PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 July 1; 66(Pt 7): o1660.
Published online 2010 June 16. doi:  10.1107/S1600536810021781
PMCID: PMC3006979

4-(8-Eth­oxy-2,3-dihydro-1H-cyclo­penta­[c]quinolin-4-yl)butane-1-peroxol

Abstract

In the title mol­ecule, C18H23NO3, the hydro­per­oxy­butyl substituent is nearly fully extended, with the four torsion angles in the range 170.23 (10)–178.71 (9)°. The O—O distance in the hydro­peroxide group is 1.4690 (13) Å. This group acts as an inter­molecular hydrogen-bond donor to a quinoline N atom. This results in dimeric units about the respective inversion centers, with graph-set notation R 2 2(18).

Related literature

For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]). For graph-set motifs, see: Etter (1990 [triangle]). For the biological activity of dihydro­quinolines, see: Babiak et al. (1999 [triangle]); Cracknell et al. (1998 [triangle]); Dillard et al. (1973 [triangle]); Fotie et al. (2010 [triangle]); Lockhart et al. (2001 [triangle]); Shah et al. (2005 [triangle]); Takahashi et al. (2006 [triangle]); Thorisson et al. (1992 [triangle]). For related structures, see: Grignon-Dubois et al. (1993 [triangle]); Noland et al. (1996 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o1660-scheme1.jpg

Experimental

Crystal data

  • C18H23NO3
  • M r = 301.37
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1660-efi2.jpg
  • a = 8.0113 (2) Å
  • b = 8.5091 (2) Å
  • c = 12.6334 (3) Å
  • α = 73.605 (1)°
  • β = 74.936 (1)°
  • γ = 78.136 (1)°
  • V = 789.63 (3) Å3
  • Z = 2
  • Cu Kα radiation
  • μ = 0.69 mm−1
  • T = 90 K
  • 0.19 × 0.17 × 0.15 mm

Data collection

  • Bruker APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2004 [triangle]) T min = 0.880, T max = 0.904
  • 9369 measured reflections
  • 2798 independent reflections
  • 2400 reflections with I > 2σ(I)
  • R int = 0.030

Refinement

  • R[F 2 > 2σ(F 2)] = 0.036
  • wR(F 2) = 0.110
  • S = 1.08
  • 2798 reflections
  • 202 parameters
  • H-atom parameters constrained
  • Δρmax = 0.22 e Å−3
  • Δρmin = −0.27 e Å−3

Data collection: APEX2 (Bruker, 2006 [triangle]); cell refinement: SAINT (Bruker, 2006 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810021781/fj2311sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810021781/fj2311Isup2.hkl

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

Acknowledgments

This work was supported by Southeastern Louisiana University’s Office of Sponsored Research through the Research Initiation Program.

supplementary crystallographic information

Comment

Dihydroquinolines are mainly known for their antioxidant activity (Thorisson et al., 1992, Lockhart et al., 2001) although they have also been reported to possess anti-inflammatory (Dillard et al., 1973), fungicidal (Cracknell et al., 1998), antiatherosclerotic (Babiak et al., 1999), and hormone receptor modulator (Takahashi et al., 2006) properties. Furthermore, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, also known as ethoxyquin, is a FDA approved antioxidant commonly used as a preservative in the food processing industry (Shah et al., 2005). We have recently reported some dihydroquinoline derivatives with outstanding antitrypanosomal activity (Fotie et al., 2010). In our effort to optimize the trypanocidal activity of this family of compound, we have synthesized the title compound, an unusual hydroperoxybutylquinoline derivative. Here we are reporting the characterization of that compound using 1H– and 13C-NMR spectroscopy, mass spectrometry, and single-crystal diffraction.

The molecular structure of the title compound is illustrated in Fig. 1. The 10-atom quinoline ring system is essentially planar, with mean deviation 0.009 Å and maximum deviation 0.017 (1) Å for both N1 and C11. The five-membered ring has the envelope conformation, with C9 at the flap position, 0.340 (2) Å out of the quinoline plane. The hydroperoxybutyl chain is extended, with torsion angle magnitudes in the range 170.23 (10) to 178.71 (9)°, and the best plane of its four C and two O atoms is approximately perpendicular to the quinoline plane, forming a dihedral angle of 89.53 (3)°. The hydroperoxy O—O distance, 1.4690 (13) Å agrees well with literature values for this group. The mean value of the 135 such distances in the Cambridge Structural Database (version 5.31, Nov. 2009; Allen 2002), after rejecting eight outliers, is 1.462 Å.

