2′,3,4,4′,5-Penta­meth­oxy­chalcone

Johannes H van Tonder; Theunis J Muller; Barend C B Bezuidenhoudt

doi:10.1107/S1600536810040845

. 2010 Oct 23;66(Pt 11):o2889–o2890. doi: 10.1107/S1600536810040845

2′,3,4,4′,5-Pentamethoxychalcone

Johannes H van Tonder ^a, Theunis J Muller ^a,^*, Barend C B Bezuidenhoudt ^a

PMCID: PMC3009150 PMID: 21589069

Abstract

In the title chalcone [systemetic name 1-(2,4-dimethoxyphenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one], C₂₀H₂₂O₆, the dihedral angle between the plane of the two benzene rings is 7.03 (4)° with all but one of the methoxy groups essentially co-planar with these rings [C—C—O—C torsion angles = −76.1 (2), −0.7 (3), 1.8 (3), −6.2 (3), 2.0 (3)°]. An intramolecular C—H⋯O interaction occurs. The crystal packing is stabilized by weak intermolecular C—H⋯O hydrogen bonds.

Related literature

For standard bond lengths, see: Allen et al. (1987 ▶). For related structures, see: Patil et al. (2006 ▶); van Tonder et al. (2010 ▶); Teh et al. (2006 ▶); Rosli et al. (2006 ▶). For the synthesis of the title compound, see: Kraus & Roy (2008 ▶). For the biological activity of flavonoids, see: Pietta et al. (2003 ▶). For non-linear optical (NLO) properties of chalcones, see: Marais et al. (2005) ▶; Uchida et al. (1998) ▶; Kitaoka et al. (1990 ▶); Goto et al. (1991 ▶); Zhang et al. (1990 ▶). For applications of NLO crystals, see: Chemla & Zyss (1987 ▶).

Experimental

Crystal data

C₂₀H₂₂O₆
M _r = 358.38
Orthorhombic,
a = 7.3041 (2) Å
b = 8.0288 (3) Å
c = 29.217 (1) Å
V = 1713.38 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.40 × 0.28 × 0.27 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.960, T _max = 0.973
30899 measured reflections
2488 independent reflections
2343 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.113
S = 1.21
2488 reflections
241 parameters
H-atom parameters constrained
Δρ_max = 0.47 e Å⁻³
Δρ_min = −0.44 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT-Plus (Bruker, 2008 ▶); data reduction: SAINT-Plus and XPREP (Bruker, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenberg & Putz, 2005 ▶); software used to prepare material for publication: WingGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810040845/zs2069sup1.cif

e-66-o2889-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810040845/zs2069Isup2.hkl

e-66-o2889-Isup2.hkl^{(119.8KB, 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
C8—H8⋯O1	0.93	2.13	2.798 (2)	127
C11—H11⋯O3ⁱ	0.93	2.4	3.306 (2)	164
C17—H17B⋯O4ⁱⁱ	0.96	2.52	3.455 (2)	165

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The University of the Free State is gratefully acknowledged for financial support.

supplementary crystallographic information

Comment

Flavonoids are a prominent class of secondary plant metabolites known for their wide range of biological activity that include antibacterial, antifungal, anti-tumor and anti-inflammatory properties (Pietta et al., 2003). Chalcones are an important subclass of these compounds and are often utilized as intermediates in the synthesis of a variety of cyclic flavonoids (Marais et al., 2005). Furthermore, many chalcone derivatives are a class of organic compounds with excellent NLO properties (Kitaoka et al., 1990; Goto et al., 1991; Zhang et al., 1990; Uchida et al., 1998; Patil et al., 2006), much better than those observed in inorganic crystals. Nonlinear optical materials capable of generating second harmonic frequency play an important role in the domain of optoelectronics and photonics (Rosli et al., 2006). NLO crystals with high conversion efficiencies for second harmonic generation (SHG) and which are transparent in the visible and ultraviolet ranges are required for numerous device applications (Chemla & Zyss, 1987). Advantages of using organic molecules as NLO materials stem from the fact that they can be designed to optimize the desired NLO properties. At the molecular level, compounds likely to exhibit larger values of molecular hyperpolarizability (β), must have polarizable electrons (e.g. π electrons) spread over a large distance. We report here the synthesis and structure of a new chalcone, the title compound C₂₀H₂₂O₆, (I).

Crystals of (I) exhibit second-order nonlinear optical properties. Bond distances in (I) have normal values (Allen et al., 1987) and these and bond angles are comparable to those in related structures (van Tonder et al., 2010; Teh et al., 2006; Patil et al., 2006; Rosli et al., 2006). The least-squares plane through the enone group (C7, C8, C9 and O3) exhibit dihedral angles of 5.25 (5)° and 3.32 (6)° with the C1—C6 and C10—C15 benzene rings, respectively. The dihedral angle between the two benzene rings is 7.03 (4)°. The methoxy group attached at C13 is twisted away from the C10—C15 benzene ring plane, with a C19—O5—C13—C12 torsion angle of -76.1 (2)°. The methoxy groups at C1, C3, C12 and C14 are almost coplanar with the C1—C6 and C10—C15 benzene rings with C16—O1—C1—C2, C17—O2—C3—C2, C18—O4—C12—C11 and C20—O6—C14—C15 torsion angles of -0.7 (3), 1.8 (3), -6.2 (3) and 2.0 (3)°, respectively. The C8—C9 bond [1.332 (3) Å] is significantly shorter than the C6—C7, C7—C8 and C9—C10 bonds [1.498 (3), 1.483 (3) and 1.473 (2) respectively]. The C8—C9 bond length indicates a double bond rather than single bonds as in the other bonds. This corresponds well with literature values (Van Tonder et al. 2010). Intramolecular C5—H5···O3, C8—H8···O1, C9—H9···O3 and C19—H19C···O4 interactions are found in the molecular structure of (I), while the molecules form chains through weak intermolecular C11—H11···O3ⁱ and C17—H17B···O4ⁱⁱ hydrogen bonds (Table 1).

Experimental

Freshly ground KOH (15.1 g; 270 mmol; 32 eq.) was added to a cold (ice bath) stirred solution of 2',4'-dimethoxyacetophenone (1.52 g; 8.4 mmol) and 3,4,5-trimethoxybenzaldehyde (1.95 g; 10.0 mmol; 1.2 eq.) in ethanol (60 ml). The temperature of the reaction mixture was allowed to rise to room temperature and stirring contined until completion of the reaction (TLC). Extraction of the water phase with ethyl acetate (3 x 100 ml) followed by neutralization with aqueous NaHCO₃ (litmus) and washing with water gave the crude chalcone after drying of the solution (Na₂SO₄) and evaporation of the solvent in vacuo at ca. 40° C. Crystallization from ethanol afforded the desired chalcone (2.15 g; 71.2%) as yellow needles. R_f 0.17 (H:A; 8:2); m.p. 85.1° C; ¹H NMR (600 MHz, CDCl₃) δ 7.70 (1H, d, J = 8.61 Hz, H-6'), 7.54 (1H, d, J = 15.72 Hz, H-β), 7.35 (1H, d, J = 15.72 Hz, H-α), 6.79 (2H, s, H-2,6), 6.53 (1H, dd, J = 2.27, 8.61 Hz, H-5'), 6.47 (1H, d, J = 2.27 Hz, H-3'), 3.86 (9H, s, –OCH₃), 3.85 (3H, s, –OCH₃), 3.83 (3H, s, –OCH₃); ¹³C NMR (151 MHz, CDCl₃) δ 190.47 (CO), 164.13, 160.31, 153.39, 142.23 (C-β), 139.97, 132.72 (C-6'), 131.01, 126.68 (C-α), 122.21, 105.49 (C-2,6), 105.23 (C-5'), 98.70 (C-3'), 60.96 (–OCH₃), 56.15 (–OCH₃), 55.75 (–OCH₃), 55.54 (–OCH₃).