organic compounds
E)-1-(1-benzofuran-2-yl)-3-(2-bromophenyl)prop-2-en-1-one monohydrate
of (2aDepartment of Physics, S. D. M College (Autonomous), Ujire 574 240, India
*Correspondence e-mail: ssatheeshchandra@rediffmail.com
The title compound, C17H11BrO2·H2O, crystallizes as a monohydrate in the chiral orthorhombic P212121, and has non-linear optical (NLO) properties. The molecule has an E conformation about the C=C bond and is relatively planar with the benzofuran and bromophenyl rings being inclined to one another by 10.60 (14)°. In the crystal, the water molecule is linked to the organic molecule by O—H⋯O hydrogen bonds, forming an R22(7) ring motif while C—H⋯O hydrogen bonds lead to the formation of helices along the b-axis direction.
Keywords: crystal structure; benzofuran; chiral; NLO properties; hydrogen bonding.
CCDC reference: 1430039
1. Related literature
For background to et al. (1999); Jayarama et al. (2013); Tomazela et al. (2000); Gu et al. (2008). For the of a similar compound, see: Benmekhbi et al. (2009).
and their biological and other properties, see: Choudary2. Experimental
2.1. Crystal data
|
Data collection: APEX2 (Bruker, 2004); cell APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97.
Supporting information
CCDC reference: 1430039
https://doi.org/10.1107/S2056989015018897/su5214sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015018897/su5214Isup3.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989015018897/su5214Isup3.cml
Chalcones are among the most abundant and ubiquitous group of natural products (Tomazela, et al., 2000). Some of the chalcone derivatives shows high second-harmonic generation conversion efficiency (Gu et al., 2008; Choudary et al., 1999; Jayarama et al., 2013). The title compound crystallizes in a non-centrosymmteric
and exhibits interesting nonlinear optical properties.In the title compound, Fig. 1, the benzofuran and bromophenyl groups are linked by a prop-2-en-1-one group. The benzofuran and bromophenyl rings are slightly non-planar with a dihedral angle of 10.60 (14) °. The torsion angle C7–C8–C9–O2 is 175.9 (4)° indicating that the O3 methoxy group is coplanar with the attached benzofuran ring. The C═C double bond shows an E conformation.
In the crystal, the water molecule is linked to the organic molecule by O—H···O hydrogen bonds forming an R22(7) ring motif (Table 1 and Fig. 2). The organic molecule is linked to the water molecule by C—H..O hydrogen bonds so forming helices along the b-axis direction (Table and Fig. 2).
2-Benzofuranyl methyl ketone (0.01 mol) and 2-bromobenzaldehyde (0.01 mol) were dissolved in methanol (60 ml). Sodium hydroxide (2 ml, 20%) was then added drop wise to the solution which was then stirred for 1.5 h. The contents of the flask were cooled using ice-cold water, and the resulting powder content was collected by filtration. The compound was dried and re-crystallized twice using acetone as solvent, yielding golden-yellow block-like crystals.
Crystal data, data collection and structure
details are summarized in Table 2. The water H atoms were located in a difference Fourier map. They were refined with distance restraints: O—H = 0.88 (2) Å, H···H = 1.43 (2) Å with Uiso(H) = 1.5Ueq(O). The C-bound H atoms were placed in calculated positions and included in the in the riding model approximation: C—H = 0.93 Å with Uiso(H) = 1.2Ueq(C).Chalcones are among the most abundant and ubiquitous group of natural products (Tomazela, et al., 2000). Some of the chalcone derivatives shows high second-harmonic generation conversion efficiency (Gu et al., 2008; Choudary et al., 1999; Jayarama et al., 2013). The title compound crystallizes in a non-centrosymmteric
and exhibits interesting nonlinear optical properties.In the title compound, Fig. 1, the benzofuran and bromophenyl groups are linked by a prop-2-en-1-one group. The benzofuran and bromophenyl rings are slightly non-planar with a dihedral angle of 10.60 (14) °. The torsion angle C7–C8–C9–O2 is 175.9 (4)° indicating that the O3 methoxy group is coplanar with the attached benzofuran ring. The C═C double bond shows an E conformation.
In the crystal, the water molecule is linked to the organic molecule by O—H···O hydrogen bonds forming an R22(7) ring motif (Table 1 and Fig. 2). The organic molecule is linked to the water molecule by C—H..O hydrogen bonds so forming helices along the b-axis direction (Table and Fig. 2).
