1,3-Bis(3,4-dimethoxy­phen­yl)prop-2-en-1-one

In the title compound, C₁₉H₂₀O₅, the dihedral angle between the benzene rings is 5.92 (6)°. The mol­ecules are linked by two pairs of C—H...O hydrogen bonds into a centrosymmetric dimer of R₂¹(6) ring motif. In addition, the crystal structure is stabilized by C—H...π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 297 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.054
• wR factor = 0.163
• Data-to-parameter ratio = 22.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         44 Perc.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Many chalcone derivatives display significant second-order nonlinear optical (NLO) properties (Patil et al., 2006; Patil, Dharmaprakash et al., 2007). As part of our ongoing studies in this area (Patil, Teh, Fun, Babu et al., 2007; Patil, Teh, Fun, Razak et al., 2007), we have prepared the title chalcone derivative, (I) (Fig. 1). Crystals of (I) do not exhibit second-order nonlinear

optical properties as they crystallize in a centrosymmetric space group.

Bond lengths and angles in (I) show normal values (Allen et al., 1987) and are comparable with those in related structures (Patil, Teh, Fun, Ramesh Babu et al., 2007; Patil, Teh, Fun, Razak et al., 2007). The enone group (C7–C9/O3) makes dihedral angles of 1.15 (7) and 4.79 (7)°, respectively, with the C1–C6 and C10–C15 benzene rings. The dihedral angle between the benzene rings is 5.92 (6)°. The four methoxy groups are almost coplanar with the attached rings,

as shown by the C16—O1—C2—C1, C17—O2—C3—C4, C18—O4—C12—C11 and C19—O5—C13—C14 torsion angles of -6.4 (3), -2.1 (3), 3.8 (3) and 3.3 (3)°, respectively.

In the crystal structure (Fig. 2), the C5—H5···O3ⁱ and C7—H7···O3ⁱ intermolecular interactions [Table 1; symmetry code: (i) -x, 2 - y, -z] form a pair of bifurcated acceptor bonds, which generate a centrosymmetric dimer of R¹₂(6) ring motif (Bernstein et al., 1995). The crystal structure is further stabilized by C—H···π interactions (Table 1) involving the C1–C6 benzene ring (centroid Cg1).

Related literature

For hydrogen-bond motifs, see Bernstein et al. (1995). For bond-length data, see Allen et al.,(1987). For related literature, see Patil et al. (2006); Patil, Dharmaprakash et al. (2007); Patil, Teh, Fun, Babu et al. (2007); Patil, Teh, Fun, Razak et al. (2007).

S2. Experimental

3,4-Dimethoxybenzaldehyde (0.01 mol) and 3,4-dimethoxyacetophenone (0.01 mol) were stirred in methanol (60 ml) at room temperature. 20% NaOH aqueous solution

(20 ml) was added and the mixture was stirred for 6 h. The resulting precipitate was filtered off, washed with water and dried. The crude product was recrystallized from acetone. Single crystals suitable for X-ray analysis were obtained by slow evaporation of an acetone solution at room temperature.

S3. Refinement

H atoms were positioned geometrically and treated as riding, with C—H = 0.93 or 0.96 Å, and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atomic numbering. The dashed line indicates a hydrogen bond.
	Fig. 2. The crystal packing of (I), viewed down the b axis. Dashed lines indicate hydrogen bonds. H atoms not involved in the hydrogen bonds have been omitted for clarity.

1,3-Bis(3,4-dimethoxyphenyl)prop-2-en-1-one

Crystal data

C19H20O5	F(000) = 696
Mr = 328.35	Dx = 1.278 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3229 reflections
a = 9.3543 (2) Å	θ = 2.3–30.1°
b = 7.9014 (2) Å	µ = 0.09 mm^−1
c = 24.0405 (6) Å	T = 297 K
β = 106.148 (2)°	Block, yellow
V = 1706.78 (7) Å^3	0.55 × 0.42 × 0.34 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	5021 independent reflections
Radiation source: fine-focus sealed tube	2222 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
Detector resolution: 8.33 pixels mm^-1	θmax = 30.1°, θmin = 2.3°
ω scans	h = −13→13
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −8→11
Tmin = 0.961, Tmax = 0.970	l = −33→33
21071 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.163	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0671P)^2 + 0.0194P] where P = (Fo^2 + 2Fc^2)/3
5021 reflections	(Δ/σ)max = 0.001
221 parameters	Δρmax = 0.13 e Å^−3
0 restraints	Δρmin = −0.15 e Å^−3