The hydroperoxide donates an intermolecular hydrogen bond to quinoline N1, with O···N distance 2.7466 (14) Å, forming discrete dimers having graph set (Etter, 1990) R22(18) about inversion centers, as illustrated in Fig. 2.

Experimental

The title compound was prepared by heating to reflux for three days, a mixture of p-phenitidine (500 mg, 3.6 mmol) and cyclopentanone (10 ml, large excess) in the presence of catalytic amounts of iodine (93 mg) and benzoyl peroxide (8.8 mg). After appropriate work-up, and purification on a silica gel column, crystals were carefully grown at room temperature, in a mixture of hexanes-dichloromethane, over the course of a week.

Mp: 131.3 - 131.6 °C. The melting point was recorded on a MEL-TEMP ELECTROTHERMAL digital melting point apparatus, and is not corrected.

ESIMS m/z (%): 316 (90) [M + CH3]+, 302 (43) [M + H]+, 286 (100) [M -16]+, 284 (94) [M - H2O]+. These fragment ions are consistent with a molecular formula of C18H23NO3. The ESIMS spectrum was recorded on a Finnigan LCQDUO spectrometer.

NMR data were collected on a Bruker AC 300 Spectrometer. 1H-NMR (300 MHz, CDCl3) δ: 1.47 (3H, t, J = 6.7 Hz), 1.68 (2H, m), 1.85 (2H, m), 2.23 (2H, m), 3.04 (4H, t, J = 7.9 Hz), 3.13 (2H, t, J = 7.3 Hz), 4.10 (2H, t, 6.7 Hz), 4.15 (2H, q, J = 6.7 Hz), 6.90 (1H, d, J = 2.4 Hz), 7.23 (1H, dd, J = 9.2 Hz and 2,4 Hz), 7.83 (1H, d, 9.2 Hz), 13.6 (1H, brs). 13C-NMR (75 MHz, CDCl3) δ: 14.9, 24.0, 25.0, 25.9, 31.4, 31.5, 35.0, 63.8, 103.0, 121.1, 125.9, 129.2, 136.0, 141.6, 149.7, 155.9, 156.6. 162.3.

Refinement

H atoms on C were placed in idealized positions with C—H distances 0.95 - 1.00 Å and thereafter treated as riding. The OH H atom was located from a difference map in the expected circle. Torsional parameters were refined for the methyl and hydroperoxy OH groups. Uiso for H were assigned as 1.2 times Ueq of the attached atoms (1.5 for methyl and OH).

Figures

Fig. 1.
Ellipsoids at the 50% level, with H atoms having arbitrary radius.
Fig. 2.
The hydrogen-bonded dimer, with graph set R22(18).

Crystal data

C18H23NO3Z = 2
Mr = 301.37F(000) = 324
Triclinic, P1Dx = 1.268 Mg m3
Hall symbol: -P 1Cu Kα radiation, λ = 1.54178 Å
a = 8.0113 (2) ÅCell parameters from 4518 reflections
b = 8.5091 (2) Åθ = 3.7–68.3°
c = 12.6334 (3) ŵ = 0.69 mm1
α = 73.605 (1)°T = 90 K
β = 74.936 (1)°Prism, colourless
γ = 78.136 (1)°0.19 × 0.17 × 0.15 mm
V = 789.63 (3) Å3

Data collection

Bruker APEXII CCD diffractometer2798 independent reflections
Radiation source: fine-focus sealed tube2400 reflections with I > 2σ(I)
graphiteRint = 0.030
[var phi] and ω scansθmax = 68.8°, θmin = 3.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)h = −9→9
Tmin = 0.880, Tmax = 0.904k = −9→10
9369 measured reflectionsl = −15→15

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.110w = 1/[σ2(Fo2) + (0.0626P)2 + 0.1754P] where P = (Fo2 + 2Fc2)/3
S = 1.08(Δ/σ)max < 0.001
2798 reflectionsΔρmax = 0.22 e Å3
202 parametersΔρmin = −0.27 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0023 (7)

