organic compounds
2-{(E)-[(2-Methyl-3-nitrophenyl)imino]methyl}-4-nitrophenol
aDepartment of Physics, Faculty of Arts & Science, Amasya University, Ipekkoy-Amasya, Turkey, bDepartment of Physics, Faculty of Arts & Science, Ondokuz Mayıs University, TR-55139, Kurupelit-Samsun, Turkey, and cFaculty of Technology, Amasya University, TR-05100 Amasya, Turkey
*Correspondence e-mail: myavuz@omu.edu.tr
The title compound, C14H11N3O5, is a Schiff base that adopts the enol–imine tautomeric form in the solid state. The dihedral angle between the aromatic rings is 37.4 (3)° and the dihedral angles between the nitro groups and their attached rings are 4.0 (6) and 46.2 (8)°. The molecular structure is stabilized by an intramolecular O—H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked by C—H⋯O interactions, forming a two-dimensional network parallel to the bc plane.
Related literature
For the biological properties of et al. (2001); Taggi et al. (2002); Barton & Ollis (1979); Layer (1963); Ingold (1969); Cohen et al. (1964); Moustakali-Mavridis et al. (1978). For tautomeric forms of Schiff base compounds, see: Tanak et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995). For a related structure, see: Tanak (2011).
see: AydoğanExperimental
Crystal data
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Data collection: X-AREA (Stoe & Cie, 2002); cell X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); 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); software used to prepare material for publication: WinGX (Farrugia, 2012).
Supporting information
https://doi.org/10.1107/S1600536813015407/bt6911sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813015407/bt6911Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536813015407/bt6911Isup3.cml
2-hydroxy-5-nitrobenzaldehyde (0.0138 g, 0.0822 mmol) was added to a solution of 2-methyl-3-nitroaniline (0.0125 g, 0.0822 mmol) in ethanol (100 ml). The reaction mixture was stirred for 24 h under reflux. Single crystals suitable for X-ray analysis were obtained from ethyl alcohol by slow evaporation (yield 52%; m.p.485–487 K).
All H atoms were positioned geometrically and treated using a riding model, fixing the bond lengths at 0.82 Å for OH, at 0.93 Å for aromatic CH, at 0.96 Å for CH3. The displacement parameters of the H atoms were constrained as Uiso(H)= 1.2Ueq(1.5Ueqfor methyl) of the parent atom.
Schiff bases, i.e., compounds having a double C=N bond, are used as starting materials in the synthesis of important drugs, such as antibiotics and antiallergic, antiphlogistic, and antitumor substances (Barton et al., 1979; Layer, 1963; Ingold 1969). On the industrial scale, they have a wide range of applications, such as dyes and pigments (Taggi et al., 2002).
