The crystal structure of the title compound, 5,3′-dihydroxy-6,7,4′-trimethoxyflavone, C
18H
16O
7, 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
CCDC reference: 159876
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (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
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.
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.
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).
5,3'-dihydroxy-6,7,4'-trimethoxyflavone
top
Crystal data top
C18H16O7 | F(000) = 720 |
Mr = 344.31 | Dx = 1.473 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54178 Å |
a = 5.5475 (8) Å | Cell parameters from 25 reflections |
b = 37.690 (5) Å | θ = 25–50° |
c = 7.4742 (6) Å | µ = 0.97 mm−1 |
β = 96.462 (9)° | T = 293 K |
V = 1552.8 (3) Å3 | Needle, yellow |
Z = 4 | 0.40 × 0.20 × 0.07 mm |
Data collection top
Enraf-Nonius CAD-4 diffractometer | 2310 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.015 |
Graphite monochromator | θmax = 68.0°, θmin = 5.0° |
ω–2θ scans | h = 0→6 |
Absorption correction: empirical (using intensity measurements) ψ-scan (3 reflections) (North et al., 1968) | k = −45→45 |
Tmin = 0.70, Tmax = 0.94 | l = −8→8 |
5869 measured reflections | 3 standard reflections every 200 reflections |
2706 independent reflections | intensity decay: 0.3% |
Refinement top
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)] = 0.038 | H-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 reflections | Δρmax = 0.21 e Å−3 |
232 parameters | Δρmin = −0.20 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0092 (9) |
Crystal data top
C18H16O7 | V = 1552.8 (3) Å3 |
Mr = 344.31 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 5.5475 (8) Å | µ = 0.97 mm−1 |
b = 37.690 (5) Å | T = 293 K |
c = 7.4742 (6) Å | 0.40 × 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 = 0.94 | 3 standard reflections every 200 reflections |
5869 measured reflections | intensity decay: 0.3% |
2706 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.121 | H-atom parameters constrained |
S = 1.09 | Δρmax = 0.21 e Å−3 |
2706 reflections | Δρmin = −0.20 e Å−3 |
232 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.3553 (2) | 0.12564 (3) | 0.35165 (14) | 0.0385 (3) | |
C2 | 0.5479 (3) | 0.10329 (4) | 0.3537 (2) | 0.0352 (4) | |
C3 | 0.7183 (3) | 0.10136 (5) | 0.4976 (2) | 0.0400 (4) | |
H3 | 0.8474 | 0.0857 | 0.4943 | 0.048* | |
C4 | 0.7062 (3) | 0.12260 (4) | 0.6540 (2) | 0.0360 (4) | |
C5 | 0.4785 (3) | 0.17112 (4) | 0.7889 (2) | 0.0355 (4) | |
C6 | 0.2879 (3) | 0.19485 (4) | 0.7744 (2) | 0.0350 (4) | |
C7 | 0.1173 (3) | 0.19443 (4) | 0.6195 (2) | 0.0342 (4) | |
C8 | 0.1416 (3) | 0.17111 (4) | 0.4787 (2) | 0.0349 (4) | |
H8 | 0.0305 | 0.1712 | 0.3758 | 0.042* | |
C9 | 0.3352 (3) | 0.14784 (4) | 0.4958 (2) | 0.0330 (4) | |
C10 | 0.5061 (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' | 0.2400 | 0.1031 | 0.0545 | 0.044* | |
