2,2′-[1,1′-(Heptane-1,7-diyldioxydinitrilo)diethylidyne]di-1-naphthol

The molecule of the title compound, C31H34N2O4, adopts an L-shaped configuration, in which the naphthalene units are approximately perpendicular, making a dihedral angle of 87.89 (3)°. Intramolecular H-bonds are formed between the OH substituents and the N atoms at each end of the molecule. In the crystal structure, each molecule links six other molecules into an infinite three-dimensional network supramolecular structure, which is built from one-dimensional zigzag chains via weak C—H⋯π stacking and intermolecular C—H⋯O hydrogen bonds.

The molecule of the title compound, C 31 H 34 N 2 O 4 , adopts an L-shaped configuration, in which the naphthalene units are approximately perpendicular, making a dihedral angle of 87.89 (3) . Intramolecular H-bonds are formed between the OH substituents and the N atoms at each end of the molecule. In the crystal structure, each molecule links six other molecules into an infinite three-dimensional network supramolecular structure, which is built from one-dimensional zigzag chains via weak C-HÁ Á Á stacking and intermolecular C-HÁ Á ÁO hydrogen bonds.

Related literature
For the potential medical applications of Schiff base compounds, see: Huang et al. (2002). For the properties of Salen-type bisoxime compounds, see: Darensbourg et al.

Comment
The design of Schiff-base compound and its analogues has received long-lasting research interest not only because of their appealing structural and topological novelty but also due to their potential medical value derived from their antiviral and the inhibition of angiogenesis (Huang et al., 2002). Salen-type bisoxime compound and its derivatives are among the design production of Schiff-base compounds, which show remarkable stability and especial electronic, bioactive and chemical properties useful for asymmetric catalysis (Darensbourg et al., 2004), for biological chemistry (Karthikeyan et al., 2006) and also for optical materials (Zhang et al., 2007). As an extension of our work (Dong et al., 2008a;Dong et al., 2008b) on the structural characterization of salen-type bisoxime compounds, here report the synthesis and structure of the title compound ( Fig. 1).
The molecule of the title compound adopts an L-shaped configuration, in which the dihedral angle between the plane of oxime functional groups and naphthalene ring is about 8.01° for C22-C33 ring and O2-N2-C21, 1.15° for C10-C19 ring and O1-N1-C9, respectively. And the naphthalene units are approximately vertical with the dihedral angle of 87.89°.
This structure can be recognized as a three-dimensional network building from some different direction one-dimensional zigzag chains (Fig. 3). The zigzag chain can be isolated from the three-dimensional network, which is linked via an intermolecular C29-H29···π interactions involving the aromatic ring C14-C19 (centroid, Cg1), and C30-H30···O3 hydrogen bonds between the phenolic-oxygen atom and the hydrogen atom of the naphthalene ring. The neighbouring opposite direction zigzag chains are linked by the other intermolecular hydrogen bonds C20-H20A···O1 between the oxime oxygen atom and the hydrogen atom of the methyl substitute of oxime group. But the adjacent parallel direction zigzag chains are holed by intermolecular C20-H20B···π interactions involving the naphthalene ring C22-C32 (centroid, Cg2). All in all, every L-shaped title compound molecule links six other molecules into an infinite three-dimensional network supramolecular structure due to head-to-arm weak C-H···π stacking and intermolecular hydrogen bonds (Fig. 2, 3).
Experimental 2,2'-[(Heptane-1,7-diyldioxy)bis(nitriloethylidyne)]dinaphthol was synthesized according to an analogous method reported earlier (Dong et al., 2008b). To an ethanol solution (5 ml) of 2-acetyl-1-naphthol (360.7 mg, 1.94 mmol) was added dropwise an ethanol solution (3 ml) of 1,7-bis(aminooxy)heptane (155.5 mg, 0.96 mmol). The mixture solution was stirred at 328-333 K for 72 h. After cooling to room temperature, the precipitate was filtered off, and washed successively three times with ethanol. The product was dried in vacuo and purified by recrystallization from ethanol to yield 369.0 mg (Yield, 77.1%) of powder; m.p. 388.5-390.5 K. Colourless block-like single crystals suitable for X-ray diffraction studies were obtained by slow evaporation from a mixed solution of dichloromethane/ethanol (1:1)  Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C-H = 0.97 (CH 2 ), C-H = 0.96 (CH 3 ), 0.93 Å (CH), 0.82 Å (OH), and U iso (H) = 1.2 U eq (C) and 1.5 U eq (O). In the absence of significant anomalous scattering effects, Friedel pairs were merged. Fig. 1. The molecular structure of the title compound with atom numbering scheme. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level.    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 Rfactors(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.