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.67098 (13)	0.57700 (17)	0.16281 (5)	0.0677 (4)
O2	0.75255 (13)	0.59791 (19)	0.06831 (5)	0.0759 (4)
O3	−0.08215 (15)	1.0025 (2)	0.06712 (5)	0.0941 (5)
O4	−0.38043 (13)	1.09985 (18)	0.20964 (5)	0.0733 (4)
O5	−0.22752 (14)	0.96920 (17)	0.30656 (5)	0.0698 (4)
C1	0.43616 (18)	0.7133 (2)	0.11822 (7)	0.0543 (5)
H1	0.4059	0.7016	0.1517	0.065*
C2	0.57227 (18)	0.6523 (2)	0.11712 (7)	0.0536 (4)
C3	0.61759 (19)	0.6654 (2)	0.06602 (7)	0.0591 (5)
C4	0.5246 (2)	0.7434 (3)	0.01857 (7)	0.0720 (6)
H4	0.5538	0.7533	−0.0152	0.086*
C5	0.3879 (2)	0.8078 (3)	0.02014 (7)	0.0678 (5)
H5	0.3271	0.8611	−0.0124	0.081*
C6	0.34124 (18)	0.7934 (2)	0.06965 (7)	0.0558 (5)
C7	0.19693 (19)	0.8618 (2)	0.07048 (7)	0.0618 (5)
H7	0.1403	0.9114	0.0364	0.074*
C8	0.13802 (19)	0.8609 (2)	0.11453 (7)	0.0618 (5)
H8	0.1914	0.8103	0.1490	0.074*
C9	−0.0071 (2)	0.9355 (2)	0.11174 (7)	0.0610 (5)
C10	−0.06215 (18)	0.9333 (2)	0.16383 (7)	0.0522 (4)
C11	−0.19713 (18)	1.0139 (2)	0.16105 (7)	0.0555 (5)
H11	−0.2515	1.0622	0.1263	0.067*
C12	−0.25045 (18)	1.0230 (2)	0.20840 (7)	0.0535 (4)
C13	−0.16737 (19)	0.9508 (2)	0.26100 (7)	0.0560 (5)
C14	−0.03606 (19)	0.8694 (2)	0.26395 (7)	0.0610 (5)
H14	0.0183	0.8205	0.2986	0.073*
C15	0.01550 (19)	0.8599 (2)	0.21544 (7)	0.0581 (5)
H15	0.1040	0.8031	0.2176	0.070*
C16	0.6347 (2)	0.5778 (3)	0.21637 (7)	0.0736 (6)
H16A	0.7159	0.5310	0.2461	0.110*
H16B	0.5469	0.5110	0.2129	0.110*
H16C	0.6167	0.6919	0.2264	0.110*
C17	0.7989 (2)	0.6041 (3)	0.01652 (8)	0.0914 (7)
H17A	0.8921	0.5461	0.0226	0.137*
H17B	0.8104	0.7200	0.0065	0.137*
H17C	0.7253	0.5505	−0.0144	0.137*
C18	−0.4705 (2)	1.1666 (3)	0.15663 (8)	0.0774 (6)
H18A	−0.5612	1.2104	0.1623	0.116*
H18C	−0.4935	1.0786	0.1280	0.116*
H18B	−0.4179	1.2560	0.1437	0.116*
C19	−0.1418 (3)	0.9055 (3)	0.36133 (8)	0.0897 (7)
H19C	−0.1914	0.9313	0.3903	0.135*
