Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Previous article
Next article
Previous article
Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Next article

organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 10| October 2011| Page o2552
https://doi.org/10.1107/S1600536811035343

1,1′-(Propane-1,3-di­yl)bis­­(3-phenyl­urea)

Pramod Pansuriya,a Hariska Naidu,a Holger B. Friedricha and Glenn E. M. Maguirea*

aSchool of Chemistry, University of KwaZulu–Natal, Durban 4000, South Africa
*Correspondence e-mail: maguireg@ukzn.ac.za

(Received 20 July 2011; accepted 30 August 2011; online 3 September 2011)

The title compound, C17H20N4O2, has crystallographic inversion symmetry. In the crystal structure, inter­molecular hydrogen bonding between adjacent urea groups gives rise to infinite polymeric chains diagonally across the bc plane. With a centroid–centroid distance of 3.295 (2) Å, π–π stacking is present in the crystal along the same plane.

Related literature

For applications of ureas, see: Park et al. (2011[Park, J., Lang, K., Abboud, K. A. & Hong, S. (2011). Chem. Eur. J. 17, 2236-2245.]); Ahmed et al. (2011[Ahmed, N., Geronimo, I., Hwang, I., Singh, N. J. & Kim, K. S. (2011). Chem. Eur. J. 17, 8542-8548.]); Sharma et al. (2010[Sharma, S. K., Wu, Y., Steinbergs, N., Crowley, M. L., Hanson, A. S., Casero, R. A. Jr & Woster, P. M. (2010). J. Med. Chem. 53, 5197-5212.]); Vos et al. (2010[Vos, M. R. J., Leclère, P. E. L. G., Meekes, H., Vlieg, E., Nolte, R. J. M. & Sommerdijk, N. A. J. M. (2010). Chem. Commun. 46, 6063-6065.]); Dawn et al. (2011[Dawn, S., Dewal, M. B., Sobransingh, D., Paderes, M. C., Wibowo, A. C., Smith, M. D., Krause, J. A., Pellechia, P. J. & Shimizu, L. S. (2011). J. Am. Chem. Soc. 133, 7025-7032.]). For related structures, see: Koevoets et al. (2005[Koevoets, R. A., Versteegen, R. M., Kooijman, H., Spek, A. L., Sijbesma, R. P. & Meijer, E. W. (2005). J. Am. Chem. Soc. 127, 2999-3003.]).

[Scheme 1]

Experimental

Crystal data

  • C17H20N4O2

  • Mr = 312.37

  • Monoclinic, C 2/c

  • a = 33.811 (7) Å

  • b = 4.598 (1) Å

  • c = 9.891 (2) Å

  • β = 98.957 (4)°

  • V = 1518.9 (6) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 173 K

  • 0.50 × 0.21 × 0.02 mm
Data collection

  • Bruker Kappa DUO APEXII diffractometer

  • Absorption correction: multi-scan (TWINABS; Sheldrick, 2007[Sheldrick, G. M. (2007). TWINABS. University of Göttingen, Germany.])Tmin = 0.955, Tmax = 0.998

  • 1930 measured reflections

  • 1930 independent reflections

  • 1811 reflections with I > 2σ(I)

  • Rint = 0.042
Refinement

  • R[F2 > 2σ(F2)] = 0.033

  • wR(F2) = 0.092

  • S = 1.05

  • 1930 reflections

  • 114 parameters

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

  • Δρmax = 0.27 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1N⋯O1i 0.834 (18) 2.124 (18) 2.8742 (14) 149.7 (13)
N2—H2N⋯O1i 0.864 (18) 2.119 (18) 2.8904 (14) 148.4 (15)
Symmetry code: (i) x, y-1, z.

Data collection: APEX2 (Bruker, 2006[Bruker (2006). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2006[Bruker (2006). 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: OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536811035343/hg5067sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811035343/hg5067Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536811035343/hg5067Isup3.cml

checkCIF report


Comment top

Bis-ureas have been employed as ligands for metal complexes used in hydrolytic kinetic resolution of epoxides (Park et al., 2011) and as chromogenic and fluorogenic receptors (Ahmed et al., 2011). These molecules have also been found to be useful as epigenetic modulators (Sharma et al., 2010), in surfactant self-assembies (Vos et al., 2010), and photo dimerizing agent for coumarins (Dawn et al., 2011).