For background to
and their biological and other properties, see: Choudary et al. (1999); Jayarama et al. (2013); Tomazela et al. (2000); Gu et al. (2008). For the of a similar compound, see: Benmekhbi et al. (2009).2-Benzofuranyl methyl ketone (0.01 mol) and 2-bromobenzaldehyde (0.01 mol) were dissolved in methanol (60 ml). Sodium hydroxide (2 ml, 20%) was then added drop wise to the solution which was then stirred for 1.5 h. The contents of the flask were cooled using ice-cold water, and the resulting powder content was collected by filtration. The compound was dried and re-crystallized twice using acetone as solvent, yielding golden-yellow block-like crystals.
detailsCrystal data, data collection and structure
details are summarized in Table 2. The water H atoms were located in a difference Fourier map. They were refined with distance restraints: O—H = 0.88 (2) Å, H···H = 1.43 (2) Å with Uiso(H) = 1.5Ueq(O). The C-bound H atoms were placed in calculated positions and included in the in the riding model approximation: C—H = 0.93 Å with Uiso(H) = 1.2Ueq(C).Data collection: APEX2 (Bruker, 2004); cell
APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. A view of the molecular structure of title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. A view along the a-axis of the crystal packing of the title compound. The intermolecular interactions are represented by dashed lines (see Table 1). |
C17H11BrO2·H2O | F(000) = 696 |
Mr = 345.18 | Dx = 1.568 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 2499 reflections |
a = 4.8614 (4) Å | θ = 4.8–41.6° |
b = 13.8220 (15) Å | µ = 2.82 mm−1 |
c = 21.755 (2) Å | T = 296 K |
V = 1461.8 (2) Å3 | Block, golden-yellow |
Z = 4 | 0.40 × 0.30 × 0.25 mm |
Bruker Kappa APEXII CCD diffractometer | 3636 independent reflections |
Radiation source: fine-focus sealed tube | 2134 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
ω and φ scan | θmax = 28.4°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | h = −6→5 |
Tmin = 0.399, Tmax = 0.539 | k = −18→18 |
3636 measured reflections | l = −28→29 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.042 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.102 | w = 1/[σ2(Fo2) + (0.0372P)2 + 0.0197P] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max = 0.001 |
3636 reflections | Δρmax = 0.42 e Å−3 |
196 parameters | Δρmin = −0.29 e Å−3 |
3 restraints | Absolute structure: Flack (1983), 1497 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.011 (11) |
C17H11BrO2·H2O | V = 1461.8 (2) Å3 |
Mr = 345.18 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 4.8614 (4) Å | µ = 2.82 mm−1 |
b = 13.8220 (15) Å | T = 296 K |
c = 21.755 (2) Å | 0.40 × 0.30 × 0.25 mm |
Bruker Kappa APEXII CCD diffractometer | 3636 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | 2134 reflections with I > 2σ(I) |
Tmin = 0.399, Tmax = 0.539 | Rint = 0.034 |
3636 measured reflections |
R[F2 > 2σ(F2)] = 0.042 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.102 | Δρmax = 0.42 e Å−3 |