have also been employed as ligands for the complexation of metal ions (Aydoğan et al., 2001). There are two characteristic properties of viz. and thermochromism (Cohen et al., 1964). In general, display two possible tautomeric forms, the enol-imine (OH) and the keto-amine (NH) forms. Depending on the tautomers, two types of intramolecular hydrogen bonds are observed in O—H···N in enol-imine and N—H···O in keto-amine tautomers (Tanak et al., 2010).In the title
(Fig. 1), the molecules of the title compound are not planar. The dihedral angle between the aromatic ring systems is 37.4 (3)°. The imino group is coplanar with the hydroxyphenyl ring as it can be shown by the C2—C1—C7—N2 torsion angle [-1.6 (8)°]. The C—O and C=N bond lengths confirm the enol-imine form of the title compound. The length of the C7=N2 double bond is 1.269 (7) Å It is consistent with the related structure (Tanak, 2011). It is also known that may exhibit thermochromism depending on the planarity or non-planarity of the molecule, respectively (Moustakali-Mavridis et al., 1978).The molecular structure is stabilized by an intramolecular hydrogen bond. The phenol H atom forms a strong intramolecular hydrogen bond with the imine N atom (Fig. 1) generating an S(6) ring motif (Bernstein et al., 1995). In the
molecules are linked together by intermolecular C—H···O interactions (Fig. 2).For the biological properties of
see: Aydoğan et al. (2001); Taggi et al. (2002); Barton & Ollis (1979); Layer (1963); Ingold (1969); Cohen et al. (1964); Moustakali-Mavridis et al. (1978). For tautomeric forms of Schiff base compounds, see: Tanak et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995). For a related structure, see: Tanak (2011).Data collection: X-AREA (Stoe & Cie, 2002); cell
X-AREA (Stoe & Cie, 2002); data reduction: X-RED32 (Stoe & Cie, 2002); 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); software used to prepare material for publication: WinGX (Farrugia, 2012).C14H11N3O5 | F(000) = 624 |
Mr = 301.26 | Dx = 1.470 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 6502 reflections |
a = 3.754 (5) Å | θ = 1.6–26.2° |
b = 15.696 (5) Å | µ = 0.11 mm−1 |
c = 23.149 (5) Å | T = 296 K |
β = 93.491 (5)° | Stick, yellow |
V = 1361.5 (19) Å3 | 0.46 × 0.20 × 0.05 mm |
Z = 4 |
Stoe IPDS II diffractometer | 2538 independent reflections |
Radiation source: fine-focus sealed tube | 923 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.181 |
Detector resolution: 6.67 pixels mm-1 | θmax = 25.7°, θmin = 1.6° |
rotation method scans | h = −4→4 |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | k = −18→19 |
Tmin = 0.600, Tmax = 0.976 | l = −22→28 |
7609 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.095 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.229 | H-atom parameters constrained |
S = 0.97 | w = 1/[σ2(Fo2) + (0.0591P)2] where P = (Fo2 + 2Fc2)/3 |
2538 reflections | (Δ/σ)max < 0.001 |
199 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C14H11N3O5 | V = 1361.5 (19) Å3 |
Mr = 301.26 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 3.754 (5) Å | µ = 0.11 mm−1 |
