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The crystal structure of the title compound, 5,3′-di­hydroxy-6,7,4′-tri­methoxy­flavone, C18H16O7, isolated from Ballota limbata Linn., contains discrete mol­ecules with normal molecular dimensions. The structure is stabilized by intramolecular and intermolecular hydrogen bonds between hydroxyl H atoms and carbonyl O atoms, with O...O interactions of 2.594 (2) and 2.673 (2) Å. The flavone moiety is essentially planar with methoxy methyl groups lying 0.169 (3)–0.851 (2) Å out of the plane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801003609/cv6007sup1.cif
Contains datablocks Global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801003609/cv6007Isup2.hkl
Contains datablock I

CCDC reference: 159876

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.038
  • wR factor = 0.121
  • Data-to-parameter ratio = 11.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry




Comment top

Ballota limbata Linn. (Labiatae) is a small prickly shrub, found in the Northern hilly areas of Pakistan. The chemical constituents of B. limbata have been investigated due to its uses in the folk medicines (Watt, 1972). Eupatorin, (I), has been previously isolated from the cytotoxic extract of Eupatorium semiserratum DC. (Kupchan et al., 1969). In this article, we describe the crystal structure of (I).

The crystal structure of (I) is composed of an essentially planar flavone moiety (Fig. 1), with a maximum deviation of 0.085 (1) Å for O1. The angles between the mean planes of the methoxy groups attached to C7, C4' and C6, and the mean-plane of the flavone moiety are 7.01 (19), 2.9 (2) and 66.57 (12)°. The methyl C atoms C11, C12, and C13 lie at -0.851 (2), 0.219 (3) and 0.169 (3) Å from the mean plane of the flavone moiety. The bond distances and angles in the structure are normal and agree well with the corresponding values reported for ten similar compounds contained in the October 2000 updates of the Cambridge Structural Database (Allen & Kennard, 1993). The mean bond distances are: O—Csp3 1.431 (3), O—Csp2 1.359 (13), Csp2—Csp2 1.442 (18) and aromatic C—C 1.393 (12) Å, while C4O2 is 1.266 (2) and C2C3 is essentially a double bond with a distance of 1.352 (2) Å.

The crystal structure is stabilized by an intramolecular hydrogen bond involving a hydroxyl H atom and the carbonyl O atom [O···O separation 2.594 (2) Å and O3—H3A···O2 angle of 148°] and an intermolecular hydrogen bond involving the other hydroxyl H atom and the carbonyl O atom of another molecule [O···O separation 2.673 (2) Å and O6—H6···O2i angle of 174° [symmetry code: (i) x - 1, y, z - 1]. In the unit cell, the molecules stack parallel to each other in a herring-bone pattern as presented in Fig. 2.

Experimental top

Ballota limbata plants were collected from Mansehra district of North Western Frontior Province, Pakistan. The shade-dried and ground whole plant material (16 kg) was extracted with methanol. The resulting gummy material (1 kg) was partitioned into hexane, chloroform, ethyl acetate and n-butanol soluble fractions. The chloroform fraction was subjected to column chromatography using a hexane/chloroform and chloroform/methanol gradient system. The fraction using chloroform/methanol (9:1) over flash silica gel afforded (I) as yellow needles.

Refinement top

The H atoms were located from difference maps and were placed at geometrically idealized positions (C—H 0.93 and 0.96 Å, and O—H 0.82 Å) utilizing riding models, and torsional parameters were refined for each methyl group. The methyl and non-methyl H atoms were allowed isotropic displacement parameters 1.5 and 1.2 times, respectively, the displacement parameters of the atoms to which they were attached.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: TEXSAN (Molecular Structure Corporation, 1994); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TEXSAN; software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. ORTEPII (Johnson, 1976) drawing of (I) with 50% probability ellipsoids.
[Figure 2] Fig. 2. Unit-cell packing of (I) showing hydrogen bonds.
5,3'-dihydroxy-6,7,4'-trimethoxyflavone top
Crystal data top
C18H16O7F(000) = 720
Mr = 344.31Dx = 1.473 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54178 Å
a = 5.5475 (8) ÅCell parameters from 25 reflections
b = 37.690 (5) Åθ = 25–50°
c = 7.4742 (6) ŵ = 0.97 mm1
β = 96.462 (9)°T = 293 K
V = 1552.8 (3) Å3Needle, yellow
Z = 40.40 × 0.20 × 0.07 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
2310 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.015
Graphite monochromatorθmax = 68.0°, θmin = 5.0°
ω–2θ scansh = 06
Absorption correction: empirical (using intensity measurements)
ψ-scan (3 reflections) (North et al., 1968)
k = 4545
Tmin = 0.70, Tmax = 0.94l = 88
5869 measured reflections3 standard reflections every 200 reflections
2706 independent reflections intensity decay: 0.3%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.121 w = 1/[σ2(Fo2) + (0.068P)2 + 0.387P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
2706 reflectionsΔρmax = 0.21 e Å3
232 parametersΔρmin = 0.20 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0092 (9)
Crystal data top
C18H16O7V = 1552.8 (3) Å3
Mr = 344.31Z = 4
Monoclinic, P21/cCu Kα radiation
a = 5.5475 (8) ŵ = 0.97 mm1
b = 37.690 (5) ÅT = 293 K
c = 7.4742 (6) Å0.40 × 0.20 × 0.07 mm
β = 96.462 (9)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
2310 reflections with I > 2σ(I)
Absorption correction: empirical (using intensity measurements)
ψ-scan (3 reflections) (North et al., 1968)
Rint = 0.015
Tmin = 0.70, Tmax = 0.943 standard reflections every 200 reflections
5869 measured reflections intensity decay: 0.3%
2706 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0380 restraints
wR(F2) = 0.121H-atom parameters constrained
S = 1.09Δρmax = 0.21 e Å3
2706 reflectionsΔρmin = 0.20 e Å3
232 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.3553 (2)0.12564 (3)0.35165 (14)0.0385 (3)
C20.5479 (3)0.10329 (4)0.3537 (2)0.0352 (4)
C30.7183 (3)0.10136 (5)0.4976 (2)0.0400 (4)
H30.84740.08570.49430.048*
C40.7062 (3)0.12260 (4)0.6540 (2)0.0360 (4)
C50.4785 (3)0.17112 (4)0.7889 (2)0.0355 (4)
C60.2879 (3)0.19485 (4)0.7744 (2)0.0350 (4)
C70.1173 (3)0.19443 (4)0.6195 (2)0.0342 (4)
C80.1416 (3)0.17111 (4)0.4787 (2)0.0349 (4)
H80.03050.17120.37580.042*
C90.3352 (3)0.14784 (4)0.4958 (2)0.0330 (4)
