organic compounds
3-[(E)-(4-Ethylphenyl)iminomethyl]benzene-1,2-diol
aDepartment of Physics, Ondokuz Mayıs University, TR-55139 Samsun, Turkey, bSinop University, Sinop Faculty of Education, Sinop, Turkey, and cPamukkale University, Denizli Technical Vocational School, Denizli, Turkey
*Correspondence e-mail: zeynep.kelesoglu@omu.edu.tr
The title compound, C15H15NO2, adopts the enol–imine tautomeric form. The dihedral angle between the two benzene rings is 48.1 (1)°. Intramolecular O—H⋯N and O—H⋯O hydrogen bonds generate S(6) and S(5) ring motifs, respectively. In the crystal, molecules are linked into centrosymmetric R22(10) dimers via pairs of O—H⋯O hydrogen bonds and the dimers may interact through very weak by π–π interactions [centroid–centroid distance = 4.150 (1) Å]. The ethyl group is disordered over two orientations, with occupancies of 0.587 (11) and 0.413 (11).
Related literature
For the photochromic and thermochromic properties of Schiff base compounds, see: Elmali et al. (1999); Guha et al. (2000); Kletski et al. (1997); Kownacki et al. (1994); Zgierski et al. (2000). For Schiff base see: Alarcon et al. (1995); Dudek et al., (1966); Salman et al. (1991, 1993). For a related structure, see: Özek et al. (2009). For graph-set motifs, see: Bernstein et al. (1995).
Experimental
Crystal data
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Refinement
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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, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
10.1107/S1600536809029924/ci2862sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809029924/ci2862Isup2.hkl
Compound (I) was prepared by refluxing a mixture of 2,3-dihidroxy benzalaldehyde (0.5 g 0.0036 mol) in ethanol (20 ml) and 4-ethylaniline (0.436 g 0.0036 mol) in ethanol (20 ml). The reaction mixture was stirred for 1 h under reflux. Single crystals of (I) suitable for X-ray analysis were obtained by slow evaporation of a methanol solution (yield 87%, m.p. 378-379 K).
The ethyl group is disordered over two orientations, with occupancies of 0.587 (11) and 0.413 (11). The Uij parameters of the disordered atoms were restrained to an approximate isotropic behaviour. The C—C distances involving disordered atoms were restrained to 1.54 (2) Å. The hydroxyl H atoms were located in a difference Fourier map and were refined freely. All other H-atoms were refined using a riding model with d(C-H) = 0.93–0.96 Å (Uiso = 1.2Ueq of the parent atom) for aromatic and ethyl C atoms and d(C-H) = 0.97 Å (Uiso=1.5Ueq of the parent atom) for methyl C atoms.
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, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).C15H15NO2 | Z = 2 |
