Molecules of the tetrahydroxyflavone luteolin, C
15H
10O
6, are essentially planar and contain an intramolecular hydrogen bond. The crystal structure is stabilized by O—H
O, C—H
O and C—H
π interactions, and contains disordered water molecules, probably corresponding to a hemihydrate.
Supporting information
CCDC reference: 217463
Key indicators
- Single-crystal X-ray study
- T = 120 K
- Mean (C-C) = 0.010 Å
- R factor = 0.093
- wR factor = 0.190
- Data-to-parameter ratio = 7.2
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level B:
REFLT_03
From the CIF: _diffrn_reflns_theta_max 27.58
From the CIF: _reflns_number_total 1471
TEST2: Reflns within _diffrn_reflns_theta_max
Count of symmetry unique reflns 1666
Completeness (_total/calc) 88.30%
Alert B: < 90% complete (theta max?)
PLAT_420 Alert B D-H Without Acceptor O4 - H4 .. ?
Alert Level C:
PLAT_601 Alert C Structure Contains Solvent Accessible VOIDS of . 34.00 A 3
General Notes
REFLT_03
From the CIF: _diffrn_reflns_theta_max 27.58
From the CIF: _reflns_number_total 1471
Count of symmetry unique reflns 1666
Completeness (_total/calc) 88.30%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 0
Fraction of Friedel pairs measured 0.000
Are heavy atom types Z>Si present no
Please check that the estimate of the number of Friedel pairs is
correct. If it is not, please give the correct count in the
_publ_section_exptl_refinement section of the submitted CIF.
0 Alert Level A = Potentially serious problem
2 Alert Level B = Potential problem
1 Alert Level C = Please check
The seeds of Daucus carota L. (family Apiaceae), commonly known as 'Wild Carrot', were purchased from B&T World Seeds, France. A voucher specimen (PH700 003) has been deposited in the herbarium of the Plant and Soil Science Department, University of Aberdeen, Scotland (ABD). Ground seeds were Soxhlet-extracted, successively, with n-hexane, dichloromethane and methanol (1.1 l each). The methanol extract was subjected to Sep-Pak (C18, 10 g cartridge) fractionation using 30, 40, 60, 80 and 100% aqueous MeOH (200 ml each). The preparative HPLC analysis (A Luna C18 preparative column 10 µ, 250 mm × 21.2 mm; mobile phase: 30–80% MeOH in water gradient over 50 min, flow rate = 20 ml min−1) of the Sep-Pak 60% MeOH fraction yielded luteolin (19 mg, retention time = 26 min), the structure of which was preliminarily determined by UV, MS, 1H and 13C NMR data analyses.
Data were collected on a weakly diffracting thin plate over 46 h. H atoms were placed in calculated positions (O—H = 0.84 Å and C—H= 0.95 Å) and allowed to ride on their parent atoms with freely refined Uiso(H). The structure contains disordered solvent, which was treated with the SQUEEZE procedure in PLATON (Spek, 2002). There are two solvent cavities per unit cell, at positions (0, 0.261, 0) and (1/2, 0.761, 0), each with a volume of 35 Å3 and each containing approximately 13 electrons. At least two diffuse peaks could be seen in each cavity in a difference map, but the small volume indicates the presence of a single water molecule (10 electrons) disordered in each cavity.
In the absence of elements heavier than oxygen, Friedel pairs were merged prior to refinement. The absolute polarity of the crystal was assigned arbitrarily (for a planar molecule, absolute configuration is meaningless).
The high value of R relates to the difficulty in obtaining suitable data from a small, thin plate of diffracting material containing diffuse solvent.
Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2002); software used to prepare material for publication: WinGX (Farrugia, 1999).
