(1E,4E)-1,5-Bis(2,4,6-trimeth­oxy­phen­yl)penta-1,4-dien-3-one

Pumsak Ruanwas; Suchada Chantrapromma; Hoong-Kun Fun

doi:10.1107/S1600536810049299

. 2010 Dec 4;67(Pt 1):o33–o34. doi: 10.1107/S1600536810049299

(1E,4E)-1,5-Bis(2,4,6-trimethoxyphenyl)penta-1,4-dien-3-one

Pumsak Ruanwas ^a, Suchada Chantrapromma ^b,^*,^‡, Hoong-Kun Fun ^c,^§

PMCID: PMC3050352 PMID: 21522745

Abstract

There are two crystallographically independent molecules in the asymmetric unit of the title bischalcone derivative, C₂₃H₂₆O₇. The molecules are unsymmetrical and almost planar: the dihedral angle between two benzene rings is 1.04 (7)° in one molecule and 2.31 (7)° in the other. The central penta-1,4-dien-3-one fragment makes dihedral angles of 7.61 (7) and 6.82 (7)° with the two adjacent benzene rings in one molecule, while the corresponding values are 7.85 (7) and 9.42 (6)° in the other. In both molecules, the three methoxy groups of the two 2,4,6-trimethoxyphenyl units are coplanar with the attached benzene rings [C—O—C—C- torsion angles of −1.5 (2), −7.2 (2) and 4.1 (2)° in one molecule and −0.7 (2), −5.5 (2) and −0.6 (2)° in the other]. The molecular conformations are stabilized by weak intramolecular C—H⋯O interactions generating two S(6) ring motifs. In the crystal, molecules are linked by weak intermolecular C—H⋯O interactions into zigzag chains parallel to the c axis. The crystal structure is further stabilized by C—H⋯π interactions and π–π interactions with centroid–centroid distances of 3.6433 (8) Å.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For related structures, see: Fun et al. (2010 ▶); Harrison et al. (2006 ▶). For background to and applications of bischalcones, see: Gomes et al. (2009 ▶); Lee et al. (2009 ▶); Quincoces et al. (2008 ▶); Uchida et al. (1998 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₃H₂₆O₇
M _r = 414.44
Monoclinic,
a = 15.7417 (2) Å
b = 15.1192 (2) Å
c = 19.4803 (3) Å
β = 117.827 (1)°
V = 4100.21 (11) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.39 × 0.32 × 0.17 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.963, T _max = 0.983
50384 measured reflections
10908 independent reflections
7903 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.139
S = 1.04
10908 reflections
553 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810049299/rz2523sup1.cif

e-67-00o33-sup1.cif^{(36KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810049299/rz2523Isup2.hkl

e-67-00o33-Isup2.hkl^{(533.4KB, hkl)}

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

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

Cg1, Cg2 and Cg3 are the centroids of the C1A–C6A, C12A–C17A and C12B–C17B rings, respectively

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7A—H7AA⋯O1A	0.93	2.42	2.787 (2)	104
C7A—H7AA⋯O2A	0.93	2.29	2.704 (2)	106
C8A—H8AA⋯O4A	0.93	2.18	2.7844 (17)	121
C7B—H7BA⋯O1B	0.93	2.49	2.8351 (19)	102
C7B—H7BA⋯O2B	0.93	2.33	2.704 (2)	104
C8B—H8BA⋯O4B	0.93	2.16	2.7643 (18)	121
C10A—H10A⋯O5A	0.93	2.26	2.852 (2)	121
C10B—H10B⋯O5B	0.93	2.26	2.855 (2)	121
C11A—H11A⋯O7A	0.93	2.23	2.6599 (17)	108
C11B—H11B⋯O7B	0.93	2.23	2.6700 (17)	108
C20A—H20C⋯O1B	0.96	2.47	3.339 (2)	151
C20B—H20E⋯O1Aⁱ	0.96	2.37	3.0238 (19)	125
C23A—H23C⋯O1Aⁱⁱ	0.96	2.39	3.319 (2)	162
C23B—H23D⋯O1Bⁱⁱ	0.96	2.41	3.262 (2)	148
C18A—H18C⋯Cg1ⁱⁱⁱ	0.96	2.65	3.4503 (17)	141
C21A—H21C⋯Cg2^iv	0.96	2.94	3.5813 (18)	126
C21B—H21E⋯Cg3^v	0.96	2.72	3.5809 (16)	150

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

PR thanks the Center of Excellence for Innovation in Chemistry (PERCH–CIC), Commission on Higher Education, Ministry of Education, and the Graduate School, Prince of Songkla University, for financial support. The authors thank the Prince of Songkla University and Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811160.

supplementary crystallographic information

Comment

Bischalcone is an important class of compounds due to their variety of properties such as non-linear optical (Uchida et al., 1998) and fluorescence properties (Gomes et al., 2009) and activities involving anti-inflammatory, antioxidant and anti-tyrosinase activities (Lee et al., 2009) and cytotoxic activities (Quincoces et al., 2008). We have previously reported the crystal structure of (1E,4E)-1,5-bis(2,4,5-trimethoxyphenyl)penta-1,4-dien-3-one (I) (Fun et al., 2010). The title bischalcone (II) was synthesized in order to study the effect of the positions of the trimethoxy substituents to its fluorescence property and anti-tyrosinase activity. Our anti-tyrosinase activity testing showed that the title bischacone possesses anti-tyrosinase activity. We report herein the crystal structure of (II).

There are two crystallograpich independent molecules (A and B) in the asymmetric unit of (II) (Fig. 1) with the same conformation but with slight differences in bond angles. The molecular structure of (II) is unsymmetrical and almost planar. The dihedral angle between the C1–C6 and C12–C17 benzene rings is 1.04 (7)° in molecule A whereas it is 2.31 (7)° in molecule B. The central penta-1,4-dien-3-one unit (C7–C11/O1) is planar with r.m.s. of 0.0124 (1) and 0.0433 (1) Å for molecule A and B, respectively. This unit makes a dihedral angles of 7.61 (7) and 6.82 (7)° with the two adjacent C1–C6 and C12–C17 benzene rings, respectively, in molecule A whereas the corresponding values are 7.85 (7) and 9.42 (6)° in molecule B. The three methoxy groups on the C1–C6 benzene ring are planarly attached, with the C18–O2–C1–C2, C19–O3–C3–C2 and C20–O4–C5–C4 torsion angles of -1.5 (2), -7.2 (2) and 4.1 (2)° in molecule A and -0.7 (2), -5.5 (2) and -0.6 (2)° in molecule B. The same orientation is observed for the three methoxy groups on the C12–C17 benzene ring as indicated by the torsion angles C21–O5–C13–C14, C22–O6–C15–C14 and C23–O7–C17–C16 of -0.1 (2), -0.7 (2) and 0.8 (2)°, respectively, for molecule A and the corresponding values of -0.9 (2), 1.6 (2) and -4.9 (2)° for molecule B. In each molecule, intramolecular C8A—H8AA···O4A and C10A—H10A···O5A [in molecule A]; C8B—H8BA···O4B and C10B—H10B···O5B [in molecule B] weak interactions (Table 1, Fig. 1) generate S(6) ring motifs (Bernstein et al., 1995). The bond distances are in normal ranges (Allen et al., 1987) and are comparable with those of related structures (Fun et al., 2010; Harrison et al., 2006). However there are less C—H···O weak interactions but more C—H···π interactions in (II) than in (I).

In the crystal packing (Fig. 2), the molecules are linked by intermolecular C—H···O weak interactions (Table 1) into zigzag chains along the c axis. The crystal is stabilized by intermolecular C—H···O weak interactions and C—H···π interactions (Table 1). π–π interactions are observed with Cg₁···Cg₃ⁱ = 3.6433 (8) Å (symmetry code: (i) x, 1/2 - y, -1/2 + z; Cg₁ and Cg₃ are the centroids of the C1A–C6A and C12B–C17B rings, respectively).

Experimental

The title compound was synthesized by dissolving the 2,4,6-trimethoxybenzaldehyde (0.5 g, 2.55 mmol) in acetone (50 ml). A NaOH 50% aqueous solution (2 ml) was then added and, after stirring at room temperature for 1h, the resulting yellow solid was collected by filtration, washed with distilled water and dried. Pale yellow block-shaped single crystals of the title compound suitable for x-ray structure determination were recrystalized from ethanol by the slow evaporation of the solvent at room temperature after a week. M. p. 494–495 K.