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 (Å2)

xyzUiso*/Ueq
O10.54940 (12)0.44045 (11)1.21141 (7)0.0202 (2)
O20.43514 (12)0.35072 (12)1.31138 (8)0.0233 (3)
H20.34290.41401.32920.035*
O30.98882 (12)0.17854 (11)0.27498 (8)0.0201 (2)
N10.84064 (14)0.40032 (13)0.66551 (9)0.0180 (3)
C10.96537 (17)0.22269 (16)0.37459 (11)0.0177 (3)
C21.08402 (17)0.17863 (16)0.44285 (11)0.0175 (3)
H2A1.19140.11040.42330.021*
C31.04475 (17)0.23589 (15)0.54275 (11)0.0166 (3)
C40.88489 (17)0.33756 (16)0.57160 (11)0.0171 (3)
C50.76525 (17)0.37924 (16)0.49902 (11)0.0184 (3)
H50.65730.44730.51720.022*
C60.80419 (17)0.32234 (16)0.40359 (11)0.0198 (3)
H60.72250.34980.35620.024*
C71.15889 (17)0.19861 (16)0.61825 (11)0.0173 (3)
C81.33845 (17)0.09920 (17)0.60806 (11)0.0203 (3)
H8A1.41230.13620.53210.024*
H8B1.3323−0.02030.62260.024*
C91.40947 (18)0.13488 (18)0.69997 (12)0.0235 (3)
H9A1.47260.03230.74040.028*
H9B1.49090.21770.66560.028*
C101.25038 (18)0.20199 (18)0.78213 (12)0.0229 (3)
H10A1.21550.11430.85070.027*
H10B1.27530.29560.80470.027*
C111.11048 (17)0.25808 (16)0.71348 (11)0.0188 (3)
C120.95014 (17)0.36144 (16)0.73497 (11)0.0184 (3)
C130.89624 (18)0.43704 (17)0.83518 (11)0.0209 (3)
H13A0.82680.54710.81390.025*
H13B1.00250.45400.85430.025*
C140.78889 (17)0.33287 (16)0.94029 (11)0.0186 (3)
H14A0.68510.31050.92130.022*
H14B0.86010.22540.96570.022*
C150.73048 (17)0.42275 (16)1.03551 (11)0.0190 (3)
H15A0.83510.44031.05610.023*
H15B0.66550.53291.00790.023*
C160.61601 (18)0.32967 (16)1.13985 (11)0.0194 (3)
H16A0.51940.29621.11960.023*
H16B0.68500.22911.17790.023*
C171.15683 (18)0.09386 (16)0.23380 (11)0.0201 (3)
H17A1.1735−0.02030.28120.024*
H17B1.25030.15260.23570.024*
C181.1631 (2)0.09065 (18)0.11403 (12)0.0256 (3)
H18A1.06820.03470.11320.038*
H18B1.27550.03090.08350.038*
H18C1.14960.20430.06760.038*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0200 (5)0.0214 (5)0.0171 (5)−0.0013 (4)0.0010 (4)−0.0070 (4)
O20.0197 (5)0.0255 (5)0.0176 (5)0.0011 (4)0.0027 (4)−0.0033 (4)
O30.0201 (5)0.0229 (5)0.0180 (5)0.0001 (4)−0.0048 (4)−0.0076 (4)
N10.0179 (6)0.0168 (6)0.0179 (6)−0.0021 (4)−0.0017 (4)−0.0044 (4)
C10.0208 (7)0.0161 (7)0.0153 (6)−0.0040 (5)−0.0026 (5)−0.0027 (5)
C20.0164 (7)0.0150 (6)0.0183 (7)−0.0013 (5)−0.0018 (5)−0.0023 (5)
C30.0171 (7)0.0141 (6)0.0166 (7)−0.0038 (5)−0.0023 (5)−0.0006 (5)
C40.0181 (7)0.0141 (6)0.0168 (7)−0.0033 (5)−0.0004 (5)−0.0022 (5)
C50.0151 (7)0.0165 (7)0.0210 (7)0.0002 (5)−0.0027 (5)−0.0029 (5)
C60.0187 (7)0.0193 (7)0.0199 (7)−0.0030 (5)−0.0051 (5)−0.0017 (5)
C70.0173 (7)0.0148 (6)0.0175 (7)−0.0039 (5)−0.0023 (5)−0.0003 (5)
C80.0176 (7)0.0211 (7)0.0201 (7)0.0016 (5)−0.0045 (5)−0.0045 (5)
C90.0183 (7)0.0282 (8)0.0235 (7)−0.0008 (6)−0.0065 (6)−0.0056 (6)
C100.0222 (7)0.0259 (8)0.0219 (7)−0.0011 (6)−0.0075 (6)−0.0071 (6)
C110.0194 (7)0.0180 (7)0.0175 (7)−0.0052 (5)−0.0029 (5)−0.0012 (5)
C120.0193 (7)0.0164 (7)0.0182 (7)−0.0043 (5)−0.0017 (5)−0.0032 (5)
C130.0215 (7)0.0203 (7)0.0212 (7)−0.0037 (5)−0.0020 (6)−0.0075 (6)
C140.0194 (7)0.0188 (7)0.0182 (7)−0.0005 (5)−0.0043 (5)−0.0067 (5)
C150.0181 (7)0.0203 (7)0.0192 (7)−0.0006 (5)−0.0041 (5)−0.0072 (5)
C160.0213 (7)0.0195 (7)0.0179 (7)0.0005 (5)−0.0043 (5)−0.0075 (5)
C170.0214 (7)0.0180 (7)0.0197 (7)−0.0001 (5)−0.0029 (5)−0.0058 (5)
C180.0307 (8)0.0246 (8)0.0226 (7)−0.0005 (6)−0.0046 (6)−0.0106 (6)

