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Acta Crystallogr Sect E Struct Rep Online. 2010 November 1; 66(Pt 11): o3003.
Published online 2010 October 31. doi:  10.1107/S1600536810043990
PMCID: PMC3009170

2-(4-Formyl-2,6-dimeth­oxy­phenoxy)­acetic acid

Abstract

In the title compound, C11H12O6, the aldehyde group is disordered over two sites in a 0.79:0.21 ratio. The carb­oxy­lic acid chain is found in the [ap,ap] conformation due to two intramolecular O—H(...)O hydrogen bonds.

Related literature

For related acetic acids substituted in the α-position, see: Lundquist et al. (1987 [triangle]). For conformational and geometric considerations of carb­oxy­lic acids, see: Lide (1964 [triangle]); Leiserowitz (1976 [triangle]). For applications of PPV oligomers, see: Chemla (1987 [triangle]); Bandyopadhyay & Pal (2003 [triangle]). For hydrogen bonding and crystal engineering, see: Desiraju (1997 [triangle]); Steiner (2002 [triangle]).

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Object name is e-66-o3003-scheme1.jpg

Experimental

Crystal data

  • C11H12O6
  • M r = 240.21
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o3003-efi1.jpg
  • a = 9.350 (2) Å
  • b = 7.416 (1) Å
  • c = 17.374 (8) Å
  • β = 113.67 (3)°
  • V = 1103.4 (6) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.12 mm−1
  • T = 293 K
  • 0.27 × 0.24 × 0.15 mm

Data collection

  • Enraf–Nonius MACH3 diffractometer
  • 4025 measured reflections
  • 2015 independent reflections
  • 1292 reflections with I > 2σ(I)
  • R int = 0.030
  • 3 standard reflections every 60 min intensity decay: 1%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.036
  • wR(F 2) = 0.093
  • S = 1.01
  • 2015 reflections
  • 171 parameters
  • 8 restraints
  • H-atom parameters constrained
  • Δρmax = 0.15 e Å−3
  • Δρmin = −0.15 e Å−3

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 [triangle]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1996 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810043990/zl2319sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810043990/zl2319Isup2.hkl

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

Acknowledgments

CMLVV thanks the Fund for Scientific Research (FWO Vlaanderen) for a grant as a research assistant. AC thanks the Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT) for a predoctoral grant.

supplementary crystallographic information

Comment

The title compound was synthesized as a precursor for asymmetric PPV-type [poly(p-phenylene vinylene)] oligomers. These compounds are promising candidates as the active materials in organic memories (Bandyopadhyay & Pal, 2003) and as nonlinear optical (NLO) materials with a high first-order hyperpolarizability (Chemla, 1987). Besides the condition that these oligomers should bear acceptor and donor substituents connected by a π-system, it is of critical importance for their usefulness as an NLO material and as a bistable organic memory material that the crystal packing is non-centrosymmetric. In particular, the compound should crystallize in a polar space group. To engineer the crystal packing in order to meet this criterion, it is necessary to introduce certain statistically well chosen synthons (Desiraju, 1997). Therefore, we opted for carboxylic acid functional groups (powerful hydrogen bond donors) in the basic structure of the organic semiconductors. To combine the electronic (A-π-D) and the structural (non-centrosymmetric space group) requirements, we used the Williamson ether synthesis to prepare the title compound as a building block for a PPV-based semiconductor bearing a carboxylic acid moiety.

The carboxylic acid moiety is found in the [ap,ap] conformation (Fig. 1): the carboxyl H atom points in the opposite direction of the carbonyl group and the O4—C41—C42—O41 torsion angle is -168.64 (19)°. The reason for this unexpected conformation is the presence of an intramolecular bifurcated hydrogen bond involving H42, O4 and O5 (Table 1 and Fig. 2). Indeed, Lide showed, based on microwave experiments on gaseous formic acid, that, in general, the sp conformer is more stable than the ap conformer by about 16 kJ mol-1 (Lide, 1964). The acetic acid chain is twisted out-of-plane by about 113° and the torsion angle O4—C41—C42—O42 is about 11°.

