of structural features indicating that the hydroxyl group alone was not a predictable design element. However, when a pair of co-crystals of dihydroxyl substituted oxalamides with dipyridyl compounds were prepared, supramolecular structures were prepared consistent with predictions. This suggests that the hydroxyl group coupled to a pyridine hydrogen-bond acceptor is a useful design element for the preparation of molecular networks.