Geometric parameters (Å, °)

O1—C161.4193 (15)C9—H9B0.9900
O1—O21.4690 (13)C10—C111.5125 (18)
O2—H20.8400C10—H10A0.9900
O3—C11.3693 (15)C10—H10B0.9900
O3—C171.4319 (16)C11—C121.4094 (19)
N1—C121.3288 (17)C12—C131.5048 (18)
N1—C41.3709 (17)C13—C141.5310 (18)
C1—C21.3729 (18)C13—H13A0.9900
C1—C61.4142 (19)C13—H13B0.9900
C2—C31.4166 (18)C14—C151.5266 (17)
C2—H2A0.9500C14—H14A0.9900
C3—C41.4147 (18)C14—H14B0.9900
C3—C71.4176 (18)C15—C161.5122 (18)
C4—C51.4208 (18)C15—H15A0.9900
C5—C61.3628 (19)C15—H15B0.9900
C5—H50.9500C16—H16A0.9900
C6—H60.9500C16—H16B0.9900
C7—C111.3691 (19)C17—C181.5087 (18)
C7—C81.5054 (18)C17—H17A0.9900
C8—C91.5420 (19)C17—H17B0.9900
C8—H8A0.9900C18—H18A0.9800
C8—H8B0.9900C18—H18B0.9800
C9—C101.5413 (19)C18—H18C0.9800
C9—H9A0.9900
C16—O1—O2105.80 (9)C7—C11—C12120.33 (12)
O1—O2—H2109.5C7—C11—C10111.14 (12)
C1—O3—C17117.05 (10)C12—C11—C10128.50 (12)
C12—N1—C4119.06 (11)N1—C12—C11121.27 (12)
O3—C1—C2125.10 (12)N1—C12—C13116.62 (11)
O3—C1—C6114.06 (11)C11—C12—C13122.09 (12)
C2—C1—C6120.84 (12)C12—C13—C14114.07 (11)
C1—C2—C3119.32 (12)C12—C13—H13A108.7
C1—C2—H2A120.3C14—C13—H13A108.7
C3—C2—H2A120.3C12—C13—H13B108.7
C4—C3—C2120.22 (12)C14—C13—H13B108.7
C4—C3—C7116.10 (12)H13A—C13—H13B107.6
C2—C3—C7123.68 (12)C15—C14—C13110.73 (11)
N1—C4—C3123.16 (12)C15—C14—H14A109.5
N1—C4—C5118.20 (12)C13—C14—H14A109.5
C3—C4—C5118.63 (12)C15—C14—H14B109.5
C6—C5—C4120.53 (12)C13—C14—H14B109.5
C6—C5—H5119.7H14A—C14—H14B108.1
C4—C5—H5119.7C16—C15—C14113.20 (11)
C5—C6—C1120.44 (12)C16—C15—H15A108.9
C5—C6—H6119.8C14—C15—H15A108.9
C1—C6—H6119.8C16—C15—H15B108.9
C11—C7—C3120.02 (12)C14—C15—H15B108.9
C11—C7—C8111.83 (11)H15A—C15—H15B107.8
C3—C7—C8128.14 (12)O1—C16—C15106.06 (11)
C7—C8—C9103.20 (11)O1—C16—H16A110.5
C7—C8—H8A111.1C15—C16—H16A110.5
C9—C8—H8A111.1O1—C16—H16B110.5
C7—C8—H8B111.1C15—C16—H16B110.5
C9—C8—H8B111.1H16A—C16—H16B108.7
H8A—C8—H8B109.1O3—C17—C18107.10 (11)
C10—C9—C8106.77 (11)O3—C17—H17A110.3
C10—C9—H9A110.4C18—C17—H17A110.3
C8—C9—H9A110.4O3—C17—H17B110.3
C10—C9—H9B110.4C18—C17—H17B110.3
C8—C9—H9B110.4H17A—C17—H17B108.6
H9A—C9—H9B108.6C17—C18—H18A109.5
C11—C10—C9103.12 (11)C17—C18—H18B109.5
C11—C10—H10A111.1H18A—C18—H18B109.5
C9—C10—H10A111.1C17—C18—H18C109.5
C11—C10—H10B111.1H18A—C18—H18C109.5
C9—C10—H10B111.1H18B—C18—H18C109.5
H10A—C10—H10B109.1
C17—O3—C1—C2−6.48 (18)C3—C7—C8—C9168.11 (13)
C17—O3—C1—C6173.01 (11)C7—C8—C9—C1018.58 (14)
O3—C1—C2—C3178.62 (11)C8—C9—C10—C11−19.42 (14)
C6—C1—C2—C3−0.8 (2)C3—C7—C11—C12−2.3 (2)
C1—C2—C3—C4−0.07 (19)C8—C7—C11—C12176.70 (12)
C1—C2—C3—C7−179.45 (12)C3—C7—C11—C10179.39 (11)
C12—N1—C4—C3−1.71 (19)C8—C7—C11—C10−1.59 (16)
C12—N1—C4—C5179.37 (11)C9—C10—C11—C713.27 (15)
C2—C3—C4—N1−178.41 (11)C9—C10—C11—C12−164.84 (13)
C7—C3—C4—N11.02 (19)C4—N1—C12—C110.34 (19)
C2—C3—C4—C50.51 (19)C4—N1—C12—C13178.70 (11)
C7—C3—C4—C5179.94 (11)C7—C11—C12—N11.7 (2)
N1—C4—C5—C6178.92 (11)C10—C11—C12—N1179.63 (12)
C3—C4—C5—C6−0.05 (19)C7—C11—C12—C13−176.59 (12)
C4—C5—C6—C1−0.8 (2)C10—C11—C12—C131.4 (2)
O3—C1—C6—C5−178.21 (11)N1—C12—C13—C1489.79 (14)
C2—C1—C6—C51.3 (2)C11—C12—C13—C14−91.87 (15)
C4—C3—C7—C111.01 (19)C12—C13—C14—C15−176.62 (11)
C2—C3—C7—C11−179.59 (12)C13—C14—C15—C16177.09 (10)
C4—C3—C7—C8−177.84 (12)O2—O1—C16—C15178.71 (9)
C2—C3—C7—C81.6 (2)C14—C15—C16—O1−170.23 (10)
C11—C7—C8—C9−10.82 (15)C1—O3—C17—C18−168.40 (11)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O2—H2···N1i0.841.932.7466 (14)165