A sawtooth motif is generated along the c axis by the CH···O interaction between H6 and O41 (Fig. 2). Its effect is reinforced by H41A contacting O11B, the aldehyde O atom of the minor conformer. Perpendicular to these sawtooth ribbons (along the a axis) C51—H51B···O11A hydrogen bonds continue the structure (Fig. 2). These corrugated sheets are then stacked along the b axis by two weak CH···O hydrogen bonds and a CH···π interaction (Fig. 3): H31B contacts O11A, H41B contacts O4 and H41A contacts the centroid of the ring [C41—H41A···Cgvi, 2.68 Å, 144°, symm. code vi = 1 - x, 1/2 + y, 3/2 - z]. Finally, there is a modest π–π interaction [Cg···Cgvii, 4.133 (2) Å, 34.09°, symm. code vii = 1 - x, 2 - y, 1 - z].

Experimental

Sodium hydroxide (5.0 g, 0.125 mol) in distilled water (20 ml) was added to a stirred solution of syringaldehyde (11.8 g, 0.065 mol) and iodoacetic acid (12.1 g, 0.065 mol) in distilled water (100 ml). The mixture was refluxed overnight and then poured into water (100 ml), which was then acidified using phosphoric acid. The mixture was left to cool in the refrigerator and the solvent was partially evaporated to precipitate the compound. The brown needle-like crystals were filtered off. The product changed colour to purple when it was exposed to air. The purple product was recrystallized from a 5:1 dichloromethane/acetone mixture to yield (54%) colourless crystals. 1H NMR (CDCl3, 400 MHz, TMS): δ 3.98 (s, 6H, H31 and H51), 4.69 (s, 2H, H41), 7.16 (s, 2H, H2 and H6), 9.89 (s, 1H, H11). 13C NMR (CDCl3, 100 MHz, TMS): δ 56.6 (C31 and C51), 70.3, (C41), 106.6 (C2 and C6), 132.9 (C1), 141.1 (C4), 152.6 (C3 and C5), 170.2 (C42), 190.5 (C11).

Refinement

The aldehyde moiety proved to be orientationally disordered over two sites in a 79:21 ratio (refined values 0.785 (6):0.215 (6)). The structure was initially refined with the aldehyde group in one position and then the second site was located in the residual electron density map. For the two aldehyde functions, consisting of three atoms, O11A and O11B were restrained to have the similar anisotropic displacement parameters, and the C1—C11A/C1—C11B and C11A—O11A/C11B—O11B distances were restrained to be equal. C11A and C11B were constrained to posses identical anisotropic displacement parameters. H atoms H11A and H11B were placed on the geometrically calculated positions and refined as 'riding'.

Figures

Fig. 1.
Molecular structure of the title compound with the numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are represented as spheres with an arbitrary radius.
Fig. 2.
Corrugated sheets in the ac plane generated by weak intermolecular hydrogen bonds and the bifurcated intramolecular hydrogen bond.
Fig. 3.
The two weak hydrogen bonds and the CH···π interaction responsible for the stacking of the sheets along the b axis.

Crystal data

C11H12O6F(000) = 504
Mr = 240.21Dx = 1.446 Mg m3
Monoclinic, P21/cMelting point: 415 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 9.350 (2) ÅCell parameters from 25 reflections
b = 7.416 (1) Åθ = 9.0–14.2°
c = 17.374 (8) ŵ = 0.12 mm1
β = 113.67 (3)°T = 293 K
V = 1103.4 (6) Å3Block, colourless
Z = 40.27 × 0.24 × 0.15 mm

Data collection

Enraf–Nonius MACH3 diffractometerRint = 0.030
Radiation source: fine-focus sealed tubeθmax = 25.3°, θmin = 2.4°
graphiteh = −11→11
ω/2θ scansk = 0→8
4025 measured reflectionsl = −20→20
2015 independent reflections3 standard reflections every 60 min
1292 reflections with I > 2σ(I) intensity decay: 1%