Crystal data top
C15H10O6 | F(000) = 592 |
Mr = 286.23 | Dx = 1.463 Mg m−3 |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C 2y | Cell parameters from 8254 reflections |
a = 35.327 (5) Å | θ = 2.9–27.5° |
b = 5.618 (1) Å | µ = 0.12 mm−1 |
c = 6.682 (1) Å | T = 120 K |
β = 101.554 (5)° | Plate, light brown |
V = 1299.3 (4) Å3 | 0.4 × 0.1 × 0.01 mm |
Z = 4 | |
Data collection top
Nonius KappaCCD area-detector diffractometer | 1262 reflections with I > 2σ(I) |
ϕ and ω scans | Rint = 0.087 |
Absorption correction: multi-scan (SORTAV; Blessing, 1995, 1997) | θmax = 27.6°, θmin = 3.1° |
Tmin = 0.911, Tmax = 1.000 | h = −45→45 |
8254 measured reflections | k = −7→7 |
1471 independent reflections | l = −8→8 |
Refinement top
Refinement on F2 | 1 restraint |
Least-squares matrix: full | Only H-atom displacement parameters refined |
R[F2 > 2σ(F2)] = 0.093 | w = 1/[σ2(Fo2) + (0.0452P)2 + 6.6344P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.190 | (Δ/σ)max < 0.001 |
S = 1.18 | Δρmax = 0.35 e Å−3 |
1471 reflections | Δρmin = −0.34 e Å−3 |
204 parameters | |
Crystal data top
C15H10O6 | V = 1299.3 (4) Å3 |
Mr = 286.23 | Z = 4 |
Monoclinic, C2 | Mo Kα radiation |
a = 35.327 (5) Å | µ = 0.12 mm−1 |
b = 5.618 (1) Å | T = 120 K |
c = 6.682 (1) Å | 0.4 × 0.1 × 0.01 mm |
β = 101.554 (5)° | |
Data collection top
Nonius KappaCCD area-detector diffractometer | 1471 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing, 1995, 1997) | 1262 reflections with I > 2σ(I) |
Tmin = 0.911, Tmax = 1.000 | Rint = 0.087 |
8254 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.093 | 1 restraint |
wR(F2) = 0.190 | Only H-atom displacement parameters refined |
S = 1.18 | Δρmax = 0.35 e Å−3 |
1471 reflections | Δρmin = −0.34 e Å−3 |
204 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.12646 (13) | 0.1650 (9) | 0.1071 (7) | 0.0257 (11) | |
O2 | 0.13361 (12) | 0.6547 (9) | −0.3352 (7) | 0.0258 (11) | |
O3 | 0.07851 (13) | 0.4290 (10) | −0.5823 (8) | 0.0325 (13) | |
H3 | 0.1009 | 0.4848 | −0.5707 | 0.03 (2)* | |
O4 | 0.02586 (14) | −0.2521 (10) | −0.3174 (9) | 0.0360 (14) | |
H4 | 0.026 | −0.3208 | −0.2055 | 0.10 (5)* | |
O5 | 0.24217 (13) | 0.2814 (9) | 0.9362 (7) | 0.0271 (12) | |
H5 | 0.2574 | 0.3965 | 0.9671 | 0.03 (2)* | |
O6 | 0.18886 (13) | −0.0343 (9) | 0.8124 (8) | 0.0289 (12) | |
H6 | 0.1686 | −0.1116 | 0.7667 | 0.02 (2)* | |
C2 | 0.15262 (16) | 0.3495 (12) | 0.1438 (11) | 0.0206 (16) | |
C3 | 0.1546 (2) | 0.5170 (13) | −0.0009 (12) | 0.0297 (17) | |
H3A | 0.1724 | 0.6447 | 0.0307 | 0.03 (2)* | |
C4 | 0.13032 (17) | 0.5045 (12) | −0.1998 (11) | 0.0201 (14) | |
C5 | 0.07756 (18) | 0.2764 (13) | −0.4265 (11) | 0.0254 (16) | |
C6 | 0.0527 (2) | 0.0894 (14) | −0.4540 (13) | 0.0320 (18) | |
H6A | 0.0359 | 0.0658 | −0.5825 | 0.11 (4)* | |
C7 | 0.05183 (17) | −0.0730 (13) | −0.2886 (13) | 0.0311 (19) | |
C8 | 0.07567 (19) | −0.0374 (14) | −0.1021 (13) | 0.0319 (18) | |
H8 | 0.0744 | −0.1394 | 0.0098 | 0.05 (3)* | |