Symmetry codes: (i) −x+1, −y+1, −z+2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2311).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Babiak, J., Elokdah, H., Miller, C. & Sulkowski, T. (1999). US Patent 5 939 435.
  • Bruker (2006). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Cracknell, M., Duriatti, A. & Kirby, N. (1998). World Patent WO 9805646.
  • Dillard, R., Pavey, D. & Benslay, D. (1973). J. Med. Chem.16, 251–253. [PubMed]
  • Etter, M. C. (1990). Acc. Chem. Res.23, 120–126.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Fotie, J., Kaiser, M., Delfin, D. A., Manley, J., Reid, C. S., Paris, J. M., Wenzler, T., Maes, L., Mahasenan, K. V., Li, C. & Werbovetz, K. A. (2010). J. Med. Chem.53, 966–982. [PubMed]
  • Grignon-Dubois, M., Fialeix, M., Laguerre, M., Leger, J.-M. & Gauffre, J.-C. (1993). J. Org. Chem.58, 1926–1931.
  • Lockhart, B., Bonhomme, N., Roger, A., Dorey, G., Casara, P. & Lestage, P. (2001). Eur. J. Pharmacol.416, 59–68. [PubMed]
  • Noland, W. E., Konkel, M. J., Konkel, L. M. C., Pearce, B. C., Barnes, C. L. & Schlemper, E. O. (1996). J. Org. Chem.61, 451–454. [PubMed]
  • Shah, A., Pierson, J. & Pavlostathisa, S. (2005). Water Res.39, 4251–4263. [PubMed]
  • Sheldrick, G. M. (2004). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Takahashi, H., Bekkali, Y., Capolino, A., Gilmore, T., Goldrick, S., Nelson, R., Terenzio, D., Wang, J., Zuvela-Jelaska, L., Proudfoot, J., Nabozny, G. & Thomson, D. (2006). Bioorg. Med. Chem. Lett.16, 1549–1552. [PubMed]
  • Thorisson, S., Gunstone, F. & Hardy, R. (1992). J. Am. Oil Chem. Soc.69, 806–809.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography