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

Nithya Mohan; S S Sreejith; M Sithambaresan; M R Prathapachandra Kurup

doi:10.1107/S1600536814000713

. 2014 Jan 22;70(Pt 2):o182–o183. doi: 10.1107/S1600536814000713

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

Nithya Mohan ^a, S S Sreejith ^a, M Sithambaresan ^b,^*, M R Prathapachandra Kurup ^a

PMCID: PMC3998335 PMID: 24764896

Abstract

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.

Related literature

For applications of Schiff bases, see: Franceschi et al. (1999 ▶); Hwang et al. (1998 ▶); Popović et al. (2002 ▶); Jones et al. (1979 ▶). For a related structure, see: Ambili et al. (2012 ▶). For the synthesis of Schiff bases, see: Tümer (2000 ▶). For ring puckering analysis, see: Cremer & Pople (1975 ▶). graphic file with name e-70-0o182-scheme1.jpg

Experimental

Crystal data

C₂₄H₃₀N₂O₄·H₂O
M _r = 428.52
Monoclinic,
a = 9.8241 (18) Å
b = 11.6975 (19) Å
c = 21.881 (4) Å
β = 111.144 (8)°
V = 2345.2 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.40 × 0.20 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.977, T _max = 0.980
16141 measured reflections
5586 independent reflections
2701 reflections with I > 2σ(I)
R _int = 0.048

Refinement

R[F ² > 2σ(F ²)] = 0.068
wR(F ²) = 0.190
S = 1.01
5586 reflections
299 parameters
5 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶) and DIAMOND (Brandenburg, 2010 ▶); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536814000713/fj2654sup1.cif

e-70-0o182-sup1.cif^{(30.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814000713/fj2654Isup2.hkl

e-70-0o182-Isup2.hkl^{(273.5KB, hkl)}

CCDC reference: http://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=981065

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg is the centroid of the C15–C20 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3′⋯N2	0.85 (1)	1.77 (3)	2.550 (4)	152 (3)
O2—H2′⋯N1	0.84 (1)	1.85 (2)	2.584 (3)	144 (4)
O1W—H1B⋯O3	0.86 (5)	2.34 (7)	3.005 (5)	134 (8)
O1W—H1B⋯O4	0.86 (5)	2.38 (8)	3.052 (5)	135 (6)
C21—H21B⋯Cg	0.97	2.92	3.810 (4)	153

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Acknowledgments

We thank the Sophisticated Analytical Instruments Facility, Cochin University of Science and Technology, for the diffraction measurements. MRPK, NM and SSS thank the Defence Research Development Organization, New Delhi, India, for financial support.

supplementary crystallographic information

1. Comment

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, P2₁/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.

Crystal system consists of intramolecular hydrogen bonds of lengths 1.79 (3) Å and 1.85 (3) Å which exists between the azomethine N atom and the neighbouring phenolic O atom leading to the formation of two six membered rings comprising of atoms C14—C15—C20—O3—H3'···N2 and C7—C6—C5—O2—H2'···N1 (Fig. 2). A C—H···π interaction between one of the hydrogen attached at C21 and the aromatic ring (C15—C20) with H···Cg distance of 2.92 Å (Fig. 3) dominates the packing of molecules in the lattice. Fig. 4 shows the packing diagram of the title compound along a axis.

2. Experimental

The title compound was prepared by following the reported procedure (Tümer, 2000). 3-Ethoxy-2-hydroxybenzaldehyde (0.166 g,1 mmol) was dissolved in ethanol and an ethanolic solution of 1, 2-diaminocyclohexane (0.044 g, 0.5 mmol) was added to it. The mixture was refluxed for 5 h. Slow evaporation of the solution yielded 0.183 g (95%) yellow block type crystals of (±)-trans-6,6'-Diethoxy-2,2'-[cyclohexane-1,2-diylbis(nitrilomethanylylidene)]diphenol monohydrate. The compound melts at 115 °C.

IR (KBr, \v in cm^-1): 1626, 3530, 2930, 1468, 1249 ¹H NMR (400 MHz, CDCl₃, δ in p.p.m.): 13.871 (s, 2H), 8.231 (s, 2H), 4.093–4.041 (q, 4H), 1.442–1.477 (t, 6H), 6.679–6.686 (m, 6H), 1.589–1.953 (m, 10H)