A second polymorph of (2E)-1-(4-fluoro­phen­yl)-3-(3,4,5-trimethoxy­phen­yl)prop-2-en-1-one

Jerry P Jasinski; Ray J Butcher; K Veena; B Narayana; H S Yathirajan

doi:10.1107/S1600536809028517

. 2009 Jul 25;65(Pt 8):o1965–o1966. doi: 10.1107/S1600536809028517

A second polymorph of (2E)-1-(4-fluorophenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one

Jerry P Jasinski ^a, Ray J Butcher ^b,^*, K Veena ^c, B Narayana ^c, H S Yathirajan ^d

PMCID: PMC2977262 PMID: 21583642

Abstract

The crystal structure of the title compound, C₁₈H₁₇FO₄, 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 space group, 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.

Related 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

C₁₈H₁₇FO₄
M _r = 316.32
Monoclinic,
a = 12.4250 (2) Å
b = 8.6280 (1) Å
c = 14.9038 (2) Å
β = 98.3217 (12)°
V = 1580.91 (4) Å³
Z = 4
Cu Kα radiation
μ = 0.85 mm⁻¹
T = 295 K
0.47 × 0.40 × 0.22 mm

Data collection

Oxford Diffraction Gemini R diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 ▶) T _min = 0.557, T _max = 0.830
8137 measured reflections
3216 independent reflections
2396 reflections with I > 2σ(I)
R _int = 0.018

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.126
S = 1.10
3216 reflections
211 parameters
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: CrysAlis Pro (Oxford Diffraction, 2007 ▶); cell refinement: 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.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809028517/sj2632sup1.cif

e-65-o1965-sup1.cif^{(19.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809028517/sj2632Isup2.hkl

e-65-o1965-Isup2.hkl^{(157.8KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3A⋯Cg2ⁱ	0.93	2.91	3.6571 (19)	138

Open in a new tab

Symmetry code: (i) Inline graphic . Cg2 is the centroid of the C10–C15 ring.

Acknowledgments

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.

supplementary crystallographic information

Comment

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.

Experimental

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%).