C100.5061 (3)0.14687 (4)0.6477 (2)0.0337 (4)
C1'0.5484 (3)0.08296 (4)0.1863 (2)0.0373 (4)
C2'0.3654 (3)0.08712 (4)0.0436 (2)0.0365 (4)
H2'0.24000.10310.05450.044*
C3'0.3680 (3)0.06781 (4)0.1140 (2)0.0366 (4)
C4'0.5564 (3)0.04374 (4)0.1315 (2)0.0398 (4)
C5'0.7371 (4)0.03966 (6)0.0103 (3)0.0550 (5)
H5'0.86280.02370.00010.066*
C6'0.7330 (4)0.05905 (6)0.1676 (2)0.0537 (5)
H6'0.85590.05590.26160.064*
O20.8642 (2)0.12084 (3)0.78969 (15)0.0449 (3)
O30.6405 (2)0.17159 (3)0.93745 (16)0.0462 (3)
H3A0.74470.15650.92830.069*
O40.2678 (2)0.22016 (3)0.90419 (16)0.0435 (3)
O50.0653 (2)0.21808 (3)0.62101 (15)0.0435 (3)
O60.1962 (2)0.07125 (4)0.25606 (16)0.0503 (4)
H60.09970.08670.23460.075*
O70.5478 (2)0.02631 (3)0.29052 (16)0.0504 (4)
C110.2154 (4)0.20668 (5)1.0740 (2)0.0498 (5)
H11A0.04990.19881.06460.075*
H11B0.23990.22511.16320.075*
H11C0.32130.18711.10860.075*
C120.2254 (4)0.22346 (5)0.4593 (3)0.0474 (5)
H12A0.13320.23060.36420.071*
H12B0.34090.24160.47900.071*
H12C0.30950.20180.42640.071*
C130.7411 (4)0.00195 (6)0.3125 (3)0.0556 (5)
H13A0.89290.01440.29960.083*
H13B0.71540.00860.43010.083*
H13C0.74440.01630.22260.083*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0416 (7)0.0415 (6)0.0301 (6)0.0103 (5)0.0052 (5)0.0072 (4)
C20.0375 (9)0.0332 (8)0.0337 (8)0.0036 (6)0.0007 (7)0.0025 (6)
C30.0421 (10)0.0416 (9)0.0344 (8)0.0098 (7)0.0037 (7)0.0049 (7)
C40.0400 (10)0.0363 (8)0.0300 (8)0.0007 (7)0.0030 (7)0.0012 (6)
C50.0424 (10)0.0358 (8)0.0275 (8)0.0022 (7)0.0003 (6)0.0002 (6)
C60.0451 (10)0.0318 (8)0.0285 (7)0.0002 (7)0.0059 (6)0.0010 (6)
C70.0383 (9)0.0326 (8)0.0322 (8)0.0024 (6)0.0066 (6)0.0046 (6)
C80.0378 (9)0.0384 (8)0.0274 (7)0.0026 (7)0.0014 (6)0.0021 (6)
C90.0394 (9)0.0327 (8)0.0266 (7)0.0003 (6)0.0018 (6)0.0014 (6)
C100.0382 (9)0.0339 (8)0.0285 (8)0.0003 (6)0.0014 (6)0.0001 (6)
C1'0.0413 (10)0.0375 (8)0.0316 (8)0.0058 (7)0.0028 (7)0.0036 (6)
C2'0.0385 (10)0.0362 (8)0.0335 (8)0.0069 (7)0.0022 (7)0.0034 (6)
C3'0.0395 (10)0.0364 (8)0.0316 (8)0.0023 (7)0.0058 (7)0.0018 (6)
C4'0.0473 (11)0.0376 (9)0.0330 (8)0.0057 (7)0.0029 (7)0.0075 (6)
C5'0.0557 (13)0.0601 (12)0.0455 (10)0.0263 (10)0.0110 (9)0.0165 (9)
C6'0.0546 (13)0.0624 (12)0.0389 (10)0.0233 (9)0.0171 (8)0.0157 (8)
O20.0468 (8)0.0516 (7)0.0332 (6)0.0107 (5)0.0093 (5)0.0053 (5)
O30.0498 (8)0.0529 (8)0.0329 (6)0.0075 (6)0.0088 (5)0.0104 (5)
O40.0627 (9)0.0353 (6)0.0329 (6)0.0038 (5)0.0067 (6)0.0050 (4)
O50.0478 (8)0.0445 (7)0.0379 (7)0.0135 (5)0.0039 (5)0.0006 (5)
O60.0501 (8)0.0588 (8)0.0378 (7)0.0178 (6)0.0141 (6)0.0139 (5)
O70.0575 (9)0.0533 (7)0.0371 (7)0.0175 (6)0.0087 (6)0.0162 (5)
C110.0627 (13)0.0546 (11)0.0325 (9)0.0065 (9)0.0077 (8)0.0042 (8)
C120.0475 (11)0.0483 (10)0.0457 (10)0.0126 (8)0.0020 (8)0.0076 (8)
C130.0591 (13)0.0571 (11)0.0483 (11)0.0186 (9)0.0038 (9)0.0210 (9)
Geometric parameters (Å, º) top
O1—C21.359 (2)C3'—O61.351 (2)
O1—C91.379 (2)C3'—C4'1.401 (2)
C2—C31.352 (2)C4'—O71.354 (2)
C2—C1'1.467 (2)C4'—C5'1.383 (3)
C3—C41.425 (2)C5'—C6'1.386 (3)
C3—H30.9300C5'—H5'0.9300
C4—O21.266 (2)C6'—H6'0.9300
C4—C101.435 (2)O3—H3A0.8200
