2-((E)-{2-[(1E)-(2,4-Dihydroxy­benzyl­idene)amino]phen­yl}iminiometh­yl)-5-hydroxy­phenolate methanol solvate

Naser Eltaher Eltayeb; Siang Guan Teoh; Suchada Chantrapromma; Hoong-Kun Fun; Rohana Adnan

doi:10.1107/S1600536808014487

. 2008 Jun 13;64(Pt 7):o1246–o1247. doi: 10.1107/S1600536808014487

2-((E)-{2-[(1E)-(2,4-Dihydroxybenzylidene)amino]phenyl}iminiomethyl)-5-hydroxyphenolate methanol solvate

Naser Eltaher Eltayeb ^a,^‡, Siang Guan Teoh ^a, Suchada Chantrapromma ^b,^§, Hoong-Kun Fun ^c,^*, Rohana Adnan ^a

PMCID: PMC2961737 PMID: 21202881

Abstract

The asymmetric unit of the title compound, C₂₀H₁₆N₂O₄·CH₃OH, contains two Schiff base zwitterions and two methanol solvent molecules. The dihedral angles between the central benzene ring and the two outer benzene rings of the Schiff base are 2.57 (7) and 52.30 (7)° in one molecule and 5.83 (7) and 49.82 (7)° in the other molecule. Intramolecular O—H⋯N and N—H⋯O hydrogen bonds generate S(6) ring motifs, whereas intramolecular N—H⋯N hydrogen bonds generate S(5) ring motifs. In the crystal structure, O—H⋯O, hydrogen bonds and weak C—H⋯O interactions link the molecules into one-dimensional chains along the b-axis direction and are further connected by O—H⋯O and weak C—H⋯O interactions into a three-dimensional network. C—H⋯π and π–π interactions [centroid–centroid distances = 3.6228 (9) and 3.6881 (9) Å] are also observed in the crystal structure.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For details of hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For related structures, see, for example: Eltayeb et al. (2007a ▶,b ▶). For background to applications of Schiff base ligands, see, for example: Dao et al. (2000 ▶); Eltayeb & Ahmed (2005a ▶,b ▶); Fakhari et al. (2005 ▶); Karthikeyan et al. (2006 ▶); Sriram et al. (2006 ▶).

Experimental

Crystal data

C₂₀H₁₆N₂O₄·CH₄O
M _r = 380.39
Triclinic,
a = 8.3672 (2) Å
b = 11.0813 (2) Å
c = 20.3217 (3) Å
α = 89.313 (1)°
β = 80.309 (1)°
γ = 79.641 (1)°
V = 1826.73 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100.0 (1) K
0.50 × 0.34 × 0.17 mm

Data collection

Bruker SMART APEX2 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.952, T _max = 0.984
42593 measured reflections
10651 independent reflections
7203 reflections with I > 2σ(I)’
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.162
S = 1.05
10651 reflections
515 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.34 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808014487/sj2499sup1.cif

e-64-o1246-sup1.cif^{(33KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808014487/sj2499Isup2.hkl

e-64-o1246-Isup2.hkl^{(520.8KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1A—H1OA⋯O5Bⁱ	0.95	1.71	2.6610 (16)	176
O3A—H3OA⋯N2A	0.96	1.78	2.6637 (16)	153
O4A—H4OA⋯O2Aⁱⁱ	0.82	1.83	2.6330 (16)	164
N1A—H1NA⋯O2A	0.92	1.84	2.6021 (16)	138
N1A—H1NA⋯N2A	0.92	2.31	2.7063 (16)	106
O1B—H1OB⋯O5Aⁱⁱⁱ	0.99	1.64	2.6205 (16)	170
O3B—H3OB⋯N2B	0.94	1.77	2.6526 (16)	154
O4B—H4OB⋯O2B^iv	0.89	1.74	2.6241 (16)	174
N1B—H1NB⋯O2B	0.87	1.88	2.6006 (16)	139
N1B—H1NB⋯N2B	0.87	2.32	2.7020 (16)	107
O5A—H5OA⋯O2B	0.84	1.91	2.7145 (16)	162
O5A—H5OA⋯O3B	0.84	2.58	2.9703 (15)	110
O5B—H5OB⋯O2A	0.91	1.83	2.7034 (16)	160
C4A—H4A⋯O5Bⁱ	0.93	2.48	3.165 (2)	131
C4B—H4B⋯O5Aⁱⁱⁱ	0.93	2.48	3.1596 (19)	130
C7A—H7A⋯O4B^iv	0.93	2.36	3.1691 (17)	146
C7B—H7B⋯O4Aⁱⁱ	0.93	2.35	3.1253 (17)	141
C12B—H12B⋯O1B^v	0.93	2.55	3.3603 (18)	146
C21B—H21D⋯O3A	0.96	2.44	3.134 (2)	129
C21B—H21D⋯Cg3^vi	0.96	2.86	3.568 (2)	132

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) . Cg3 is the centroid of the C15A–C20A ring.