S = 1.01 | Δρmin = −0.29 e Å−3 |
3636 reflections | Absolute structure: Flack (1983), 1497 Friedel pairs |
196 parameters | Absolute structure parameter: −0.011 (11) |
3 restraints |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 | ||
Br1 | 1.34723 (10) | 0.98219 (3) | 0.06738 (2) | 0.0902 (2) | |
O1 | 0.3289 (4) | 0.93267 (17) | 0.32535 (10) | 0.0513 (5) | |
O2 | 0.6697 (5) | 0.99535 (19) | 0.23842 (13) | 0.0720 (7) | |
C1 | 0.1694 (7) | 0.8801 (2) | 0.36525 (14) | 0.0463 (8) | |
C2 | −0.0186 (7) | 0.9171 (3) | 0.40591 (16) | 0.0593 (10) | |
H2 | −0.0523 | 0.9831 | 0.4093 | 0.071* | |
C3 | −0.1522 (7) | 0.8509 (3) | 0.44089 (16) | 0.0634 (10) | |
H3 | −0.2812 | 0.8724 | 0.4694 | 0.076* | |
C4 | −0.1034 (7) | 0.7519 (3) | 0.43576 (17) | 0.0607 (9) | |
H4 | −0.2020 | 0.7091 | 0.4603 | 0.073* | |
C5 | 0.0860 (7) | 0.7169 (3) | 0.39547 (16) | 0.0587 (10) | |
H5 | 0.1185 | 0.6507 | 0.3923 | 0.070* | |
C6 | 0.2301 (6) | 0.7824 (3) | 0.35908 (14) | 0.0444 (8) | |
C7 | 0.4402 (6) | 0.7757 (3) | 0.31357 (15) | 0.0468 (8) | |
H7 | 0.5256 | 0.7195 | 0.2997 | 0.056* | |
C8 | 0.4907 (6) | 0.8671 (3) | 0.29448 (15) | 0.0463 (9) | |
C9 | 0.6756 (7) | 0.9078 (3) | 0.24929 (15) | 0.0503 (8) | |
C10 | 0.8640 (6) | 0.8424 (2) | 0.21760 (14) | 0.0446 (7) | |
H10 | 0.8712 | 0.7779 | 0.2297 | 0.054* | |
C11 | 1.0223 (6) | 0.8713 (3) | 0.17288 (16) | 0.0480 (8) | |
H11 | 1.0081 | 0.9361 | 0.1619 | 0.058* | |
C12 | 1.2190 (6) | 0.8136 (3) | 0.13815 (14) | 0.0439 (8) | |
C13 | 1.2629 (7) | 0.7170 (3) | 0.15197 (16) | 0.0523 (9) | |
H13 | 1.1617 | 0.6892 | 0.1837 | 0.063* | |
C14 | 1.4478 (7) | 0.6610 (3) | 0.12115 (19) | 0.0615 (10) | |
H14 | 1.4691 | 0.5961 | 0.1315 | 0.074* | |
C15 | 1.6028 (7) | 0.7008 (3) | 0.07476 (17) | 0.0603 (10) | |
H15 | 1.7313 | 0.6633 | 0.0539 | 0.072* | |
C16 | 1.5667 (7) | 0.7964 (3) | 0.05931 (16) | 0.0557 (9) | |
H16 | 1.6695 | 0.8239 | 0.0278 | 0.067* | |
C17 | 1.3787 (7) | 0.8507 (3) | 0.09068 (14) | 0.0493 (8) | |
O1S | 0.1601 (7) | 1.1082 (2) | 0.23870 (17) | 0.0950 (10) | |
H1SA | 0.179 (11) | 1.078 (4) | 0.2780 (12) | 0.143* | |
H1SB | 0.300 (9) | 1.070 (3) | 0.220 (2) | 0.143* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.1130 (4) | 0.0695 (3) | 0.0881 (3) | 0.0070 (3) | 0.0327 (3) | 0.0255 (2) |
O1 | 0.0458 (12) | 0.0526 (14) | 0.0555 (14) | 0.0017 (11) | 0.0037 (12) | −0.0104 (11) |
O2 | 0.0594 (14) | 0.0592 (19) | 0.0974 (19) | 0.0071 (14) | 0.0271 (13) | 0.0068 (15) |
C1 | 0.0391 (17) | 0.057 (2) | 0.0426 (18) | −0.0028 (18) | −0.0028 (16) | −0.0049 (15) |
C2 | 0.0461 (19) | 0.079 (3) | 0.053 (2) | 0.0023 (19) | 0.0023 (17) | −0.016 (2) |
C3 | 0.0426 (18) | 0.104 (3) | 0.044 (2) | −0.003 (2) | 0.0102 (19) | −0.009 (2) |
C4 | 0.056 (2) | 0.081 (3) | 0.0447 (19) | −0.0068 (19) | 0.002 (2) | 0.008 (2) |
C5 | 0.058 (2) | 0.065 (2) | 0.054 (2) | 0.0003 (19) | −0.0023 (18) | 0.0054 (19) |
C6 | 0.0340 (17) | 0.058 (2) | 0.0408 (17) | 0.0013 (15) | −0.0096 (14) | −0.0056 (16) |