C9 | 0.10104 (19) | 0.1464 (14) | −0.0807 (11) | 0.0253 (15) | |
C10 | 0.1032 (2) | 0.3133 (14) | −0.2351 (12) | 0.0272 (17) | |
C11 | 0.17618 (18) | 0.3345 (13) | 0.3490 (11) | 0.0230 (15) | |
C12 | 0.17082 (19) | 0.1511 (14) | 0.4789 (11) | 0.0267 (16) | |
H12 | 0.1517 | 0.0333 | 0.4346 | 0.03 (2)* | |
C13 | 0.1936 (2) | 0.1398 (12) | 0.6749 (11) | 0.0252 (16) | |
C14 | 0.22093 (17) | 0.3136 (13) | 0.7433 (11) | 0.0234 (16) | |
C15 | 0.22675 (18) | 0.4970 (13) | 0.6154 (11) | 0.0241 (16) | |
H15 | 0.246 | 0.6136 | 0.6613 | 0.03 (2)* | |
C16 | 0.20440 (18) | 0.5109 (13) | 0.4191 (11) | 0.0260 (16) | |
H16 | 0.2081 | 0.6388 | 0.3319 | 0.04 (2)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.030 (2) | 0.028 (3) | 0.018 (3) | −0.001 (2) | 0.0024 (19) | 0.002 (2) |
O2 | 0.031 (2) | 0.025 (3) | 0.022 (3) | −0.007 (2) | 0.005 (2) | 0.002 (2) |
O3 | 0.032 (3) | 0.039 (3) | 0.025 (3) | −0.004 (2) | 0.002 (2) | 0.002 (3) |
O4 | 0.036 (3) | 0.033 (3) | 0.032 (3) | −0.004 (2) | −0.009 (2) | 0.006 (3) |
O5 | 0.028 (2) | 0.024 (3) | 0.025 (3) | −0.007 (2) | −0.0040 (19) | −0.003 (2) |
O6 | 0.035 (3) | 0.027 (3) | 0.022 (3) | −0.003 (2) | −0.001 (2) | 0.006 (2) |
C2 | 0.013 (3) | 0.023 (3) | 0.024 (4) | −0.001 (2) | 0.000 (2) | −0.003 (3) |
C3 | 0.046 (4) | 0.015 (3) | 0.028 (5) | −0.005 (3) | 0.009 (3) | −0.008 (3) |
C4 | 0.019 (3) | 0.024 (3) | 0.018 (4) | −0.002 (3) | 0.006 (2) | −0.001 (3) |
C5 | 0.028 (3) | 0.018 (3) | 0.031 (5) | −0.003 (3) | 0.007 (3) | 0.009 (3) |
C6 | 0.036 (4) | 0.034 (4) | 0.024 (5) | 0.001 (3) | 0.002 (3) | 0.000 (3) |
C7 | 0.017 (3) | 0.024 (4) | 0.049 (6) | −0.002 (3) | −0.002 (3) | −0.005 (4) |
C8 | 0.034 (3) | 0.032 (4) | 0.029 (5) | 0.002 (3) | 0.003 (3) | 0.011 (3) |
C9 | 0.030 (3) | 0.027 (4) | 0.019 (4) | −0.003 (3) | 0.006 (3) | −0.004 (3) |
C10 | 0.030 (3) | 0.033 (4) | 0.017 (4) | 0.002 (3) | 0.003 (3) | 0.002 (3) |
C11 | 0.025 (3) | 0.025 (4) | 0.021 (4) | 0.001 (3) | 0.010 (3) | 0.003 (3) |
C12 | 0.032 (3) | 0.030 (4) | 0.016 (4) | −0.002 (3) | 0.000 (3) | −0.005 (3) |
C13 | 0.044 (4) | 0.018 (3) | 0.014 (4) | 0.005 (3) | 0.005 (3) | 0.001 (3) |
C14 | 0.021 (3) | 0.029 (4) | 0.018 (4) | 0.007 (3) | −0.002 (3) | −0.005 (3) |
C15 | 0.025 (3) | 0.023 (3) | 0.024 (4) | −0.004 (3) | 0.007 (3) | 0.003 (3) |
C16 | 0.029 (3) | 0.022 (3) | 0.028 (5) | 0.003 (3) | 0.007 (3) | 0.009 (3) |
Geometric parameters (Å, º) top
O1—C2 | 1.377 (8) | C5—C10 | 1.426 (9) |
O1—C9 | 1.393 (8) | C6—C7 | 1.438 (11) |
O2—C4 | 1.260 (8) | C6—H6A | 0.95 |
O3—C5 | 1.354 (8) | C7—C8 | 1.372 (10) |
O3—H3 | 0.84 | C8—C9 | 1.356 (10) |
O4—C7 | 1.349 (8) | C8—H8 | 0.95 |
O4—H4 | 0.84 | C9—C10 | 1.408 (10) |
O5—C14 | 1.367 (7) | C11—C12 | 1.384 (10) |
O5—H5 | 0.84 | C11—C16 | 1.417 (10) |
O6—C13 | 1.375 (8) | C12—C13 | 1.394 (9) |
O6—H6 | 0.84 | C12—H12 | 0.95 |
C2—C3 | 1.361 (10) | C13—C14 | 1.385 (9) |
C2—C11 | 1.457 (9) | C14—C15 | 1.380 (10) |
C3—C4 | 1.432 (9) | C15—C16 | 1.391 (9) |
C3—H3A | 0.95 | C15—H15 | 0.95 |
C4—C10 | 1.428 (10) | C16—H16 | 0.95 |
