Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801008571/tk6019sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801008571/tk6019Isup2.hkl |
CCDC reference: 170763
6-Methylflavone was obtained by the Baker-Venkataraman method and the structure confirmed by 1H, and 13C NMR, mass spectrometry and infra-red spectroscopy. The product was recrystallized by slow evaporation from methanol (1.64 g, 60%), m.p. 397–400. λmax/cm-1 2900 (ArC-H), 1640 (C=O), 1450, 1375, 1300, 1220, 1165, 1130, 1085, 1040, 1025, 975, 900, 850, 835, 815, 770, 720, 660; δH (300 MHz; CDCl3) 2.48 (3H, s, CH3), 6.83 (1H, s, C(3)—H), 7.49–7.57 (5H, m, C(2')-H, C(3')-H, C(4')-H), 7.92–7.96 (2H, m, C(7)—H, C(8)—H), 8.03 (1H, symm. m, C(5)—H); δC (75 MHz; CDCl3) 21.01 (CH3), 107.50 (C-8), 117.93 (C-3), 123.72 (C-5a), 125.14 (C-4), 126.33 (C-3'), 129.09 (C-2'), 131.56 (C-5), 132.00 (C-1'), 135.04 (C-7), 135.26 (C-6), 154.63 (C-2), 163.29 (C-8a), 178.55 (C-4); m/z 236 ([M]+, 100%), 235 (31), 208 (51), 134 (29), 106 (19), 105 (28), 78 (12), 77 (14).
Crystals of (I) were mounted using silicone oil which acted as both a coating and an adhesive.
H atoms were included in calculated positions (riding model) with Uiso set at 1.2(CH) and 1.5(CH3) times the Ueq of the parent atoms.
Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997).
Fig. 1. A general view of the molecular structure of (I). The ellipsoids are drawn at the 50% probability level (Farrugia, 1997). |
C16H12O2 | Dx = 1.335 Mg m−3 |
Mr = 236.26 | Melting point = 124–127 K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 4.7103 (8) Å | Cell parameters from 999 reflections |
b = 11.684 (2) Å | θ = 1.9–28.3° |
c = 21.352 (4) Å | µ = 0.09 mm−1 |
β = 90.043 (3)° | T = 150 K |
V = 1175.1 (3) Å3 | Prism, colourless |
Z = 4 | 0.25 × 0.15 × 0.15 mm |
F(000) = 496 |
Bruker SMART 1000 CCD diffractometer | 1644 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.033 |
Graphite monochromator | θmax = 28.3°, θmin = 1.9° |
ω–scan | h = −6→6 |
7396 measured reflections | k = −10→15 |
2758 independent reflections | l = −28→28 |
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)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.127 | H-atom parameters constrained |
S = 0.93 | w = 1/[σ2(Fo2) + (0.0696P)2] where P = (Fo2 + 2Fc2)/3 |
2758 reflections | (Δ/σ)max < 0.001 |
164 parameters | Δρmax = 0.26 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C16H12O2 | V = 1175.1 (3) Å3 |
Mr = 236.26 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 4.7103 (8) Å | µ = 0.09 mm−1 |
b = 11.684 (2) Å | T = 150 K |
c = 21.352 (4) Å | 0.25 × 0.15 × 0.15 mm |
β = 90.043 (3)° |
Bruker SMART 1000 CCD diffractometer | 1644 reflections with I > 2σ(I) |
7396 measured reflections | Rint = 0.033 |
2758 independent reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.127 | H-atom parameters constrained |
S = 0.93 | Δρmax = 0.26 e Å−3 |
2758 reflections | Δρmin = −0.20 e Å−3 |
164 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.1397 (2) | 0.74957 (9) | 0.14860 (5) | 0.0299 (3) | |
O2 | −0.2213 (3) | 0.43274 (10) | 0.13297 (6) | 0.0443 (4) | |
