organic compounds
(E)-4-Hydroxy-2-{[(2-phenylethyl)iminiumyl]methyl}phenolate
aFacultad de Ciencias Químicas, Universidad de Colima, Carretera Coquimatlán-Colima, Coquimatlán Colima, México, CP 28400, bLaboratorio 26, Departamento de Química, Centro de Investigacion y de Estudios Avanzados del Instituto, Politécnico Nacional, Av. IPN 2508, San Pedro Zacatenco, CP 07360, México, D.F., and cDepartamento de Ciencias-Básicas Químicas, Unidad Profesional Interdisciplinaria de Biotecnologia, del IPN, Avenida Acueducto s/n, Barrio la Laguna Ticoman, CP 07340, GAM, México, D.F.
*Correspondence e-mail: fjmartin@ucol.mx
The title Schiff base compound, C15H15NO2, crystallized as the iminium–phenolate zwitterion. The H atom is localized on the imine N atom, forming a strong intramolecular hydrogen bond with the phenolate O atom, and giving rise to an S(6) ring motif. The molecule has an E conformation about the C=N bond. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming chains propagating along [010]. There are also C—H⋯O interactions present.
Related literature
For general background to the characteristics of et al. (1995); Hadjoudis et al. (2004). For related structures, see: Dominiak et al. (2006); Santos-Contreras et al. (2009); Ng (2008). For hydrogen-bond motifs, see: Bernstein et al. (1995).
see: KrauseExperimental
Crystal data
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Refinement
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Data collection: COLLECT (Nonius, 1998); cell HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2004 (Burla et al., 2005); 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 publication routines (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536812025408/su2447sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812025408/su2447Isup2.hkl
The title compound was prepared by condensation of 5-hydroxysalicylaldehyde (0.5 g, 3.62 mmol) with phenethylamine (0.438 g, 0.454 ml, 3.62 mmol) in toluene, at 298 K with stirring for 5 min. Orange crystals, suitable for X-ray analysis, were obtained by slow evaporation from a saturated dimethylsulfoxide solution [Yield of 0.78 g (90%); M.p. 396–397 K]. Spectroscopic data for the title compound are available in the archived CIF.
The amino and OH H atoms were located in a difference Fourier map. In the final cycles of
they and the C-bound H atoms were included in calculated positions and treated as riding atoms: O-H = 0.82 Å, N-H = 0.86 Å, C-H = 0.95 and 0.99 Å for CH and CH2 H atoms, respectively, with Uiso(H) = k × Ueq(O,N,C) where k = 1.5 for the OH H atom and = 1.2 for other H atoms.Schiff base compounds are highly versatile compounds widely applied in different study fields. They have been used as selective prodrugs for histamine (Krause et al., 1995). and as materials of interest because of their thermochromic and photochromic properties (Hadjoudis et al., 2004). When an OH functionality is also present in the same molecule, tautomeric N—H or O—H equilibrium can be performed, thus these compounds can exist as O—H···N (imines), O···H—N (enamines) and also as N+—H···O- zwitterionic forms (Dominiak et al., 2006, Ng, 2008, Santos-Contreras et al., 2009) Herein we demonstrate that the title compound exist as the N+—H···O- zwitterionic form, with the H atom closing a six membered ring.
The title compound, Fig. 1, exists as a zwitterion with the hydrogen atom being localized on the imine N atom N8. The C1═O1 and N8═C7 bond lengths [1.3206 (14) and 1.2985 (16) Å, respectively] reveal significant double-bond character. The phenolate ring shows a certain distortion in the C—C bond lengths, but nevertheless an alternating long-short pattern is observed, in agreement with delocalized bonding. The C2—C7 bond distance of 1.4407 (16) Å is in the range for a single bond character. The intramolecular N8-H8···O1 hydrogen bond gives rise to the formation of an S(6) ring motif (Table 1; Bernstein et al., 1995).
In the crystal, an O-H···O hydrogen bond links the molecules to form C(7) chains (Bernstein et al., 1995) that propagate along the b axis direction (Table 1 and Fig. 2). There are also C-H···O interactions present (Table 1).