b = 15.696 (5) Å | T = 296 K |
c = 23.149 (5) Å | 0.46 × 0.20 × 0.05 mm |
β = 93.491 (5)° |
Stoe IPDS II diffractometer | 2538 independent reflections |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | 923 reflections with I > 2σ(I) |
Tmin = 0.600, Tmax = 0.976 | Rint = 0.181 |
7609 measured reflections |
R[F2 > 2σ(F2)] = 0.095 | 0 restraints |
wR(F2) = 0.229 | H-atom parameters constrained |
S = 0.97 | Δρmax = 0.23 e Å−3 |
2538 reflections | Δρmin = −0.25 e Å−3 |
199 parameters |
Experimental. 215 frames, detector distance = 130 mm |
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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O3 | 0.7299 (11) | 0.2631 (3) | 0.1412 (2) | 0.0806 (15) | |
H2 | 0.7392 | 0.2252 | 0.1656 | 0.121* | |
O2 | 0.0339 (12) | 0.0664 (4) | −0.0715 (2) | 0.0844 (15) | |
N2 | 0.6571 (12) | 0.1125 (4) | 0.1845 (2) | 0.0592 (14) | |
N1 | 0.1412 (12) | 0.1407 (4) | −0.0677 (2) | 0.0635 (15) | |
C13 | 0.6662 (13) | 0.0823 (4) | 0.2872 (3) | 0.0533 (16) | |
O1 | 0.1280 (16) | 0.1866 (4) | −0.1100 (3) | 0.110 (2) | |
C1 | 0.4754 (13) | 0.1458 (4) | 0.0866 (3) | 0.0536 (16) | |
C7 | 0.5162 (13) | 0.0880 (4) | 0.1361 (3) | 0.0579 (17) | |
H7 | 0.4371 | 0.0321 | 0.1321 | 0.070* | |
C10 | 0.8803 (16) | −0.0853 (5) | 0.2670 (3) | 0.0689 (19) | |
H10 | 0.9492 | −0.1411 | 0.2600 | 0.083* | |
C11 | 0.8347 (15) | −0.0593 (5) | 0.3228 (3) | 0.0677 (18) | |
H11 | 0.8708 | −0.0967 | 0.3537 | 0.081* | |
C5 | 0.2981 (13) | 0.1707 (4) | −0.0126 (3) | 0.0559 (16) | |
C6 | 0.3326 (13) | 0.1173 (4) | 0.0339 (3) | 0.0564 (16) | |
H6 | 0.2586 | 0.0610 | 0.0299 | 0.068* | |
C12 | 0.7342 (14) | 0.0238 (5) | 0.3314 (3) | 0.0610 (18) | |
O4 | 0.8401 (14) | 0.1172 (4) | 0.4082 (2) | 0.1012 (18) | |
N3 | 0.7006 (16) | 0.0501 (5) | 0.3918 (3) | 0.0765 (17) | |
C4 | 0.4026 (15) | 0.2570 (5) | −0.0082 (3) | 0.068 (2) | |
H4 | 0.3767 | 0.2933 | −0.0400 | 0.082* | |
C2 | 0.5843 (14) | 0.2325 (5) | 0.0912 (3) | 0.0608 (18) | |
C9 | 0.8248 (14) | −0.0294 (5) | 0.2215 (3) | 0.0643 (18) | |
H9 | 0.8636 | −0.0472 | 0.1840 | 0.077* | |
C3 | 0.5415 (16) | 0.2853 (5) | 0.0436 (3) | 0.0676 (19) | |
H3 | 0.6103 | 0.3421 | 0.0472 | 0.081* | |
O5 | 0.5514 (16) | 0.0028 (5) | 0.4243 (3) | 0.114 (2) | |
C8 | 0.7111 (12) | 0.0532 (4) | 0.2312 (3) | 0.0535 (16) | |
C14 | 0.5391 (16) | 0.1734 (4) | 0.2969 (3) | 0.0726 (19) | |
H14A | 0.5093 | 0.2023 | 0.2604 | 0.109* | |
H14B | 0.7128 | 0.2029 | 0.3216 | 0.109* | |
H14C | 0.3153 | 0.1720 | 0.3149 | 0.109* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O3 | 0.091 (3) | 0.065 (4) | 0.083 (4) | −0.017 (2) | −0.011 (3) | −0.012 (3) |
O2 | 0.107 (3) | 0.066 (4) | 0.079 (4) | −0.024 (3) | −0.002 (3) | −0.005 (3) |
N2 | 0.056 (3) | 0.057 (4) | 0.064 (4) | −0.002 (2) | 0.003 (3) | −0.007 (3) |
N1 | 0.074 (3) | 0.059 (5) | 0.058 (4) | −0.002 (3) | 0.005 (3) | 0.003 (3) |
