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 November 1; 66(Pt 11): o3009.
Published online 2010 October 31. doi:  10.1107/S1600536810042935
PMCID: PMC3009067

3-Methyl-1,4-diphenyl-1H-pyrazolo­[3,4-b]quinoline

Abstract

In the title mol­ecule, C23H17N3, the phenyl substituents at positions 1 and 4 are twisted relative to the central core by 27.09 (5) and 66.62 (4)°, respectively. In the crystal, mol­ecules are assembled into centrosymmetric dimers via π–π stacking inter­actions between the 1H-pyrazolo­[3,4-b]quinoline ­units, with an inter­planar distance of 3.601 (2) Å and by weak inter­molecular C—H(...)N inter­actions.

Related literature

For the synthesis of 1,3 and 4-substituted 1H-pyrazolo­[3,4-b]quinoline derivatives using Friedländer condensation, see: Danel (1996 [triangle]); Woo et al. (2002 [triangle]). For selected photophysical properties of 1H-pyrazolo­[3,4-b]quinoline derivatives, see: Gondek et al. (2006 [triangle]). For related structures, see: Szlachcic & Stadnicka (2010 [triangle]); Szlachcic et al. (2010 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o3009-scheme1.jpg

Experimental

Crystal data

  • C23H17N3
  • M r = 335.40
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o3009-efi1.jpg
  • a = 9.2120 (4) Å
  • b = 9.9377 (5) Å
  • c = 10.3440 (4) Å
  • α = 92.278 (2)°
  • β = 113.376 (2)°
  • γ = 90.152 (2)°
  • V = 868.37 (7) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 293 K
  • 0.50 × 0.42 × 0.15 mm

Data collection

  • Nonius KappaCCD diffractometer
  • Absorption correction: multi-scan (DENZO and SCALEPACK; Otwinowski & Minor, 1997 [triangle]) T min = 0.963, T max = 0.989
  • 6556 measured reflections
  • 4964 independent reflections
  • 3285 reflections with I > 2σ(I)
  • R int = 0.020

Refinement

  • R[F 2 > 2σ(F 2)] = 0.053
  • wR(F 2) = 0.139
  • S = 1.02
  • 4964 reflections
  • 236 parameters
  • H-atom parameters constrained
  • Δρmax = 0.24 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: COLLECT (Nonius, 1998 [triangle]); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 [triangle]); data reduction: DENZO (Otwinowski & Minor, 1997 [triangle]) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810042935/gk2306sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810042935/gk2306Isup2.hkl

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

Acknowledgments

The authors are grateful to the Ministry of Science and Higher Education, Poland, for financial support of this work through grant No. N N204 216734.

supplementary crystallographic information

Comment

The title compound and other 1H-pyrazolo[3,4-b]quinoline (PQ) derivatives containing hydrogen, methyl or phenyl substituents and their combination, showed important photophysical properties (Gondek et al., 2006) which could be utilized in organic light-emitting diodes (OLED) fabrication. To synthesize 1,3,4-substituted PQ derivatives, a method of preparation introduced by Danel (1996) was used. The results of using the title compound in OLED preparation will be published elsewhere.

The shape of the title molecule is shown in Fig. 1. The core of the molecule, 1H-pyrazolo[3,4-b]quinoline, is planar and aromatic. The planes of phenyl substituents at positions 1 and 4 are twisted against the core moiety with the torsion angles N2—N1—C11—C16 = -15.7 (2) and C3a—C4—C41—C46 = 116.7 (2)°. The conformation of the molecule is stabilized by two intramolecular interactions of C—H···N type in which N2 and N9 atoms are acceptors.

The packing of the molecules (Fig. 2) is determined by one weak intermolecular hydrogen bond C46—H46···N9 (-x + 1, -y + 1, -z), and π-π interactions: with Cg1 (N1—N2—C3—C3a—C9a)···Cg3 (C4a—C5—C6—C7—C8—C8a at 1 - x, 1 - y, -z) = 3.731 and Cg2 (C3a—C4—C4a—C8a—N9—C9a)···Cg2 (C3a—C4—C4a—C8a—N9—C9a at 1 - x, 1 - y, -z) = 3.799 Å resulting in forming molecular dimers. The two C—H···π interactions are described by the geometry parameters (H···A /Å, D···A /Å, <DHA /°, respectively) given below:

C6—H6···Cg5 (C41—C42—C43—C44—C45—C46 at 2 - x, 1 - y, -z): 2.967, 3.750, 143;

C31—H31···Cg1 (N1—N2—C3—C3a—C9a at 1 - x, -y, -z): 3.172, 3.875, 132.

