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ISSN: 2056-9890

Tri­ethyl­ammonium 3,4-dihy­dr­oxy­benzoate monohydrate

aSchool of Chemistry and Environment, South China Normal University, Guangzhou 510631, People's Republic of China
*Correspondence e-mail: licaizhu1977@yahoo.com.cn

(Received 3 November 2010; accepted 10 November 2010; online 13 November 2010)

In the structure of the title compound, C6H16N+·C7H5O4·H2O, O—H⋯O and N—H⋯O hydrogen bonds link the components into a three-dimensional array. The 3,4-dihy­droxy­benzoate anion is approximately planar, with a maximum deviation of 0.083 (2) Å.

Related literature

For protocatechuic acid (3,4-dihy­droxy­benzoic acid) and its pharmacological activity, see: An et al. (2006[An, L. J., Guan, S., Shi, G. F., Bao, Y. M., Duan, Y. L. & Jiang, B. (2006). Food Chem. Toxicol. 44, 436-443.]); Guan et al. (2006[Guan, S., Bao, Y. M., Jiang, B. & An, L. J. (2006). Eur. J. Pharmacol. 538, 73-79.]); Lin et al. (2009[Lin, C. Y., Huang, C. S., Huang, C. Y. & Yin, M. C. (2009). J. Agric. Food Chem. 57, 6661-6667.]); Tseng et al. (1998[Tseng, T. H., Hsu, J. D., Lo, M. H., Chu, C. Y., Chou, F. P., Huang, C. L. & Wang, C. J. (1998). Cancer Lett. 126, 199-207.]); Yip et al. (2006[Yip, E. C. H., Chan, A. S. L., Pang, H., Tam, Y. K. & Wong, Y. H. (2006). Cell Biol. Toxicol. 22, 293-302.]).

[Scheme 1]

Experimental

Crystal data
  • C6H16N+·C7H5O4·H2O

  • Mr = 273.32

  • Orthorhombic, P 21 21 21

  • a = 10.7163 (16) Å

  • b = 11.5973 (17) Å

  • c = 11.7690 (17) Å

  • V = 1462.7 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 296 K

  • 0.30 × 0.28 × 0.28 mm

Data collection
  • Bruker APEXII area-detector diffractometer

  • 7531 measured reflections

  • 1519 independent reflections

  • 1211 reflections with I > 2σ(I)

  • Rint = 0.043

Refinement
  • R[F2 > 2σ(F2)] = 0.038

  • wR(F2) = 0.093

  • S = 1.04

  • 1519 reflections

  • 186 parameters

  • 3 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.20 e Å−3

  • Δρmin = −0.14 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1W—H2W⋯O2i 0.87 (4) 1.98 (2) 2.845 (3) 173 (4)
O1W—H1W⋯O3ii 0.84 (2) 2.14 (2) 2.951 (3) 162 (4)
N1—H14⋯O2i 0.92 (2) 1.83 (2) 2.734 (3) 166 (5)
O3—H3⋯O1iii 0.82 1.84 2.656 (3) 173
O4—H4A⋯O1iv 0.82 1.82 2.639 (3) 174
Symmetry codes: (i) x-1, y, z; (ii) [-x+{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}]; (iii) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+2]; (iv) [-x+2, y-{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2004[Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Protocatechuic acid (3,4-dihydroxybenzoic acid) is one of the main secondary metabolites in the plant kingdom (Guan et al., 2006). Significantly, it has been found that protocatechuic acid and its derivatives possess diverse pharmacological activities such as antioxidant, antiapoptosis, anticarcinogen, anticoagulatory and antiinflammatory (An et al., 2006; Lin et al., 2009; Tseng et al., 1998; Yip et al., 2006). The molecular and crystal structure of the title compound, a triethylammonium of protocatechuic acid, is presented in this article.