C5—O31.348 (2)O4—C111.427 (2)
C5—C61.380 (2)O5—C121.431 (2)
C5—C101.418 (2)O6—H60.8200
C6—O41.374 (2)O7—C131.435 (2)
C6—C71.411 (2)C11—H11A0.9600
C7—O51.351 (2)C11—H11B0.9600
C7—C81.389 (2)C11—H11C0.9600
C8—C91.382 (2)C12—H12A0.9600
C8—H80.9300C12—H12B0.9600
C9—C101.395 (2)C12—H12C0.9600
C1'—C6'1.383 (2)C13—H13A0.9600
C1'—C2'1.396 (2)C13—H13B0.9600
C2'—C3'1.386 (2)C13—H13C0.9600
C2'—H2'0.9300
C2—O1—C9119.97 (12)O6—C3'—C4'117.16 (14)
C3—C2—O1121.41 (14)C2'—C3'—C4'119.89 (15)
C3—C2—C1'125.58 (15)O7—C4'—C5'124.74 (16)
O1—C2—C1'113.00 (13)O7—C4'—C3'116.29 (15)
C2—C3—C4121.93 (15)C5'—C4'—C3'118.96 (15)
C2—C3—H3119.0C4'—C5'—C6'120.77 (17)
C4—C3—H3119.0C4'—C5'—H5'119.6
O2—C4—C3122.39 (15)C6'—C5'—H5'119.6
O2—C4—C10121.56 (15)C1'—C6'—C5'120.82 (16)
C3—C4—C10116.04 (14)C1'—C6'—H6'119.6
O3—C5—C6119.34 (14)C5'—C6'—H6'119.6
O3—C5—C10120.27 (15)C5—O3—H3A109.5
C6—C5—C10120.38 (15)C6—O4—C11114.93 (13)
O4—C6—C5121.14 (15)C7—O5—C12118.77 (13)
O4—C6—C7119.15 (14)C3'—O6—H6109.5
C5—C6—C7119.63 (14)C4'—O7—C13117.25 (14)
O5—C7—C8124.09 (15)O4—C11—H11A109.5
O5—C7—C6114.87 (14)O4—C11—H11B109.5
C8—C7—C6121.04 (15)H11A—C11—H11B109.5
C9—C8—C7118.17 (14)O4—C11—H11C109.5
C9—C8—H8120.9H11A—C11—H11C109.5
C7—C8—H8120.9H11B—C11—H11C109.5
O1—C9—C8116.31 (14)O5—C12—H12A109.5
O1—C9—C10120.85 (14)O5—C12—H12B109.5
C8—C9—C10122.83 (14)H12A—C12—H12B109.5
C9—C10—C5117.94 (15)O5—C12—H12C109.5
C9—C10—C4119.72 (14)H12A—C12—H12C109.5
C5—C10—C4122.30 (15)H12B—C12—H12C109.5
C6'—C1'—C2'118.60 (15)O7—C13—H13A109.5
C6'—C1'—C2119.95 (15)O7—C13—H13B109.5
C2'—C1'—C2121.46 (15)H13A—C13—H13B109.5
C3'—C2'—C1'120.95 (15)O7—C13—H13C109.5
C3'—C2'—H2'119.5H13A—C13—H13C109.5
C1'—C2'—H2'119.5H13B—C13—H13C109.5
O6—C3'—C2'122.94 (15)
C9—O1—C2—C32.3 (2)O2—C4—C10—C9179.72 (15)
C9—O1—C2—C1'176.85 (13)C3—C4—C10—C91.6 (2)
O1—C2—C3—C40.2 (3)O2—C4—C10—C52.5 (3)
C1'—C2—C3—C4178.81 (16)C3—C4—C10—C5176.18 (15)
C2—C3—C4—O2179.62 (17)C3—C2—C1'—C6'0.9 (3)
C2—C3—C4—C101.7 (3)O1—C2—C1'—C6'179.98 (17)
O3—C5—C6—O43.6 (2)C3—C2—C1'—C2'179.11 (17)
C10—C5—C6—O4175.43 (14)O1—C2—C1'—C2'0.0 (2)
O3—C5—C6—C7179.81 (15)C6'—C1'—C2'—C3'0.1 (3)
C10—C5—C6—C71.2 (2)C2—C1'—C2'—C3'179.90 (16)
O4—C6—C7—O55.0 (2)C1'—C2'—C3'—O6179.29 (17)
C5—C6—C7—O5178.33 (14)C1'—C2'—C3'—C4'0.1 (3)
O4—C6—C7—C8174.97 (14)O6—C3'—C4'—O70.2 (2)
C5—C6—C7—C81.7 (2)C2'—C3'—C4'—O7179.05 (16)
O5—C7—C8—C9178.94 (14)O6—C3'—C4'—C5'179.45 (18)
C6—C7—C8—C91.1 (2)C2'—C3'—C4'—C5'0.2 (3)
C2—O1—C9—C8176.48 (14)O7—C4'—C5'—C6'179.1 (2)
C2—O1—C9—C102.3 (2)C3'—C4'—C5'—C6'0.1 (3)
C7—C8—C9—O1178.77 (14)C2'—C1'—C6'—C5'0.2 (3)
C7—C8—C9—C100.0 (2)C2—C1'—C6'—C5'179.8 (2)
O1—C9—C10—C5178.22 (14)C4'—C5'—C6'—C1'0.1 (4)
C8—C9—C10—C50.5 (2)C5—C6—O4—C1168.3 (2)
O1—C9—C10—C40.3 (2)C7—C6—O4—C11115.09 (17)
C8—C9—C10—C4178.38 (15)C8—C7—O5—C129.5 (2)
O3—C5—C10—C9179.11 (15)C6—C7—O5—C12170.45 (15)
C6—C5—C10—C90.1 (2)C5'—C4'—O7—C130.2 (3)
O3—C5—C10—C41.3 (2)C3'—C4'—O7—C13179.00 (17)
C6—C5—C10—C4177.71 (15)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3A···O20.821.862.594 (2)148
O6—H6···O2i0.821.862.673 (2)174
Symmetry code: (i) x1, y, z1.