Experimental

The title compound was synthesized using procedure already described in literature (Danel, 1996) from 2-aminobenzophenone and 5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one (10 mmol of each substrate, ethylene glycol as a solvent). The product was purified by flash chromatography on Al2O3 with chloroform as a solvent, followed by crystallization from toluene/petroleum ether to give 2.38 g (71% yield) of light-yellow crystalline solid, mp. 438–440 K. 1H NMR (CDCl3): δ 2.14 (s, 3H), 7.25–7.30 (m, 1H), 7.36 (ddd, J = 8.6, 6.7, 1.3 Hz, 1H), 7.44–7.47 (m, 2H), 7.52–7.60 (m, 5H). 7.71–7.77 (m, 2H), 8.20 (d, J = 8.4 Hz, 1H), 8.49–8.53 (m, 2H). 13C NMR (CDCl3): δ 14.9, 116.3, 120.3, 123.6, 123.9, 124.9, 127.0, 128.3, 128.7, 129.0 (two signals), 129.7, 130.3, 135.0, 140.0, 143.8, 144.4, 148.5, 150.2. Single crystals suitable for X-ray diffraction were grown by slow evaporation from toluene solution at ambient conditions.

Refinement

H atoms were included into refinement in geometrically calculated positions, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq for the aromatic CH groups and C—H = 0.96 Å and Uiso(H) = 1.5Ueq for methyl groups. The positions of H atoms were constrained as a part of a riding model. In the case of methyl group the torsion angle along the Caromatic—Cmethyl bond was refined using AFIX 137 procedure (SHELXL-97; Sheldrick, 2008).

Figures

Fig. 1.
The conformation of the 3-methyl-1,4-diphenyl-1H-pyrazolo[3,4-b]quinoline molecule with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
Fig. 2.
The unit-cell contents of the title compound in projection along [001] showing molecular dimers formation.

Crystal data

C23H17N3Z = 2
Mr = 335.40F(000) = 352
Triclinic, P1Dx = 1.283 Mg m3
Hall symbol: -P 1Melting point = 438–440 K
a = 9.2120 (4) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.9377 (5) ÅCell parameters from 2458 reflections
c = 10.3440 (4) Åθ = 1.0–30.0°
α = 92.278 (2)°µ = 0.08 mm1
β = 113.376 (2)°T = 293 K
γ = 90.152 (2)°Plate, green–yellow
V = 868.37 (7) Å30.50 × 0.42 × 0.15 mm

Data collection

Nonius KappaCCD diffractometer4964 independent reflections
Radiation source: fine-focus sealed tube3285 reflections with I > 2σ(I)
horizontally mounted graphite crystalRint = 0.020
Detector resolution: 9 pixels mm-1θmax = 30.0°, θmin = 2.9°
[var phi] and ο scans to fill Ewald sphereh = −12→11
Absorption correction: multi-scan (DENZO and SCALEPACK; Otwinowski & Minor, 1997)k = −13→7
Tmin = 0.963, Tmax = 0.989l = −14→13
6556 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.053Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.139H-atom parameters constrained
S = 1.02w = 1/[σ2(Fo2) + (0.054P)2 + 0.1697P] where P = (Fo2 + 2Fc2)/3
4964 reflections(Δ/σ)max < 0.001
236 parametersΔρmax = 0.24 e Å3
0 restraintsΔρmin = −0.17 e Å3
0 constraints

