6,6′-Di-tert-butyl-2,2′-[1,2-phenyl­ene­bis(nitrilo­methyl­idyne)]diphenol

Naser Eltaher Eltayeb; Siang Guan Teoh; Chin Sing Yeap; Hoong-Kun Fun; Rohana Adnan

doi:10.1107/S1600536809048922

. 2009 Nov 21;65(Pt 12):o3142–o3143. doi: 10.1107/S1600536809048922

6,6′-Di-tert-butyl-2,2′-[1,2-phenylenebis(nitrilomethylidyne)]diphenol

Naser Eltaher Eltayeb ^a,^‡, Siang Guan Teoh ^a, Chin Sing Yeap ^b,^§, Hoong-Kun Fun ^b,^*,^¶, Rohana Adnan ^a

PMCID: PMC2972107 PMID: 21578863

Abstract

The molecule of the title Schiff base compound, C₂₈H₃₂N₂O₂, has a twisted geometry, the dihedral angles between the central benzene ring and the other two benzene rings being 29.12 (14) and 26.01 (14)°. Four intramolecular C—H⋯O hydrogen bonds and two intramolecular O—H⋯N hydrogen bonds stabilize the molecular structure. In the crystal packing, molecules are stacked along the a axis and stabilized by π–π interactions [centroid–centroid distance = 3.6724 (17) Å]. The crystal studied was found to be a non-merohedral twin, the refined ratio of twin components being 0.374 (5):0.626 (5).

Related literature

For biological applications of Schiff base derivatives, see: Dao et al. (2000 ▶); Eltayeb & Ahmed (2005a ▶,b ▶); Karthikeyan et al. (2006 ▶); Sriram et al. (2006 ▶). For related structures, see: Eltayeb et al. (2007a ▶,b ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶). graphic file with name e-65-o3142-scheme1.jpg

Experimental

Crystal data

C₂₈H₃₂N₂O₂
M _r = 428.56
Triclinic,
a = 6.8312 (9) Å
b = 13.9632 (16) Å
c = 14.0689 (15) Å
α = 116.615 (5)°
β = 99.068 (4)°
γ = 98.209 (4)°
V = 1149.6 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 100 K
0.87 × 0.20 × 0.05 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.936, T _max = 0.996
4021 measured reflections
4021 independent reflections
3241 reflections with I > 2σ(I)

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.206
S = 1.19
4021 reflections
304 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.39 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; 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, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809048922/lh2954sup1.cif

e-65-o3142-sup1.cif^{(24.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809048922/lh2954Isup2.hkl

e-65-o3142-Isup2.hkl^{(197.1KB, 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
O2—H1O2⋯N2	0.91 (5)	1.73 (4)	2.584 (3)	156 (4)
O1—H1O1⋯N1	0.91 (5)	1.77 (6)	2.609 (3)	151 (5)
C22—H22A⋯O1	0.96	2.34	2.993 (3)	125
C23—H23A⋯O1	0.96	2.34	2.987 (4)	124
C26—H26B⋯O2	0.96	2.31	2.963 (4)	125
C27—H27C⋯O2	0.96	2.37	3.011 (4)	124

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Acknowledgments

The authors thank the Malaysian Government, the Ministry of Higher Education, (MOHE) and Universiti Sains Malaysia (USM) for the FRGS and RU research grants (PKIMIA/815002 and PKIMIA/811120). The International University of Africa (Sudan) is acknowledged for providing study leave to NEE. HKF and CSY thank USM for the Research University Golden Goose grant (1001/PFIZIK/811012). CSY thanks USM for the award of a USM Fellowship.

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). Previously, we have reported the crystal structures of 2,2'-[1,2-phenylenebis(nitrilomethylidyne)]bis(5-methylphenol) (Eltayeb et al., 2007a) and 6,6'-dimethyl-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenol (Eltayeb et al., 2007b). In this paper, we report the crystal structure of the title compound, obtained by the reaction of o-phenylenediamine and 3-tert-butyl-2-hydroxybenzaldehyde.

The title compound (Fig. 1) has a slightly twisted geometry with the dihedral angles between the two benzene rings (C1–C6 and C15–C20) with the central benzene ring (C8–C13) being 29.12 (14) and 26.01 (14)°. The geometrical parameters are comparable to previously reported structures (Eltayeb et al., 2007a,b). Two bifurcated intramolecular C—H···O hydrogen bonds and two intramolecular O—H···N hydrogen bonds stabilized the molecular structure (Fig. 1, Table 1). In the crystal packing (Fig. 2), the molecules are stacked along the a axis and stabilized by Cg1···Cg1 = 3.6724 (17) Å interactions [Cg1 is the centroid of C1–C6 phenyl ring; 1 - x, -y, 1 - z].

Experimental

To a solution of o-phenylenediamine (0.216 g, 2 mmol) in ethanol (20 ml) was added 3-tert-butyl-2-hydroxybenzaldehyde (0.7 ml, 4 mmol). The mixture was refluxed with stirring for 30 min. The resultant orange solution was filtered. Yellow precipitate obtained was dissolved in acetone. Yellow crystals suitable for XRD formed after a few days of slow evaporation of the solvent at room temperature.