(±)-trans-6,6′-Diethoxy-2,2′-[cyclohexane-1,2-diylbis(nitrilomethanylylidene)]diphenol monohydrate

In the title hydrate, C24H30N2O4·H2O, the organic molecule adopts an E conformation with respect to the azomethine double bonds. The cyclohexane ring is in a chair conformation. The dihedral angle between benzene rings is 79.6 (2)°. Two intramolecular O—H⋯N hydrogen bonds are present. In the crystal, the components are linked by O–H⋯O hydrogen bonds and weak C—H⋯π interactions, generating a three-dimensional supramolecular architecture.

In the title hydrate, C 24 H 30 N 2 O 4 ÁH 2 O, the organic molecule adopts an E conformation with respect to the azomethine double bonds. The cyclohexane ring is in a chair conformation. The dihedral angle between benzene rings is 79.6 (2) . Two intramolecular O-HÁ Á ÁN hydrogen bonds are present. In the crystal, the components are linked by O-HÁ Á ÁO hydrogen bonds and weak C-HÁ Á Á interactions, generating a threedimensional supramolecular architecture.
Cg is the centroid of the C15-C20 ring. Schiff bases are an important class of ligands in molecular design devoted to energy storage such as molecular batteries (Franceschi, et al. 1999) and also in transition metal catalysis (Hwang, et al. 1998). Schiff base having intramolecular hydrogen bonding shows photophysical properties such as thermochromism and photochromism (Popović, et al. 2002).
Schiff bases also have an ability to reversibly bind oxygen (Jones, et al.1979).
The title compound crystallizes in the monoclinic, P2 1 /c space group. The bond lengths and the bond angles agree with the related structure (Ambili, et al., 2012). The torsional angle, 177.9 (3)° of the azomethine linkage, C9-N2-C14-C15 reveals that the title compound adopts E conformation (Fig. 1). The mean plane deviation calculations show that the molecule as a whole is non-planar. Ring puckering analysis (Cremer & Pople, 1975) and least square plane calculations show that the cyclohexyl ring adopts a chair conformation (Q T = 0.565 (4) Å) with the equatorial substitution at C9 for N2 and axial substitution at C8 for N1.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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-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.