In the asymmetric unit of the title compound, illustrated in Fig. 1, there are a triethylammonium cation, one singly deprotonated 3,4-dihydroxybenzoate anion and one water molecule. The 3,4-dihydroxybenzoate anion is approximately planar, with a maximum deviation of any non-H atom from its plane of 0.083 (2) Å for atom O1. The orientations of the three ethyl groups of the triethylammonium cation are different. Two of the ethyl substituents are rougly in plane with the nitrogen atom and the methylene carbon atoms. The torsion angles of these two groups against the N—H bond are -53.1 for C10—C11, and -61.8 for C12—C13. The third ethyl group, C8—C9, is rotated out of this plane and is pointing downward with respect to the N—H bond with a torsion angle of 175.4°. The water molecule forms two O—H···O hydrogen bonds with two 3,4-dihydroxybenzoate anions involving O1w—H1w···O3ii and O1w—H2w···O2i (see Table 1 for symmetry operators and bonding geometries). The hydroxy groups of the 3,4-dihydroxybenzoate anion form O—H···O hydrogen bonds to the carboxylate groups of two adjacent anions. The N1—H14···O2i hydrogen bond between the triethylammonium cation and the 3,4-dihydroxybenzoate anion is the main force influencing the orientation of the triethylammonium cation. These hydrogen bonds link the triethylammonium cations, 3,4-dihydroxybenzoate anions and water molecules into a three-dimensional array (Fig. 2).

Related literature top

For protocatechuic acid (3,4-dihydroxybenzoic acid) and its pharmacological activity, see: An et al. (2006); Guan et al. (2006); Lin et al. (2009); Tseng et al. (1998); Yip et al. (2006).

Experimental top

A solution of triethylamine (2 mmol in 0.5 ml water) was added dropwise to a solution of protocatechuic acid (2 mmol) in acetonitrile (15 ml), and the mixture was stirred for 30 min at room temperature. After several days colourless block-like crystals, suitable for X-ray diffraction analysis, were obtained by slow evaporation of the solution.

Refinement top

H14 atom of the triethylammonium cation and H atoms of the water molecule were found from difference Fourier maps and refined isotropically with a restraint of N—H = 0.89 (2) Å, O—H = 0.86 (2) Å and Uiso(H) = 1.5 Ueq(N, O). All other H atoms were positioned geometrically and refined as riding, with O—H = 0.82 Å and C—H = 0.93, 0.96 or 0.97 Å, and with Uiso(H) = 1.2 or 1.5 Ueq(C, O).

Structure description top

Protocatechuic acid (3,4-dihydroxybenzoic acid) is one of the main secondary metabolites in the plant kingdom (Guan et al., 2006). Significantly, it has been found that protocatechuic acid and its derivatives possess diverse pharmacological activities such as antioxidant, antiapoptosis, anticarcinogen, anticoagulatory and antiinflammatory (An et al., 2006; Lin et al., 2009; Tseng et al., 1998; Yip et al., 2006). The molecular and crystal structure of the title compound, a triethylammonium of protocatechuic acid, is presented in this article.

In the asymmetric unit of the title compound, illustrated in Fig. 1, there are a triethylammonium cation, one singly deprotonated 3,4-dihydroxybenzoate anion and one water molecule. The 3,4-dihydroxybenzoate anion is approximately planar, with a maximum deviation of any non-H atom from its plane of 0.083 (2) Å for atom O1. The orientations of the three ethyl groups of the triethylammonium cation are different. Two of the ethyl substituents are rougly in plane with the nitrogen atom and the methylene carbon atoms. The torsion angles of these two groups against the N—H bond are -53.1 for C10—C11, and -61.8 for C12—C13. The third ethyl group, C8—C9, is rotated out of this plane and is pointing downward with respect to the N—H bond with a torsion angle of 175.4°. The water molecule forms two O—H···O hydrogen bonds with two 3,4-dihydroxybenzoate anions involving O1w—H1w···O3ii and O1w—H2w···O2i (see Table 1 for symmetry operators and bonding geometries). The hydroxy groups of the 3,4-dihydroxybenzoate anion form O—H···O hydrogen bonds to the carboxylate groups of two adjacent anions. The N1—H14···O2i hydrogen bond between the triethylammonium cation and the 3,4-dihydroxybenzoate anion is the main force influencing the orientation of the triethylammonium cation. These hydrogen bonds link the triethylammonium cations, 3,4-dihydroxybenzoate anions and water molecules into a three-dimensional array (Fig. 2).