Acknowledgments

The authors thank the Malaysian Government, the Ministry of Science, Technology and Innovation (MOSTI) and Universiti Sains Malaysia for E-Science Fund and RU research grants (PKIMIA/613308, PKIMIA/815002, 203/PKIMIA/671083) and a fellowship for NEE. The International University of Africa (Sudan) is acknowledged for providing study leave to NEE. The authors also thank Universiti Sains Malaysia for the Fundamental Research Grant Scheme (FRGS) grant No. 203/PFIZIK/671064.

supplementary crystallographic information

Comment

Schiff bases have received much attention because of their potential applications with some of these compounds exhibiting various pharmacological activities, as noted by their anticancer (Dao et al., 2000), anti-HIV (Sriram et al., 2006), antibacterial and antifungal (Karthikeyan et al., 2006) properties. In addition, some of them may be used as analytical reagents for the determination of trace elements (Eltayeb & Ahmed, 2005a,b) such as nickel in some natural food products (Fakhari et al., 2005). We reported the crystal structures of 5,5'-Dimethoxy-2,2'-[1,2-phenylenebis(nitrilomethylidyne)diphenol (Eltayeb et al., 2007a) and 4,4'-Dimethoxy-2,2'-[1,2-phenylenebis(nitrilomethylidyne)diphenol (Eltayeb et al., 2007b) and we report here the structure of the title compound (I), a closely-related Schiff base.

The asymmetric unit of (I) (Fig. 1) contains two Schiff base zwitterions and two methanol molecules (A and B). The zwitterion results from protonation of the imine N1A and N1B atoms with protons from the O2A and O2B hydroxy groups resulting in the formation of iminium and hydroxyphenolate groups. In the structure, the hydroxyphenolate ring (C1–C6/O1-O2) is nearly coplanar with the phenyl ring (C8–C13) as indicated by the dihedral angles between these two rings being 2.57 (7)° in molecule A and 5.83 (7)° in molecule B and the torsion angle C8/N1/C7/C6 = 179.33 (2)° in molecule A and 178.07 (12)° in molecule B. The C8–C13 phenyl ring makes a dihedral angle of 52.30 (7)° with the dihydroxyphenyl ring (C15–C20/O3–O4) in molecule A [49.82 (7)° in molecule B].

Intramolecular hydrogen bonds, O3A—H3OA···N2A, N1A—H1NA···O2A, O3B—H3OB···N2B and N1B—H1NB···O2B (Table 1) generate S(6) ring motifs whereas N1A—H1NA···N2A and N1B—H1NB···N2B generate S(5) ring motifs (Bernstein et al., 1995). Bond lengths and angles are in normal ranges (Allen et al., 1987) and comparable to those in related structures (Eltayeb et al., 2007a,b). In the crystal packing (Fig. 2), O—H···O, hydrogen bonds and weak C—H···O interactions (Table 1) link the molecules into one dimensional chains along the b direction and are further connected by O—H···O and weak C—H···O interactions (Table 1) into a three-dimensional network (Table 1). The crystal is further stabilized by weak C—H···π interactions (Table 1). π···π interactions were also observed with the distances of Cg₁···Cg₅ = 3.6228 (9) Å and Cg₂···Cg₄ = 3.6881 (9) Å (symmetry code : x, y, z in each case); Cg₁, Cg₂, Cg₃, Cg₄ and Cg₅ are the centroids of the C1A–C6A, C8A–C13A, C15A–C20A, C1B–C6B and C8B–C13B benzene rings, respectively.

Experimental

The title compound was synthesized by adding 2,4-dihydroxybenzaldehyde (0.552 g, 4 mmol) to a solution of o-phenylenediamine (0.216 g, 2 mmol) in ethanol (20 ml). The mixture was refluxed with stirring for half an hour. The resultant yellow solution was filtered. Yellow single crystals of the title compound suitable for x-ray structure determination were recrystallized from ethanol by slow evaporation of the solvent at room temperature over several days.