Mr = 241.28 | F(000) = 256 |
Triclinic, P1 | Dx = 1.239 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.1893 (4) Å | Cell parameters from 8683 reflections |
b = 8.7704 (6) Å | θ = 1.6–28.0° |
c = 12.7605 (9) Å | µ = 0.08 mm−1 |
α = 87.326 (6)° | T = 296 K |
β = 86.397 (6)° | Prism, red |
γ = 69.394 (5)° | 0.54 × 0.41 × 0.31 mm |
V = 646.85 (8) Å3 |
Stoe IPDS II diffractometer | 2668 independent reflections |
Radiation source: fine-focus sealed tube | 1896 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
Detector resolution: 6.67 pixels mm-1 | θmax = 26.5°, θmin = 1.6° |
rotation method scans | h = −7→7 |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | k = −11→11 |
Tmin = 0.966, Tmax = 0.979 | l = −15→15 |
8683 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.051 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.148 | w = 1/[σ2(Fo2) + (0.0674P)2 + 0.1042P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
2668 reflections | Δρmax = 0.24 e Å−3 |
191 parameters | Δρmin = −0.13 e Å−3 |
28 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.030 (7) |
C15H15NO2 | γ = 69.394 (5)° |
Mr = 241.28 | V = 646.85 (8) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.1893 (4) Å | Mo Kα radiation |
b = 8.7704 (6) Å | µ = 0.08 mm−1 |
c = 12.7605 (9) Å | T = 296 K |
α = 87.326 (6)° | 0.54 × 0.41 × 0.31 mm |
β = 86.397 (6)° |
Stoe IPDS II diffractometer | 2668 independent reflections |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | 1896 reflections with I > 2σ(I) |
Tmin = 0.966, Tmax = 0.979 | Rint = 0.042 |
8683 measured reflections |
R[F2 > 2σ(F2)] = 0.051 | 28 restraints |
wR(F2) = 0.148 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | Δρmax = 0.24 e Å−3 |
2668 reflections | Δρmin = −0.13 e Å−3 |
191 parameters |
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 | Occ. (<1) | |
C1 | 0.5280 (3) | 0.5619 (2) | 0.34375 (15) | 0.0590 (5) | |
C2 | 0.3189 (3) | 0.5824 (2) | 0.40019 (14) | 0.0557 (4) | |
C3 | 0.2107 (3) | 0.7228 (2) | 0.45769 (15) | 0.0583 (5) | |
C4 | 0.3058 (3) | 0.8430 (2) | 0.45564 (17) | 0.0664 (5) | |
H4 | 0.2322 | 0.9372 | 0.4932 | 0.080* | |
C5 | 0.5101 (4) | 0.8250 (2) | 0.39809 (18) | 0.0717 (6) | |
H5 | 0.5719 | 0.9076 | 0.3964 | 0.086* | |
C6 | 0.6212 (4) | 0.6859 (2) | 0.34379 (17) | 0.0700 (5) | |
H6 | 0.7600 | 0.6736 | 0.3065 | 0.084* | |
C7 | 0.6472 (3) | 0.4135 (2) | 0.28805 (15) | 0.0636 (5) | |
H7 | 0.7913 | 0.3996 | 0.2554 | 0.076* | |
C8 | 0.6932 (3) | 0.1541 (2) | 0.23042 (15) | 0.0629 (5) | |
C9 | 0.9261 (4) | 0.0745 (3) | 0.24457 (18) | 0.0752 (6) | |
H9 | 1.0026 | 0.1169 | 0.2892 | 0.090* | |
C10 | 1.0450 (4) | −0.0671 (3) | 0.1929 (2) | 0.0914 (8) | |