C13 | 0.051 (3) | 0.049 (4) | 0.060 (4) | 0.001 (3) | 0.001 (3) | −0.007 (3) |
O1 | 0.165 (5) | 0.086 (5) | 0.075 (4) | −0.011 (4) | −0.013 (3) | 0.018 (3) |
C1 | 0.049 (3) | 0.049 (5) | 0.062 (4) | −0.005 (3) | −0.001 (3) | −0.001 (3) |
C7 | 0.051 (3) | 0.053 (5) | 0.069 (5) | 0.000 (3) | 0.002 (3) | −0.005 (4) |
C10 | 0.078 (4) | 0.051 (5) | 0.076 (5) | 0.007 (3) | −0.005 (4) | −0.002 (4) |
C11 | 0.076 (4) | 0.055 (5) | 0.071 (5) | 0.004 (3) | −0.005 (3) | 0.003 (4) |
C5 | 0.052 (3) | 0.051 (5) | 0.064 (5) | 0.001 (3) | −0.002 (3) | −0.006 (4) |
C6 | 0.056 (3) | 0.047 (4) | 0.066 (5) | −0.006 (3) | 0.001 (3) | −0.001 (4) |
C12 | 0.055 (3) | 0.063 (5) | 0.064 (5) | −0.002 (3) | −0.006 (3) | −0.007 (4) |
O4 | 0.115 (4) | 0.089 (5) | 0.099 (4) | −0.007 (3) | −0.004 (3) | −0.027 (3) |
N3 | 0.083 (4) | 0.071 (5) | 0.074 (5) | 0.010 (3) | −0.005 (3) | −0.002 (4) |
C4 | 0.061 (4) | 0.054 (5) | 0.090 (6) | 0.003 (3) | 0.002 (4) | 0.003 (4) |
C2 | 0.056 (3) | 0.063 (5) | 0.062 (5) | −0.003 (3) | −0.005 (3) | −0.008 (4) |
C9 | 0.058 (3) | 0.061 (5) | 0.073 (5) | 0.003 (3) | −0.003 (3) | −0.015 (4) |
C3 | 0.076 (4) | 0.054 (5) | 0.072 (5) | −0.005 (3) | 0.002 (4) | 0.000 (4) |
O5 | 0.140 (5) | 0.112 (6) | 0.093 (5) | −0.012 (4) | 0.027 (4) | 0.023 (4) |
C8 | 0.040 (3) | 0.060 (5) | 0.059 (5) | −0.005 (3) | −0.006 (3) | −0.001 (4) |
C14 | 0.077 (4) | 0.060 (5) | 0.081 (5) | 0.015 (3) | 0.001 (3) | −0.011 (4) |
O3—C2 | 1.339 (7) | C11—C12 | 1.375 (9) |
O3—H2 | 0.8200 | C11—H11 | 0.9300 |
O2—N1 | 1.235 (7) | C5—C6 | 1.364 (9) |
N2—C7 | 1.269 (7) | C5—C4 | 1.412 (9) |
N2—C8 | 1.430 (8) | C6—H6 | 0.9300 |
N1—O1 | 1.214 (7) | C12—N3 | 1.469 (9) |
N1—C5 | 1.451 (8) | O4—N3 | 1.228 (8) |
C13—C12 | 1.388 (9) | N3—O5 | 1.217 (8) |
C13—C8 | 1.395 (8) | C4—C3 | 1.353 (9) |
C13—C14 | 1.528 (9) | C4—H4 | 0.9300 |
C1—C6 | 1.377 (8) | C2—C3 | 1.382 (9) |
C1—C2 | 1.423 (9) | C9—C8 | 1.388 (9) |
C1—C7 | 1.462 (9) | C9—H9 | 0.9300 |
C7—H7 | 0.9300 | C3—H3 | 0.9300 |
C10—C11 | 1.374 (9) | C14—H14A | 0.9600 |
C10—C9 | 1.377 (9) | C14—H14B | 0.9600 |
C10—H10 | 0.9300 | C14—H14C | 0.9600 |
C2—O3—H2 | 109.5 | C11—C12—N3 | 116.4 (6) |
C7—N2—C8 | 120.2 (6) | C13—C12—N3 | 119.5 (7) |
O1—N1—O2 | 120.5 (6) | O5—N3—O4 | 122.4 (8) |
O1—N1—C5 | 120.7 (7) | O5—N3—C12 | 119.0 (7) |
O2—N1—C5 | 118.8 (6) | O4—N3—C12 | 118.5 (7) |
C12—C13—C8 | 116.2 (6) | C3—C4—C5 | 118.0 (7) |
C12—C13—C14 | 123.7 (6) | C3—C4—H4 | 121.0 |
C8—C13—C14 | 120.0 (6) | C5—C4—H4 | 121.0 |
C6—C1—C2 | 118.1 (6) | O3—C2—C3 | 119.7 (7) |
C6—C1—C7 | 120.7 (6) | O3—C2—C1 | 120.6 (6) |
C2—C1—C7 | 121.2 (6) | C3—C2—C1 | 119.7 (6) |
N2—C7—C1 | 121.6 (6) | C10—C9—C8 | 120.3 (7) |
N2—C7—H7 | 119.2 | C10—C9—H9 | 119.8 |
C1—C7—H7 | 119.2 | C8—C9—H9 | 119.8 |
C11—C10—C9 | 120.5 (7) | C4—C3—C2 | 122.0 (7) |
C11—C10—H10 | 119.7 | C4—C3—H3 | 119.0 |
C9—C10—H10 | 119.7 | C2—C3—H3 | 119.0 |
C10—C11—C12 | 118.0 (7) | C9—C8—C13 | 120.8 (6) |
C10—C11—H11 | 121.0 | C9—C8—N2 | 121.1 (6) |