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' | 0.8628 | 0.0237 | 0.0001 | 0.066* | |
C6' | 0.7330 (4) | 0.05905 (6) | 0.1676 (2) | 0.0537 (5) | |
H6' | 0.8559 | 0.0559 | 0.2616 | 0.064* | |
O2 | 0.8642 (2) | 0.12084 (3) | 0.78969 (15) | 0.0449 (3) | |
O3 | 0.6405 (2) | 0.17159 (3) | 0.93745 (16) | 0.0462 (3) | |
H3A | 0.7447 | 0.1565 | 0.9283 | 0.069* | |
O4 | 0.2678 (2) | 0.22016 (3) | 0.90419 (16) | 0.0435 (3) | |
O5 | −0.0653 (2) | 0.21808 (3) | 0.62101 (15) | 0.0435 (3) | |
O6 | 0.1962 (2) | 0.07125 (4) | −0.25606 (16) | 0.0503 (4) | |
H6 | 0.0997 | 0.0867 | −0.2346 | 0.075* | |
O7 | 0.5478 (2) | 0.02631 (3) | −0.29052 (16) | 0.0504 (4) | |
C11 | 0.2154 (4) | 0.20668 (5) | 1.0740 (2) | 0.0498 (5) | |
H11A | 0.0499 | 0.1988 | 1.0646 | 0.075* | |
H11B | 0.2399 | 0.2251 | 1.1632 | 0.075* | |
H11C | 0.3213 | 0.1871 | 1.1086 | 0.075* | |
C12 | −0.2254 (4) | 0.22346 (5) | 0.4593 (3) | 0.0474 (5) | |
H12A | −0.1332 | 0.2306 | 0.3642 | 0.071* | |
H12B | −0.3409 | 0.2416 | 0.4790 | 0.071* | |
H12C | −0.3095 | 0.2018 | 0.4264 | 0.071* | |
C13 | 0.7411 (4) | 0.00195 (6) | −0.3125 (3) | 0.0556 (5) | |
H13A | 0.8929 | 0.0144 | −0.2996 | 0.083* | |
H13B | 0.7154 | −0.0086 | −0.4301 | 0.083* | |
H13C | 0.7444 | −0.0163 | −0.2226 | 0.083* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0416 (7) | 0.0415 (6) | 0.0301 (6) | 0.0103 (5) | −0.0052 (5) | −0.0072 (4) |
C2 | 0.0375 (9) | 0.0332 (8) | 0.0337 (8) | 0.0036 (6) | −0.0007 (7) | −0.0025 (6) |
C3 | 0.0421 (10) | 0.0416 (9) | 0.0344 (8) | 0.0098 (7) | −0.0037 (7) | −0.0049 (7) |
C4 | 0.0400 (10) | 0.0363 (8) | 0.0300 (8) | 0.0007 (7) | −0.0030 (7) | 0.0012 (6) |
C5 | 0.0424 (10) | 0.0358 (8) | 0.0275 (8) | −0.0022 (7) | 0.0003 (6) | −0.0002 (6) |
C6 | 0.0451 (10) | 0.0318 (8) | 0.0285 (7) | −0.0002 (7) | 0.0059 (6) | −0.0010 (6) |
C7 | 0.0383 (9) | 0.0326 (8) | 0.0322 (8) | 0.0024 (6) | 0.0066 (6) | 0.0046 (6) |
C8 | 0.0378 (9) | 0.0384 (8) | 0.0274 (7) | 0.0026 (7) | −0.0014 (6) | 0.0021 (6) |
C9 | 0.0394 (9) | 0.0327 (8) | 0.0266 (7) | 0.0003 (6) | 0.0018 (6) | −0.0014 (6) |
C10 | 0.0382 (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) |
O2 | 0.0468 (8) | 0.0516 (7) | 0.0332 (6) | 0.0107 (5) | −0.0093 (5) | −0.0053 (5) |
O3 | 0.0498 (8) | 0.0529 (8) | 0.0329 (6) | 0.0075 (6) | −0.0088 (5) | −0.0104 (5) |
O4 | 0.0627 (9) | 0.0353 (6) | 0.0329 (6) | 0.0038 (5) | 0.0067 (6) | −0.0050 (4) |
O5 | 0.0478 (8) | 0.0445 (7) | 0.0379 (7) | 0.0135 (5) | 0.0039 (5) | −0.0006 (5) |
O6 | 0.0501 (8) | 0.0588 (8) | 0.0378 (7) | 0.0178 (6) | −0.0141 (6) | −0.0139 (5) |
O7 | 0.0575 (9) | 0.0533 (7) | 0.0371 (7) | 0.0175 (6) | −0.0087 (6) | −0.0162 (5) |
C11 | 0.0627 (13) | 0.0546 (11) | 0.0325 (9) | 0.0065 (9) | 0.0077 (8) | −0.0042 (8) |
C12 | 0.0475 (11) | 0.0483 (10) | 0.0457 (10) | 0.0126 (8) | 0.0020 (8) | 0.0076 (8) |
