organic compounds
7-Ethoxy-4′-methoxyisoflavone (monoethylformononetin)
aDepartment of Chemistry and Chemical Engineering, Weinan Teachers University, weinan 714000, People's Republic of China
*Correspondence e-mail: wqiuya1978@163.com
The title compound, C18H16O4, is composed of a benzopyranone core with a 4-methoxyphenyl subsituent in the 3-position and an additional ethoxy group in the 7-position. The benzopyranone ring is not coplanar with the benzene ring, the dihedral angle between them being 41.76 (7)°. The methoxy and ethoxy substituents are nearly coplanar with the ring systems to which they are attached. Individual molecules are linked by two kinds of intermolecular hydrogen bonds into chains containing classical R22(8) rings. The chains are further assembled by aromatic F-tape and T-tape stacking interactions and additional intermolecular hydrogen bonding to give a two-dimensional network.
Related literature
For related literature, see: Cassidy et al. (1994); Janiak (2000); Jha et al. (1985); Potter (1995); Sirtori et al. (1995); Zhang et al. (2005).
Experimental
Crystal data
|
Refinement
|
Data collection: SMART (Bruker, 1999); cell SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536808010672/im2059sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808010672/im2059Isup2.hkl
Formononetin (1.0 g) was dissolved into acetone (30 ml) and KOH (1 ml, 0.3%). Diethylsulfate (1 ml) was added dropwise to the solution under vigorous stirring. The mixture was stirred at room temperature for 3 h and then poured into water (50 ml). A white precipitation appeared, which was filtered after 4 h and terated with NaOH (50 ml, 2 mol/L) to remove traces of remaining formonetin. The precipitate was filtered and washed with water until the pH of the filtrate was 7 yielding the title compound, 4'-methoxy-7-ethoxylisoflavone (yield: 82.4%). Crystals of (I) suitable for X-ray analysis were obtained by slow evaporation of the solvent from an ethanolic solution after 3 d at room temperature.
H atoms bound to O atoms were found in difference maps and refined using a riding model. H atoms bound to C atoms were placed in calculated positions (C—H=0.93–0.97 Å) and refined using a riding model, allowing for
of the rigid methyl groups. Uiso(H) values were constrained to be 1.2Ueq (attached atom) [1.5Ueq(C) for methyl H atoms].Data collection: SMART (Bruker, 1999); cell
SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C18H16O4 | V = 736.5 (6) Å3 |
Mr = 296.31 | Z = 2 |
Triclinic, P1 | F(000) = 312 |
Hall symbol: -P 1 | Dx = 1.336 Mg m−3 |
a = 6.234 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 10.257 (5) Å | Cell parameters from 2633 reflections |
c = 12.159 (6) Å | µ = 0.09 mm−1 |
α = 80.837 (7)° | T = 296 K |
β = 87.728 (8)° | Hexagonal, colorless |
γ = 73.653 (7)° | 0.35 × 0.31 × 0.27 mm |