C5—C6 | 1.358 (10) | | |
| | | |
C2—O1—C9 | 120.3 (5) | C7—C8—H8 | 120.7 |
C5—O3—H3 | 109.5 | C8—C9—O1 | 116.4 (7) |
C7—O4—H4 | 109.5 | C8—C9—C10 | 124.1 (7) |
C14—O5—H5 | 109.5 | O1—C9—C10 | 119.4 (6) |
C13—O6—H6 | 109.5 | C9—C10—C5 | 116.3 (6) |
C3—C2—O1 | 121.5 (6) | C9—C10—C4 | 120.8 (6) |
C3—C2—C11 | 127.4 (6) | C5—C10—C4 | 122.8 (7) |
O1—C2—C11 | 111.1 (6) | C12—C11—C16 | 119.3 (6) |
C2—C3—C4 | 121.2 (6) | C12—C11—C2 | 120.6 (6) |
C2—C3—H3A | 119.4 | C16—C11—C2 | 120.1 (6) |
C4—C3—H3A | 119.4 | C11—C12—C13 | 119.8 (7) |
O2—C4—C10 | 122.7 (6) | C11—C12—H12 | 120.1 |
O2—C4—C3 | 120.6 (6) | C13—C12—H12 | 120.1 |
C10—C4—C3 | 116.6 (6) | O6—C13—C14 | 116.8 (6) |
O3—C5—C6 | 120.1 (6) | O6—C13—C12 | 122.4 (7) |
O3—C5—C10 | 119.2 (6) | C14—C13—C12 | 120.7 (7) |
C6—C5—C10 | 120.7 (7) | O5—C14—C15 | 124.1 (6) |
C5—C6—C7 | 120.0 (7) | O5—C14—C13 | 115.6 (6) |
C5—C6—H6A | 120 | C15—C14—C13 | 120.1 (6) |
C7—C6—H6A | 120 | C14—C15—C16 | 120.0 (6) |
O4—C7—C8 | 121.0 (7) | C14—C15—H15 | 120 |
O4—C7—C6 | 118.9 (6) | C16—C15—H15 | 120 |
C8—C7—C6 | 120.1 (7) | C15—C16—C11 | 120.1 (7) |
C9—C8—C7 | 118.7 (7) | C15—C16—H16 | 120 |
C9—C8—H8 | 120.7 | C11—C16—H16 | 120 |
| | | |
C9—O1—C2—C3 | −0.3 (9) | C6—C5—C10—C4 | 178.8 (7) |
C9—O1—C2—C11 | 179.9 (6) | O2—C4—C10—C9 | 178.6 (7) |
O1—C2—C3—C4 | −1.9 (10) | C3—C4—C10—C9 | −0.5 (10) |
C11—C2—C3—C4 | 177.8 (6) | O2—C4—C10—C5 | 0.1 (11) |
C2—C3—C4—O2 | −176.9 (6) | C3—C4—C10—C5 | −179.0 (7) |
C2—C3—C4—C10 | 2.2 (10) | C3—C2—C11—C12 | −179.6 (7) |
O3—C5—C6—C7 | 179.8 (6) | O1—C2—C11—C12 | 0.2 (8) |
C10—C5—C6—C7 | 0.5 (11) | C3—C2—C11—C16 | 1.6 (10) |
C5—C6—C7—O4 | 177.5 (7) | O1—C2—C11—C16 | −178.6 (6) |
C5—C6—C7—C8 | 0.9 (11) | C16—C11—C12—C13 | −1.1 (10) |
O4—C7—C8—C9 | −179.4 (7) | C2—C11—C12—C13 | −179.9 (7) |
C6—C7—C8—C9 | −3.0 (11) | C11—C12—C13—O6 | 178.2 (6) |
C7—C8—C9—O1 | −175.6 (7) | C11—C12—C13—C14 | 1.7 (10) |
C7—C8—C9—C10 | 3.8 (11) | O6—C13—C14—O5 | 4.7 (9) |
C2—O1—C9—C8 | −178.5 (6) | C12—C13—C14—O5 | −178.6 (6) |
C2—O1—C9—C10 | 2.1 (9) | O6—C13—C14—C15 | −178.7 (6) |
C8—C9—C10—C5 | −2.4 (10) | C12—C13—C14—C15 | −2.0 (10) |
O1—C9—C10—C5 | 177.0 (7) | O5—C14—C15—C16 | 178.0 (7) |
C8—C9—C10—C4 | 179.0 (7) | C13—C14—C15—C16 | 1.7 (10) |
O1—C9—C10—C4 | −1.6 (10) | C14—C15—C16—C11 | −1.2 (10) |
O3—C5—C10—C9 | −179.2 (6) | C12—C11—C16—C15 | 0.9 (10) |
C6—C5—C10—C9 | 0.2 (10) | C2—C11—C16—C15 | 179.7 (6) |
O3—C5—C10—C4 | −0.6 (10) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O2 | 0.84 | 2.00 | 2.614 (7) | 130 |
O5—H5···O5i | 0.84 | 2.26 | 2.955 (7) | 141 |
O5—H5···O6i | 0.84 | 2.19 | 2.862 (7) | 137 |
O6—H6···O2ii | 0.84 | 1.84 | 2.658 (7) | 165 |
C3—H3A···O6iii | 0.95 | 2.46 | 3.159 (9) | 130 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+2; (ii) x, y−1, z+1; (iii) x, y+1, z−1. |
Experimental details
Crystal data |
Chemical formula | C15H10O6 |
Mr | 286.23 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 120 |
a, b, c (Å) | 35.327 (5), 5.618 (1), 6.682 (1) |
β (°) | 101.554 (5) |
V (Å3) | 1299.3 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.4 × 0.1 × 0.01 |
|
Data collection |
Diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SORTAV; Blessing, 1995, 1997) |
Tmin, Tmax | 0.911, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8254, 1471, 1262 |
Rint | 0.087 |
(sin θ/λ)max (Å−1) | 0.651 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.093, 0.190, 1.18 |
No. of reflections | 1471 |
No. of parameters | 204 |
No. of restraints | 1 |
H-atom treatment | Only H-atom displacement parameters refined |
Δρmax, Δρmin (e Å−3) | 0.35, −0.34 |
Selected geometric parameters (Å, º) topO2—C4 | 1.260 (8) | O5—C14 | 1.367 (7) |
O3—C5 | 1.354 (8) | O6—C13 | 1.375 (8) |
O4—C7 | 1.349 (8) | C2—C11 | 1.457 (9) |
| | | |
C3—C2—C11 | 127.4 (6) | O1—C2—C11 | 111.1 (6) |
| | | |
O6—C13—C14—O5 | 4.7 (9) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O2 | 0.84 | 2.00 | 2.614 (7) | 130 |
O5—H5···O5i | 0.84 | 2.26 | 2.955 (7) | 141 |
O5—H5···O6i | 0.84 | 2.19 | 2.862 (7) | 137 |
O6—H6···O2ii | 0.84 | 1.84 | 2.658 (7) | 165 |
C3—H3A···O6iii | 0.95 | 2.46 | 3.159 (9) | 130 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+2; (ii) x, y−1, z+1; (iii) x, y+1, z−1. |
C—H···π interactions (Å, °) topC—H | CgI | symmetry code | H···CgI | C—H···CgI | C···CgI |
C15—H15 | 1 | 0.5 − x,0.5 + y,1 − z | 2.87 | 130 | 3.553 (7) |
Cg1 is the centre of gravity of the aromatic ring C11–C16. |
There is an extensive body of literature on the biological activity of luteolin (5,7,3',4'-tetrahydroxyflavone), (I), including a dedicated web site (luteolin.com). Many herbs containing luteolin have been used as traditional medicines to treat a wide variety of symptoms, and anti-inflammatory and anti-oxidant activity are particularly important features of this flavonoid. A recent example of its structure elucidation by spectroscopy has been published (Owen et al., 2003).
The atomic arrangement in (I) is shown in Fig. 1. The molecule is essentially planar, with a dihedral angle between the endocyclic atoms of the pyrone ring system and the phenyl ring of only 2.1 (3)°. The largest torsion angle [O6—C13—C14—O5 = 4.7 (9)°] involves hydroxy O atoms associated with intermolecular hydrogen bonding.
Within the crystal structure, hydrogen bonding is extensive (Table 2). An intramolecular hydrogen bond is present between the carbonyl and hydroxy groups at C4 and C5, respectively. The H12···O1 separation is also short at 2.31 Å, but the C12—H12···O1 angle is only 101°. The hydroxy group at C7 is believed to be linked with the solvent through hydrogen bonding, but the quality of the data cannot confirm this association. Apart from the classical hydrogen bonding, a C—H···O interaction and a C—H···π (Table 3) contact are also present. Crystal structures of related hydroxyflavones include cirsimaritin (Chou et al., 2002), pachypodol (Smith et al., 2001) and 5-hydroxy-3,7,4'-trimethoxyflavone (Gajhede et al., 1989).