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.093w = 1/[σ2(Fo2) + (0.0427P)2 + 0.1341P] where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
2015 reflectionsΔρmax = 0.15 e Å3
171 parametersΔρmin = −0.15 e Å3
8 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0086 (18)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
O11A0.8177 (2)0.6876 (3)0.52772 (13)0.0677 (9)0.785 (6)
C11A0.6811 (5)0.6988 (12)0.5115 (3)0.0490 (13)0.785 (6)
H11A0.61210.64820.46130.059*0.785 (6)
C11B0.720 (3)0.712 (5)0.5283 (16)0.0490 (13)0.215 (6)
H11B0.82780.71810.55710.059*0.215 (6)
O11B0.6629 (10)0.6437 (14)0.4603 (6)0.078 (3)0.215 (6)
O40.39907 (13)1.04247 (17)0.70196 (7)0.0376 (3)
O50.22382 (14)0.89227 (19)0.55872 (8)0.0449 (4)
O30.71034 (14)1.0208 (2)0.76755 (8)0.0478 (4)
C60.4523 (2)0.7946 (3)0.53433 (11)0.0388 (5)
H60.39230.74390.48240.047*
C20.7062 (2)0.8612 (3)0.64352 (11)0.0414 (5)
H20.81440.85450.66380.050*
C50.38175 (19)0.8774 (2)0.58135 (10)0.0345 (4)
O420.13206 (15)0.9328 (2)0.70058 (9)0.0604 (5)
H420.16550.95780.66490.091*
C40.47318 (19)0.9529 (2)0.65853 (10)0.0334 (4)
O410.22968 (17)0.8754 (2)0.83608 (9)0.0623 (5)
C10.6143 (2)0.7884 (3)0.56601 (11)0.0392 (5)
C410.4098 (2)0.9607 (3)0.77859 (11)0.0380 (4)
H41A0.46341.04160.82520.046*
H41B0.47010.85020.78800.046*
C30.6358 (2)0.9442 (2)0.69064 (11)0.0369 (4)
C420.2502 (2)0.9191 (3)0.77494 (12)0.0429 (5)
C510.1233 (2)0.8060 (3)0.48261 (12)0.0551 (6)
H51A0.13740.85990.43590.083*
H51B0.01670.82020.47550.083*
H51C0.14840.68000.48530.083*
C310.8750 (3)0.9877 (4)0.80939 (15)0.0730 (7)
H31A0.89410.86020.81200.110*
H31B0.91281.03590.86530.110*
H31C0.92821.04490.77880.110*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O11A0.0510 (16)0.0877 (17)0.0786 (16)0.0113 (11)0.0409 (12)0.0007 (12)
C11A0.050 (3)0.052 (2)0.049 (3)0.002 (3)0.025 (3)0.002 (2)
C11B0.050 (3)0.052 (2)0.049 (3)0.002 (3)0.025 (3)0.002 (2)
O11B0.084 (6)0.101 (7)0.053 (6)0.007 (5)0.031 (5)−0.019 (5)
O40.0424 (7)0.0359 (7)0.0372 (7)0.0054 (6)0.0188 (6)0.0017 (6)
O50.0315 (7)0.0590 (9)0.0409 (7)0.0027 (6)0.0109 (6)−0.0073 (6)
O30.0327 (7)0.0590 (9)0.0445 (8)−0.0028 (6)0.0080 (6)−0.0074 (7)
C60.0424 (11)0.0409 (11)0.0330 (9)0.0001 (9)0.0149 (8)0.0011 (9)
C20.0340 (10)0.0435 (11)0.0503 (11)0.0039 (9)0.0206 (9)0.0078 (9)
C50.0327 (9)0.0366 (10)0.0354 (9)0.0020 (8)0.0148 (8)0.0043 (8)
O420.0361 (7)0.0922 (13)0.0540 (9)0.0028 (8)0.0193 (7)0.0085 (9)
C40.0364 (9)0.0309 (10)0.0375 (9)0.0034 (8)0.0196 (8)0.0026 (8)
O410.0623 (9)0.0806 (12)0.0556 (9)0.0015 (9)0.0359 (8)0.0100 (8)
C10.0452 (10)0.0375 (11)0.0438 (11)0.0053 (9)0.0271 (9)0.0068 (9)
C410.0399 (10)0.0419 (11)0.0321 (9)0.0023 (9)0.0142 (8)−0.0017 (8)
C30.0349 (9)0.0359 (10)0.0394 (10)−0.0019 (8)0.0144 (8)0.0036 (9)
C420.0434 (11)0.0454 (12)0.0433 (11)0.0047 (9)0.0210 (9)0.0012 (9)
C510.0376 (11)0.0738 (16)0.0470 (12)−0.0074 (11)0.0095 (9)−0.0118 (11)
C310.0452 (13)0.0778 (18)0.0681 (15)0.0078 (12)−0.0066 (11)−0.0103 (14)

Geometric parameters (Å, °)