Bruker SMART CCD area-detector diffractometer | 2572 independent reflections |
Radiation source: fine-focus sealed tube | 1732 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.019 |
ϕ and ω scans | θmax = 25.1° |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | h = −6→7 |
Tmin = 0.968, Tmax = 0.975 | k = −12→11 |
3678 measured reflections | l = −13→14 |
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)] = 0.040 | H-atom parameters constrained |
wR(F2) = 0.123 | w = 1/[σ2(Fo2) + (0.0722P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
2572 reflections | Δρmax = 0.18 e Å−3 |
202 parameters | Δρmin = −0.15 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.021 (5) |
C18H16O4 | γ = 73.653 (7)° |
Mr = 296.31 | V = 736.5 (6) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.234 (3) Å | Mo Kα radiation |
b = 10.257 (5) Å | µ = 0.09 mm−1 |
c = 12.159 (6) Å | T = 296 K |
α = 80.837 (7)° | 0.35 × 0.31 × 0.27 mm |
β = 87.728 (8)° |
Bruker SMART CCD area-detector diffractometer | 2572 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | 1732 reflections with I > 2σ(I) |
Tmin = 0.968, Tmax = 0.975 | Rint = 0.019 |
3678 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.123 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.18 e Å−3 |
2572 reflections | Δρmin = −0.15 e Å−3 |
202 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 | 0.4540 (2) | 0.17252 (13) | 0.40797 (10) | 0.0661 (4) | |
O2 | −0.17446 (17) | 0.70638 (13) | 0.09853 (9) | 0.0568 (4) | |
O3 | 0.36722 (16) | 0.77566 (12) | −0.07427 (9) | 0.0501 (3) | |
O4 | −0.0813 (2) | 1.17079 (13) | −0.30131 (10) | 0.0628 (4) | |
C1 | 0.6401 (4) | 0.1505 (2) | 0.48100 (17) | 0.0836 (7) | |
H1A | 0.7738 | 0.1451 | 0.4379 | 0.125* | |
H1B | 0.6568 | 0.0660 | 0.5314 | 0.125* | |
H1C | 0.6143 | 0.2254 | 0.5227 | 0.125* | |
C2 | 0.4019 (3) | 0.29134 (18) | 0.33118 (13) | 0.0518 (5) | |
C3 | 0.5249 (3) | 0.3858 (2) | 0.31458 (14) | 0.0574 (5) | |
H3 | 0.6505 | 0.3730 | 0.3583 | 0.069* | |
C4 | 0.4600 (3) | 0.49962 (18) | 0.23260 (13) | 0.0518 (5) | |
H4 | 0.5444 | 0.5622 | 0.2219 | 0.062* | |
C5 | 0.2730 (3) | 0.52354 (17) | 0.16568 (13) | 0.0432 (4) | |
C6 | 0.1484 (3) | 0.42862 (17) | 0.18588 (13) | 0.0459 (4) | |
H6 | 0.0202 | 0.4425 | 0.1439 | 0.055* | |
C7 | 0.2120 (3) | 0.31489 (18) | 0.26689 (13) | 0.0495 (4) | |
H7 | 0.1264 | 0.2529 | 0.2787 | 0.059* | |
C8 | 0.2177 (2) | 0.64102 (16) | 0.07294 (12) | 0.0403 (4) | |
C9 | 0.3870 (3) | 0.67076 (17) | 0.01147 (13) | 0.0459 (4) | |
H9 | 0.5303 | 0.6143 | 0.0294 | 0.055* | |
C10 | 0.1585 (2) | 0.85994 (16) | −0.10328 (12) | 0.0413 (4) | |
C11 | −0.0298 (2) | 0.83924 (16) | −0.04665 (12) | 0.0394 (4) | |
C12 | −0.0106 (2) | 0.72643 (17) | 0.04624 (12) | 0.0417 (4) | |
C13 | 0.1508 (3) | 0.96676 (18) | −0.19021 (13) | 0.0480 (4) | |