The closest reported structures are 3,3'-bis-phenyl-(butylene-1,4)-bisurea and 3,3'-bis-phenyl-(heptylene-1,7)-bisurea (Koevoets et al., 2005). In the butylene derivatives a transoid arrangement is evident whereas the heptylene molecule adopts a cisoid arrangement of the two urea groups. The title compound has an odd number of carbons in its aliphatic chain (propylene). This leads to a cisoid arrangement of the two urea groups (Fig. 1).

The asymmetric unit of the title compund, C17H20N4O2, contains half molecule of 1,1'-(propane-1,3-diyl)bis(3-phenylurea) and the complete molecule is generated by inversion symmetry (i) : 1-x, y, 1.5-z. Intermolecular hydrogen bonding between adjacent urea groups N1–H1–O1, 2.8742 (14) Å and N2–H2–O1, 2.8904 (14) Å gives rise to infinite polymeric chains across the bc plane (Fig. 2), The spacing between the two hydrogen-bonded urea groups is 4.59 Å in the title compound, while it is 4.64 Å for the even butylene spacer and 4.63 Å for the odd heptylene spacer. With a centroid distance of less than 3.5 Å, π-π stacking is present in the crystal along the same plane.

Related literature top

For applications of ureas, see: Park et al. (2011); Ahmed et al. (2011); Sharma et al. (2010); Vos et al. (2010); Dawn et al. (2011). For related structures, see: Koevoets et al. (2005).

Experimental top

A solution of phenyl isocyanate (6.76 g, 50 mmol) in diethylether (15 ml) was added dropwise at 15 °C to a vigorously stirred solution of anhydrous propane-1,3-diamine (7.41 g, 100 mmol) in isopropyl alcohol (100 ml) over a period of 30 min.The reaction mixture was stirred for 2 hrs at room temperature and quenched with water (200 ml). The reaction mixture was maintained overnight at room temperature. Then the reaction mixture was acidified with conc. HCl to pH 2.6. The solvents were evaporated under vacuum, the residue was suspended in hot water for 30 min and the resulting precipitate was filtered. The product was washed with ice cold water and dried. The yield was 2.70 g (40%).

Crystals suitable for single-crystal X-ray diffraction were grown in methanol: methylenechloride (1:2) at room temperature. M.p. = 504 K.

Refinement top

All non-hydrogen atoms were refined anisotropically. All hydrogen atoms, except the H atoms H1N and H2N on N1 and N2, were positioned geometrically with C—H distances ranging from 0.95 Å to 0.99 Å and refined as riding on their parent atoms with Uiso (H) = 1.2Ueq (C). The positions of H1N and H2N were located in the difference electron density maps and refined independently.

Structure description top

Bis-ureas have been employed as ligands for metal complexes used in hydrolytic kinetic resolution of epoxides (Park et al., 2011) and as chromogenic and fluorogenic receptors (Ahmed et al., 2011). These molecules have also been found to be useful as epigenetic modulators (Sharma et al., 2010), in surfactant self-assembies (Vos et al., 2010), and photo dimerizing agent for coumarins (Dawn et al., 2011).

The closest reported structures are 3,3'-bis-phenyl-(butylene-1,4)-bisurea and 3,3'-bis-phenyl-(heptylene-1,7)-bisurea (Koevoets et al., 2005). In the butylene derivatives a transoid arrangement is evident whereas the heptylene molecule adopts a cisoid arrangement of the two urea groups. The title compound has an odd number of carbons in its aliphatic chain (propylene). This leads to a cisoid arrangement of the two urea groups (Fig. 1).

The asymmetric unit of the title compund, C17H20N4O2, contains half molecule of 1,1'-(propane-1,3-diyl)bis(3-phenylurea) and the complete molecule is generated by inversion symmetry (i) : 1-x, y, 1.5-z. Intermolecular hydrogen bonding between adjacent urea groups N1–H1–O1, 2.8742 (14) Å and N2–H2–O1, 2.8904 (14) Å gives rise to infinite polymeric chains across the bc plane (Fig. 2), The spacing between the two hydrogen-bonded urea groups is 4.59 Å in the title compound, while it is 4.64 Å for the even butylene spacer and 4.63 Å for the odd heptylene spacer. With a centroid distance of less than 3.5 Å, π-π stacking is present in the crystal along the same plane.