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
N10.34388 (14)0.18687 (11)0.08010 (12)0.0397 (3)
N20.28625 (15)0.11194 (12)−0.04633 (13)0.0438 (3)
C30.37588 (17)0.13841 (14)−0.11453 (15)0.0416 (3)
C3A0.49700 (16)0.23706 (13)−0.03567 (14)0.0351 (3)
C40.61386 (15)0.31001 (13)−0.05685 (14)0.0344 (3)
C4A0.70159 (15)0.40697 (13)0.05158 (14)0.0345 (3)
C50.82339 (17)0.49062 (14)0.04416 (15)0.0418 (3)
H50.84500.4851−0.03640.050*
C60.90904 (18)0.57853 (16)0.15214 (17)0.0478 (4)
H60.98700.63300.14410.057*
C70.88014 (19)0.58731 (16)0.27575 (17)0.0514 (4)
H70.94020.64660.34970.062*
C80.76495 (18)0.50976 (15)0.28780 (16)0.0464 (4)
H80.74760.51630.37040.056*
C8A0.67061 (15)0.41895 (13)0.17655 (14)0.0356 (3)
N90.55506 (13)0.34765 (11)0.19637 (12)0.0381 (3)
C9A0.47232 (15)0.26467 (13)0.08992 (14)0.0343 (3)
C110.25132 (16)0.19574 (13)0.16186 (14)0.0378 (3)
C120.31890 (19)0.24076 (15)0.30166 (16)0.0487 (4)
H120.42600.26390.34360.058*
C130.2259 (2)0.25117 (17)0.37876 (19)0.0579 (4)
H130.27060.28310.47230.069*
C140.0681 (2)0.21477 (17)0.3187 (2)0.0591 (4)
H140.00640.22200.37120.071*
C150.00234 (19)0.16761 (17)0.18044 (19)0.0553 (4)
H15−0.10380.14130.14010.066*
C160.09222 (17)0.15891 (15)0.10080 (17)0.0455 (3)
H160.04640.12850.00680.055*
C310.3400 (2)0.06994 (18)−0.25516 (17)0.0578 (4)
H31A0.42090.0063−0.24770.087*
H31B0.33650.1358−0.32170.087*
H31C0.23950.0237−0.28660.087*
C410.64981 (16)0.28577 (13)−0.18381 (14)0.0357 (3)
C420.70864 (19)0.16239 (15)−0.20626 (16)0.0462 (4)
H420.72430.0953−0.14210.055*
C430.7441 (2)0.13829 (17)−0.32315 (18)0.0540 (4)
H430.78360.0555−0.33710.065*
C440.72084 (19)0.23688 (18)−0.41857 (17)0.0524 (4)
H440.74430.2207−0.49730.063*
C450.66269 (18)0.35998 (17)−0.39743 (16)0.0491 (4)
H450.64680.4265−0.46220.059*
C460.62795 (17)0.38491 (14)−0.28066 (15)0.0417 (3)
H460.58980.4684−0.26670.050*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N10.0428 (6)0.0404 (6)0.0370 (6)−0.0120 (5)0.0179 (5)−0.0042 (5)
N20.0489 (7)0.0417 (6)0.0396 (6)−0.0131 (5)0.0172 (5)−0.0058 (5)
C30.0461 (8)0.0386 (7)0.0390 (7)−0.0073 (6)0.0164 (6)−0.0017 (6)
C3A0.0399 (7)0.0325 (6)0.0335 (6)−0.0019 (5)0.0153 (6)0.0008 (5)
C40.0363 (7)0.0329 (6)0.0353 (7)0.0014 (5)0.0156 (6)0.0018 (5)
C4A0.0342 (7)0.0335 (6)0.0375 (7)−0.0004 (5)0.0162 (6)−0.0003 (5)
C50.0409 (8)0.0449 (8)0.0444 (8)−0.0061 (6)0.0223 (6)−0.0029 (6)
C60.0417 (8)0.0495 (8)0.0561 (9)−0.0134 (6)0.0243 (7)−0.0065 (7)
C70.0485 (9)0.0547 (9)0.0517 (9)−0.0176 (7)0.0225 (7)−0.0156 (7)
C80.0461 (8)0.0537 (8)0.0429 (8)−0.0131 (7)0.0230 (7)−0.0122 (7)
C8A0.0351 (7)0.0359 (6)0.0372 (7)−0.0031 (5)0.0160 (6)−0.0012 (5)
N90.0389 (6)0.0401 (6)0.0370 (6)−0.0073 (5)0.0173 (5)−0.0032 (5)
C9A0.0359 (7)0.0331 (6)0.0352 (6)−0.0033 (5)0.0155 (5)0.0018 (5)
C110.0420 (7)0.0326 (6)0.0419 (7)−0.0047 (5)0.0198 (6)0.0043 (6)
C120.0521 (9)0.0529 (9)0.0428 (8)−0.0151 (7)0.0210 (7)−0.0023 (7)
C130.0749 (12)0.0548 (9)0.0531 (10)−0.0144 (8)0.0360 (9)−0.0073 (8)
C140.0658 (11)0.0563 (10)0.0722 (12)0.0003 (8)0.0455 (10)0.0011 (9)
C150.0425 (9)0.0590 (10)0.0689 (11)−0.0006 (7)0.0265 (8)0.0083 (9)
C160.0411 (8)0.0467 (8)0.0467 (8)−0.0052 (6)0.0151 (7)0.0040 (7)
C310.0659 (11)0.0612 (10)0.0460 (9)−0.0213 (8)0.0237 (8)−0.0155 (8)
C410.0369 (7)0.0365 (7)0.0355 (7)−0.0032 (5)0.0167 (6)−0.0012 (6)
C420.0563 (9)0.0398 (7)0.0454 (8)0.0040 (6)0.0235 (7)0.0007 (6)
C430.0632 (10)0.0498 (9)0.0546 (10)0.0061 (8)0.0301 (8)−0.0069 (8)
C440.0532 (9)0.0675 (10)0.0417 (8)−0.0034 (8)0.0256 (7)−0.0085 (8)
C450.0523 (9)0.0582 (9)0.0403 (8)−0.0035 (7)0.0218 (7)0.0067 (7)
C460.0453 (8)0.0412 (7)0.0421 (8)0.0010 (6)0.0212 (6)0.0029 (6)