H13 | 0.2807 | 0.9761 | −0.2269 | 0.058* | |
C14 | −0.0519 (3) | 1.05814 (17) | −0.22079 (13) | 0.0476 (4) | |
C15 | −0.2471 (3) | 1.04083 (18) | −0.16642 (14) | 0.0521 (5) | |
H15 | −0.3851 | 1.1025 | −0.1875 | 0.063* | |
C16 | −0.2340 (3) | 0.93317 (18) | −0.08245 (14) | 0.0488 (4) | |
H16 | −0.3648 | 0.9219 | −0.0480 | 0.059* | |
C17 | 0.1156 (3) | 1.2050 (2) | −0.34750 (15) | 0.0656 (5) | |
H17A | 0.1971 | 1.1364 | −0.3918 | 0.079* | |
H17B | 0.2131 | 1.2079 | −0.2882 | 0.079* | |
C18 | 0.0418 (4) | 1.3431 (2) | −0.41900 (17) | 0.0805 (6) | |
H18A | −0.0447 | 1.3373 | −0.4807 | 0.121* | |
H18B | 0.1706 | 1.3717 | −0.4463 | 0.121* | |
H18C | −0.0479 | 1.4088 | −0.3757 | 0.121* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0788 (9) | 0.0575 (9) | 0.0569 (8) | −0.0217 (7) | −0.0114 (6) | 0.0143 (7) |
O2 | 0.0417 (6) | 0.0653 (9) | 0.0612 (7) | −0.0198 (6) | 0.0080 (5) | 0.0033 (6) |
O3 | 0.0385 (6) | 0.0487 (8) | 0.0558 (7) | −0.0100 (5) | 0.0055 (5) | 0.0082 (6) |
O4 | 0.0693 (8) | 0.0575 (9) | 0.0555 (8) | −0.0191 (7) | −0.0097 (6) | 0.0146 (7) |
C1 | 0.0906 (16) | 0.0762 (16) | 0.0733 (14) | −0.0212 (12) | −0.0252 (11) | 0.0223 (12) |
C2 | 0.0603 (11) | 0.0489 (11) | 0.0432 (10) | −0.0163 (9) | 0.0018 (8) | 0.0030 (8) |
C3 | 0.0548 (11) | 0.0615 (13) | 0.0542 (11) | −0.0196 (9) | −0.0114 (8) | 0.0049 (9) |
C4 | 0.0522 (10) | 0.0521 (11) | 0.0537 (10) | −0.0233 (9) | −0.0052 (8) | 0.0020 (9) |
C5 | 0.0418 (9) | 0.0451 (10) | 0.0433 (9) | −0.0149 (7) | 0.0017 (7) | −0.0036 (8) |
C6 | 0.0458 (9) | 0.0490 (11) | 0.0444 (9) | −0.0171 (8) | 0.0007 (7) | −0.0045 (8) |
C7 | 0.0540 (10) | 0.0490 (11) | 0.0486 (10) | −0.0224 (8) | 0.0041 (7) | −0.0034 (8) |
C8 | 0.0405 (8) | 0.0411 (10) | 0.0409 (8) | −0.0158 (7) | −0.0009 (6) | −0.0034 (7) |
C9 | 0.0392 (9) | 0.0413 (10) | 0.0524 (10) | −0.0088 (7) | −0.0007 (7) | 0.0029 (8) |
C10 | 0.0398 (8) | 0.0418 (10) | 0.0410 (9) | −0.0107 (7) | −0.0005 (6) | −0.0036 (8) |
C11 | 0.0387 (8) | 0.0400 (10) | 0.0397 (8) | −0.0126 (7) | −0.0012 (6) | −0.0037 (7) |
C12 | 0.0401 (9) | 0.0460 (10) | 0.0426 (9) | −0.0174 (7) | 0.0009 (7) | −0.0079 (8) |
C13 | 0.0492 (10) | 0.0486 (11) | 0.0455 (10) | −0.0167 (8) | 0.0046 (7) | −0.0007 (8) |
C14 | 0.0568 (10) | 0.0455 (11) | 0.0397 (9) | −0.0159 (8) | −0.0069 (7) | 0.0001 (8) |
C15 | 0.0439 (10) | 0.0488 (11) | 0.0606 (11) | −0.0107 (8) | −0.0107 (8) | −0.0007 (9) |
C16 | 0.0387 (9) | 0.0521 (11) | 0.0556 (10) | −0.0153 (8) | −0.0010 (7) | −0.0039 (9) |
C17 | 0.0787 (13) | 0.0561 (13) | 0.0550 (11) | −0.0167 (10) | 0.0116 (9) | 0.0053 (10) |
C18 | 0.1102 (17) | 0.0565 (14) | 0.0655 (13) | −0.0205 (12) | 0.0130 (12) | 0.0099 (11) |
O1—C2 | 1.379 (2) | C7—H7 | 0.9300 |
O1—C1 | 1.433 (2) | C8—C9 | 1.346 (2) |
O2—C12 | 1.2307 (18) | C8—C12 | 1.464 (2) |
O3—C9 | 1.3557 (19) | C9—H9 | 0.9300 |
