organic compounds
A second polymorph of (2E)-1-(4-fluorophenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one
aDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA, bDepartment of Chemistry, Howard University, 525 College Street NW, Washington DC 20059, USA, cDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri 574 199, India, and dDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India
*Correspondence e-mail: rbutcher99@yahoo.com
The 18H17FO4, reported here is a polymorph of the structure first reported by Patil et al. [Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. A (2007), 461, 123–130]. It is a chalcone analog and consists of substituted phenyl rings bonded at the opposite ends of a propenone group, the biologically active region. The dihedral angle between the mean planes of the aromatic rings within the 4-fluorophenyl and trimethoxyphenyl groups is 28.7 (1)° compared to 20.8 (6)° in the published structure. The angles between the mean plane of the prop-2-ene-1-one group and the mean plane of aromatic rings within the 4-fluorophenyl and trimethoxyphenyl groups are 30.3 (4) and 7.4 (7)°, respectively, in contast to 10.7 (3) and 12.36° for the polymorph. While the two 3-methoxy groups are in the plane of the trimethoxy-substituted ring, the 4-methoxy group is in a synclinical [−sc = −78.1 (2)°] or anticlinical [+ac = 104.0 (4)°] position, compared to a +sc [53.0 (4)°] or −ac [−132.4 (7)°] position. While no classical hydrogen bonds are present, weak intermolecular C—H⋯π-ring interactions are observed which contribute to the stability of the crystal packing. The two polymorphs crystallize in the same P21/c, but have different cell parameters for the a, b and c axes and the β angle. A comparison of the molecular geometries of both polymorphs to a geometry optimized density functional theory (DFT) calculation at the B3-LYP/6–311+G(d,p) level for each structure provides additional support to these observations.
of the title compound, CRelated literature
For general background to the biological activity of similar compounds, see: Dimmock et al. (1999); Lin et al. (2002); Nakamura et al. (2002); Nowakowska (2007); Opletalova & Sedivy (1999). For related structures, see: Butcher et al. (2006, 2007); Chopra et al. (2007); Fun et al. (2008); Jasinski et al. (2009); Patil et al. (2007); Qiu et al. (2006); Teh et al. (2007). For density functional theory (DFT), see: Becke (1988, 1993); Hehre et al. (1986); Lee et al. (1988); Schmidt & Polik (2007). For a description of the Cambridge Structural Database, see: Allen (2002). For the GAUSSIAN03 program package, see: Frisch et al. (2004).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis Pro (Oxford Diffraction, 2007); cell CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED; 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/S1600536809028517/sj2632sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809028517/sj2632Isup2.hkl
The title compound was synthesized by the reported procedure (Patil et al., 2007). The solid product obtained was filtered and recrystallized from ethanol. X-ray quality crystals were grown from ethyl acetate solution by slow evaporation (m.p.: 362-364 K). Analysis for C18H17FO4: Found (calculated): C: 68.27 (68.35%); H:5.36 (5.42%).
All of the H atoms were placed in their calculated positions and then refined using the riding model with C—H = 0.93–0.96 Å, and with Uiso(H) = 1.18–1.50 Ueq(C).
