N,N′-Bis(pyridin-3-ylmethyl)ethanediamide monohydrate: crystal structure, Hirshfeld surface analysis and computational study

Abstract

The molecular structure of the title bis-pyridyl substituted diamide hydrate, C14H14N4O2·H2O, features a central C2N2O2 residue (r.m.s. deviation = 0.0205 Å) linked at each end to 3-pyridyl rings through methylene groups. The pyridyl rings lie to the same side of the plane, i.e. have a syn-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 anti disposition between the carbonyl-O atoms in the core, two intramolecular amide-N—H...O(carbonyl) hydrogen bonds are formed, each closing an S(5) loop. Supramolecular tapes are formed in the crystal via amide-N—H...O(carbonyl) hydrogen bonds and ten-membered {...HNC2O}2 synthons. Two symmetry-related tapes are linked by a helical chain of hydrogen-bonded water molecules via water-O—H...N(pyridyl) hydrogen bonds. The resulting aggregate is parallel to the b-axis direction. Links between these, via methylene-C—H...O(water) and methylene-C—H...π(pyridyl) interactions, give rise to a layer parallel to (10\overline{1}); the layers stack without directional interactions between them. The analysis of the Hirshfeld surfaces point to the importance of the specified hydrogen-bonding interactions, and to the significant influence of the water molecule of crystallization upon the molecular packing. The analysis also indicates the contribution of methylene-C—H...O(carbonyl) and pyridyl-C—H...C(carbonyl) contacts to the stability of the inter-layer region. The calculated interaction energies are consistent with importance of significant electrostatic attractions in the crystal.