C7 | 0.0383 (17) | 0.056 (2) | 0.0460 (19) | 0.0050 (15) | −0.0053 (15) | −0.0044 (17) |
C8 | 0.0323 (16) | 0.060 (2) | 0.047 (2) | 0.0051 (16) | −0.0044 (14) | −0.0082 (18) |
C9 | 0.0368 (17) | 0.060 (2) | 0.054 (2) | −0.0001 (18) | −0.0042 (16) | −0.0041 (17) |
C10 | 0.0346 (16) | 0.052 (2) | 0.0469 (18) | −0.0021 (17) | 0.0011 (16) | 0.0002 (15) |
C11 | 0.0423 (16) | 0.055 (2) | 0.047 (2) | 0.0008 (16) | −0.0021 (16) | 0.0048 (16) |
C12 | 0.0302 (16) | 0.060 (2) | 0.0419 (18) | −0.0028 (15) | −0.0042 (13) | −0.0007 (16) |
C13 | 0.050 (2) | 0.056 (2) | 0.051 (2) | 0.0004 (17) | 0.0043 (15) | 0.0046 (18) |
C14 | 0.059 (2) | 0.057 (2) | 0.068 (3) | 0.0079 (19) | −0.003 (2) | −0.001 (2) |
C15 | 0.051 (2) | 0.074 (3) | 0.055 (2) | 0.0128 (19) | 0.0024 (18) | −0.014 (2) |
C16 | 0.0437 (18) | 0.085 (3) | 0.0389 (19) | −0.0034 (18) | 0.0069 (15) | 0.0009 (19) |
C17 | 0.0434 (18) | 0.063 (2) | 0.0418 (18) | −0.0013 (18) | −0.0009 (15) | 0.0050 (15) |
O1S | 0.098 (2) | 0.071 (2) | 0.117 (3) | 0.0067 (18) | 0.019 (2) | 0.0037 (18) |
Br1—C17 | 1.893 (4) | C9—C10 | 1.460 (5) |
O1—C1 | 1.372 (4) | C10—C11 | 1.303 (4) |
O1—C8 | 1.375 (4) | C10—H10 | 0.9300 |
O2—C9 | 1.234 (4) | C11—C12 | 1.456 (4) |
C1—C2 | 1.370 (5) | C11—H11 | 0.9300 |
C1—C6 | 1.390 (5) | C12—C13 | 1.385 (5) |
C2—C3 | 1.356 (5) | C12—C17 | 1.390 (4) |
C2—H2 | 0.9300 | C13—C14 | 1.363 (5) |
C3—C4 | 1.393 (5) | C13—H13 | 0.9300 |
C3—H3 | 0.9300 | C14—C15 | 1.374 (5) |
C4—C5 | 1.361 (5) | C14—H14 | 0.9300 |
C4—H4 | 0.9300 | C15—C16 | 1.375 (5) |
C5—C6 | 1.392 (5) | C15—H15 | 0.9300 |
C5—H5 | 0.9300 | C16—C17 | 1.366 (5) |
C6—C7 | 1.426 (4) | C16—H16 | 0.9300 |
C7—C8 | 1.353 (5) | O1S—H1SA | 0.958 (19) |
C7—H7 | 0.9300 | O1S—H1SB | 0.954 (19) |
C8—C9 | 1.446 (5) | ||
C1—O1—C8 | 106.5 (3) | C8—C9—C10 | 118.1 (3) |
C2—C1—O1 | 126.0 (3) | C11—C10—C9 | 122.2 (3) |
C2—C1—C6 | 124.5 (3) | C11—C10—H10 | 118.9 |
O1—C1—C6 | 109.5 (3) | C9—C10—H10 | 118.9 |
C3—C2—C1 | 115.5 (4) | C10—C11—C12 | 127.4 (4) |
C3—C2—H2 | 122.2 | C10—C11—H11 | 116.3 |
C1—C2—H2 | 122.2 | C12—C11—H11 | 116.3 |
C2—C3—C4 | 122.4 (3) | C13—C12—C17 | 115.6 (3) |
C2—C3—H3 | 118.8 | C13—C12—C11 | 121.1 (3) |
C4—C3—H3 | 118.8 | C17—C12—C11 | 123.4 (3) |
C5—C4—C3 | 121.1 (3) | C14—C13—C12 | 122.8 (3) |
C5—C4—H4 | 119.4 | C14—C13—H13 | 118.6 |
C3—C4—H4 | 119.4 | C12—C13—H13 | 118.6 |
C4—C5—C6 | 118.4 (4) | C13—C14—C15 | 119.7 (4) |
C4—C5—H5 | 120.8 | C13—C14—H14 | 120.2 |
C6—C5—H5 | 120.8 | C15—C14—H14 | 120.2 |
C1—C6—C5 | 118.1 (3) | C14—C15—C16 | 119.7 (3) |
C1—C6—C7 | 106.4 (3) | C14—C15—H15 | 120.2 |
C5—C6—C7 | 135.5 (4) | C16—C15—H15 | 120.2 |
C8—C7—C6 | 106.4 (3) | C17—C16—C15 | 119.4 (3) |
C8—C7—H7 | 126.8 | C17—C16—H16 | 120.3 |
C6—C7—H7 | 126.8 | C15—C16—H16 | 120.3 |
C7—C8—O1 | 111.2 (3) | C16—C17—C12 | 122.8 (3) |
C7—C8—C9 | 133.2 (3) | C16—C17—Br1 | 116.6 (3) |
O1—C8—C9 | 115.6 (3) | C12—C17—Br1 | 120.6 (3) |
O2—C9—C8 | 119.8 (3) | H1SA—O1S—H1SB | 94 (2) |
O2—C9—C10 | 122.1 (3) | ||
C8—O1—C1—C2 | 178.7 (3) | O1—C8—C9—O2 | −3.8 (5) |
