Probing the intermolecular interactions of aromatic amides containing N-heterocycles and triptycene

A series of aromatic amides incorporated with N-heterocycles or triptycene units are synthesized and studied for probing the effects of such chemical modifications on the intermolecular interactions. Single crystals of a number of heterocyclic amides and the triptycene-containing amide were obtained. Crystal structures, hydrogen bonds, lattice energy, solubility, and melting points were compared amongst relevant molecules. Suitably positioned nitrogen atoms from heterocycles are found to form intramolecular H-bonds with amide NHs at the expense of weakening or disrupting the intermolecular H-bonds. The effects of such H-bonding changes on solubility and melting point are nonetheless limited. Uniquely, the triptycene unit effectively improves the solubility of the amide without tempering the thermal resistance of the molecule.