C13 | 0.0591 (13) | 0.0571 (11) | 0.0483 (11) | 0.0186 (9) | −0.0038 (9) | −0.0210 (9) |
Geometric parameters (Å, º) top
O1—C2 | 1.359 (2) | C3'—O6 | 1.351 (2) |
O1—C9 | 1.379 (2) | C3'—C4' | 1.401 (2) |
C2—C3 | 1.352 (2) | C4'—O7 | 1.354 (2) |
C2—C1' | 1.467 (2) | C4'—C5' | 1.383 (3) |
C3—C4 | 1.425 (2) | C5'—C6' | 1.386 (3) |
C3—H3 | 0.9300 | C5'—H5' | 0.9300 |
C4—O2 | 1.266 (2) | C6'—H6' | 0.9300 |
C4—C10 | 1.435 (2) | O3—H3A | 0.8200 |
C5—O3 | 1.348 (2) | O4—C11 | 1.427 (2) |
C5—C6 | 1.380 (2) | O5—C12 | 1.431 (2) |
C5—C10 | 1.418 (2) | O6—H6 | 0.8200 |
C6—O4 | 1.374 (2) | O7—C13 | 1.435 (2) |
C6—C7 | 1.411 (2) | C11—H11A | 0.9600 |
C7—O5 | 1.351 (2) | C11—H11B | 0.9600 |
C7—C8 | 1.389 (2) | C11—H11C | 0.9600 |
C8—C9 | 1.382 (2) | C12—H12A | 0.9600 |
C8—H8 | 0.9300 | C12—H12B | 0.9600 |
C9—C10 | 1.395 (2) | C12—H12C | 0.9600 |
C1'—C6' | 1.383 (2) | C13—H13A | 0.9600 |
C1'—C2' | 1.396 (2) | C13—H13B | 0.9600 |
C2'—C3' | 1.386 (2) | C13—H13C | 0.9600 |
C2'—H2' | 0.9300 | | |
| | | |
C2—O1—C9 | 119.97 (12) | O6—C3'—C4' | 117.16 (14) |
C3—C2—O1 | 121.41 (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—C4 | 121.93 (15) | C5'—C4'—C3' | 118.96 (15) |
C2—C3—H3 | 119.0 | C4'—C5'—C6' | 120.77 (17) |
C4—C3—H3 | 119.0 | C4'—C5'—H5' | 119.6 |
O2—C4—C3 | 122.39 (15) | C6'—C5'—H5' | 119.6 |
O2—C4—C10 | 121.56 (15) | C1'—C6'—C5' | 120.82 (16) |
C3—C4—C10 | 116.04 (14) | C1'—C6'—H6' | 119.6 |
O3—C5—C6 | 119.34 (14) | C5'—C6'—H6' | 119.6 |
O3—C5—C10 | 120.27 (15) | C5—O3—H3A | 109.5 |
C6—C5—C10 | 120.38 (15) | C6—O4—C11 | 114.93 (13) |
O4—C6—C5 | 121.14 (15) | C7—O5—C12 | 118.77 (13) |
O4—C6—C7 | 119.15 (14) | C3'—O6—H6 | 109.5 |
C5—C6—C7 | 119.63 (14) | C4'—O7—C13 | 117.25 (14) |
O5—C7—C8 | 124.09 (15) | O4—C11—H11A | 109.5 |
O5—C7—C6 | 114.87 (14) | O4—C11—H11B | 109.5 |
C8—C7—C6 | 121.04 (15) | H11A—C11—H11B | 109.5 |
C9—C8—C7 | 118.17 (14) | O4—C11—H11C | 109.5 |
C9—C8—H8 | 120.9 | H11A—C11—H11C | 109.5 |
C7—C8—H8 | 120.9 | H11B—C11—H11C | 109.5 |
O1—C9—C8 | 116.31 (14) | O5—C12—H12A | 109.5 |
O1—C9—C10 | 120.85 (14) | O5—C12—H12B | 109.5 |
C8—C9—C10 | 122.83 (14) | H12A—C12—H12B | 109.5 |
C9—C10—C5 | 117.94 (15) | O5—C12—H12C | 109.5 |
C9—C10—C4 | 119.72 (14) | H12A—C12—H12C | 109.5 |
C5—C10—C4 | 122.30 (15) | H12B—C12—H12C | 109.5 |
C6'—C1'—C2' | 118.60 (15) | O7—C13—H13A | 109.5 |
C6'—C1'—C2 | 119.95 (15) | O7—C13—H13B | 109.5 |
C2'—C1'—C2 | 121.46 (15) | H13A—C13—H13B | 109.5 |
C3'—C2'—C1' | 120.95 (15) | O7—C13—H13C | 109.5 |
C3'—C2'—H2' | 119.5 | H13A—C13—H13C | 109.5 |
C1'—C2'—H2' | 119.5 | H13B—C13—H13C | 109.5 |
O6—C3'—C2' | 122.94 (15) | | |
| | | |
C9—O1—C2—C3 | 2.3 (2) | O2—C4—C10—C9 | −179.72 (15) |
C9—O1—C2—C1' | −176.85 (13) | C3—C4—C10—C9 | 1.6 (2) |
O1—C2—C3—C4 | −0.2 (3) | O2—C4—C10—C5 | 2.5 (3) |
C1'—C2—C3—C4 | 178.81 (16) | C3—C4—C10—C5 | −176.18 (15) |
C2—C3—C4—O2 | 179.62 (17) | C3—C2—C1'—C6' | 0.9 (3) |