For protocatechuic acid (3,4-dihydroxybenzoic acid) and its pharmacological activity, see: An et al. (2006); Guan et al. (2006); Lin et al. (2009); Tseng et al. (1998); Yip et al. (2006).

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure showing the atomic-numbering scheme and displacement ellipsoids drawn at the 50% probability level.
[Figure 2] Fig. 2. The molecular packing showing the intermolecular hydrogen bonding interactions as broken lines.
Triethylammonium 3,4-dihydroxybenzoate monohydrate top
Crystal data top
C6H16N+·C7H5O4·H2OF(000) = 592
Mr = 273.32Dx = 1.241 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 1465 reflections
a = 10.7163 (16) Åθ = 2.5–21.3°
b = 11.5973 (17) ŵ = 0.10 mm1
c = 11.7690 (17) ÅT = 296 K
V = 1462.7 (4) Å3Block, colourless
Z = 40.30 × 0.28 × 0.28 mm
Data collection top
Bruker APEXII area-detector
diffractometer
1211 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.043
Graphite monochromatorθmax = 25.2°, θmin = 2.5°
φ and ω scansh = 126
7531 measured reflectionsk = 1313
1519 independent reflectionsl = 1414
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.093H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0404P)2 + 0.2897P]
where P = (Fo2 + 2Fc2)/3
1519 reflections(Δ/σ)max < 0.001
186 parametersΔρmax = 0.20 e Å3
3 restraintsΔρmin = 0.14 e Å3
Crystal data top
C6H16N+·C7H5O4·H2OV = 1462.7 (4) Å3
Mr = 273.32Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 10.7163 (16) ŵ = 0.10 mm1
b = 11.5973 (17) ÅT = 296 K
c = 11.7690 (17) Å0.30 × 0.28 × 0.28 mm
Data collection top
Bruker APEXII area-detector
diffractometer
1211 reflections with I > 2σ(I)
7531 measured reflectionsRint = 0.043
1519 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0383 restraints
wR(F2) = 0.093H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.20 e Å3
1519 reflectionsΔρmin = 0.14 e Å3
186 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.9308 (3)0.5565 (2)0.8260 (2)0.0342 (6)
H10.95650.50650.76880.041*
C60.9902 (3)0.6627 (2)0.8383 (2)0.0325 (6)
C30.7962 (3)0.5995 (2)0.9826 (2)0.0368 (7)
C20.8350 (3)0.5241 (2)0.8967 (2)0.0344 (6)
C50.9503 (3)0.7362 (2)0.9238 (2)0.0414 (7)
H50.98910.80730.93340.050*
C40.8538 (3)0.7050 (2)0.9948 (2)0.0422 (7)
H40.82730.75551.05130.051*
C71.0953 (3)0.6967 (2)0.7614 (2)0.0359 (7)
O11.1524 (2)0.79093 (17)0.78093 (16)0.0458 (5)
O21.12389 (19)0.6316 (2)0.68029 (18)0.0531 (6)
O40.7734 (2)0.42081 (17)0.89033 (19)0.0537 (6)
H4A0.80110.38310.83700.081*
O30.7002 (2)0.56347 (19)1.05036 (17)0.0491 (6)
H30.68530.61291.09830.074*
N10.3697 (2)0.6142 (2)0.6203 (2)0.0417 (6)
C100.4121 (3)0.6946 (3)0.5286 (3)0.0608 (9)
H10A0.49490.67200.50390.073*