For applications of ureas, see: Park et al. (2011); Ahmed et al. (2011); Sharma et al. (2010); Vos et al. (2010); Dawn et al. (2011). For related structures, see: Koevoets et al. (2005).

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with atomic numbering scheme. The hydrogen atoms have been omitted clarity. Displacement elipsoids are drawn at 40% probability. The symmetry code is (i) : 1-x,y, 1.5-z.
[Figure 2] Fig. 2. The hydrogen bonding interactions of the title compound along the [001] axis. All hydrogen atoms except those involved in hydrogen bonding interactions have been omitted for clarity. Displacement elipsoids are drawn at 40% probability.
1,1'-(Propane-1,3-diyl)bis(3-phenylurea) top
Crystal data top
C17H20N4O2F(000) = 664
Mr = 312.37Dx = 1.366 Mg m−3
Monoclinic, C2/cMelting point: 504 K
Hall symbol: -C 2ycMo Kα radiation, λ = 0.71073 Å
a = 33.811 (7) ÅCell parameters from 1930 reflections
b = 4.598 (1) Åθ = 2.4–28.5°
c = 9.891 (2) ŵ = 0.09 mm−1
β = 98.957 (4)°T = 173 K
V = 1518.9 (6) Å3Plate, colourless
Z = 40.50 × 0.21 × 0.02 mm
Data collection top
Bruker Kappa DUO APEXII
diffractometer		1930 independent reflections
Radiation source: fine-focus sealed tube1811 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.042
0.5° φ scans and ω scansθmax = 28.5°, θmin = 2.4°
Absorption correction: multi-scan
(TWINABS; Sheldrick, 2007)		h = −44→44
Tmin = 0.955, Tmax = 0.998k = 0→6
1930 measured reflectionsl = 0→13
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)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.092H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.0565P)2 + 0.4485P]
where P = (Fo2 + 2Fc2)/3
1930 reflections(Δ/σ)max = 0.001
114 parametersΔρmax = 0.27 e Å−3
0 restraintsΔρmin = −0.19 e Å−3
Crystal data top
C17H20N4O2V = 1518.9 (6) Å3
Mr = 312.37Z = 4
Monoclinic, C2/cMo Kα radiation
a = 33.811 (7) ŵ = 0.09 mm−1
b = 4.598 (1) ÅT = 173 K
c = 9.891 (2) Å0.50 × 0.21 × 0.02 mm
β = 98.957 (4)°
Data collection top
Bruker Kappa DUO APEXII
diffractometer		1930 independent reflections
Absorption correction: multi-scan
(TWINABS; Sheldrick, 2007)		1811 reflections with I > 2σ(I)
Tmin = 0.955, Tmax = 0.998Rint = 0.042
1930 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0330 restraints
wR(F2) = 0.092H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.27 e Å−3
1930 reflectionsΔρmin = −0.19 e Å−3
114 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*/UeqOcc. (<1)
O10.42150 (2)0.94129 (16)0.45600 (10)0.0258 (2)
N10.39232 (3)0.5132 (2)0.37683 (12)0.0243 (2)
H1N0.3915 (4)0.335 (4)0.3917 (18)0.035 (4)*
N20.44667 (3)0.5183 (2)0.54828 (11)0.0228 (2)
H2N0.4448 (5)0.331 (4)0.5513 (17)0.039 (5)*
C10.36029 (3)0.6418 (2)0.28699 (11)0.0204 (2)
C20.36739 (3)0.8527 (3)0.19350 (13)0.0243 (2)
H20.39400.91500.18970.029*
C30.33567 (4)0.9726 (3)0.10557 (14)0.0285 (3)
H30.34051.11880.04230.034*