O3—C10 | 1.3675 (18) | C10—C13 | 1.388 (2) |
O4—C14 | 1.365 (2) | C10—C11 | 1.388 (2) |
O4—C17 | 1.439 (2) | C11—C16 | 1.399 (2) |
C1—H1A | 0.9600 | C11—C12 | 1.465 (2) |
C1—H1B | 0.9600 | C13—C14 | 1.369 (2) |
C1—H1C | 0.9600 | C13—H13 | 0.9300 |
C2—C3 | 1.383 (3) | C14—C15 | 1.404 (2) |
C2—C7 | 1.387 (2) | C15—C16 | 1.366 (2) |
C3—C4 | 1.384 (2) | C15—H15 | 0.9300 |
C3—H3 | 0.9300 | C16—H16 | 0.9300 |
C4—C5 | 1.390 (2) | C17—C18 | 1.499 (3) |
C4—H4 | 0.9300 | C17—H17A | 0.9700 |
C5—C6 | 1.395 (2) | C17—H17B | 0.9700 |
C5—C8 | 1.485 (2) | C18—H18A | 0.9600 |
C6—C7 | 1.376 (2) | C18—H18B | 0.9600 |
C6—H6 | 0.9300 | C18—H18C | 0.9600 |
C2—O1—C1 | 117.47 (14) | O3—C10—C13 | 115.53 (13) |
C9—O3—C10 | 118.54 (12) | O3—C10—C11 | 121.09 (14) |
C14—O4—C17 | 117.60 (14) | C13—C10—C11 | 123.36 (15) |
O1—C1—H1A | 109.5 | C10—C11—C16 | 116.07 (15) |
O1—C1—H1B | 109.5 | C10—C11—C12 | 120.89 (14) |
H1A—C1—H1B | 109.5 | C16—C11—C12 | 123.03 (13) |
O1—C1—H1C | 109.5 | O2—C12—C8 | 122.74 (15) |
H1A—C1—H1C | 109.5 | O2—C12—C11 | 122.28 (15) |
H1B—C1—H1C | 109.5 | C8—C12—C11 | 114.98 (12) |
O1—C2—C3 | 124.71 (16) | C14—C13—C10 | 118.61 (15) |
O1—C2—C7 | 116.29 (15) | C14—C13—H13 | 120.7 |
C3—C2—C7 | 118.99 (17) | C10—C13—H13 | 120.7 |
C2—C3—C4 | 119.61 (16) | O4—C14—C13 | 124.46 (15) |
C2—C3—H3 | 120.2 | O4—C14—C15 | 115.48 (16) |
C4—C3—H3 | 120.2 | C13—C14—C15 | 120.05 (16) |
C3—C4—C5 | 122.27 (15) | C16—C15—C14 | 119.81 (16) |
C3—C4—H4 | 118.9 | C16—C15—H15 | 120.1 |
C5—C4—H4 | 118.9 | C14—C15—H15 | 120.1 |
C4—C5—C6 | 117.05 (15) | C15—C16—C11 | 122.07 (14) |
C4—C5—C8 | 120.86 (13) | C15—C16—H16 | 119.0 |
C6—C5—C8 | 122.00 (14) | C11—C16—H16 | 119.0 |
C7—C6—C5 | 121.12 (15) | O4—C17—C18 | 107.74 (16) |
C7—C6—H6 | 119.4 | O4—C17—H17A | 110.2 |
C5—C6—H6 | 119.4 | C18—C17—H17A | 110.2 |
C6—C7—C2 | 120.92 (15) | O4—C17—H17B | 110.2 |
C6—C7—H7 | 119.5 | C18—C17—H17B | 110.2 |
C2—C7—H7 | 119.5 | H17A—C17—H17B | 108.5 |
C9—C8—C12 | 118.69 (15) | C17—C18—H18A | 109.5 |
C9—C8—C5 | 118.03 (14) | C17—C18—H18B | 109.5 |
C12—C8—C5 | 123.28 (12) | H18A—C18—H18B | 109.5 |
C8—C9—O3 | 125.81 (15) | C17—C18—H18C | 109.5 |
C8—C9—H9 | 117.1 | H18A—C18—H18C | 109.5 |
O3—C9—H9 | 117.1 | H18B—C18—H18C | 109.5 |
C1—O1—C2—C3 | 4.6 (3) | O3—C10—C11—C12 | 0.1 (2) |
C1—O1—C2—C7 | −175.63 (15) | C13—C10—C11—C12 | −178.56 (13) |
O1—C2—C3—C4 | 178.07 (15) | C9—C8—C12—O2 | −179.79 (15) |
C7—C2—C3—C4 | −1.7 (3) | C5—C8—C12—O2 | −0.5 (2) |
C2—C3—C4—C5 | 0.3 (3) | C9—C8—C12—C11 | −0.6 (2) |
C3—C4—C5—C6 | 1.2 (2) | C5—C8—C12—C11 | 178.64 (13) |
C3—C4—C5—C8 | −175.40 (14) | C10—C11—C12—O2 | 179.37 (14) |
C4—C5—C6—C7 | −1.5 (2) | C16—C11—C12—O2 | 0.6 (2) |
C8—C5—C6—C7 | 175.13 (14) | C10—C11—C12—C8 | 0.2 (2) |
C5—C6—C7—C2 | 0.1 (2) | C16—C11—C12—C8 | −178.60 (14) |
O1—C2—C7—C6 | −178.32 (13) | O3—C10—C13—C14 | −177.57 (13) |
C3—C2—C7—C6 | 1.5 (3) | C11—C10—C13—C14 | 1.2 (2) |
C4—C5—C8—C9 | 39.5 (2) | C17—O4—C14—C13 | −7.9 (2) |
C6—C5—C8—C9 | −136.98 (16) | C17—O4—C14—C15 | 170.69 (14) |
C4—C5—C8—C12 | −139.76 (16) | C10—C13—C14—O4 | 176.99 (14) |
C6—C5—C8—C12 | 43.8 (2) | C10—C13—C14—C15 | −1.6 (2) |
C12—C8—C9—O3 | 0.8 (2) | O4—C14—C15—C16 | −178.21 (13) |
C5—C8—C9—O3 | −178.50 (13) | C13—C14—C15—C16 | 0.5 (2) |
C10—O3—C9—C8 | −0.5 (2) | C14—C15—C16—C11 | 1.1 (2) |
C9—O3—C10—C13 | 178.77 (13) | C10—C11—C16—C15 | −1.5 (2) |
C9—O3—C10—C11 | 0.0 (2) | C12—C11—C16—C15 | 177.38 (14) |
O3—C10—C11—C16 | 179.00 (13) | C14—O4—C17—C18 | −170.80 (14) |
C13—C10—C11—C16 | 0.3 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···O2i | 0.93 | 2.52 | 3.105 (2) | 121 |
C16—H16···O3ii | 0.93 | 2.60 | 3.315 (2) | 134 |
C17—H17B···O2iii | 0.97 | 2.58 | 3.358 (3) | 138 |
Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z; (iii) −x, −y+2, −z. |
Experimental details
Crystal data | |
Chemical formula | C18H16O4 |
Mr | 296.31 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 6.234 (3), 10.257 (5), 12.159 (6) |
α, β, γ (°) | 80.837 (7), 87.728 (8), 73.653 (7) |
V (Å3) | 736.5 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.35 × 0.31 × 0.27 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 1999) |
Tmin, Tmax | 0.968, 0.975 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3678, 2572, 1732 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.597 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.123, 1.04 |
No. of reflections | 2572 |
No. of parameters | 202 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.18, −0.15 |
Computer programs: SMART (Bruker, 1999), SAINT-Plus (Bruker, 1999), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···O2i | 0.93 | 2.52 | 3.105 (2) | 121.4 |
C16—H16···O3ii | 0.93 | 2.60 | 3.315 (2) | 134.3 |
C17—H17B···O2iii | 0.97 | 2.58 | 3.358 (3) | 137.8 |
Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z; (iii) −x, −y+2, −z. |
Acknowledgements
The author is grateful for financial support from the Science and Technology Postgraduate Project of Weinan Teachers University, China (No. 08YKZ006)
References
Bruker (1999). SMART, SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cassidy, A., Bingham, S. & Setchell, K. D. (1994). Am. J. Clin. Nutr. 60, 333–340. CAS PubMed Web of Science Google Scholar
Janiak, C. (2000). J. Chem. Soc. Dalton Trans. pp. 3885–3896. Web of Science CrossRef Google Scholar
Jha, H. C., von Recklinghausen, G. & Zilliken, F. (1985). Biochem. Pharmacol. 34, 1367–1372. CrossRef CAS PubMed Web of Science Google Scholar
Potter, S. M. (1995). J. Nutr. 125, 606S–611S. CAS PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sirtori, C. R., Lovati, M. R. & Manzoni, C. (1995). J. Nutr. 125, 598S–605S. CAS PubMed Google Scholar
Zhang, Z. T., Wang, Q.-Y., He, Y. & Yu, K.-B. (2005). J. Chem. Crystallogr. 35, 89–94. Web of Science CSD CrossRef Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The isoflavone derivative formononetin (4'-methoxy-7-hydroxyisoflavone) displays a wide range of biological activities, such as antioxidant effect (Jha et al., 1985), inhibiting cardiovascular disease (Potter et al., 1995; Sirtori et al., 1995) and balancing women's hormones (Cassidy et al., 1994). The title compound 4'-methoxy-7-ethoxylisoflavone, (I), is a derivative of formononetin and has potential medical applications.
The title compound is composed of a benzopyranone core with a p-methoxyphenyl substituent in 3-position and an additional ethoxy group in 7-position (Fig. 1). The geometry of the isoflavone skeleton of (I) is similar to that of monoethyldaidzein (Zhang et al., 2005) with respect to most of the bond distances and angles. The atoms of the benzopyranone moiety, including ring A (C10,C11,C13–C16) and C (O3/C8—C12), display an almost coplanar configuration with a mean deviation to the least square plane of 0.0152 (17) Å. To minimize steric pressure, the two rigid ring systems, benzene ring B (C2—C7) and the benzopyranone moiety, are rotated by 41.76 (7)° with respect to each other. The methoxy group at atom C2 is nearly coplanar with the benzopyranone moiety, as indicated by the torsional angle C1—O1—C2—C3 = 4.6 (3)°; The ethoxy group at atom C14 is also nearly coplanar with the attached ring, the torsional angle C17—O4—C14—C13 being -7.9 (2)°.
A one-dimensional infinite chain is formed by two intermolecular hydrogen bonds of the C–H···O type (C9—H9···O2 and C16—H16···O3, Fig. 2, Table 1). This combination of hydrogen bonds generates R22(8) rings propagating as an infinite one-dimensional chain along a axis.
As shown in Fig. 3, two isoflavone skeletons arrange in an anti-parallel fashion with aromatic F-tape and T-tape stacking interactions linking two molecules into a dimeric structure. The two benzopyranone moieties stack with each other with a CgAC-CgAC* distance of 3.686 (2) Å (CgAC and CgAC* are the centres of benzopyranone moieties at (x, y, z) and (-x, 2 - y, -z), respectively). The interplanar spacing measures to 3.425 (2) Å. In addition, another T-tape stacking interaction between H18C and CgB* (the centroid of ring B at (-x, 2 - y, -z)) of 2.818 (3) Å is observed. Both distances obviously lie in the normal range of F-tape and T-tape π-π stacking interactions (Janiak, 2000). At the same time, the carbonyl oxygen atom O2 acts as a hydrogen bond acceptor towards H17B of a neighboring molecule also leading to the formation of a dimeric substructure. The intermolecular hydrogen bond C17—H17B···O2 together with the aromatic F-tape and T-tape stacking interactions assemble the chains mentioned above into a two-dimensional network structure.