C1 | −0.1137 (4) | 0.52883 (14) | 0.13807 (7) | 0.0310 (4) | |
C2 | 0.0931 (3) | 0.57314 (14) | 0.09453 (7) | 0.0310 (4) | |
H2 | 0.1488 | 0.5274 | 0.0611 | 0.037* | |
C3 | 0.2090 (3) | 0.67804 (14) | 0.10033 (7) | 0.0270 (4) | |
C4 | −0.0587 (3) | 0.71459 (13) | 0.19192 (7) | 0.0271 (4) | |
C5 | −0.1869 (3) | 0.60763 (13) | 0.18931 (7) | 0.0269 (4) | |
C6 | −0.3861 (3) | 0.57969 (14) | 0.23574 (7) | 0.0299 (4) | |
H6 | −0.4718 | 0.5080 | 0.2349 | 0.036* | |
C7 | −0.4586 (3) | 0.65577 (14) | 0.28278 (7) | 0.0295 (4) | |
C8 | −0.3264 (4) | 0.76346 (14) | 0.28275 (7) | 0.0325 (4) | |
H8 | −0.3748 | 0.8163 | 0.3135 | 0.039* | |
C9 | −0.1273 (4) | 0.79302 (14) | 0.23852 (7) | 0.0326 (4) | |
H9 | −0.0399 | 0.8644 | 0.2398 | 0.039* | |
C10 | 0.4199 (3) | 0.73010 (14) | 0.05827 (7) | 0.0280 (4) | |
C11 | 0.5532 (4) | 0.83208 (15) | 0.07408 (8) | 0.0371 (4) | |
H11 | 0.5062 | 0.8689 | 0.1113 | 0.045* | |
C12 | 0.7551 (4) | 0.87919 (16) | 0.03500 (9) | 0.0470 (5) | |
H12 | 0.8431 | 0.9475 | 0.0460 | 0.056* | |
C13 | 0.8275 (4) | 0.82568 (16) | −0.02031 (8) | 0.0428 (5) | |
H13 | 0.9649 | 0.8575 | −0.0463 | 0.051* | |
C14 | 0.6961 (4) | 0.72534 (15) | −0.03687 (8) | 0.0385 (4) | |
H14 | 0.7444 | 0.6892 | −0.0742 | 0.046* | |
C15 | 0.4930 (4) | 0.67802 (15) | 0.00156 (8) | 0.0347 (4) | |
H15 | 0.4032 | 0.6105 | −0.0103 | 0.042* | |
C16 | −0.6683 (4) | 0.62485 (15) | 0.33332 (8) | 0.0376 (4) | |
H16A | −0.8012 | 0.5698 | 0.3173 | 0.056* | |
H16B | −0.7682 | 0.6923 | 0.3464 | 0.056* | |
H16C | −0.5689 | 0.5927 | 0.3684 | 0.056* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0366 (7) | 0.0238 (6) | 0.0294 (6) | −0.0026 (5) | 0.0080 (5) | −0.0034 (4) |
O2 | 0.0555 (9) | 0.0298 (7) | 0.0475 (7) | −0.0131 (6) | 0.0152 (6) | −0.0094 (6) |
C1 | 0.0349 (10) | 0.0252 (9) | 0.0328 (9) | 0.0004 (7) | 0.0032 (7) | −0.0013 (7) |
C2 | 0.0353 (10) | 0.0283 (9) | 0.0295 (8) | 0.0016 (7) | 0.0065 (7) | −0.0062 (7) |
C3 | 0.0291 (9) | 0.0276 (9) | 0.0245 (8) | 0.0046 (7) | 0.0019 (7) | −0.0017 (6) |
C4 | 0.0302 (9) | 0.0261 (9) | 0.0249 (8) | 0.0016 (7) | 0.0040 (7) | 0.0011 (6) |
C5 | 0.0289 (9) | 0.0242 (9) | 0.0276 (8) | 0.0018 (7) | 0.0020 (7) | 0.0004 (6) |
C6 | 0.0294 (9) | 0.0280 (9) | 0.0324 (9) | −0.0016 (7) | 0.0022 (7) | 0.0007 (7) |
C7 | 0.0275 (9) | 0.0325 (9) | 0.0287 (8) | 0.0039 (7) | 0.0012 (7) | 0.0039 (7) |
C8 | 0.0423 (11) | 0.0288 (9) | 0.0263 (8) | 0.0060 (8) | 0.0054 (8) | −0.0028 (7) |
C9 | 0.0423 (11) | 0.0242 (9) | 0.0313 (9) | −0.0011 (7) | 0.0031 (8) | −0.0017 (7) |
C10 | 0.0296 (9) | 0.0263 (9) | 0.0282 (8) | 0.0031 (7) | 0.0008 (7) | 0.0025 (7) |
C11 | 0.0442 (11) | 0.0315 (10) | 0.0356 (9) | −0.0023 (8) | 0.0097 (8) | −0.0050 (8) |
C12 | 0.0560 (13) | 0.0359 (11) | 0.0492 (11) | −0.0126 (9) | 0.0181 (9) | −0.0044 (9) |
C13 | 0.0466 (12) | 0.0402 (11) | 0.0418 (10) | −0.0028 (9) | 0.0160 (9) | 0.0068 (8) |
C14 | 0.0489 (12) | 0.0370 (11) | 0.0297 (9) | 0.0051 (9) | 0.0090 (8) | 0.0011 (8) |
C15 | 0.0422 (11) | 0.0310 (10) | 0.0309 (8) | −0.0007 (8) | 0.0043 (8) | −0.0022 (7) |
C16 | 0.0373 (11) | 0.0405 (11) | 0.0351 (9) | 0.0023 (8) | 0.0091 (8) | 0.0015 (8) |
O1—C3 | 1.3667 (18) | C8—H8 | 0.9300 |
O1—C4 | 1.3773 (18) | C9—H9 | 0.9300 |
O2—C1 | 1.2365 (19) | C10—C11 | 1.388 (2) |
C1—C2 | 1.443 (2) | C10—C15 | 1.398 (2) |
C1—C5 | 1.471 (2) | C11—C12 | 1.380 (2) |
C2—C3 | 1.347 (2) | C11—H11 | 0.9300 |
C2—H2 | 0.9300 | C12—C13 | 1.379 (2) |
C3—C10 | 1.471 (2) | C12—H12 | 0.9300 |
C4—C5 | 1.389 (2) | C13—C14 | 1.372 (3) |
C4—C9 | 1.391 (2) | C13—H13 | 0.9300 |
C5—C6 | 1.404 (2) | C14—C15 | 1.377 (2) |
C6—C7 | 1.384 (2) | C14—H14 | 0.9300 |
C6—H6 | 0.9300 | C15—H15 | 0.9300 |
C7—C8 | 1.404 (2) | C16—H16A | 0.9600 |
C7—C16 | 1.507 (2) | C16—H16B | 0.9600 |
C8—C9 | 1.375 (2) | C16—H16C | 0.9600 |
C3—O1—C4 | 119.18 (12) | C8—C9—H9 | 120.5 |
O2—C1—C2 | 123.07 (15) | C4—C9—H9 | 120.5 |
O2—C1—C5 | 122.52 (15) | C11—C10—C15 | 118.19 (15) |
C2—C1—C5 | 114.41 (14) | C11—C10—C3 | 120.79 (14) |
C3—C2—C1 | 122.72 (14) | C15—C10—C3 | 121.03 (15) |
C3—C2—H2 | 118.6 | C12—C11—C10 | 120.46 (15) |
C1—C2—H2 | 118.6 | C12—C11—H11 | 119.8 |
C2—C3—O1 | 121.92 (14) | C10—C11—H11 | 119.8 |
C2—C3—C10 | 126.41 (14) | C13—C12—C11 | 120.51 (18) |
O1—C3—C10 | 111.67 (13) | C13—C12—H12 | 119.7 |
O1—C4—C5 | 122.36 (13) | C11—C12—H12 | 119.7 |
O1—C4—C9 | 116.30 (14) | C14—C13—C12 | 119.76 (16) |
C5—C4—C9 | 121.34 (14) | C14—C13—H13 | 120.1 |
C4—C5—C6 | 118.14 (14) | C12—C13—H13 | 120.1 |
C4—C5—C1 | 119.39 (14) | C13—C14—C15 | 120.20 (16) |
C6—C5—C1 | 122.47 (14) | C13—C14—H14 | 119.9 |
C7—C6—C5 | 121.90 (15) | C15—C14—H14 | 119.9 |
C7—C6—H6 | 119.0 | C14—C15—C10 | 120.86 (16) |
C5—C6—H6 | 119.0 | C14—C15—H15 | 119.6 |
C6—C7—C8 | 117.75 (14) | C10—C15—H15 | 119.6 |
C6—C7—C16 | 121.85 (15) | C7—C16—H16A | 109.5 |
C8—C7—C16 | 120.40 (14) | C7—C16—H16B | 109.5 |
C9—C8—C7 | 121.87 (15) | H16A—C16—H16B | 109.5 |
C9—C8—H8 | 119.1 | C7—C16—H16C | 109.5 |
C7—C8—H8 | 119.1 | H16A—C16—H16C | 109.5 |
C8—C9—C4 | 118.99 (15) | H16B—C16—H16C | 109.5 |
O2—C1—C2—C3 | 179.85 (17) | C5—C6—C7—C16 | −178.81 (15) |
C5—C1—C2—C3 | −0.1 (2) | C6—C7—C8—C9 | −1.2 (3) |
C1—C2—C3—O1 | 0.7 (3) | C16—C7—C8—C9 | 177.86 (15) |
C1—C2—C3—C10 | −179.86 (15) | C7—C8—C9—C4 | 1.1 (3) |
C4—O1—C3—C2 | −1.4 (2) | O1—C4—C9—C8 | 179.32 (14) |
C4—O1—C3—C10 | 179.06 (13) | C5—C4—C9—C8 | 0.0 (2) |
C3—O1—C4—C5 | 1.6 (2) | C2—C3—C10—C11 | −170.71 (17) |
C3—O1—C4—C9 | −177.71 (14) | O1—C3—C10—C11 | 8.8 (2) |
O1—C4—C5—C6 | 179.81 (14) | C2—C3—C10—C15 | 8.9 (3) |
C9—C4—C5—C6 | −0.9 (2) | O1—C3—C10—C15 | −171.61 (14) |
O1—C4—C5—C1 | −1.1 (2) | C15—C10—C11—C12 | −0.9 (3) |
C9—C4—C5—C1 | 178.21 (14) | C3—C10—C11—C12 | 178.66 (17) |
O2—C1—C5—C4 | −179.66 (16) | C10—C11—C12—C13 | 0.0 (3) |
C2—C1—C5—C4 | 0.3 (2) | C11—C12—C13—C14 | 0.5 (3) |
O2—C1—C5—C6 | −0.6 (3) | C12—C13—C14—C15 | −0.1 (3) |
C2—C1—C5—C6 | 179.39 (15) | C13—C14—C15—C10 | −0.9 (3) |
C4—C5—C6—C7 | 0.8 (2) | C11—C10—C15—C14 | 1.4 (3) |
C1—C5—C6—C7 | −178.28 (15) | C3—C10—C15—C14 | −178.20 (16) |
C5—C6—C7—C8 | 0.2 (2) |
Experimental details
Crystal data | |
Chemical formula | C16H12O2 |
Mr | 236.26 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 4.7103 (8), 11.684 (2), 21.352 (4) |
β (°) | 90.043 (3) |
V (Å3) | 1175.1 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.25 × 0.15 × 0.15 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7396, 2758, 1644 |
Rint | 0.033 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.127, 0.93 |
No. of reflections | 2758 |
No. of parameters | 164 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.26, −0.20 |
Computer programs: SMART (Siemens, 1995), SMART, SAINT (Siemens, 1995), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997).
Flavones and related compounds are known to exhibit a wide range of interesting biological activities. (Agullo et al., 1997; Carlo et al., 1993; Miksicek, 1993; Wang et al., 1999). 6-Methylflavone is one of a number of flavones that have interesting modulatory activities at GABA-A receptors. (Medina et al., 1998; Campbell, 2001). The title compound, (I), was synthesized as part of an on-going structure–activity study to determine the properties of these compounds that confer this activity in order to aid the design of more active compounds.
All bond lengths and angles in (I) (Fig. 1) are as expected. Rings AC and B are planar; the maximum deviations are 0.008 (2) and 0.007 (1) Å from the ring planes AC and B, respectively.
The average C—C bond length for rings A and B are 1.394 (2) and 1.383 (2) Å, respectively. The dihedral angle between the phenyl and the γ-pyrone ring is small (8.9 (3) Å) as expected in the generally preferred conformation of flavones. The small dihedral angle results in a relatively short C3—C10 bond length of 1.472 (2) Å which is consistent with bond lengths and dihedral angles found in other flavones. Flavone-3'sulfonamide has a dihedral angle of 8.2 (3)° and the C3—C10 bond length of 1.478 (3) Å. (Kendi et al., 2000). In 5-hydroxyflavone, the dihedral angle is 5.2 (9)° and the C3—C10 bond length is 1.465 (4) Å. (Shoja, 1990). 5,7-Dihydroxy-4'-methoxyflavone with a dihedral angle of 3.1° has a C3—C10 bond length of 1.453 (9) Å. (Shoja, 1992). However, in 2'-methyl-3'-nitroflavone, the dihedral angle is 139.8 (2)° and the C3—C10 bond length is 1.491 (8) Å. (Kendi et al., 1996) and in 5,4'-dihydroxy-3,6,7,8-tetramethoxyflavone a large dihedral of angle of 164.4 (6)° and a C2—C10 bond length of 1.503 (8) Å are found (Vijayalakshmi et al., 1986).
The small dihedral angle between the phenyl and the γ-pyrone ring and shorter C1'-C2 bond length results in less delocalization of the π electrons in C3—C2—C1—O2, resulting in longer C2=C3 and C4=O2 bond lengths. 6-Methylflavone has a C2=C3 bond length of 1.348 (2) Å and a C4=O2 bond length of 1.237 (2) Å, a situation which is similar to flavone 3'-sulfonamide with a dihedral angle of 5.2 (9)°, and C2=C3 and C4=O2 bond lengths of 1.346 (3) and 1.247 (3) Å, respectively (Kendi et al., 2000). Conversely, 2'-methyl-3'nitro-flavone with the larger dihedral angle of 139.8 (2)° and longer C3—C10 bond length, has shorter C2=C3 and C4=O2 bond lengths of 1.322 (9) and 1.227 (8) Å, respectively (Kendi et al., 1996).
The widening of the O1—C4—C5 angle to 122.32 (13)° and the narrowing of the C2—C1—C5 angle to 114.51 (14)° in the γ-pyrone ring may be attributed to the ring strain caused by the neighbouring Csp2 - Csp2 atoms.