H19A	−0.0452	0.9573	0.3716	0.135*
H19B	−0.1313	0.7851	0.3589	0.135*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0567 (8)	0.0852 (10)	0.0633 (7)	0.0140 (7)	0.0199 (6)	0.0091 (7)
O2	0.0597 (8)	0.1047 (11)	0.0700 (8)	0.0131 (7)	0.0292 (6)	−0.0088 (7)
O3	0.0822 (10)	0.1380 (15)	0.0661 (9)	0.0465 (10)	0.0273 (7)	0.0263 (9)
O4	0.0603 (8)	0.0915 (11)	0.0706 (8)	0.0226 (7)	0.0223 (6)	0.0034 (7)
O5	0.0727 (8)	0.0810 (10)	0.0593 (7)	0.0073 (7)	0.0245 (6)	−0.0009 (6)
C1	0.0559 (11)	0.0594 (12)	0.0521 (9)	0.0004 (9)	0.0224 (8)	−0.0002 (8)
C2	0.0500 (10)	0.0582 (12)	0.0521 (9)	−0.0001 (9)	0.0133 (8)	−0.0010 (8)
C3	0.0525 (11)	0.0672 (13)	0.0607 (10)	0.0012 (9)	0.0206 (8)	−0.0068 (9)
C4	0.0727 (13)	0.0936 (16)	0.0565 (11)	0.0063 (12)	0.0291 (10)	0.0025 (10)
C5	0.0657 (12)	0.0835 (15)	0.0558 (10)	0.0111 (11)	0.0194 (9)	0.0103 (9)
C6	0.0536 (10)	0.0609 (12)	0.0549 (10)	0.0032 (9)	0.0182 (8)	0.0014 (9)
C7	0.0578 (11)	0.0684 (13)	0.0583 (10)	0.0073 (9)	0.0147 (8)	0.0053 (9)
C8	0.0587 (11)	0.0703 (13)	0.0566 (10)	0.0139 (10)	0.0164 (8)	0.0030 (9)
C9	0.0583 (11)	0.0667 (13)	0.0570 (10)	0.0100 (10)	0.0147 (9)	0.0027 (9)
C10	0.0517 (10)	0.0500 (11)	0.0546 (9)	0.0030 (8)	0.0140 (8)	−0.0027 (8)
C11	0.0525 (10)	0.0571 (12)	0.0529 (9)	0.0055 (9)	0.0082 (8)	−0.0019 (8)
C12	0.0474 (10)	0.0536 (12)	0.0589 (10)	0.0023 (8)	0.0138 (8)	−0.0055 (8)
C13	0.0589 (11)	0.0527 (12)	0.0571 (10)	−0.0039 (9)	0.0173 (8)	−0.0066 (8)
C14	0.0573 (11)	0.0661 (13)	0.0574 (10)	0.0093 (10)	0.0123 (8)	0.0083 (9)
C15	0.0539 (10)	0.0551 (12)	0.0644 (11)	0.0073 (9)	0.0149 (8)	0.0019 (9)
C16	0.0699 (13)	0.0931 (16)	0.0571 (11)	0.0074 (11)	0.0165 (9)	0.0116 (10)
C17	0.0727 (14)	0.137 (2)	0.0752 (13)	0.0074 (14)	0.0383 (11)	−0.0219 (13)
C18	0.0624 (12)	0.0841 (16)	0.0814 (13)	0.0231 (11)	0.0128 (10)	0.0030 (11)
C19	0.1086 (17)	0.1071 (19)	0.0558 (11)	0.0154 (15)	0.0268 (11)	0.0106 (11)

