Structural consequences of strong and weak interactions to binary benzoic acid/bipyridine supramolecular assemblies

The crystal chemistry of a family of bimolecular complexes constructed from benzoic acid/bipyridine and benzoic acid/bipyridine-N-oxide components is described. The building blocks used in this investigation follow a retrosynthetic approach based on the complementary nature of carboxyl center dot center dot center dot pyridine/pyridine-N-oxide supramolecular synthons. These strong interactions largely form predictable discrete heterotrimers; however, the weaker, no less important, secondary interactions (e.g., C-H center dot center dot center dot acceptor and pi center dot center dot center dot pi stacking) control alignment of each heterotrimer resulting in a variety of packing motifs. The observed interplay of strong and weak interactions supports the need to examine and design molecular frameworks based on the full range of known contacts responsible for crystal cohesion. By introducing a structural family with similar topological features, the current study provides a means of exploring the interdependency of structural features to molecular alignment in competitive crystal environments.