H10 | 1.2010 | −0.1202 | 0.2041 | 0.110* | |
C11 | 0.9377 (5) | −0.1323 (3) | 0.1246 (2) | 0.0994 (8) | |
C12 | 0.7038 (5) | −0.0553 (3) | 0.1148 (2) | 0.0949 (8) | |
H12 | 0.6263 | −0.0994 | 0.0718 | 0.114* | |
C13 | 0.5816 (4) | 0.0857 (3) | 0.16706 (18) | 0.0789 (6) | |
H13 | 0.4233 | 0.1347 | 0.1595 | 0.095* | |
C14A | 1.0861 (17) | −0.2683 (8) | 0.0432 (7) | 0.120 (3) | 0.587 (11) |
H14A | 0.9952 | −0.2714 | −0.0153 | 0.144* | 0.587 (11) |
H14B | 1.2235 | −0.2474 | 0.0164 | 0.144* | 0.587 (11) |
C15A | 1.1473 (16) | −0.4208 (9) | 0.1053 (5) | 0.143 (3) | 0.587 (11) |
H15A | 1.2155 | −0.5112 | 0.0597 | 0.214* | 0.587 (11) |
H15B | 1.0107 | −0.4296 | 0.1409 | 0.214* | 0.587 (11) |
H15C | 1.2558 | −0.4216 | 0.1561 | 0.214* | 0.587 (11) |
C14B | 1.0391 (18) | −0.3057 (11) | 0.0870 (10) | 0.116 (4) | 0.413 (11) |
H14C | 1.0239 | −0.3787 | 0.1441 | 0.139* | 0.413 (11) |
H14D | 0.9493 | −0.3172 | 0.0303 | 0.139* | 0.413 (11) |
C15B | 1.273 (2) | −0.3543 (17) | 0.0517 (11) | 0.164 (5) | 0.413 (11) |
H15D | 1.2997 | −0.4273 | −0.0053 | 0.246* | 0.413 (11) |
H15E | 1.3686 | −0.4085 | 0.1082 | 0.246* | 0.413 (11) |
H15F | 1.3090 | −0.2601 | 0.0282 | 0.246* | 0.413 (11) |
N1 | 0.5630 (3) | 0.30067 (18) | 0.28177 (13) | 0.0637 (4) | |
O1 | 0.2152 (2) | 0.46864 (15) | 0.40254 (11) | 0.0659 (4) | |
O2 | 0.0118 (2) | 0.74271 (17) | 0.51685 (13) | 0.0749 (5) | |
H1 | 0.314 (5) | 0.386 (3) | 0.358 (2) | 0.099 (8)* | |
H2 | −0.027 (5) | 0.655 (4) | 0.515 (2) | 0.111 (9)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0606 (11) | 0.0534 (10) | 0.0622 (11) | −0.0192 (8) | −0.0047 (9) | 0.0012 (8) |
C2 | 0.0577 (10) | 0.0463 (9) | 0.0641 (11) | −0.0189 (8) | −0.0078 (8) | −0.0009 (7) |
C3 | 0.0546 (10) | 0.0491 (9) | 0.0695 (12) | −0.0150 (8) | −0.0065 (8) | −0.0049 (8) |
C4 | 0.0681 (12) | 0.0502 (10) | 0.0818 (13) | −0.0197 (9) | −0.0128 (10) | −0.0079 (9) |
C5 | 0.0766 (13) | 0.0580 (11) | 0.0896 (15) | −0.0339 (10) | −0.0112 (11) | 0.0003 (10) |
C6 | 0.0674 (12) | 0.0667 (12) | 0.0807 (14) | −0.0301 (10) | −0.0005 (10) | 0.0004 (10) |
C7 | 0.0628 (11) | 0.0606 (11) | 0.0638 (12) | −0.0185 (9) | 0.0036 (9) | −0.0008 (9) |
C8 | 0.0712 (12) | 0.0564 (10) | 0.0585 (11) | −0.0195 (9) | 0.0014 (9) | −0.0034 (8) |
C9 | 0.0736 (13) | 0.0669 (12) | 0.0793 (14) | −0.0156 (10) | −0.0063 (10) | −0.0143 (10) |
C10 | 0.0826 (16) | 0.0733 (14) | 0.1042 (19) | −0.0078 (12) | −0.0029 (13) | −0.0206 (13) |
C11 | 0.112 (2) | 0.0714 (14) | 0.104 (2) | −0.0159 (14) | −0.0015 (15) | −0.0307 (13) |
C12 | 0.117 (2) | 0.0750 (15) | 0.0955 (18) | −0.0321 (15) | −0.0172 (15) | −0.0207 (13) |
C13 | 0.0826 (15) | 0.0695 (13) | 0.0861 (15) | −0.0265 (11) | −0.0127 (12) | −0.0062 (11) |