C12—C11—H11 | 121.0 | C13—C8—N2 | 118.0 (6) |
C6—C5—C4 | 121.3 (6) | C13—C14—H14A | 109.5 |
C6—C5—N1 | 120.5 (6) | C13—C14—H14B | 109.5 |
C4—C5—N1 | 118.1 (6) | H14A—C14—H14B | 109.5 |
C5—C6—C1 | 120.9 (6) | C13—C14—H14C | 109.5 |
C5—C6—H6 | 119.6 | H14A—C14—H14C | 109.5 |
C1—C6—H6 | 119.6 | H14B—C14—H14C | 109.5 |
C11—C12—C13 | 124.0 (7) | ||
C8—N2—C7—C1 | −176.5 (5) | C11—C12—N3—O4 | 132.5 (6) |
C6—C1—C7—N2 | 177.9 (5) | C13—C12—N3—O4 | −47.3 (8) |
C2—C1—C7—N2 | −1.6 (8) | C6—C5—C4—C3 | 0.5 (8) |
C9—C10—C11—C12 | −0.3 (9) | N1—C5—C4—C3 | 178.6 (5) |
O1—N1—C5—C6 | −176.0 (6) | C6—C1—C2—O3 | −179.0 (5) |
O2—N1—C5—C6 | 1.3 (8) | C7—C1—C2—O3 | 0.5 (8) |
O1—N1—C5—C4 | 6.0 (8) | C6—C1—C2—C3 | 0.6 (8) |
O2—N1—C5—C4 | −176.8 (5) | C7—C1—C2—C3 | −179.9 (5) |
C4—C5—C6—C1 | −0.9 (9) | C11—C10—C9—C8 | −2.0 (9) |
N1—C5—C6—C1 | −178.9 (5) | C5—C4—C3—C2 | 0.4 (9) |
C2—C1—C6—C5 | 0.3 (8) | O3—C2—C3—C4 | 178.6 (6) |
C7—C1—C6—C5 | −179.2 (5) | C1—C2—C3—C4 | −0.9 (9) |
C10—C11—C12—C13 | 1.9 (9) | C10—C9—C8—C13 | 2.8 (8) |
C10—C11—C12—N3 | −177.9 (5) | C10—C9—C8—N2 | 179.1 (5) |
C8—C13—C12—C11 | −1.1 (8) | C12—C13—C8—C9 | −1.3 (7) |
C14—C13—C12—C11 | 177.3 (6) | C14—C13—C8—C9 | −179.7 (5) |
C8—C13—C12—N3 | 178.7 (5) | C12—C13—C8—N2 | −177.6 (5) |
C14—C13—C12—N3 | −3.0 (8) | C14—C13—C8—N2 | 3.9 (7) |
C11—C12—N3—O5 | −44.0 (8) | C7—N2—C8—C9 | 39.8 (7) |
C13—C12—N3—O5 | 136.2 (6) | C7—N2—C8—C13 | −143.9 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H2···N2 | 0.82 | 1.85 | 2.589 (8) | 149 |
C6—H6···O2i | 0.93 | 2.50 | 3.333 (9) | 149 |
C4—H4···O4ii | 0.93 | 2.59 | 3.274 (9) | 131 |
Symmetry codes: (i) −x, −y, −z; (ii) x, −y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C14H11N3O5 |
Mr | 301.26 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 3.754 (5), 15.696 (5), 23.149 (5) |
β (°) | 93.491 (5) |
V (Å3) | 1361.5 (19) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.46 × 0.20 × 0.05 |
Data collection | |
Diffractometer | Stoe IPDS II |
Absorption correction | Integration (X-RED32; Stoe & Cie, 2002) |
Tmin, Tmax | 0.600, 0.976 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7609, 2538, 923 |
Rint | 0.181 |
(sin θ/λ)max (Å−1) | 0.610 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.095, 0.229, 0.97 |
No. of reflections | 2538 |
No. of parameters | 199 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.23, −0.25 |
Computer programs: X-AREA (Stoe & Cie, 2002), X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), WinGX (Farrugia, 2012).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H2···N2 | 0.82 | 1.85 | 2.589 (8) | 148.7 |
C6—H6···O2i | 0.93 | 2.50 | 3.333 (9) | 149.1 |
C4—H4···O4ii | 0.93 | 2.59 | 3.274 (9) | 131.1 |
Symmetry codes: (i) −x, −y, −z; (ii) x, −y+1/2, z−1/2. |
Acknowledgements
The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS II diffractometer (purchased under grant No. F279 of the University Research Fund).