C2—C3—C4—C10 | −1.7 (3) | O1—C2—C1'—C6' | 179.98 (17) |
O3—C5—C6—O4 | 3.6 (2) | C3—C2—C1'—C2' | −179.11 (17) |
C10—C5—C6—O4 | −175.43 (14) | O1—C2—C1'—C2' | 0.0 (2) |
O3—C5—C6—C7 | −179.81 (15) | C6'—C1'—C2'—C3' | −0.1 (3) |
C10—C5—C6—C7 | 1.2 (2) | C2—C1'—C2'—C3' | 179.90 (16) |
O4—C6—C7—O5 | −5.0 (2) | C1'—C2'—C3'—O6 | −179.29 (17) |
C5—C6—C7—O5 | 178.33 (14) | C1'—C2'—C3'—C4' | −0.1 (3) |
O4—C6—C7—C8 | 174.97 (14) | O6—C3'—C4'—O7 | 0.2 (2) |
C5—C6—C7—C8 | −1.7 (2) | C2'—C3'—C4'—O7 | −179.05 (16) |
O5—C7—C8—C9 | −178.94 (14) | O6—C3'—C4'—C5' | 179.45 (18) |
C6—C7—C8—C9 | 1.1 (2) | C2'—C3'—C4'—C5' | 0.2 (3) |
C2—O1—C9—C8 | 176.48 (14) | O7—C4'—C5'—C6' | 179.1 (2) |
C2—O1—C9—C10 | −2.3 (2) | C3'—C4'—C5'—C6' | −0.1 (3) |
C7—C8—C9—O1 | −178.77 (14) | C2'—C1'—C6'—C5' | 0.2 (3) |
C7—C8—C9—C10 | 0.0 (2) | C2—C1'—C6'—C5' | −179.8 (2) |
O1—C9—C10—C5 | 178.22 (14) | C4'—C5'—C6'—C1' | −0.1 (4) |
C8—C9—C10—C5 | −0.5 (2) | C5—C6—O4—C11 | −68.3 (2) |
O1—C9—C10—C4 | 0.3 (2) | C7—C6—O4—C11 | 115.09 (17) |
C8—C9—C10—C4 | −178.38 (15) | C8—C7—O5—C12 | −9.5 (2) |
O3—C5—C10—C9 | −179.11 (15) | C6—C7—O5—C12 | 170.45 (15) |
C6—C5—C10—C9 | −0.1 (2) | C5'—C4'—O7—C13 | −0.2 (3) |
O3—C5—C10—C4 | −1.3 (2) | C3'—C4'—O7—C13 | 179.00 (17) |
C6—C5—C10—C4 | 177.71 (15) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O2 | 0.82 | 1.86 | 2.594 (2) | 148 |
O6—H6···O2i | 0.82 | 1.86 | 2.673 (2) | 174 |
Symmetry code: (i) x−1, y, z−1. |
Experimental details
Crystal data |
Chemical formula | C18H16O7 |
Mr | 344.31 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 5.5475 (8), 37.690 (5), 7.4742 (6) |
β (°) | 96.462 (9) |
V (Å3) | 1552.8 (3) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 0.97 |
Crystal size (mm) | 0.40 × 0.20 × 0.07 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | Empirical (using intensity measurements) ψ-scan (3 reflections) (North et al., 1968) |
Tmin, Tmax | 0.70, 0.94 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5869, 2706, 2310 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.601 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.121, 1.09 |
No. of reflections | 2706 |
No. of parameters | 232 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.21, −0.20 |
Selected geometric parameters (Å, º) topO1—C2 | 1.359 (2) | C3'—O6 | 1.351 (2) |
O1—C9 | 1.379 (2) | C4'—O7 | 1.354 (2) |
C4—O2 | 1.266 (2) | O4—C11 | 1.427 (2) |
C5—O3 | 1.348 (2) | O5—C12 | 1.431 (2) |
C6—O4 | 1.374 (2) | O7—C13 | 1.435 (2) |
C7—O5 | 1.351 (2) | | |
| | | |
C2—O1—C9 | 119.97 (12) | C7—O5—C12 | 118.77 (13) |
C6—O4—C11 | 114.93 (13) | C4'—O7—C13 | 117.25 (14) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O2 | 0.82 | 1.86 | 2.594 (2) | 148 |
O6—H6···O2i | 0.82 | 1.86 | 2.673 (2) | 174 |
Symmetry code: (i) x−1, y, z−1. |
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 C4═O2 is 1.266 (2) and C2═C3 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.