Supramolecular synthons in phenol–isonicotinamide adducts

Abstract

Molecular complexes of four phenols (hydroquinone, resorcinol, phloroglucinol and 4-hydroxybenzoic acid) with isonicotinamide are characterized by X-ray diffraction. (Hydroquinone)_0.5·(isonicotinamide) 1 and (resorcinol)·(isonicotinamide)₂2 have tapes of O–H⋯N and amide N–H⋯O dimer synthons. In (phloroglucinol)·(isonicotinamide)₂·(H₂O)₂3, six component self-assembly results in stacked dimers with four O–H⋯N and four amide N–H⋯O hydrogen bonds and the third phenol OH aggregates with two water molecules in a supramolecular chair cyclohexane array. Phenol⋯pyridine and amide N–H⋯O dimers are robust synthons in 1–3 for the self-assembly of 0D discrete aggregates and infinite 1D chains. Hydrogen bonding of amide dimers via N–H⋯O_phenol/water is ascribed to cooperative effects. The crystal structure of (4-hydroxybenzoic acid)·(isonicotinamide) 4 establishes the robustness of phenol⋯pyridine hydrogen bonding in the presence of carboxylic acid groups. Molecular components in 4 are arranged as zigzag tapes of O–H⋯N hydrogen bonds and acid⋯amide heterodimers. Supramolecular synthesis with phenol–isonicotinamide adducts expands the versatility of isonicotinamide as a co-crystallizing agent in crystal engineering.