Establishing Supramolecular Control over Solid-State Architectures: A Simple Mix and Match Strategy

With the help of robust principles of crystal engineering,
it is
possible to construct co-crystals where two or more different molecular entities coexist in the same crystalline lattice; the supramolecular
assembly is driven by noncovalent interactions, most commonly by hydrogen
bonds. We have synthesized two ditopic amide based ligands (N-(4-pyridin-2-yl)isonicotinamide) and (N-(3-pyridin-2-yl)nicotinamide) and systematically established their
binding preferences when faced with aliphatic dicarboxylic acids with
an odd and even number of carbon atoms. Each ligand was co-crystallized
with four odd and four even-chain dicarboxylic acids, and 13/16 reactions
produced crystals suitable for single-crystal structure determination.
On the basis of these results, it is clear that carefully selected
systems can be manipulated to produce assemblies in the solid state
with very precise control over topology and dimensionality. These
ligands can be made to produce either 0-D or 1-D architectures simply
by fine-tuning the choice of co-crystallizing agent in the supramolecular
synthesis. This mix-and-match strategy allows us to mimic the reliability
and versatility of covalent synthesis, in terms of successfully preparing
a target with predetermined connectivity and metrics.