New supramolecular arrays based on interactions between carboxylate and urea groups: solid-state and solution behavior

The urea-carboxylate interaction is introduced as a potentially general motif for the control of solid-state packing patterns. We show that simple phenylurea carboxylate derivatives can form extended hydrogen-bonded ribbons in the crystal in which the zig-zag shape of the aggregate is controlled by the relative orientation of the two substituents about the phenyl core. We also show that an alternative type of aggregation may occur in solution involving the formation of cyclic aggregates. Again, the size and stability of the aggregate is dependent on the substitution pattern of the monomer.