Geometric parameters (Å, °)

N1—C9A1.3790 (16)C12—C131.385 (2)
N1—N21.3842 (16)C12—H120.9300
N1—C111.4201 (17)C13—C141.376 (3)
N2—C31.3132 (18)C13—H130.9300
C3—C3A1.4422 (19)C14—C151.374 (3)
C3—C311.492 (2)C14—H140.9300
C3A—C41.3885 (18)C15—C161.381 (2)
C3A—C9A1.4217 (18)C15—H150.9300
C4—C4A1.4249 (18)C16—H160.9300
C4—C411.4876 (18)C31—H31A0.9600
C4A—C51.4228 (18)C31—H31B0.9600
C4A—C8A1.4308 (18)C31—H31C0.9600
C5—C61.361 (2)C41—C421.3898 (19)
C5—H50.9300C41—C461.3907 (19)
C6—C71.405 (2)C42—C431.384 (2)
C6—H60.9300C42—H420.9300
C7—C81.358 (2)C43—C441.375 (2)
C7—H70.9300C43—H430.9300
C8—C8A1.4190 (19)C44—C451.381 (2)
C8—H80.9300C44—H440.9300
C8A—N91.3631 (16)C45—C461.381 (2)
N9—C9A1.3160 (17)C45—H450.9300
C11—C121.383 (2)C46—H460.9300
C11—C161.3875 (19)
C9A—N1—N2110.06 (11)C11—C12—H12120.3
C9A—N1—C11129.37 (11)C13—C12—H12120.3
N2—N1—C11119.07 (11)C14—C13—C12120.78 (16)
C3—N2—N1108.04 (11)C14—C13—H13119.6
N2—C3—C3A110.55 (12)C12—C13—H13119.6
N2—C3—C31119.20 (13)C15—C14—C13119.47 (15)
C3A—C3—C31130.23 (13)C15—C14—H14120.3
C4—C3A—C9A118.45 (12)C13—C14—H14120.3
C4—C3A—C3136.89 (13)C14—C15—C16120.71 (16)
C9A—C3A—C3104.51 (11)C14—C15—H15119.6
C3A—C4—C4A116.60 (12)C16—C15—H15119.6
C3A—C4—C41122.02 (12)C15—C16—C11119.61 (15)
C4A—C4—C41121.36 (11)C15—C16—H16120.2
C5—C4A—C4123.14 (12)C11—C16—H16120.2
C5—C4A—C8A117.71 (12)C3—C31—H31A109.5
C4—C4A—C8A119.12 (11)C3—C31—H31B109.5
C6—C5—C4A121.57 (13)H31A—C31—H31B109.5
C6—C5—H5119.2C3—C31—H31C109.5
C4A—C5—H5119.2H31A—C31—H31C109.5
C5—C6—C7120.27 (13)H31B—C31—H31C109.5
C5—C6—H6119.9C42—C41—C46118.74 (12)
C7—C6—H6119.9C42—C41—C4119.81 (12)
C8—C7—C6120.36 (14)C46—C41—C4121.45 (12)
C8—C7—H7119.8C43—C42—C41120.68 (14)
C6—C7—H7119.8C43—C42—H42119.7
C7—C8—C8A121.18 (14)C41—C42—H42119.7
C7—C8—H8119.4C44—C43—C42119.96 (14)
C8A—C8—H8119.4C44—C43—H43120.0
N9—C8A—C8117.20 (12)C42—C43—H43120.0
N9—C8A—C4A123.94 (12)C43—C44—C45119.95 (14)
C8—C8A—C4A118.86 (12)C43—C44—H44120.0
C9A—N9—C8A114.32 (11)C45—C44—H44120.0
N9—C9A—N1125.83 (12)C46—C45—C44120.36 (14)
N9—C9A—C3A127.35 (12)C46—C45—H45119.8
N1—C9A—C3A106.81 (11)C44—C45—H45119.8
C12—C11—C16119.95 (13)C45—C46—C41120.30 (13)
C12—C11—N1120.37 (13)C45—C46—H46119.9
C16—C11—N1119.67 (13)C41—C46—H46119.9
C11—C12—C13119.46 (15)
C9A—N1—N2—C31.12 (16)C11—N1—C9A—N914.3 (2)
C11—N1—N2—C3168.47 (12)N2—N1—C9A—C3A−0.24 (15)
N1—N2—C3—C3A−1.54 (16)C11—N1—C9A—C3A−165.91 (13)