Geometric parameters (Å, º)

O1—C2	1.3599 (19)	C9—C10	1.480 (2)
O1—C16	1.4200 (19)	C10—C15	1.379 (2)
O2—C3	1.357 (2)	C10—C11	1.399 (2)
O2—C17	1.428 (2)	C11—C12	1.366 (2)
O3—C9	1.2268 (19)	C11—H11	0.93
O4—C12	1.3667 (19)	C12—C13	1.408 (2)
O4—C18	1.420 (2)	C13—C14	1.371 (2)
O5—C13	1.3712 (18)	C14—C15	1.382 (2)
O5—C19	1.429 (2)	C14—H14	0.93
C1—C2	1.368 (2)	C15—H15	0.93
C1—C6	1.405 (2)	C16—H16A	0.96
C1—H1	0.93	C16—H16B	0.96
C2—C3	1.411 (2)	C16—H16C	0.96
C3—C4	1.373 (2)	C17—H17A	0.96
C4—C5	1.386 (2)	C17—H17B	0.96
C4—H4	0.93	C17—H17C	0.96
C5—C6	1.382 (2)	C18—H18A	0.96
C5—H5	0.93	C18—H18C	0.96
C6—C7	1.460 (2)	C18—H18B	0.96
C7—C8	1.323 (2)	C19—H19C	0.96
C7—H7	0.93	C19—H19A	0.96
C8—C9	1.465 (2)	C19—H19B	0.96
C8—H8	0.93
C2—O1—C16	116.78 (13)	C11—C12—O4	125.09 (15)
C3—O2—C17	117.08 (15)	C11—C12—C13	119.27 (15)
C12—O4—C18	117.07 (13)	O4—C12—C13	115.63 (14)
C13—O5—C19	116.69 (14)	C14—C13—O5	124.69 (15)
C2—C1—C6	121.24 (14)	C14—C13—C12	119.97 (15)
C2—C1—H1	119.4	O5—C13—C12	115.34 (15)
C6—C1—H1	119.4	C13—C14—C15	119.98 (16)
O1—C2—C1	124.40 (14)	C13—C14—H14	120.0
O1—C2—C3	115.76 (15)	C15—C14—H14	120.0
C1—C2—C3	119.84 (16)	C10—C15—C14	121.07 (16)
O2—C3—C4	125.27 (15)	C10—C15—H15	119.5
O2—C3—C2	115.93 (16)	C14—C15—H15	119.5
C4—C3—C2	118.81 (16)	O1—C16—H16A	109.5
C3—C4—C5	121.21 (16)	O1—C16—H16B	109.5
C3—C4—H4	119.4	H16A—C16—H16B	109.5
C5—C4—H4	119.4	O1—C16—H16C	109.5
C6—C5—C4	120.52 (17)	H16A—C16—H16C	109.5
C6—C5—H5	119.7	H16B—C16—H16C	109.5
C4—C5—H5	119.7	O2—C17—H17A	109.5
C5—C6—C1	118.35 (15)	O2—C17—H17B	109.5
C5—C6—C7	119.75 (16)	H17A—C17—H17B	109.5
C1—C6—C7	121.90 (14)	O2—C17—H17C	109.5
C8—C7—C6	127.00 (16)	H17A—C17—H17C	109.5
C8—C7—H7	116.5	H17B—C17—H17C	109.5
C6—C7—H7	116.5	O4—C18—H18A	109.5
C7—C8—C9	123.26 (17)	O4—C18—H18C	109.5
C7—C8—H8	118.4	H18A—C18—H18C	109.5
C9—C8—H8	118.4	O4—C18—H18B	109.5
O3—C9—C8	120.76 (16)	H18A—C18—H18B	109.5
O3—C9—C10	119.71 (16)	H18C—C18—H18B	109.5
C8—C9—C10	119.51 (15)	O5—C19—H19C	109.5
C15—C10—C11	118.48 (15)	O5—C19—H19A	109.5
C15—C10—C9	123.09 (15)	H19C—C19—H19A	109.5
C11—C10—C9	118.41 (15)	O5—C19—H19B	109.5
C12—C11—C10	121.20 (15)	H19C—C19—H19B	109.5
C12—C11—H11	119.4	H19A—C19—H19B	109.5
C10—C11—H11	119.4
C16—O1—C2—C1	−6.4 (3)	O3—C9—C10—C15	179.77 (18)
C16—O1—C2—C3	173.75 (15)	C8—C9—C10—C15	−1.7 (3)
C6—C1—C2—O1	178.49 (16)	O3—C9—C10—C11	−2.2 (3)
C6—C1—C2—C3	−1.7 (3)	C8—C9—C10—C11	176.37 (16)
C17—O2—C3—C4	−2.1 (3)	C15—C10—C11—C12	1.1 (3)
C17—O2—C3—C2	177.85 (17)	C9—C10—C11—C12	−176.99 (16)
O1—C2—C3—O2	1.4 (2)	C10—C11—C12—O4	179.64 (16)
C1—C2—C3—O2	−178.40 (16)	C10—C11—C12—C13	0.4 (3)
O1—C2—C3—C4	−178.63 (17)	C18—O4—C12—C11	3.8 (3)
C1—C2—C3—C4	1.5 (3)	C18—O4—C12—C13	−176.98 (16)
O2—C3—C4—C5	179.54 (18)	C19—O5—C13—C14	3.3 (3)
C2—C3—C4—C5	−0.4 (3)	C19—O5—C13—C12	−176.65 (17)
C3—C4—C5—C6	−0.6 (3)	C11—C12—C13—C14	−1.4 (3)
C4—C5—C6—C1	0.5 (3)	O4—C12—C13—C14	179.34 (16)
C4—C5—C6—C7	−179.96 (18)	C11—C12—C13—O5	178.57 (15)
C2—C1—C6—C5	0.7 (3)	O4—C12—C13—O5	−0.7 (2)
C2—C1—C6—C7	−178.87 (16)	O5—C13—C14—C15	−179.22 (16)
C5—C6—C7—C8	−178.66 (19)	C12—C13—C14—C15	0.7 (3)
C1—C6—C7—C8	0.9 (3)	C11—C10—C15—C14	−1.8 (3)
C6—C7—C8—C9	178.91 (18)	C9—C10—C15—C14	176.23 (16)
C7—C8—C9—O3	0.5 (3)	C13—C14—C15—C10	0.9 (3)
C7—C8—C9—C10	−178.07 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···O3^i	0.93	2.54	3.390 (2)	151
C7—H7···O3^i	0.93	2.49	3.357 (2)	155
C17—H17C···Cg1^ii	0.96	2.98	3.865 (2)	154

Symmetry codes: (i) −x, −y+2, −z; (ii) −x+1, −y+1, −z.