The title structure closely resembles that of N,-bis(2,5-dihydroxybezyl idene)-1,2-diaminobenzene (Dominiak et al., 2006) and 4-chloro-2-[tris(hydroxymethyl)methyliminiomethyl]phenolate (Ng, 2008).
For general background to the characteristics of
see: Krause et al. (1995); Hadjoudis et al. (2004). For related structures, see: Dominiak et al. (2006); Santos-Contreras et al. (2009); Ng (2008). For hydrogen-bond motifs, see: Bernstein et al. (1995).Data collection: COLLECT (Nonius, 1998); cell
HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2004 (Burla et al., 2005); 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 publication routines (Farrugia, 1999).C15H15NO2 | F(000) = 512 |
Mr = 241.28 | Dx = 1.265 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 14042 reflections |
a = 9.5010 (19) Å | θ = 2.9–27.5° |
b = 12.936 (3) Å | µ = 0.08 mm−1 |
c = 12.551 (4) Å | T = 170 K |
β = 124.81 (2)° | Prism, orange |
V = 1266.5 (6) Å3 | 0.50 × 0.20 × 0.20 mm |
Z = 4 |
Nonius KappaCCD diffractometer | 2773 independent reflections |
Radiation source: Enraf Nonius FR590 | 2367 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
Detector resolution: 9 pixels mm-1 | θmax = 27.5°, θmin = 4.1° |
CCD rotation images, thick slices scans | h = −10→12 |
Absorption correction: for a sphere (Dwiggins, 1975) | k = −16→16 |
Tmin = 0.861, Tmax = 0.862 | l = −13→13 |
15718 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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.107 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0502P)2 + 0.3688P] where P = (Fo2 + 2Fc2)/3 |
2773 reflections | (Δ/σ)max < 0.001 |
163 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C15H15NO2 | V = 1266.5 (6) Å3 |
Mr = 241.28 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.5010 (19) Å | µ = 0.08 mm−1 |
b = 12.936 (3) Å | T = 170 K |
c = 12.551 (4) Å | 0.50 × 0.20 × 0.20 mm |
β = 124.81 (2)° |
Nonius KappaCCD diffractometer | 2773 independent reflections |
Absorption correction: for a sphere (Dwiggins, 1975) | 2367 reflections with I > 2σ(I) |
Tmin = 0.861, Tmax = 0.862 | Rint = 0.029 |
15718 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.107 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.25 e Å−3 |
2773 reflections | Δρmin = −0.22 e Å−3 |
163 parameters |
Experimental. Spectroscopic data for the title compound: FT—IR by ATR (cm-1): 1643 (C═ N as intense band), 1496 (Asymmetrical C=C—O···H stretch), 3311 (free phenolic O—H intense broad band), 3059 (intramolecular hydrogen bonding N—H···O, as a weak broad band). LC/MS/TOF on HPLC-methanol solution, m/z (%) calculated: 242.1181 (100); found 242.1175 (100) [M+H]+, molecular formula C15H15NO2. 1H NMR (CDCl3, 300.1MHz): δ 6.83 (m, H5 and H6), 6.67 (s, H3), 8.12 (s, H7), 3.84 (t, H9), 3.00 (t, H10), 7.19–7.32 (m, H12—H16). 13C NMR (CDCl3, 75.4MHz): δ 147.5 (C1), 118.4 (C2), 116.6 (C3), 144.0 (C4), 119.9 (C5), 117.6 (C6), 164.5 (C7), 61.1 (C9), 37.3 (C10), 139.3 (C11), 128.9 (C13, C15), 128.5 (C12, C16), 126.4 (C14). |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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 | ||