C40.29688 (4)0.8801 (3)0.10954 (14)0.0297 (3)
H40.27520.96310.04940.036*
C50.28992 (4)0.6679 (3)0.20069 (14)0.0303 (3)
H50.26330.60250.20230.036*
C60.32140 (4)0.5478 (3)0.29065 (14)0.0267 (3)
H60.31640.40260.35410.032*
C70.42011 (3)0.6716 (2)0.46010 (12)0.0194 (2)
C80.47434 (3)0.6748 (2)0.64875 (13)0.0247 (3)
H8A0.45900.80790.69980.030*
H8B0.49210.79510.60070.030*
C90.50000.4779 (3)0.75000.0195 (3)
H9B0.48290.35230.79800.023*0.50
H9A0.51710.35230.70200.023*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0313 (4)0.0117 (4)0.0306 (4)0.0004 (3)−0.0070 (4)−0.0002 (3)
N10.0283 (4)0.0126 (4)0.0281 (5)−0.0010 (4)−0.0078 (4)0.0011 (4)
N20.0262 (4)0.0130 (4)0.0260 (5)−0.0007 (3)−0.0057 (4)0.0003 (4)
C10.0240 (5)0.0158 (5)0.0195 (5)0.0011 (4)−0.0025 (4)−0.0027 (4)
C20.0259 (5)0.0235 (5)0.0228 (6)−0.0003 (4)0.0018 (4)0.0003 (5)
C30.0366 (6)0.0261 (6)0.0215 (5)0.0016 (5)0.0008 (5)0.0045 (5)
C40.0295 (6)0.0282 (6)0.0277 (6)0.0056 (5)−0.0073 (5)−0.0024 (5)
C50.0239 (5)0.0311 (6)0.0343 (7)−0.0022 (4)−0.0010 (5)−0.0025 (5)
C60.0291 (5)0.0237 (5)0.0256 (6)−0.0042 (4)−0.0005 (5)0.0014 (5)
C70.0225 (5)0.0149 (4)0.0201 (5)0.0004 (4)0.0006 (4)−0.0007 (4)
C80.0273 (5)0.0148 (5)0.0280 (6)−0.0005 (4)−0.0086 (5)−0.0002 (4)
C90.0205 (6)0.0147 (6)0.0216 (7)0.000−0.0023 (6)0.000
Geometric parameters (Å, º) top
O1—C71.2416 (13)C3—H30.9500
N1—C71.3607 (14)C4—C51.373 (2)
N1—C11.4187 (14)C4—H40.9500
N1—H1N0.833 (19)C5—C61.3909 (17)
N2—C71.3492 (14)C5—H50.9500
N2—C81.4463 (14)C6—H60.9500
N2—H2N0.862 (19)C8—C91.5180 (14)
C1—C21.3866 (17)C8—H8A0.9900
C1—C61.3898 (17)C8—H8B0.9900
C2—C31.3857 (16)C9—C8i1.5180 (14)
C2—H20.9500C9—H9B0.9900
C3—C41.3850 (19)C9—H9A0.9900
C7—N1—C1122.95 (9)C6—C5—H5119.7
C7—N1—H1N117.3 (11)C1—C6—C5119.51 (13)
C1—N1—H1N118.5 (11)C1—C6—H6120.2
C7—N2—C8118.57 (9)C5—C6—H6120.2
C7—N2—H2N119.8 (11)O1—C7—N2121.22 (10)
C8—N2—H2N121.1 (11)O1—C7—N1122.76 (10)
C2—C1—C6119.85 (11)N2—C7—N1116.02 (9)
C2—C1—N1120.98 (11)N2—C8—C9113.49 (9)
C6—C1—N1119.15 (11)N2—C8—H8A108.9
C3—C2—C1119.95 (11)C9—C8—H8A108.9
C3—C2—H2120.0N2—C8—H8B108.9
C1—C2—H2120.0C9—C8—H8B108.9
C4—C3—C2120.25 (13)H8A—C8—H8B107.7
C4—C3—H3119.9C8i—C9—C8106.78 (12)
C2—C3—H3119.9C8i—C9—H9B110.4
C5—C4—C3119.78 (11)C8—C9—H9B110.4
C5—C4—H4120.1C8i—C9—H9A110.4
C3—C4—H4120.1C8—C9—H9A110.4
C4—C5—C6120.65 (12)H9B—C9—H9A108.6
C4—C5—H5119.7
C7—N1—C1—C253.70 (18)N1—C1—C6—C5−178.50 (11)
C7—N1—C1—C6−128.16 (14)C4—C5—C6—C1−0.7 (2)
C6—C1—C2—C31.05 (18)C8—N2—C7—O16.54 (18)
N1—C1—C2—C3179.18 (11)C8—N2—C7—N1−173.82 (12)
C1—C2—C3—C4−0.77 (19)C1—N1—C7—O1−6.0 (2)
C2—C3—C4—C5−0.2 (2)C1—N1—C7—N2174.39 (12)
C3—C4—C5—C61.0 (2)C7—N2—C8—C9174.67 (10)
C2—C1—C6—C5−0.34 (19)N2—C8—C9—C8i−177.37 (13)
Symmetry code: (i) −x+1, y, −z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O1ii0.834 (18)2.124 (18)2.8742 (14)149.7 (13)
N2—H2N···O1ii0.864 (18)2.119 (18)2.8904 (14)148.4 (15)
Symmetry code: (ii) x, y−1, z.