C8—O1—C1—C6 | −0.4 (3) | C7—C8—C9—C10 | −3.6 (6) |
O1—C1—C2—C3 | −179.9 (3) | O1—C8—C9—C10 | 176.5 (3) |
C6—C1—C2—C3 | −1.0 (5) | O2—C9—C10—C11 | −5.2 (5) |
C1—C2—C3—C4 | −0.3 (5) | C8—C9—C10—C11 | 174.5 (3) |
C2—C3—C4—C5 | 1.0 (6) | C9—C10—C11—C12 | 179.5 (3) |
C3—C4—C5—C6 | −0.3 (5) | C10—C11—C12—C13 | −2.0 (5) |
C2—C1—C6—C5 | 1.6 (5) | C10—C11—C12—C17 | 179.6 (3) |
O1—C1—C6—C5 | −179.3 (3) | C17—C12—C13—C14 | −0.5 (5) |
C2—C1—C6—C7 | −178.3 (3) | C11—C12—C13—C14 | −179.0 (3) |
O1—C1—C6—C7 | 0.8 (3) | C12—C13—C14—C15 | 1.0 (5) |
C4—C5—C6—C1 | −0.9 (5) | C13—C14—C15—C16 | −1.0 (5) |
C4—C5—C6—C7 | 179.0 (3) | C14—C15—C16—C17 | 0.5 (5) |
C1—C6—C7—C8 | −0.9 (3) | C15—C16—C17—C12 | −0.1 (5) |
C5—C6—C7—C8 | 179.1 (3) | C15—C16—C17—Br1 | 178.9 (3) |
C6—C7—C8—O1 | 0.8 (4) | C13—C12—C17—C16 | 0.1 (5) |
C6—C7—C8—C9 | −179.1 (3) | C11—C12—C17—C16 | 178.6 (3) |
C1—O1—C8—C7 | −0.3 (4) | C13—C12—C17—Br1 | −178.9 (2) |
C1—O1—C8—C9 | 179.6 (3) | C11—C12—C17—Br1 | −0.4 (4) |
C7—C8—C9—O2 | 176.0 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1S—H1SA···O1 | 0.96 (2) | 2.37 (4) | 3.181 (4) | 142 (4) |
O1S—H1SB···O2 | 0.95 (2) | 2.11 (4) | 2.928 (4) | 143 (4) |
C7—H7···O1Si | 0.93 | 2.32 | 3.229 (5) | 164 |
C10—H10···O1Si | 0.93 | 2.45 | 3.375 (5) | 174 |
Symmetry code: (i) −x+1, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1S—H1SA···O1 | 0.96 (2) | 2.37 (4) | 3.181 (4) | 142 (4) |
O1S—H1SB···O2 | 0.95 (2) | 2.11 (4) | 2.928 (4) | 143 (4) |
C7—H7···O1Si | 0.93 | 2.32 | 3.229 (5) | 164 |
C10—H10···O1Si | 0.93 | 2.45 | 3.375 (5) | 174 |
Symmetry code: (i) −x+1, y−1/2, −z+1/2. |
Acknowledgements
We are grateful to Professor Jayarama A, Department of Physics & Karnataka Government Research Center (KGRC), Sahyadri College of Engineering & Management, Mangalore, for supporting this study.
References
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. CrossRef Web of Science IUCr Journals Google Scholar
Benmekhbi, L., Belhouas, R., Bouacida, S., Mosbah, S. & Bencharif, L. (2009). Acta Cryst. E65, o1472–o1473. Web of Science CSD CrossRef IUCr Journals Google Scholar
Bruker (2004). APEX2, SAINT, XPREP and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Choudary, B. M., Lakshmi Kantam, M., Venkat Reddy, C. R., Koteswara Rao, K. & Figueras, F. (1999). J. Mol. Catal. A Chem. 146, 279–284. Web of Science CrossRef CAS Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Gu, B., Ji, W., Patil, P. S. & Dharmaprakash, S. M. (2008). J. Appl. Phys. 103, 103511–103516. Web of Science CrossRef Google Scholar
Jayarama, A., Ravindra, H. J., Menezes, A. P., Dharmaprakash, S. M. & Ng, S. W. (2013). J. Mol. Catal. A Chem. 1051, 285–291. CAS Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tomazela, D. M., Pupo, M. T., Passador, E. A. P., da Silva, M. F. das G. F., Vieira, P. C., Fernandes, J. B., Fo, E. R., Oliva, G. & Pirani, J. R. (2000). Phytochemistry, 55, 643–651. Google Scholar
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.