References
Aydoğan, F., Öcal, N., Turgut, Z. & Yolaçan, C. (2001). Bull. Korean Chem. Soc. 22, 476–480. CAS Google Scholar
Barton, D. & Ollis, W. D. (1979). Comprehensive Organic Chemistry, vol 2. Oxford: Pergamon. Google Scholar
Bernstein, J., Davies, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Cohen, M. D., Schmidt, G. M. J. & Flavian, S. (1964). J. Chem. Soc. pp. 2041–2051. CrossRef Web of Science Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Ingold, C. K. (1969). Structure and Mechanism in Organic Chemistry, 2nd ed. Ithaca: Cornell University Press. Google Scholar
Layer, R. W. (1963). Chem. Rev. 63, 489–510. CrossRef CAS Web of Science Google Scholar
Moustakali-Mavridis, I., Hadjoudis, E. & Mavridis, A. (1978). Acta Cryst. B34, 3709–3715. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stoe & Cie (2002). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany. Google Scholar
Taggi, A. E., Hafez, A. M., Wack, H., Young, B., Ferraris, D. & Lectka, T. (2002). J. Am. Chem. Soc. 124, 6626–6635. Web of Science CrossRef PubMed CAS Google Scholar
Tanak, H. (2011). J. Phys. Chem. A, 115, 13865–13876. Web of Science CrossRef CAS PubMed Google Scholar
Tanak, H., Agar, A. & Yavuz, M. (2010). J. Mol. Model. 16, 577–587. Web of Science CSD CrossRef PubMed CAS Google Scholar
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Schiff bases, i.e., compounds having a double C=N bond, are used as starting materials in the synthesis of important drugs, such as antibiotics and antiallergic, antiphlogistic, and antitumor substances (Barton et al., 1979; Layer, 1963; Ingold 1969). On the industrial scale, they have a wide range of applications, such as dyes and pigments (Taggi et al., 2002). Schiff bases have also been employed as ligands for the complexation of metal ions (Aydoğan et al., 2001). There are two characteristic properties of Schiff bases, viz. Photochromism and thermochromism (Cohen et al., 1964). In general, Schiff bases display two possible tautomeric forms, the enol-imine (OH) and the keto-amine (NH) forms. Depending on the tautomers, two types of intramolecular hydrogen bonds are observed in Schiff bases: O—H···N in enol-imine and N—H···O in keto-amine tautomers (Tanak et al., 2010).
In the title crystal structure (Fig. 1), the molecules of the title compound are not planar. The dihedral angle between the aromatic ring systems is 37.4 (3)°. The imino group is coplanar with the hydroxyphenyl ring as it can be shown by the C2—C1—C7—N2 torsion angle [-1.6 (8)°]. The C—O and C=N bond lengths confirm the enol-imine form of the title compound. The length of the C7=N2 double bond is 1.269 (7) Å It is consistent with the related structure (Tanak, 2011). It is also known that Schiff bases may exhibit thermochromism depending on the planarity or non-planarity of the molecule, respectively (Moustakali-Mavridis et al., 1978).
The molecular structure is stabilized by an intramolecular hydrogen bond. The phenol H atom forms a strong intramolecular hydrogen bond with the imine N atom (Fig. 1) generating an S(6) ring motif (Bernstein et al., 1995). In the crystal structure, molecules are linked together by intermolecular C—H···O interactions (Fig. 2).