C14A | 0.144 (6) | 0.085 (4) | 0.129 (5) | −0.042 (4) | 0.014 (4) | 0.013 (3) |
C15A | 0.182 (7) | 0.098 (5) | 0.114 (4) | −0.007 (4) | 0.007 (4) | −0.021 (3) |
C14B | 0.137 (6) | 0.059 (5) | 0.136 (7) | −0.016 (4) | 0.034 (5) | −0.044 (5) |
C15B | 0.156 (8) | 0.135 (7) | 0.185 (9) | −0.036 (6) | 0.038 (7) | −0.029 (6) |
N1 | 0.0668 (10) | 0.0559 (9) | 0.0655 (10) | −0.0181 (7) | 0.0016 (7) | −0.0054 (7) |
O1 | 0.0642 (8) | 0.0517 (7) | 0.0840 (10) | −0.0234 (6) | 0.0090 (7) | −0.0149 (6) |
O2 | 0.0646 (9) | 0.0587 (8) | 0.1033 (12) | −0.0236 (7) | 0.0119 (7) | −0.0265 (7) |
C1—C2 | 1.399 (3) | C11—C12 | 1.376 (4) |
C1—C6 | 1.399 (3) | C11—C14B | 1.514 (7) |
C1—C7 | 1.445 (3) | C11—C14A | 1.603 (8) |
C2—O1 | 1.361 (2) | C12—C13 | 1.379 (3) |
C2—C3 | 1.395 (2) | C12—H12 | 0.93 |
C3—O2 | 1.364 (2) | C13—H13 | 0.93 |
C3—C4 | 1.375 (3) | C14A—C15A | 1.464 (11) |
C4—C5 | 1.385 (3) | C14A—H14A | 0.97 |
C4—H4 | 0.93 | C14A—H14B | 0.97 |
C5—C6 | 1.367 (3) | C15A—H15A | 0.96 |
C5—H5 | 0.93 | C15A—H15B | 0.96 |
C6—H6 | 0.93 | C15A—H15C | 0.96 |
C7—N1 | 1.278 (2) | C14B—C15B | 1.405 (15) |
C7—H7 | 0.93 | C14B—H14C | 0.97 |
C8—C13 | 1.378 (3) | C14B—H14D | 0.97 |
C8—C9 | 1.382 (3) | C15B—H15D | 0.96 |
C8—N1 | 1.419 (2) | C15B—H15E | 0.96 |
C9—C10 | 1.375 (3) | C15B—H15F | 0.96 |
C9—H9 | 0.93 | O1—H1 | 0.95 (3) |
C10—C11 | 1.383 (4) | O2—H2 | 0.88 (3) |
C10—H10 | 0.93 | ||
C2—C1—C6 | 118.93 (17) | C10—C11—C14A | 121.0 (4) |
C2—C1—C7 | 120.31 (17) | C11—C12—C13 | 121.7 (2) |
C6—C1—C7 | 120.76 (18) | C11—C12—H12 | 119.2 |
O1—C2—C3 | 117.70 (17) | C13—C12—H12 | 119.2 |
O1—C2—C1 | 122.45 (16) | C8—C13—C12 | 120.2 (2) |
C3—C2—C1 | 119.85 (16) | C8—C13—H13 | 119.9 |
O2—C3—C4 | 119.15 (17) | C12—C13—H13 | 119.9 |
O2—C3—C2 | 121.02 (16) | C15A—C14A—C11 | 104.1 (6) |
C4—C3—C2 | 119.83 (18) | C15A—C14A—H14A | 110.9 |
C3—C4—C5 | 120.55 (18) | C11—C14A—H14A | 110.9 |
C3—C4—H4 | 119.7 | C15A—C14A—H14B | 110.9 |
C5—C4—H4 | 119.7 | C11—C14A—H14B | 110.9 |
C6—C5—C4 | 120.14 (19) | H14A—C14A—H14B | 109.0 |
C6—C5—H5 | 119.9 | C14A—C15A—H15A | 109.5 |
C4—C5—H5 | 119.9 | C14A—C15A—H15B | 109.5 |
C5—C6—C1 | 120.7 (2) | H15A—C15A—H15B | 109.5 |
C5—C6—H6 | 119.7 | C14A—C15A—H15C | 109.5 |
C1—C6—H6 | 119.7 | H15A—C15A—H15C | 109.5 |
N1—C7—C1 | 122.76 (18) | H15B—C15A—H15C | 109.5 |
N1—C7—H7 | 118.6 | C15B—C14B—C11 | 114.5 (9) |
C1—C7—H7 | 118.6 | C15B—C14B—H14C | 108.6 |
C13—C8—C9 | 118.79 (18) | C11—C14B—H14C | 108.6 |
C13—C8—N1 | 118.77 (19) | C15B—C14B—H14D | 108.6 |
C9—C8—N1 | 122.40 (18) | C11—C14B—H14D | 108.6 |
C10—C9—C8 | 120.3 (2) | H14C—C14B—H14D | 107.6 |
C10—C9—H9 | 119.9 | C14B—C15B—H15D | 109.5 |
C8—C9—H9 | 119.9 | C14B—C15B—H15E | 109.5 |