H10B0.41780.77200.55950.073*
C120.3732 (4)0.4905 (3)0.5826 (3)0.0574 (9)
H12A0.32050.48170.51620.069*
H12B0.45780.47100.56080.069*
C110.3266 (4)0.6960 (4)0.4277 (3)0.0885 (14)
H11A0.32830.62200.39120.133*
H11B0.35360.75410.37510.133*
H11C0.24310.71280.45230.133*
C130.3304 (5)0.4082 (3)0.6726 (4)0.0840 (13)
H13A0.38830.40940.73480.126*
H13B0.32640.33180.64150.126*
H13C0.24930.43070.69900.126*
C80.4404 (3)0.6357 (3)0.7284 (3)0.0577 (9)
H8A0.40010.59340.78940.069*
H8B0.43490.71710.74660.069*
C90.5759 (3)0.6018 (4)0.7247 (4)0.0822 (13)
H9A0.58250.51970.71610.123*
H9B0.61590.62490.79410.123*
H9C0.61570.63920.66160.123*
H140.288 (2)0.633 (4)0.637 (4)0.123*
O1W0.0402 (3)0.5325 (3)0.4727 (2)0.0719 (8)
H1W0.035 (2)0.514 (4)0.482 (4)0.108*
H2W0.066 (4)0.568 (3)0.533 (3)0.108*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0341 (15)0.0357 (15)0.0328 (14)0.0014 (13)0.0032 (13)0.0061 (12)
C60.0319 (15)0.0328 (15)0.0329 (14)0.0021 (12)0.0029 (12)0.0010 (12)
C30.0340 (16)0.0435 (17)0.0327 (15)0.0026 (14)0.0009 (13)0.0001 (13)
C20.0343 (16)0.0341 (14)0.0347 (14)0.0005 (12)0.0006 (13)0.0044 (13)
C50.0458 (19)0.0339 (15)0.0446 (16)0.0034 (14)0.0005 (15)0.0077 (14)
C40.0415 (17)0.0403 (18)0.0448 (17)0.0033 (15)0.0063 (15)0.0131 (14)
C70.0336 (16)0.0405 (17)0.0335 (15)0.0009 (14)0.0043 (12)0.0001 (13)
O10.0550 (13)0.0438 (12)0.0387 (11)0.0165 (11)0.0005 (10)0.0018 (9)
O20.0471 (14)0.0624 (14)0.0497 (12)0.0131 (11)0.0134 (11)0.0191 (11)
O40.0581 (15)0.0441 (13)0.0590 (15)0.0146 (11)0.0204 (12)0.0139 (11)
O30.0463 (14)0.0550 (13)0.0459 (12)0.0037 (11)0.0149 (10)0.0132 (10)
N10.0393 (15)0.0445 (14)0.0413 (14)0.0017 (12)0.0058 (12)0.0020 (11)
C100.055 (2)0.061 (2)0.067 (2)0.0040 (19)0.0120 (18)0.0178 (18)
C120.065 (2)0.0475 (19)0.060 (2)0.0024 (17)0.0031 (19)0.0145 (17)
C110.081 (3)0.117 (4)0.068 (3)0.002 (3)0.003 (2)0.039 (3)
C130.098 (3)0.055 (2)0.099 (3)0.013 (2)0.013 (3)0.013 (2)
C80.060 (2)0.060 (2)0.0527 (19)0.0054 (19)0.0044 (18)0.0096 (17)
C90.055 (2)0.099 (3)0.094 (3)0.003 (2)0.018 (2)0.003 (3)
O1W0.0682 (19)0.0815 (19)0.0658 (16)0.0147 (16)0.0034 (15)0.0133 (14)
Geometric parameters (Å, º) top
C1—C21.374 (4)C10—C111.500 (5)
C1—C61.395 (4)C10—H10A0.9700
C1—H10.9300C10—H10B0.9700
C6—C51.387 (4)C12—C131.497 (5)
C6—C71.498 (4)C12—H12A0.9700
C3—O31.368 (3)C12—H12B0.9700
C3—C41.378 (4)C11—H11A0.9600
C3—C21.400 (4)C11—H11B0.9600
C2—O41.370 (3)C11—H11C0.9600
C5—C41.379 (4)C13—H13A0.9600
C5—H50.9300C13—H13B0.9600
C4—H40.9300C13—H13C0.9600
C7—O21.255 (3)C8—C91.505 (5)
C7—O11.273 (3)C8—H8A0.9700
O4—H4A0.8200C8—H8B0.9700
O3—H30.8200C9—H9A0.9600
N1—C101.497 (4)C9—H9B0.9600
N1—C121.501 (4)C9—H9C0.9600
N1—C81.502 (4)O1W—H1W0.841 (19)