Experimental details

Crystal data
Chemical formulaC18H16O7
Mr344.31
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)5.5475 (8), 37.690 (5), 7.4742 (6)
β (°) 96.462 (9)
V3)1552.8 (3)
Z4
Radiation typeCu Kα
µ (mm1)0.97
Crystal size (mm)0.40 × 0.20 × 0.07
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionEmpirical (using intensity measurements)
ψ-scan (3 reflections) (North et al., 1968)
Tmin, Tmax0.70, 0.94
No. of measured, independent and
observed [I > 2σ(I)] reflections
5869, 2706, 2310
Rint0.015
(sin θ/λ)max1)0.601
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.121, 1.09
No. of reflections2706
No. of parameters232
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.21, 0.20

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, TEXSAN (Molecular Structure Corporation, 1994), SAPI91 (Fan, 1991), SHELXL97 (Sheldrick, 1997), TEXSAN.

Selected geometric parameters (Å, º) top
O1—C21.359 (2)C3'—O61.351 (2)
O1—C91.379 (2)C4'—O71.354 (2)
C4—O21.266 (2)O4—C111.427 (2)
C5—O31.348 (2)O5—C121.431 (2)
C6—O41.374 (2)O7—C131.435 (2)
C7—O51.351 (2)
C2—O1—C9119.97 (12)C7—O5—C12118.77 (13)
C6—O4—C11114.93 (13)C4'—O7—C13117.25 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3A···O20.821.862.594 (2)148
O6—H6···O2i0.821.862.673 (2)174
Symmetry code: (i) x1, y, z1.
 

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