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell
CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); 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).C18H17FO4 | F(000) = 664 |
Mr = 316.32 | Dx = 1.329 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54184 Å |
Hall symbol: -P 2ybc | Cell parameters from 4493 reflections |
a = 12.4250 (2) Å | θ = 4.3–77.3° |
b = 8.6280 (1) Å | µ = 0.85 mm−1 |
c = 14.9038 (2) Å | T = 295 K |
β = 98.3217 (12)° | Prism, colorless |
V = 1580.91 (4) Å3 | 0.47 × 0.40 × 0.22 mm |
Z = 4 |
Oxford Diffraction Gemini R diffractometer | 3216 independent reflections |
Radiation source: fine-focus sealed tube | 2396 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
Detector resolution: 10.5081 pixels mm-1 | θmax = 77.9°, θmin = 5.9° |
ϕ and ω scans | h = −14→15 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | k = −10→9 |
Tmin = 0.557, Tmax = 0.830 | l = −18→18 |
8137 measured reflections |
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)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.126 | H-atom parameters constrained |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0683P)2 + 0.1035P] where P = (Fo2 + 2Fc2)/3 |
3216 reflections | (Δ/σ)max < 0.001 |
211 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C18H17FO4 | V = 1580.91 (4) Å3 |
Mr = 316.32 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 12.4250 (2) Å | µ = 0.85 mm−1 |
b = 8.6280 (1) Å | T = 295 K |
c = 14.9038 (2) Å | 0.47 × 0.40 × 0.22 mm |
β = 98.3217 (12)° |
Oxford Diffraction Gemini R diffractometer | 3216 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | 2396 reflections with I > 2σ(I) |
Tmin = 0.557, Tmax = 0.830 | Rint = 0.018 |
8137 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.126 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.13 e Å−3 |
3216 reflections | Δρmin = −0.18 e Å−3 |
211 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 | ||
O4 | 0.54332 (9) | 0.78663 (17) | 0.56646 (8) | 0.0813 (4) | |
F | 0.12194 (11) | 0.38071 (16) | −0.04098 (8) | 0.0982 (4) | |
O1 | 0.01131 (9) | 0.41222 (15) | 0.35678 (8) | 0.0737 (3) | |
O2 | 0.33800 (9) | 0.64264 (16) | 0.79007 (7) | 0.0751 (3) | |
O3 | 0.51516 (9) | 0.76879 (15) | 0.74012 (8) | 0.0716 (3) | |
C1 | 0.10184 (11) | 0.43862 (16) | 0.22896 (11) | 0.0576 (3) | |
C2 | 0.16144 (13) | 0.54012 (19) | 0.18363 (12) | 0.0684 (4) | |
H2A | 0.1980 | 0.6219 | 0.2152 | 0.082* | |
C3 | 0.16769 (15) | 0.5225 (2) | 0.09261 (12) | 0.0745 (4) | |
H3A | 0.2071 | 0.5920 | 0.0625 | 0.089* | |
C4 | 0.11452 (13) | 0.4002 (2) | 0.04776 (12) | 0.0698 (4) | |
C5 | 0.05441 (14) | 0.2970 (2) | 0.08954 (14) | 0.0765 (5) | |
H5A | 0.0189 | 0.2149 | 0.0574 | 0.092* | |
C6 | 0.04768 (13) | 0.31760 (19) | 0.17996 (13) | 0.0695 (4) | |
H6A | 0.0061 | 0.2493 | 0.2090 | 0.083* | |
C7 | 0.09279 (11) | 0.45582 (16) | 0.32705 (11) | 0.0591 (3) | |
C8 | 0.18590 (12) | 0.52523 (19) | 0.38636 (11) | 0.0633 (4) | |
H8A | 0.2441 | 0.5643 | 0.3605 | 0.076* | |
C9 | 0.18866 (11) | 0.53327 (18) | 0.47527 (11) | 0.0612 (4) | |
H9A | 0.1275 | 0.4964 | 0.4978 | 0.073* | |
C10 | 0.27643 (11) | 0.59319 (17) | 0.54241 (10) | 0.0572 (3) | |
C11 | 0.26418 (11) | 0.58419 (18) | 0.63367 (10) | 0.0605 (4) | |
H11A | 0.2019 | 0.5398 | 0.6505 | 0.073* | |
C12 | 0.34453 (11) | 0.64123 (18) | 0.69953 (10) | 0.0587 (3) | |
C13 | 0.43756 (12) | 0.70811 (18) | 0.67455 (10) | 0.0591 (3) | |
C14 | 0.44971 (11) | 0.71778 (19) | 0.58304 (10) | 0.0611 (4) | |
C15 | 0.36992 (12) | 0.66065 (19) | 0.51690 (10) | 0.0611 (4) | |
H15A | 0.3783 | 0.6670 | 0.4560 | 0.073* | |
C16 | 0.25626 (17) | 0.5508 (3) | 0.82150 (13) | 0.0855 (5) | |
H16A | 0.1858 | 0.5875 | 0.7950 | 0.128* | |
H16B | 0.2630 | 0.5581 | 0.8863 | 0.128* | |
H16C | 0.2647 | 0.4448 | 0.8044 | 0.128* | |
C17 | 0.60831 (14) | 0.6733 (3) | 0.75995 (13) | 0.0836 (5) | |
H17A | 0.5874 | 0.5746 | 0.7817 | 0.125* | |
H17B | 0.6597 | 0.7219 | 0.8056 | 0.125* | |
H17C | 0.6410 | 0.6586 | 0.7060 | 0.125* | |
C18 | 0.56292 (15) | 0.7943 (3) | 0.47481 (13) | 0.0864 (6) | |
H18A | 0.5608 | 0.6918 | 0.4496 | 0.130* | |
H18B | 0.6332 | 0.8392 | 0.4727 | 0.130* | |
H18C | 0.5080 | 0.8571 | 0.4403 | 0.130* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O4 | 0.0623 (7) | 0.1152 (10) | 0.0677 (7) | −0.0271 (7) | 0.0134 (5) | −0.0012 (6) |
F | 0.1049 (8) | 0.1062 (9) | 0.0868 (7) | −0.0161 (7) | 0.0246 (6) | −0.0256 (6) |
O1 | 0.0523 (6) | 0.0813 (8) | 0.0886 (8) | −0.0117 (5) | 0.0137 (5) | 0.0053 (6) |
O2 | 0.0684 (7) | 0.0970 (8) | 0.0630 (6) | −0.0017 (6) | 0.0201 (5) | 0.0015 (6) |
O3 | 0.0601 (6) | 0.0861 (8) | 0.0679 (6) | −0.0012 (5) | 0.0075 (5) | −0.0097 (5) |
C1 | 0.0414 (6) | 0.0491 (7) | 0.0814 (9) | −0.0007 (6) | 0.0063 (6) | −0.0042 (6) |
C2 | 0.0646 (9) | 0.0594 (9) | 0.0810 (10) | −0.0177 (7) | 0.0099 (7) | −0.0098 (7) |
C3 | 0.0732 (10) | 0.0666 (10) | 0.0854 (11) | −0.0157 (8) | 0.0173 (8) | −0.0035 (8) |
C4 | 0.0600 (8) | 0.0715 (10) | 0.0785 (10) | −0.0014 (7) | 0.0121 (7) | −0.0144 (8) |
C5 | 0.0625 (9) | 0.0657 (10) | 0.1020 (13) | −0.0142 (8) | 0.0148 (8) | −0.0260 (9) |
C6 | 0.0559 (8) | 0.0569 (8) | 0.0981 (12) | −0.0121 (7) | 0.0188 (8) | −0.0114 (8) |
C7 | 0.0456 (7) | 0.0498 (7) | 0.0817 (9) | 0.0004 (6) | 0.0092 (6) | 0.0014 (6) |
C8 | 0.0479 (7) | 0.0645 (9) | 0.0787 (10) | −0.0036 (6) | 0.0135 (6) | −0.0061 (7) |
C9 | 0.0474 (7) | 0.0602 (8) | 0.0763 (9) | 0.0007 (6) | 0.0098 (6) | 0.0070 (7) |
C10 | 0.0474 (7) | 0.0563 (8) | 0.0683 (8) | 0.0046 (6) | 0.0094 (6) | 0.0031 (6) |
C11 | 0.0493 (7) | 0.0617 (8) | 0.0728 (9) | 0.0039 (6) | 0.0167 (6) | 0.0076 (7) |
C12 | 0.0522 (7) | 0.0622 (8) | 0.0633 (8) | 0.0106 (6) | 0.0137 (6) | 0.0038 (6) |
C13 | 0.0511 (7) | 0.0624 (8) | 0.0645 (8) | 0.0053 (6) | 0.0103 (6) | −0.0023 (6) |
C14 | 0.0486 (7) | 0.0690 (9) | 0.0670 (9) | −0.0016 (6) | 0.0128 (6) | 0.0014 (7) |
C15 | 0.0527 (7) | 0.0716 (9) | 0.0600 (8) | 0.0002 (7) | 0.0113 (6) | 0.0022 (7) |
C16 | 0.0891 (12) | 0.0958 (13) | 0.0777 (11) | −0.0033 (10) | 0.0325 (9) | 0.0095 (9) |
C17 | 0.0593 (9) | 0.1147 (15) | 0.0747 (11) | 0.0075 (10) | 0.0026 (8) | −0.0003 (10) |
C18 | 0.0681 (10) | 0.1196 (16) | 0.0749 (11) | −0.0239 (11) | 0.0224 (8) | 0.0043 (10) |
O4—C14 | 1.3602 (18) | C8—H8A | 0.9300 |
O4—C18 | 1.423 (2) | C9—C10 | 1.463 (2) |
F—C4 | 1.350 (2) | C9—H9A | 0.9300 |
O1—C7 | 1.2218 (18) | C10—C11 | 1.393 (2) |
O2—C12 | 1.3635 (18) | C10—C15 | 1.400 (2) |
O2—C16 | 1.420 (2) | C11—C12 | 1.385 (2) |
O3—C13 | 1.3734 (19) | C11—H11A | 0.9300 |
O3—C17 | 1.417 (2) | C12—C13 | 1.390 (2) |
C1—C2 | 1.384 (2) | C13—C14 | 1.396 (2) |
C1—C6 | 1.391 (2) | C14—C15 | 1.384 (2) |
C1—C7 | 1.490 (2) | C15—H15A | 0.9300 |
C2—C3 | 1.378 (2) | C16—H16A | 0.9600 |
C2—H2A | 0.9300 | C16—H16B | 0.9600 |
C3—C4 | 1.367 (2) | C16—H16C | 0.9600 |
C3—H3A | 0.9300 | C17—H17A | 0.9600 |
C4—C5 | 1.368 (3) | C17—H17B | 0.9600 |
C5—C6 | 1.374 (3) | C17—H17C | 0.9600 |
C5—H5A | 0.9300 | C18—H18A | 0.9600 |
C6—H6A | 0.9300 | C18—H18B | 0.9600 |
C7—C8 | 1.477 (2) | C18—H18C | 0.9600 |
C8—C9 | 1.322 (2) | ||
C14—O4—C18 | 117.66 (13) | C12—C11—C10 | 120.19 (13) |
C12—O2—C16 | 117.99 (14) | C12—C11—H11A | 119.9 |
C13—O3—C17 | 113.25 (13) | C10—C11—H11A | 119.9 |
C2—C1—C6 | 118.10 (15) | O2—C12—C11 | 124.36 (13) |
C2—C1—C7 | 122.51 (13) | O2—C12—C13 | 115.61 (13) |
C6—C1—C7 | 119.38 (13) | C11—C12—C13 | 119.98 (13) |
C3—C2—C1 | 121.37 (15) | O3—C13—C12 | 119.54 (13) |
C3—C2—H2A | 119.3 | O3—C13—C14 | 120.55 (13) |
C1—C2—H2A | 119.3 | C12—C13—C14 | 119.88 (14) |
C4—C3—C2 | 118.33 (16) | O4—C14—C15 | 124.71 (14) |
C4—C3—H3A | 120.8 | O4—C14—C13 | 114.82 (13) |
C2—C3—H3A | 120.8 | C15—C14—C13 | 120.47 (13) |
F—C4—C3 | 118.60 (16) | C14—C15—C10 | 119.45 (14) |
F—C4—C5 | 118.96 (15) | C14—C15—H15A | 120.3 |
C3—C4—C5 | 122.45 (16) | C10—C15—H15A | 120.3 |
C4—C5—C6 | 118.50 (15) | O2—C16—H16A | 109.5 |
C4—C5—H5A | 120.8 | O2—C16—H16B | 109.5 |
C6—C5—H5A | 120.8 | H16A—C16—H16B | 109.5 |
C5—C6—C1 | 121.24 (15) | O2—C16—H16C | 109.5 |
C5—C6—H6A | 119.4 | H16A—C16—H16C | 109.5 |
C1—C6—H6A | 119.4 | H16B—C16—H16C | 109.5 |
O1—C7—C8 | 121.74 (15) | O3—C17—H17A | 109.5 |
O1—C7—C1 | 120.62 (13) | O3—C17—H17B | 109.5 |
C8—C7—C1 | 117.64 (12) | H17A—C17—H17B | 109.5 |
C9—C8—C7 | 121.69 (14) | O3—C17—H17C | 109.5 |
C9—C8—H8A | 119.2 | H17A—C17—H17C | 109.5 |
C7—C8—H8A | 119.2 | H17B—C17—H17C | 109.5 |
C8—C9—C10 | 127.76 (14) | O4—C18—H18A | 109.5 |
C8—C9—H9A | 116.1 | O4—C18—H18B | 109.5 |
C10—C9—H9A | 116.1 | H18A—C18—H18B | 109.5 |
C11—C10—C15 | 120.04 (13) | O4—C18—H18C | 109.5 |
C11—C10—C9 | 118.17 (13) | H18A—C18—H18C | 109.5 |
C15—C10—C9 | 121.77 (13) | H18B—C18—H18C | 109.5 |
C6—C1—C2—C3 | −0.2 (2) | C16—O2—C12—C11 | 14.4 (2) |
C7—C1—C2—C3 | −179.40 (14) | C16—O2—C12—C13 | −168.15 (15) |
C1—C2—C3—C4 | −0.9 (3) | C10—C11—C12—O2 | 177.51 (14) |
C2—C3—C4—F | −178.84 (16) | C10—C11—C12—C13 | 0.2 (2) |
C2—C3—C4—C5 | 1.0 (3) | C17—O3—C13—C12 | 104.04 (17) |
F—C4—C5—C6 | 179.78 (15) | C17—O3—C13—C14 | −78.13 (19) |
C3—C4—C5—C6 | −0.1 (3) | O2—C12—C13—O3 | 0.4 (2) |
C4—C5—C6—C1 | −1.0 (3) | C11—C12—C13—O3 | 177.92 (13) |
C2—C1—C6—C5 | 1.2 (2) | O2—C12—C13—C14 | −177.47 (13) |
C7—C1—C6—C5 | −179.61 (15) | C11—C12—C13—C14 | 0.1 (2) |
C2—C1—C7—O1 | 149.90 (16) | C18—O4—C14—C15 | −2.9 (3) |
C6—C1—C7—O1 | −29.3 (2) | C18—O4—C14—C13 | 177.40 (16) |
C2—C1—C7—C8 | −30.8 (2) | O3—C13—C14—O4 | 1.6 (2) |
C6—C1—C7—C8 | 150.00 (14) | C12—C13—C14—O4 | 179.41 (14) |
O1—C7—C8—C9 | 4.9 (2) | O3—C13—C14—C15 | −178.09 (15) |
C1—C7—C8—C9 | −174.35 (14) | C12—C13—C14—C15 | −0.3 (2) |
C7—C8—C9—C10 | 177.60 (14) | O4—C14—C15—C10 | −179.47 (15) |
C8—C9—C10—C11 | −177.15 (15) | C13—C14—C15—C10 | 0.2 (2) |
C8—C9—C10—C15 | 4.0 (2) | C11—C10—C15—C14 | 0.1 (2) |
C15—C10—C11—C12 | −0.3 (2) | C9—C10—C15—C14 | 178.96 (14) |
C9—C10—C11—C12 | −179.18 (14) |
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3A···Cg2i | 0.93 | 2.91 | 3.6571 (19) | 138 |
Symmetry code: (i) x, −y+3/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C18H17FO4 |
Mr | 316.32 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 295 |
a, b, c (Å) | 12.4250 (2), 8.6280 (1), 14.9038 (2) |
β (°) | 98.3217 (12) |
V (Å3) | 1580.91 (4) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 0.85 |
Crystal size (mm) | 0.47 × 0.40 × 0.22 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini R diffractometer |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.557, 0.830 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8137, 3216, 2396 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.634 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.126, 1.10 |
No. of reflections | 3216 |
No. of parameters | 211 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.18 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3A···Cg2i | 0.93 | 2.91 | 3.6571 (19) | 138.0 |
Symmetry code: (i) x, −y+3/2, z−1/2. |
Acknowledgements
KV thanks the UGC-SAP for the award of a Junior Research Fellowship. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.
References
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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.
Chalcones are unique molecules with significant biological activity (Dimmock et al. 1999). Chalcones and their analogs have been shown to have potential antifungal (Opletalova & Sedivy, 1999), anti-tuberculosis (Lin et al. 2002), anti-infective and anti-inflammatory properties (Nowakowska, 2007). The synthesis and biological activity of some fluorinated chalcone derivatives have also been reported (Nakamura et al. 2002). Structures of a series of substituted (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-phenylprop-2-en-1-ones have also been reported. (Chopra et al. 2007). As a continuation of our work on chalcones (Jasinski et al. 2009) and in view of the importance of fluoro-chalcones, this paper describes a new polymorphic form of (I), C18H17FO4, (2E)-1-(4-fluorophenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one, first reported by Patil et al. (2007). Substantial changes in the cell parameters provides solid support for the recognition of this new polymorphic form for (I).
The title compound,(I), is a chalcone analog and consists of substituted phenyl rings bonded at the opposite ends of a propenone moiety, the biologically active region (Fig. 1). The dihedral angle between the mean planes of the phenyl rings with the 4-fluorophenyl and trimethoxyphenyl substituents is 28.7 (1)° compared to 20.8 (6)° in the polymorph. The angles between the mean plane of the prop-2-ene-1-one group and those of the 4-fluorophenyl and trimethoxyphenyl rings are 30.3 (4)° and 7.4 (7)°, respectively, compared to 10.7 (3)° and 12.36° as reported by Patil et al (2007). While the two meta -methoxy groups are in the plane of the trimethoxy substituted phenyl ring, the para -methoxy group is in a synclinical (-sc) (torsion angle C(12)-C(13)-C(17)-O(3) = -78.1 (2)°) or anticlinical (+ac) (torsion angle C(14)-C(13)-C(17)-O(3) = 104.0 (4)°) orientation, compared to the (+sc) (torsion angle C(12)-C(13)-C(17)-O(3) = 53.0 (4)°) or -ac (torsion angle C(14)-C(13)-C(17)-O(3) =-132.4 (7)°) orientation as reported by Patil et al. (2007). While no classical hydrogen bonds are present, weak C(3)-H(3A)···Cg2 [C(3)-H(3A)···Cg2 = 138°; C(3)···Cg2 = 3.6571 (19) Å; x,3/2-y, -1/2+z; where Cg2 = C(10)-C(15)] C—H···π-ring intermolecular interactions are observed which contribute to the stability of the crystal packing (Fig. 2). The two polymorphs crystallize in the same space group,P21/c, but have different cell parameters for the a [12.4250 (2)Å vs 7.693 (0)Å], b [8.62800 (10)Å vs 15.232 (1)Å], c [14.9038 (2)Å vs 14.128 (1)Å] axes and β angle [98.3217 (12)° vs 106.60 (0)°].
A geometry optimized density functional theory (DFT) calculation (Schmidt & Polik, 2007) was performed for each of the two polymorphs, with the GAUSSIAN03 program package (Frisch et al. 2004) employing the B3-LYP (Becke three parameter Lee-Yang-Parr) exchange correlation functional, which combines the hybrid exchange functional of Becke (Becke, 1988,1993) with the gradient-correlation functional of Lee, Yang and Parr (Lee et al. 1988) and the 6–311+G(d,p) basis set (Hehre et al. 1986). Starting geometries were taken from X-ray refinement data for (I) and from coordinates from the Cambridge Structural Database (CSD) (Allen, 2002) for the Patil et al. (2007) structure (SIRDUT). Interestingly, both structures converged to nearly the same geometric state. The dihedral angle between the mean planes of the phenyl rings within the 4-fluorophenyl and trimethoxyphenyl groups became 18.0 (9)° compared to 19.3 (6)° (SIRDUT). The angle between the mean plane of the prop-2-ene-1-one group and the mean plane of phenyl rings within the 4-fluorophenyl and trimethoxyphenyl groups became 14.0 (3)° and 5.2 (3)°, respectively, versus 14.4 (9)° and 5.2 (5)° (SIRDUT), significantly different from that observed in the crystalline state for each polymorph. In addition, the para methoxy group became synclinical (-sc) (torsion angle C(12)—C(13)—C(17)—O(3) = -77.8 (2)°) or anticlinical (+ac) (torsion angle C(14)—C(13)—C(17)—O(3) = 106.2 (8)°) in (I), compared to a (+sc) (torsion angle C(12)—C(13)—C(17)—O(3) = 79.2 (4)°°) or -ac (torsion angle C(14)—C(13)—C(17)—O(3) = -104.9 (5)°) in SIRDUT. It is clear that each polymeric form adjusted itself in different ways to achieve the DFT calculated geometric state. Bond distances and bond angles are relatively unchanged between the DFT calculated values and the observed values in (I) and SIRDUT with the exception of the para methoxy group as described earlier.