N1—H140.92 (2)O1W—H2W0.87 (4)
C2—C1—C6121.3 (3)C11—C10—H10B109.0
C2—C1—H1119.3H10A—C10—H10B107.8
C6—C1—H1119.3C13—C12—N1113.1 (3)
C5—C6—C1118.6 (3)C13—C12—H12A108.9
C5—C6—C7120.6 (2)N1—C12—H12A108.9
C1—C6—C7120.9 (2)C13—C12—H12B108.9
O3—C3—C4123.2 (3)N1—C12—H12B108.9
O3—C3—C2117.0 (3)H12A—C12—H12B107.8
C4—C3—C2119.8 (3)C10—C11—H11A109.5
O4—C2—C1124.5 (2)C10—C11—H11B109.5
O4—C2—C3116.3 (2)H11A—C11—H11B109.5
C1—C2—C3119.3 (3)C10—C11—H11C109.5
C4—C5—C6120.7 (3)H11A—C11—H11C109.5
C4—C5—H5119.7H11B—C11—H11C109.5
C6—C5—H5119.7C12—C13—H13A109.5
C3—C4—C5120.4 (3)C12—C13—H13B109.5
C3—C4—H4119.8H13A—C13—H13B109.5
C5—C4—H4119.8C12—C13—H13C109.5
O2—C7—O1122.5 (3)H13A—C13—H13C109.5
O2—C7—C6119.0 (2)H13B—C13—H13C109.5
O1—C7—C6118.6 (2)N1—C8—C9114.8 (3)
C2—O4—H4A109.5N1—C8—H8A108.6
C3—O3—H3109.5C9—C8—H8A108.6
C10—N1—C12112.0 (2)N1—C8—H8B108.6
C10—N1—C8110.7 (3)C9—C8—H8B108.6
C12—N1—C8113.3 (3)H8A—C8—H8B107.6
C10—N1—H14107 (3)C8—C9—H9A109.5
C12—N1—H14108 (3)C8—C9—H9B109.5
C8—N1—H14105 (3)H9A—C9—H9B109.5
N1—C10—C11113.0 (3)C8—C9—H9C109.5
N1—C10—H10A109.0H9A—C9—H9C109.5
C11—C10—H10A109.0H9B—C9—H9C109.5
N1—C10—H10B109.0H1W—O1W—H2W108 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W···O2i0.87 (4)1.98 (2)2.845 (3)173 (4)
O1W—H1W···O3ii0.84 (2)2.14 (2)2.951 (3)162 (4)
N1—H14···O2i0.92 (2)1.83 (2)2.734 (3)166 (5)
O3—H3···O1iii0.821.842.656 (3)173
O4—H4A···O1iv0.821.822.639 (3)174
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y+1, z1/2; (iii) x1/2, y+3/2, z+2; (iv) x+2, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC6H16N+·C7H5O4·H2O
Mr273.32
Crystal system, space groupOrthorhombic, P212121
Temperature (K)296
a, b, c (Å)10.7163 (16), 11.5973 (17), 11.7690 (17)
V3)1462.7 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.30 × 0.28 × 0.28
Data collection
DiffractometerBruker APEXII area-detector
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
7531, 1519, 1211
Rint0.043
(sin θ/λ)max1)0.599
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.093, 1.04
No. of reflections1519
No. of parameters186
No. of restraints3
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.20, 0.14

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W···O2i0.87 (4)1.98 (2)2.845 (3)173 (4)
O1W—H1W···O3ii0.841 (19)2.14 (2)2.951 (3)162 (4)
N1—H14···O2i0.92 (2)1.83 (2)2.734 (3)166 (5)
O3—H3···O1iii0.821.842.656 (3)172.8
O4—H4A···O1iv0.821.822.639 (3)174.1
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y+1, z1/2; (iii) x1/2, y+3/2, z+2; (iv) x+2, y1/2, z+3/2.
 

Acknowledgements

The author acknowledges South China Normal University for supporting this work.

References

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