C9—C10—C11 | 121.5 (2) | H15D—C15B—H15E | 109.5 |
C9—C10—H10 | 119.3 | C14B—C15B—H15F | 109.5 |
C11—C10—H10 | 119.3 | H15D—C15B—H15F | 109.5 |
C12—C11—C10 | 117.4 (2) | H15E—C15B—H15F | 109.5 |
C12—C11—C14B | 116.2 (5) | C7—N1—C8 | 120.19 (17) |
C10—C11—C14B | 123.6 (5) | C2—O1—H1 | 103.8 (15) |
C12—C11—C14A | 120.4 (4) | C3—O2—H2 | 111.0 (18) |
C6—C1—C2—O1 | 178.84 (17) | C9—C10—C11—C12 | −3.7 (4) |
C7—C1—C2—O1 | −2.3 (3) | C9—C10—C11—C14B | −164.1 (6) |
C6—C1—C2—C3 | −1.9 (3) | C9—C10—C11—C14A | 164.1 (4) |
C7—C1—C2—C3 | 177.02 (17) | C10—C11—C12—C13 | 2.8 (4) |
O1—C2—C3—O2 | 2.1 (3) | C14B—C11—C12—C13 | 164.7 (6) |
C1—C2—C3—O2 | −177.26 (17) | C14A—C11—C12—C13 | −165.0 (4) |
O1—C2—C3—C4 | −178.37 (17) | C9—C8—C13—C12 | −3.3 (3) |
C1—C2—C3—C4 | 2.3 (3) | N1—C8—C13—C12 | 179.0 (2) |
O2—C3—C4—C5 | 178.65 (18) | C11—C12—C13—C8 | 0.6 (4) |
C2—C3—C4—C5 | −0.9 (3) | C12—C11—C14A—C15A | −109.9 (7) |
C3—C4—C5—C6 | −0.9 (3) | C10—C11—C14A—C15A | 82.7 (8) |
C4—C5—C6—C1 | 1.4 (3) | C14B—C11—C14A—C15A | −21.5 (12) |
C2—C1—C6—C5 | 0.0 (3) | C12—C11—C14B—C15B | 151.7 (11) |
C7—C1—C6—C5 | −178.83 (18) | C10—C11—C14B—C15B | −47.7 (16) |
C2—C1—C7—N1 | 4.6 (3) | C14A—C11—C14B—C15B | 45.5 (13) |
C6—C1—C7—N1 | −176.53 (19) | C1—C7—N1—C8 | −176.85 (17) |
C13—C8—C9—C10 | 2.5 (3) | C13—C8—N1—C7 | −139.4 (2) |
N1—C8—C9—C10 | −179.9 (2) | C9—C8—N1—C7 | 43.0 (3) |
C8—C9—C10—C11 | 1.1 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.95 (3) | 1.72 (3) | 2.596 (2) | 152 (2) |
O2—H2···O1 | 0.88 (3) | 2.29 (3) | 2.7307 (19) | 111 (2) |
O2—H2···O1i | 0.88 (3) | 2.06 (3) | 2.818 (2) | 143 (2) |
Symmetry code: (i) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C15H15NO2 |
Mr | 241.28 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 6.1893 (4), 8.7704 (6), 12.7605 (9) |
α, β, γ (°) | 87.326 (6), 86.397 (6), 69.394 (5) |
V (Å3) | 646.85 (8) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.54 × 0.41 × 0.31 |
Data collection | |
Diffractometer | Stoe IPDS II diffractometer |
Absorption correction | Integration (X-RED32; Stoe & Cie, 2002) |
Tmin, Tmax | 0.966, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8683, 2668, 1896 |
Rint | 0.042 |
(sin θ/λ)max (Å−1) | 0.628 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.051, 0.148, 1.03 |
No. of reflections | 2668 |
No. of parameters | 191 |
No. of restraints | 28 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.24, −0.13 |
Computer programs: X-AREA (Stoe & Cie, 2002), X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.95 (3) | 1.72 (3) | 2.596 (2) | 152 (2) |
O2—H2···O1 | 0.88 (3) | 2.29 (3) | 2.7307 (19) | 111 (2) |
O2—H2···O1i | 0.88 (3) | 2.06 (3) | 2.818 (2) | 143 (2) |