O11A—C11A1.195 (5)C2—C11.384 (3)
C11A—C11.485 (4)C2—H20.9300
C11A—H11A0.9300C5—C41.386 (2)
C11B—O11B1.196 (17)O42—C421.324 (2)
C11B—C11.498 (16)O42—H420.8200
C11B—H11B0.9300C4—C31.395 (2)
O4—C41.382 (2)O41—C421.197 (2)
O4—C411.430 (2)C41—C421.500 (3)
O5—C51.371 (2)C41—H41A0.9700
O5—C511.430 (2)C41—H41B0.9700
O3—C31.359 (2)C51—H51A0.9600
O3—C311.435 (3)C51—H51B0.9600
C6—C51.383 (2)C51—H51C0.9600
C6—C11.389 (3)C31—H31A0.9600
C6—H60.9300C31—H31B0.9600
C2—C31.383 (3)C31—H31C0.9600
O11A—C11A—C1124.3 (3)C6—C1—C11B130.1 (9)
O11A—C11A—H11A117.8O4—C41—C42110.56 (15)
C1—C11A—H11A117.8O4—C41—H41A109.5
O11B—C11B—C1118.8 (19)C42—C41—H41A109.5
O11B—C11B—H11B120.6O4—C41—H41B109.5
C1—C11B—H11B120.6C42—C41—H41B109.5
C4—O4—C41116.19 (13)H41A—C41—H41B108.1
C5—O5—C51117.50 (14)O3—C3—C2126.16 (16)
C3—O3—C31116.68 (16)O3—C3—C4114.84 (16)
C5—C6—C1118.91 (17)C2—C3—C4119.00 (16)
C5—C6—H6120.5O41—C42—O42121.25 (19)
C1—C6—H6120.5O41—C42—C41121.93 (18)
C3—C2—C1119.53 (17)O42—C42—C41116.83 (16)
C3—C2—H2120.2O5—C51—H51A109.5
C1—C2—H2120.2O5—C51—H51B109.5
O5—C5—C6125.46 (16)H51A—C51—H51B109.5
O5—C5—C4114.83 (15)O5—C51—H51C109.5
C6—C5—C4119.71 (15)H51A—C51—H51C109.5
C42—O42—H42109.5H51B—C51—H51C109.5
O4—C4—C5118.19 (15)O3—C31—H31A109.5
O4—C4—C3120.58 (16)O3—C31—H31B109.5
C5—C4—C3121.20 (16)H31A—C31—H31B109.5
C2—C1—C6121.65 (17)O3—C31—H31C109.5
C2—C1—C11A122.7 (2)H31A—C31—H31C109.5
C6—C1—C11A115.7 (2)H31B—C31—H31C109.5
C2—C1—C11B108.2 (9)
C51—O5—C5—C63.9 (3)O11A—C11A—C1—C6177.2 (6)
C51—O5—C5—C4−175.66 (17)O11A—C11A—C1—C11B0(7)
C1—C6—C5—O5−179.30 (17)O11B—C11B—C1—C2−179 (3)
C1—C6—C5—C40.2 (3)O11B—C11B—C1—C60(4)
C41—O4—C4—C5112.81 (18)O11B—C11B—C1—C11A3(4)
C41—O4—C4—C3−69.2 (2)C4—O4—C41—C42−120.89 (17)
O5—C5—C4—O4−3.6 (2)C31—O3—C3—C2−10.5 (3)
C6—C5—C4—O4176.83 (16)C31—O3—C3—C4169.40 (19)
O5—C5—C4—C3178.46 (16)C1—C2—C3—O3179.70 (17)
C6—C5—C4—C3−1.1 (3)C1—C2—C3—C4−0.2 (3)
C3—C2—C1—C6−0.7 (3)O4—C4—C3—O33.3 (2)
C3—C2—C1—C11A179.4 (5)C5—C4—C3—O3−178.83 (17)
C3—C2—C1—C11B178.6 (17)O4—C4—C3—C2−176.79 (17)
C5—C6—C1—C20.6 (3)C5—C4—C3—C21.1 (3)
C5—C6—C1—C11A−179.4 (4)O4—C41—C42—O41−168.63 (19)
C5—C6—C1—C11B−178 (2)O4—C41—C42—O4211.4 (2)
O11A—C11A—C1—C2−2.9 (10)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O42—H42···O40.822.112.617 (2)120
O42—H42···O50.822.182.932 (2)153
C6—H6···O41i0.932.543.468 (3)176
C41—H41A···O11Bii0.972.713.189 (9)111
C51—H51B···O11Aiii0.962.573.369 (3)141
C31—H31B···O11Aiv0.962.703.454 (3)136
C41—H41B···O4v0.972.563.527 (3)173

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) x, −y+3/2, z+1/2; (iii) x−1, y, z; (iv) −x+2, y+1/2, −z+3/2; (v) −x+1, y−1/2, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZL2319).

References

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