N1—N2—C3—C31179.75 (13)C4—C3A—C9A—N9−4.6 (2)
N2—C3—C3A—C4−173.86 (15)C3—C3A—C9A—N9179.13 (13)
C31—C3—C3A—C44.7 (3)C4—C3A—C9A—N1175.65 (12)
N2—C3—C3A—C9A1.37 (16)C3—C3A—C9A—N1−0.64 (14)
C31—C3—C3A—C9A179.90 (16)C9A—N1—C11—C12−31.2 (2)
C9A—C3A—C4—C4A0.62 (18)N2—N1—C11—C12164.26 (12)
C3—C3A—C4—C4A175.37 (15)C9A—N1—C11—C16148.85 (14)
C9A—C3A—C4—C41178.75 (12)N2—N1—C11—C16−15.73 (19)
C3—C3A—C4—C41−6.5 (2)C16—C11—C12—C13−1.3 (2)
C3A—C4—C4A—C5−179.09 (13)N1—C11—C12—C13178.74 (13)
C41—C4—C4A—C52.8 (2)C11—C12—C13—C141.3 (3)
C3A—C4—C4A—C8A3.01 (18)C12—C13—C14—C150.0 (3)
C41—C4—C4A—C8A−175.13 (12)C13—C14—C15—C16−1.3 (3)
C4—C4A—C5—C6−177.40 (14)C14—C15—C16—C111.3 (2)
C8A—C4A—C5—C60.5 (2)C12—C11—C16—C150.0 (2)
C4A—C5—C6—C70.9 (2)N1—C11—C16—C15−179.99 (13)
C5—C6—C7—C8−1.0 (3)C3A—C4—C41—C42−64.18 (18)
C6—C7—C8—C8A−0.4 (3)C4A—C4—C41—C42113.86 (15)
C7—C8—C8A—N9−178.35 (14)C3A—C4—C41—C46116.72 (15)
C7—C8—C8A—C4A1.8 (2)C4A—C4—C41—C46−65.24 (18)
C5—C4A—C8A—N9178.31 (13)C46—C41—C42—C43−0.3 (2)
C4—C4A—C8A—N9−3.7 (2)C4—C41—C42—C43−179.45 (14)
C5—C4A—C8A—C8−1.87 (19)C41—C42—C43—C44−0.1 (2)
C4—C4A—C8A—C8176.15 (13)C42—C43—C44—C450.2 (3)
C8—C8A—N9—C9A−179.62 (13)C43—C44—C45—C460.1 (2)
C4A—C8A—N9—C9A0.20 (19)C44—C45—C46—C41−0.6 (2)
C8A—N9—C9A—N1−176.24 (12)C42—C41—C46—C450.7 (2)
C8A—N9—C9A—C3A4.0 (2)C4—C41—C46—C45179.80 (13)
N2—N1—C9A—N9179.99 (13)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C12—H12···N90.932.443.0012 (18)119
C46—H46···N9i0.932.523.4164 (18)163
C16—H16···N20.932.482.799 (2)100

Symmetry codes: (i) −x+1, −y+1, −z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GK2306).

References

  • Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst.27, 435.
  • Danel, A. (1996). PhD thesis, University of Agriculture, Kraków, Poland.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Gondek, E., Kityk, I. V., Sanetra, J., Szlachcic, P., Armatys, P., Wisla, A. & Danel, A. (2006). Opt. Laser Technol.38, 487–492.
  • Nonius (1998). COLLECT Nonius BV, Delft, The Netherlands.
  • Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Szlachcic, P., Jarosz, B. & Stadnicka, K. (2010). Acta Cryst. C66, o488–o492. [PubMed]
  • Szlachcic, P. & Stadnicka, K. (2010). Acta Cryst. E66, o575. [PMC free article] [PubMed]
  • Woo, E. P., Inbasekaram, M., Wu, W. & Bernius, M. T. (2002). US Patent 6 353 083.

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