O1 | 0.88467 (11) | 0.43206 (6) | 0.61806 (8) | 0.0320 (3) | |
O4 | 0.99566 (15) | 0.00918 (7) | 0.64559 (9) | 0.0460 (3) | |
N8 | 0.75925 (13) | 0.42202 (8) | 0.37321 (9) | 0.0284 (3) | |
C1 | 0.90916 (14) | 0.33115 (8) | 0.62390 (11) | 0.0245 (3) | |
C2 | 0.85954 (14) | 0.27185 (8) | 0.51050 (10) | 0.0241 (3) | |
C3 | 0.88858 (15) | 0.16354 (9) | 0.51983 (11) | 0.0272 (3) | |
C4 | 0.96636 (16) | 0.11344 (9) | 0.63837 (11) | 0.0290 (3) | |
C5 | 1.01496 (15) | 0.17148 (9) | 0.75028 (11) | 0.0288 (3) | |
C6 | 0.98611 (15) | 0.27637 (9) | 0.74326 (11) | 0.0276 (3) | |
C7 | 0.78312 (14) | 0.32274 (9) | 0.38709 (11) | 0.0256 (3) | |
C9 | 0.68816 (16) | 0.47659 (9) | 0.24949 (12) | 0.0325 (4) | |
C10 | 0.52322 (16) | 0.53653 (10) | 0.20739 (13) | 0.0364 (4) | |
C11 | 0.55332 (15) | 0.62068 (9) | 0.30222 (11) | 0.0314 (3) | |
C12 | 0.48187 (17) | 0.61459 (12) | 0.37397 (13) | 0.0408 (4) | |
C13 | 0.51032 (18) | 0.69276 (14) | 0.46060 (14) | 0.0495 (5) | |
C14 | 0.60966 (18) | 0.77808 (13) | 0.47683 (14) | 0.0470 (5) | |
C15 | 0.68349 (17) | 0.78487 (10) | 0.40787 (13) | 0.0399 (4) | |
C16 | 0.65511 (16) | 0.70707 (10) | 0.32130 (12) | 0.0332 (4) | |
H3 | 0.85445 | 0.12504 | 0.44421 | 0.0326* | |
H4 | 1.03190 | −0.01141 | 0.71879 | 0.0689* | |
H5 | 1.06841 | 0.13740 | 0.83162 | 0.0345* | |
H6 | 1.01819 | 0.31299 | 0.81963 | 0.0332* | |
H7 | 0.74885 | 0.28207 | 0.31297 | 0.0307* | |
H8 | 0.78653 | 0.45796 | 0.44009 | 0.0341* | |
H9A | 0.66198 | 0.42590 | 0.18137 | 0.0389* | |
H9B | 0.77472 | 0.52552 | 0.25890 | 0.0389* | |
H10A | 0.47519 | 0.56802 | 0.12123 | 0.0437* | |
H10B | 0.43734 | 0.48727 | 0.19847 | 0.0437* | |
H12 | 0.41353 | 0.55663 | 0.36330 | 0.0490* | |
H13 | 0.46162 | 0.68769 | 0.50873 | 0.0594* | |
H14 | 0.62724 | 0.83176 | 0.53491 | 0.0565* | |
H15 | 0.75308 | 0.84257 | 0.42000 | 0.0479* | |
H16 | 0.70530 | 0.71235 | 0.27424 | 0.0398* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0424 (5) | 0.0208 (4) | 0.0295 (4) | 0.0003 (3) | 0.0185 (4) | −0.0023 (3) |
O4 | 0.0827 (8) | 0.0218 (4) | 0.0385 (5) | 0.0085 (5) | 0.0376 (5) | 0.0045 (4) |
N8 | 0.0316 (5) | 0.0272 (5) | 0.0248 (5) | 0.0016 (4) | 0.0151 (4) | 0.0004 (4) |
C1 | 0.0234 (5) | 0.0229 (5) | 0.0270 (6) | −0.0020 (4) | 0.0142 (5) | −0.0025 (4) |
C2 | 0.0230 (5) | 0.0248 (6) | 0.0249 (6) | −0.0016 (4) | 0.0140 (5) | −0.0007 (4) |
C3 | 0.0324 (6) | 0.0245 (6) | 0.0272 (6) | −0.0024 (4) | 0.0185 (5) | −0.0041 (4) |
C4 | 0.0374 (6) | 0.0209 (5) | 0.0327 (6) | 0.0000 (5) | 0.0223 (5) | −0.0001 (4) |
C5 | 0.0340 (6) | 0.0269 (6) | 0.0260 (6) | −0.0001 (5) | 0.0175 (5) | 0.0025 (4) |
C6 | 0.0309 (6) | 0.0266 (6) | 0.0242 (6) | −0.0024 (5) | 0.0150 (5) | −0.0034 (4) |
C7 | 0.0250 (5) | 0.0266 (6) | 0.0262 (6) | −0.0006 (4) | 0.0152 (5) | −0.0022 (4) |
C9 | 0.0375 (7) | 0.0311 (6) | 0.0282 (6) | 0.0038 (5) | 0.0184 (5) | 0.0049 (5) |
C10 | 0.0318 (6) | 0.0347 (7) | 0.0327 (7) | 0.0034 (5) | 0.0125 (5) | 0.0044 (5) |
C11 | 0.0253 (6) | 0.0348 (6) | 0.0299 (6) | 0.0077 (5) | 0.0132 (5) | 0.0087 (5) |
C12 | 0.0288 (6) | 0.0540 (8) | 0.0385 (7) | 0.0031 (6) | 0.0185 (6) | 0.0116 (6) |
C13 | 0.0347 (7) | 0.0833 (12) | 0.0348 (7) | 0.0142 (7) | 0.0224 (6) | 0.0074 (7) |
C14 | 0.0340 (7) | 0.0616 (10) | 0.0349 (8) | 0.0144 (7) | 0.0134 (6) | −0.0054 (6) |
C15 | 0.0324 (7) | 0.0371 (7) | 0.0403 (7) | 0.0061 (5) | 0.0149 (6) | 0.0020 (5) |
C16 | 0.0312 (6) | 0.0356 (7) | 0.0342 (7) | 0.0058 (5) | 0.0195 (5) | 0.0065 (5) |
O1—C1 | 1.3206 (14) | C12—C13 | 1.394 (2) |
O4—C4 | 1.3696 (16) | C13—C14 | 1.390 (3) |
O4—H4 | 0.8200 | C14—C15 | 1.394 (3) |
N8—C7 | 1.2985 (16) | C15—C16 | 1.3898 (19) |
N8—C9 | 1.4725 (16) | C3—H3 | 0.9500 |
N8—H8 | 0.8600 | C5—H5 | 0.9500 |
C1—C6 | 1.4250 (17) | C6—H6 | 0.9500 |
C1—C2 | 1.4389 (16) | C7—H7 | 0.9500 |
C2—C7 | 1.4407 (16) | C9—H9A | 0.9900 |
C2—C3 | 1.4199 (16) | C9—H9B | 0.9900 |
C3—C4 | 1.3872 (17) | C10—H10A | 0.9900 |
C4—C5 | 1.4175 (17) | C10—H10B | 0.9900 |
C5—C6 | 1.3771 (17) | C12—H12 | 0.9500 |
C9—C10 | 1.546 (2) | C13—H13 | 0.9500 |
C10—C11 | 1.5148 (19) | C14—H14 | 0.9500 |
C11—C16 | 1.406 (2) | C15—H15 | 0.9500 |
C11—C12 | 1.406 (2) | C16—H16 | 0.9500 |
C4—O4—H4 | 109.00 | C4—C3—H3 | 120.00 |
C7—N8—C9 | 123.74 (10) | C4—C5—H5 | 119.00 |
C9—N8—H8 | 118.00 | C6—C5—H5 | 119.00 |
C7—N8—H8 | 118.00 | C1—C6—H6 | 119.00 |
O1—C1—C2 | 121.62 (10) | C5—C6—H6 | 119.00 |
O1—C1—C6 | 121.22 (10) | N8—C7—H7 | 119.00 |
C2—C1—C6 | 117.17 (10) | C2—C7—H7 | 119.00 |
C1—C2—C7 | 119.95 (10) | N8—C9—H9A | 109.00 |
C1—C2—C3 | 120.40 (10) | N8—C9—H9B | 109.00 |
C3—C2—C7 | 119.64 (10) | C10—C9—H9A | 109.00 |
C2—C3—C4 | 120.59 (11) | C10—C9—H9B | 109.00 |
O4—C4—C3 | 119.65 (11) | H9A—C9—H9B | 108.00 |
C3—C4—C5 | 119.21 (11) | C9—C10—H10A | 109.00 |
O4—C4—C5 | 121.14 (10) | C9—C10—H10B | 109.00 |
C4—C5—C6 | 121.21 (11) | C11—C10—H10A | 109.00 |
C1—C6—C5 | 121.41 (11) | C11—C10—H10B | 109.00 |
N8—C7—C2 | 122.58 (11) | H10A—C10—H10B | 108.00 |
N8—C9—C10 | 111.47 (13) | C11—C12—H12 | 120.00 |
C9—C10—C11 | 113.07 (12) | C13—C12—H12 | 120.00 |
C10—C11—C12 | 121.30 (13) | C12—C13—H13 | 120.00 |
C10—C11—C16 | 120.53 (14) | C14—C13—H13 | 120.00 |
C12—C11—C16 | 118.18 (12) | C13—C14—H14 | 120.00 |
C11—C12—C13 | 120.64 (15) | C15—C14—H14 | 120.00 |
C12—C13—C14 | 120.24 (17) | C14—C15—H15 | 120.00 |
C13—C14—C15 | 119.97 (15) | C16—C15—H15 | 120.00 |
C14—C15—C16 | 119.87 (15) | C11—C16—H16 | 119.00 |
C11—C16—C15 | 121.08 (15) | C15—C16—H16 | 119.00 |
C2—C3—H3 | 120.00 | ||
C9—N8—C7—C2 | 177.35 (15) | O4—C4—C5—C6 | 179.78 (16) |
C7—N8—C9—C10 | 121.46 (15) | C3—C4—C5—C6 | 0.1 (3) |
C6—C1—C2—C3 | −0.5 (2) | C4—C5—C6—C1 | −1.1 (2) |
C6—C1—C2—C7 | −179.18 (14) | N8—C9—C10—C11 | 62.54 (15) |
O1—C1—C6—C5 | −178.71 (15) | C9—C10—C11—C12 | −113.64 (16) |
C2—C1—C6—C5 | 1.3 (2) | C9—C10—C11—C16 | 65.94 (16) |
O1—C1—C2—C7 | 0.8 (2) | C10—C11—C12—C13 | −179.82 (14) |
O1—C1—C2—C3 | 179.54 (14) | C16—C11—C12—C13 | 0.6 (2) |
C7—C2—C3—C4 | 178.19 (15) | C10—C11—C16—C15 | 179.90 (13) |
C1—C2—C3—C4 | −0.5 (2) | C12—C11—C16—C15 | −0.5 (2) |
C3—C2—C7—N8 | −177.33 (15) | C11—C12—C13—C14 | 0.2 (2) |
C1—C2—C7—N8 | 1.4 (2) | C12—C13—C14—C15 | −1.0 (2) |
C2—C3—C4—C5 | 0.7 (2) | C13—C14—C15—C16 | 1.1 (2) |
C2—C3—C4—O4 | −178.96 (15) | C14—C15—C16—C11 | −0.3 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N8—H8···O1 | 0.86 | 1.90 | 2.5884 (15) | 137 |
O4—H4···O1i | 0.82 | 1.87 | 2.6902 (15) | 176 |
C6—H6···O4ii | 0.95 | 2.59 | 3.2818 (18) | 130 |
Symmetry codes: (i) −x+2, y−1/2, −z+3/2; (ii) −x+2, y+1/2, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | C15H15NO2 |
Mr | 241.28 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 170 |
a, b, c (Å) | 9.5010 (19), 12.936 (3), 12.551 (4) |
β (°) | 124.81 (2) |
V (Å3) | 1266.5 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.50 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | For a sphere (Dwiggins, 1975) |
Tmin, Tmax | 0.861, 0.862 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15718, 2773, 2367 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.107, 1.02 |
No. of reflections | 2773 |
No. of parameters | 163 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.22 |
Computer programs: COLLECT (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor 1997), HKL DENZO/SCALEPACK (Otwinowski & Minor, 1997), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX publication routines (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N8—H8···O1 | 0.86 | 1.90 | 2.5884 (15) | 137 |
O4—H4···O1i | 0.82 | 1.87 | 2.6902 (15) | 176 |
C6—H6···O4ii | 0.95 | 2.59 | 3.2818 (18) | 130 |
Symmetry codes: (i) −x+2, y−1/2, −z+3/2; (ii) −x+2, y+1/2, −z+3/2. |
Acknowledgements
The authors gratefully acknowledge financial support from FRABA-Universidad de Colima 764/11, CINVESTAV-IPN and SIP-IPN
References
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N. L. (1995). Angew. Chem. Int. Ed. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Dominiak, P. M., Makal, A., Mallinson, P. R., Trzcinska, K., Eilmes, J., Grech, E., Chruszcz, M., Minor, W. & Wozniak, K. (2006). Chem. Eur. J. 12, 1941–1949. Web of Science CSD CrossRef PubMed CAS Google Scholar
Dwiggins, C. W. (1975). Acta Cryst. A31, 146–148. CrossRef IUCr Journals Web of Science Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Hadjoudis, E., Rontoyianni, A., Ambroziak, K., Dziembowska, T. & Mavridis, I. M. (2004). J. Photochem. Photobiol. A, 162, 521–530. Web of Science CSD CrossRef CAS Google Scholar
Krause, M., Rouleau, A., Stark, H., Luger, P., Lipp, R., Garbarg, M., Schwartz, J. C. & Schunack, W. (1995). J. Med. Chem. 38, 4070–4079. CSD CrossRef CAS PubMed Web of Science Google Scholar
Ng, S. W. (2008). Acta Cryst. E64, o2455. Web of Science CrossRef IUCr Journals Google Scholar
Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr, pp. 307–326. New York: Academic Press. Google Scholar
Santos-Contreras, R. J., Ramos-Organillo, A., García-Báez, E. V., Padilla-Martínez, I. I. & Martínez-Martínez, F. J. (2009). Acta Cryst. C65, o8–o10. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Schiff base compounds are highly versatile compounds widely applied in different study fields. They have been used as selective prodrugs for histamine (Krause et al., 1995). and as materials of interest because of their thermochromic and photochromic properties (Hadjoudis et al., 2004). When an OH functionality is also present in the same molecule, tautomeric N—H or O—H equilibrium can be performed, thus these compounds can exist as O—H···N (imines), O···H—N (enamines) and also as N+—H···O- zwitterionic forms (Dominiak et al., 2006, Ng, 2008, Santos-Contreras et al., 2009) Herein we demonstrate that the title compound exist as the N+—H···O- zwitterionic form, with the H atom closing a six membered ring.
The title compound, Fig. 1, exists as a zwitterion with the hydrogen atom being localized on the imine N atom N8. The C1═O1 and N8═C7 bond lengths [1.3206 (14) and 1.2985 (16) Å, respectively] reveal significant double-bond character. The phenolate ring shows a certain distortion in the C—C bond lengths, but nevertheless an alternating long-short pattern is observed, in agreement with delocalized bonding. The C2—C7 bond distance of 1.4407 (16) Å is in the range for a single bond character. The intramolecular N8-H8···O1 hydrogen bond gives rise to the formation of an S(6) ring motif (Table 1; Bernstein et al., 1995).
In the crystal, an O-H···O hydrogen bond links the molecules to form C(7) chains (Bernstein et al., 1995) that propagate along the b axis direction (Table 1 and Fig. 2). There are also C-H···O interactions present (Table 1).
The title structure closely resembles that of N,-bis(2,5-dihydroxybezyl idene)-1,2-diaminobenzene (Dominiak et al., 2006) and 4-chloro-2-[tris(hydroxymethyl)methyliminiomethyl]phenolate (Ng, 2008).