1,1′-[(5-Hydroxymethyl-1,3-phenylene)bis(methylene)]dipyridin-4(1H)-one monohydrate

The asymmetric unit of the title compound, C19H18N2O3, comprises a whole organic dipyridinone molecule plus a water molecule of crystallization. The planes of the pyridinone rings are approximately perpendicular with the plane of the central aromatic ring [dihedral angles = 80.68 (8) and 83.65 (8)°]. The C—O bond of the hydroxy group subtends an angle of 31.71 (10)° with the plane through the central aromatic ring. The crystal packing is mediated by the presence of several O—H⋯O hydrogen-bonding interactions and while the water molecules form a C 2 1(4) chain parallel to the c axis of the unit cell, the pendant hydroxy groups are engaged in O—H⋯O=C hydrogen bonds described by a C 1 1(12) graph-set motif which runs parallel to the a axis.

The asymmetric unit of the title compound, C 19 H 18 N 2 O 3 , comprises a whole organic dipyridinone molecule plus a water molecule of crystallization. The planes of the pyridinone rings are approximately perpendicular with the plane of the central aromatic ring [dihedral angles = 80.68 (8) and 83.65 (8) ]. The C-O bond of the hydroxy group subtends an angle of 31.71 (10) with the plane through the central aromatic ring. The crystal packing is mediated by the presence of several O-HÁ Á ÁO hydrogen-bonding interactions and while the water molecules form a C 2 1 (4) chain parallel to the c axis of the unit cell, the pendant hydroxy groups are engaged in O-HÁ Á ÁO C hydrogen bonds described by a C 1 1 (12) graph-set motif which runs parallel to the a axis.
Due to tautomeric equilibrium of this latter reagent, the nucleophilic attack occurred via the nitrogen atom and not via the oxygen. Spontaneous oxidation gave rise to the title compound whose crystal structure we wish to report here.
The asymmetric unit of the title compound (I) comprises a whole molecular unit, C 19 H 18 N 2 O 3 , and a water molecule of crystallization as depicted in Figure  The presence of polar O-H bonds and the C═O moieties located in opposite positions of the organic moiety permits the existence of several hydrogen bonding interactions whose geometric details are tabulated in Table 1. On the one hand, the two hydrogen atoms of the water molecule of crystallization interact with neighbouring O3 atoms from adjacent organic molecules, leading to the formation of a supramolecular polymeric chain parallel to the c-axis of the unit cell, describing

Refinement
Hydrogen atoms  and O-H = 0.84 Å (-OH). The isotropic thermal displacement parameters associated with these atoms were fixed at 1.2 (for those bound to carbon) or 1.5 (for that associated with the hydroxy group) ×U eq of the parent atom. Hydrogen atoms associated with the water molecule of crystallization were directly located from difference Fourier maps and were included in the structure with the O-H and H···H distances restrained to 0.95 (1) and 1.55 (1) Å, respectively, and U iso (H)=1.5×U eq (O).
In the absence of significant anomalous scattering effects, 2147 Friedel pairs were averaged in the final refinement. Fig. 1. Asymmetric unit of the title compound showing the labeling scheme for all non-hydrogen atoms which are represented as thermal ellipsoids drawn at the 50% probability level. Hydrogen atoms are represented as small spheres with arbitrary radii.    Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-supplementary materials sup-4 factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.