,'-Bis(pyridin-3-ylmeth-yl)ethanedi-amide monohydrate: crystal structure, Hirshfeld surface analysis and computational study.

The mol-ecular structure of the title bis-pyridyl substituted di-amide hydrate, CHNO·HO, features a central CNO residue (r.m.s. deviation = 0.0205 Å) linked at each end to 3-pyridyl rings through methyl-ene groups. The pyridyl rings lie to the same side of the plane, have a -periplanar relationship, and form dihedral angles of 59.71 (6) and 68.42 (6)° with the central plane. An almost orthogonal relationship between the pyridyl rings is indicated by the dihedral angle between them [87.86 (5)°]. Owing to an disposition between the carbonyl-O atoms in the core, two intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds are formed, each closing an (5) loop. Supra-molecular tapes are formed in the crystal amide-N-H⋯O(carbon-yl) hydrogen bonds and ten-membered {⋯HNCO} synthons. Two symmetry-related tapes are linked by a helical chain of hydrogen-bonded water mol-ecules water-O-H⋯N(pyrid-yl) hydrogen bonds. The resulting aggregate is parallel to the -axis direction. Links between these, methyl-ene-C-H⋯O(water) and methyl-ene-C-H⋯π(pyrid-yl) inter-actions, give rise to a layer parallel to (10); the layers stack without directional inter-actions between them. The analysis of the Hirshfeld surfaces point to the importance of the specified hydrogen-bonding inter-actions, and to the significant influence of the water mol-ecule of crystallization upon the mol-ecular packing. The analysis also indicates the contribution of methyl-ene-C-H⋯O(carbon-yl) and pyridyl-C-H⋯C(carbon-yl) contacts to the stability of the inter-layer region. The calculated inter-action energies are consistent with importance of significant electrostatic attractions in the crystal.