Symmetry code: (i) −x, −y+1, −z+1. |
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 F.279 of the University Research Fund).
References
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There has been considerable interest in some Schiff bases derived from salicylaldehyde and substituted salicylaldehyde because they show thermochromism and photochromism in the solid state (Kownacki et al., 1994). The tautomerism in the Schiff base ligands plays an important role for distinguishing their photochromic (Guha et al., 2000) and thermochromic (Zgierski et al., 2000) characteristics. It has been proposed that molecules showing thermochromism are planar, while those showing photochromism are non-planar (Kletski et al., 1997), both phenomena being associated with a proton transfer (Elmali et al., 1999). Schiff bases derived from the condensation of salicylaldehyde with aniline and substituted aniline, and naphthaldehyde with aniline exists as enol-imine (Dudek et al., 1966), keto-amine (Salman et al., 1991), or enol-imine/keto-amine form (Salman et al., 1993; Alarcon et al., 1995) in all solvents.
The X-ray analysis shows that the title compound prefers an enol-imine tautomeric form, with a strong intramolecular O1—H1···N1 hydrogen bond. This is also confirmed by the C2—O1 [1.361 (2) Å], C7—N1 [1.278 (2) Å], C1—C7 [1.445 (2) Å] and C1—C2 [1.399 (2) Å] bond lengths (Fig. 1). The C2—O1 bond length of 1.361 (2) Å indicates a single-bond character and the C7—N1 bond length of 1.278 (2) Å indicates a high degree of double-bond character. Similar results were observed for (E)-4-methoxy-2-[(o-tolilimino)methyl]phenol [C—O = 1.357 (2) Å, C═N= 1.286 (2) Å; Özek et al., 2009]. An intramolecular O2—H2···O1 hydrogen bond is also observed. The O—H···N and O—H···O hydrogen bonds generate S(6) and S(5) ring motifs, respectively (Bernstein et al., 1995).
The dihedral angle between benzene rings A(C1-C6) and B(C8-C13) is 48.1 (1)°. The nearly planar S(6) ring C(O1/H1/N1/C1/C2/C7) is oriented with respect to rings A and B at dihedral angles of A/C = 1.89 (42)° and B/C = 46.23 (25)°. It is known that Schiff bases may exhibit thermochromism or photochromism, depending on the planarity or non-planarity of the molecule, respectively. Since the title moleclule is non-planar, one can expect photochromic properties in title compound.
In the crystal structure, molecules are linked into centrosymmetric R22(10) dimers via O—H···O hydrogen bonds (Table 2). A very weak π–π interaction occurs between A(C1-C6) rings at (x, y, z) and (1-x, 1-y, 1-z), with a ring centroid-to centroid distance of 4.150 (1) Å; only atoms C1, C2 and C3 are involved in the interactions as the rings are displaced.