Experimental details

Crystal data
Chemical formulaC17H20N4O2
Mr312.37
Crystal system, space groupMonoclinic, C2/c
Temperature (K)173
a, b, c (Å)33.811 (7), 4.598 (1), 9.891 (2)
β (°) 98.957 (4)
V (Å3)1518.9 (6)
Z4
Radiation typeMo Kα
µ (mm−1)0.09
Crystal size (mm)0.50 × 0.21 × 0.02
Data collection
DiffractometerBruker Kappa DUO APEXII
Absorption correctionMulti-scan
(TWINABS; Sheldrick, 2007)
Tmin, Tmax0.955, 0.998
No. of measured, independent and
observed [I > 2σ(I)] reflections		1930, 1930, 1811
Rint0.042
(sin θ/λ)max (Å−1)0.672
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.092, 1.05
No. of reflections1930
No. of parameters114
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.27, −0.19

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O1i0.834 (18)2.124 (18)2.8742 (14)149.7 (13)
N2—H2N···O1i0.864 (18)2.119 (18)2.8904 (14)148.4 (15)
Symmetry code: (i) x, y−1, z.
 

Acknowledgements

The authors wish to thank Dr Hong Su from the the University of the Cape Town for his assistance with the data collection and refinement and the National Research Foundation c*change for support.

References

First citationAhmed, N., Geronimo, I., Hwang, I., Singh, N. J. & Kim, K. S. (2011). Chem. Eur. J. 17, 8542–8548.  Web of Science CSD CrossRef CAS PubMed Google Scholar
 First citationBruker (2006). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationDawn, S., Dewal, M. B., Sobransingh, D., Paderes, M. C., Wibowo, A. C., Smith, M. D., Krause, J. A., Pellechia, P. J. & Shimizu, L. S. (2011). J. Am. Chem. Soc. 133, 7025–7032.  Web of Science CSD CrossRef CAS PubMed Google Scholar
 First citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationKoevoets, R. A., Versteegen, R. M., Kooijman, H., Spek, A. L., Sijbesma, R. P. & Meijer, E. W. (2005). J. Am. Chem. Soc. 127, 2999–3003.  Web of Science CSD CrossRef PubMed CAS Google Scholar
 First citationPark, J., Lang, K., Abboud, K. A. & Hong, S. (2011). Chem. Eur. J. 17, 2236–2245.  Web of Science CSD CrossRef CAS PubMed Google Scholar
 First citationSharma, S. K., Wu, Y., Steinbergs, N., Crowley, M. L., Hanson, A. S., Casero, R. A. Jr & Woster, P. M. (2010). J. Med. Chem. 53, 5197–5212.  Web of Science CrossRef CAS PubMed Google Scholar
 First citationSheldrick, G. M. (2007). TWINABS. University of Göttingen, Germany.  Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationVos, M. R. J., Leclère, P. E. L. G., Meekes, H., Vlieg, E., Nolte, R. J. M. & Sommerdijk, N. A. J. M. (2010). Chem. Commun. 46, 6063–6065.  Web of Science CrossRef CAS 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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 10| October 2011| Page o2552
https://doi.org/10.1107/S1600536811035343
Follow Acta Cryst. E
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS