supplementary materials


rk2393 scheme

Acta Cryst. (2013). E69, o367    [ doi:10.1107/S1600536813003486 ]

1-(3,5-Dimethylphenyl)-2-(4-fluorophenyl)-1H-phenanthro[9,10-d]imidazole

R. Sathishkumar, T. Mohandas, P. Sakthivel and J. Jayabharathi

Abstract top

In the title compound, C29H21FN2, the phenanthro tricyclic ring system is essentially planar with a maximum deviation of 0.030 (2) Å and makes dihedral angles between of 77.96 (6) and 37.18 (7)° with the dimethylphenyl and fluorophenyl rings, respectively. The crystal packing features weak C-H...[pi] interactions involving the dimethylphenyl and other phenyl rings.

Comment top

The derivatives of phenanthroline, which have excellent hole blocking and electron transporting properties, are likely to have interesting value in the construction of molecular devices (Yamada et al., 1992).

Indeed, various imidazole derivatives have shown a broad range of bioactivities, such as antineoplastic, immunosuppressive and anti-inflammatory activities (Nebert et al., 1987).

The large variety of complexes based on phenanthroline and its derivatives allows the formation of many different molecular systems with various applications ranging from metallo-supramolecular chemistry (Lehn et al., 1996), metal sensors (Walters et al., 2000), molecular electronics (Peng et al., 1997) and photo sensitizers (Hara et al., 2001).

The molecular structure is shown in Fig.1. The phenanthro tricycle is essentialy planar. The dihedral angles between phenanthro tricycle to the dimethylphenyl is 77.96 (6)° and to that of fluorophenyl ring is 37.18 (7)° respectively.

Further the crystal is stabilized by intermolecular C–H···π interactions (Table 1), where Cg1 is the centre of gravity of C7/C8/C13/C14/C19/C20 and Cg2 is the centre of gravity of (C8-C13). The symmetry code are: (i) 1/2-x, 1/2+y, 1/2-z.

Related literature top

For the use of phenanthroline derivatives in the construction of molecular devices, see: Yamada et al. (1992). For the biological activity of imidazole, see: Nebert & Gonzalez (1987). For related metallo-supramolecular chemistry, see: Lehn (1996). For applications of complexes based on phenanthroline, see: Walters et al. (2000); Peng et al. (1997); Hara et al. (2001).

Experimental top

A mixture of phenanthrene-9,10-dione (1.0 g, 4.8 mmol), ammonium acetate (1.48 g, 19.2 mmol), 4-fluorobenzaldehyde (0.62 g, 4.8 mmol) and 3,5-dimethyl aniline (3.82 g, 24 mmol) have been refluxed in ethanol (20 ml) at 353 K. The reaction was monitored by TLC and purified by column chromatography using petroleum ether : ethyl acetate (9:1) as the eluent. Yield: 0.78 g (50%). The compound was dissolved in DMSO and allowed to slow evaporation and single crystals were grown within a period of one week.

Refinement top

All the hydrogen atoms were geometrically fixed and allowed to ride on their parent atoms with C–H = 0.93-0.96Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and Uiso(H) = 1.2Ueq(C) for aryl H atoms.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: APEX2 and SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as spheres with arbitrary radius.
[Figure 2] Fig. 2. A packing diagram of the title compound. The molecules are connected by C–H···π interactions as shown by dashed line.
1-(3,5-Dimethylphenyl)-2-(4-fluorophenyl)-1H-phenanthro[9,10-d]imidazole top
Crystal data top
C29H21FN2F(000) = 872
Mr = 416.48Dx = 1.288 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 6884 reflections
a = 8.5680 (2) Åθ = 2.6–25.8°
b = 10.6070 (3) ŵ = 0.08 mm1
c = 23.6900 (6) ÅT = 295 K
β = 93.899 (1)°Block, colourless
V = 2147.98 (10) Å30.30 × 0.20 × 0.20 mm
Z = 4
Data collection top
Bruker Kappa APEXII CCD
diffractometer
3777 independent reflections
Radiation source: fine-focus sealed tube2957 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
ω– and φ–scansθmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
h = 1010
Tmin = 0.952, Tmax = 0.995k = 1212
19934 measured reflectionsl = 2828
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.039H-atom parameters constrained
wR(F2) = 0.109 w = 1/[σ2(Fo2) + (0.047P)2 + 0.6584P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
3777 reflectionsΔρmax = 0.24 e Å3
292 parametersΔρmin = 0.15 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: 0.0229 (14)
Crystal data top
C29H21FN2V = 2147.98 (10) Å3
Mr = 416.48Z = 4
Monoclinic, P21/nMo Kα radiation
a = 8.5680 (2) ŵ = 0.08 mm1
b = 10.6070 (3) ÅT = 295 K
c = 23.6900 (6) Å0.30 × 0.20 × 0.20 mm
β = 93.899 (1)°
Data collection top
Bruker Kappa APEXII CCD
diffractometer
3777 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
2957 reflections with I > 2σ(I)
Tmin = 0.952, Tmax = 0.995Rint = 0.034
19934 measured reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.039H-atom parameters constrained
wR(F2) = 0.109Δρmax = 0.24 e Å3
S = 1.02Δρmin = 0.15 e Å3
3777 reflectionsAbsolute structure: ?
292 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
F10.12516 (16)0.11339 (12)0.46971 (5)0.0814 (5)
N10.17180 (15)0.00029 (12)0.20526 (5)0.0432 (4)
N20.01474 (14)0.16068 (12)0.23196 (5)0.0397 (4)
C10.13686 (19)0.43494 (15)0.31531 (7)0.0426 (5)
C20.03897 (18)0.35869 (15)0.28130 (7)0.0417 (5)
C30.08624 (17)0.23859 (14)0.26818 (6)0.0384 (5)
C40.22859 (18)0.19160 (15)0.28854 (7)0.0428 (5)
C50.32914 (18)0.26633 (16)0.32246 (7)0.0482 (6)
C60.2809 (2)0.38706 (16)0.33513 (7)0.0486 (6)
C70.03496 (17)0.16561 (14)0.17341 (6)0.0385 (5)
C80.02988 (18)0.24785 (15)0.13278 (7)0.0424 (5)
C90.1372 (2)0.34535 (16)0.14610 (8)0.0520 (6)
C100.1931 (2)0.41945 (19)0.10496 (9)0.0624 (7)
C110.1435 (3)0.3995 (2)0.04904 (9)0.0740 (8)
C120.0414 (3)0.3043 (2)0.03479 (8)0.0692 (8)
C130.0186 (2)0.22404 (17)0.07527 (7)0.0504 (6)
C140.1241 (2)0.12002 (17)0.05928 (7)0.0505 (6)
C150.1728 (3)0.0935 (2)0.00278 (8)0.0742 (8)
C160.2694 (3)0.0054 (3)0.01118 (9)0.0833 (9)
C170.3242 (3)0.0829 (2)0.02974 (9)0.0705 (8)
C180.2803 (2)0.06043 (17)0.08542 (8)0.0537 (6)
C190.18058 (18)0.04040 (16)0.10068 (7)0.0442 (5)
C200.13220 (17)0.06682 (14)0.15854 (6)0.0395 (5)
C210.09957 (18)0.05819 (14)0.24857 (7)0.0401 (5)
C220.10644 (18)0.01699 (15)0.30742 (7)0.0412 (5)
C230.1144 (2)0.11111 (16)0.31864 (7)0.0507 (6)
C240.1214 (2)0.15484 (17)0.37296 (8)0.0551 (6)
C250.1211 (2)0.07015 (18)0.41601 (7)0.0542 (6)
C260.1164 (3)0.05626 (19)0.40719 (8)0.0627 (7)
C270.1093 (2)0.09943 (17)0.35261 (8)0.0547 (6)
C280.4870 (2)0.2170 (2)0.34406 (10)0.0739 (8)
C290.0858 (2)0.56524 (16)0.33040 (8)0.0557 (6)
H20.058290.388340.267360.0501*
H40.257410.109850.279590.0514*
H60.347640.437960.357780.0584*
H90.170760.359640.183720.0624*
H100.264400.483270.114570.0749*
H110.179750.451040.021020.0888*
H120.010260.292010.003180.0830*
H150.138310.144520.025780.0890*
H160.299000.020760.049060.0999*
H170.390330.149890.019600.0846*
H180.316910.112320.113280.0644*
H230.115070.168320.288880.0608*
H240.126260.240890.380170.0661*
H260.117850.112370.437310.0753*
H270.106360.185780.345980.0656*
H28A0.499530.227710.384350.1108*
H28B0.494600.129140.334950.1108*
H28C0.567590.262830.326620.1108*
H29A0.024930.561220.362910.0836*
H29B0.176190.617120.338820.0836*
H29C0.023570.600760.299110.0836*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F10.1151 (10)0.0821 (9)0.0484 (7)0.0124 (7)0.0160 (6)0.0106 (6)
N10.0415 (7)0.0419 (8)0.0456 (8)0.0017 (6)0.0016 (6)0.0019 (6)
N20.0403 (7)0.0382 (7)0.0399 (7)0.0021 (6)0.0023 (6)0.0012 (6)
C10.0456 (9)0.0402 (9)0.0425 (9)0.0079 (7)0.0076 (7)0.0003 (7)
C20.0367 (8)0.0415 (9)0.0468 (9)0.0007 (7)0.0021 (7)0.0017 (7)
C30.0359 (8)0.0394 (9)0.0396 (8)0.0042 (7)0.0011 (6)0.0001 (7)
C40.0408 (9)0.0404 (9)0.0474 (9)0.0003 (7)0.0042 (7)0.0017 (7)
C50.0386 (9)0.0512 (10)0.0539 (10)0.0057 (8)0.0027 (8)0.0066 (8)
C60.0463 (9)0.0503 (10)0.0486 (10)0.0156 (8)0.0018 (8)0.0014 (8)
C70.0358 (8)0.0382 (9)0.0412 (9)0.0061 (7)0.0005 (7)0.0004 (7)
C80.0387 (8)0.0423 (9)0.0464 (9)0.0077 (7)0.0049 (7)0.0021 (7)
C90.0512 (10)0.0495 (10)0.0559 (11)0.0006 (8)0.0079 (8)0.0031 (8)
C100.0623 (12)0.0551 (12)0.0715 (14)0.0063 (9)0.0171 (10)0.0046 (10)
C110.0864 (16)0.0722 (14)0.0662 (14)0.0087 (12)0.0262 (12)0.0136 (11)
C120.0818 (14)0.0790 (14)0.0478 (11)0.0010 (12)0.0121 (10)0.0069 (10)
C130.0497 (10)0.0559 (11)0.0463 (10)0.0089 (8)0.0084 (8)0.0036 (8)
C140.0500 (10)0.0582 (11)0.0430 (9)0.0104 (8)0.0017 (8)0.0030 (8)
C150.0824 (15)0.0948 (17)0.0446 (11)0.0068 (13)0.0011 (10)0.0024 (11)
C160.0932 (17)0.1064 (19)0.0476 (12)0.0068 (15)0.0140 (11)0.0170 (12)
C170.0713 (13)0.0731 (14)0.0644 (13)0.0016 (11)0.0145 (11)0.0180 (11)
C180.0517 (10)0.0528 (11)0.0547 (11)0.0040 (8)0.0091 (8)0.0088 (8)
C190.0400 (9)0.0462 (9)0.0456 (9)0.0095 (7)0.0025 (7)0.0069 (8)
C200.0357 (8)0.0397 (9)0.0426 (9)0.0051 (7)0.0012 (7)0.0015 (7)
C210.0368 (8)0.0377 (9)0.0454 (9)0.0010 (7)0.0000 (7)0.0011 (7)
C220.0364 (8)0.0428 (9)0.0443 (9)0.0022 (7)0.0023 (7)0.0006 (7)
C230.0621 (11)0.0431 (10)0.0467 (10)0.0068 (8)0.0022 (8)0.0040 (8)
C240.0676 (12)0.0421 (10)0.0558 (11)0.0066 (9)0.0059 (9)0.0051 (8)
C250.0586 (11)0.0606 (12)0.0441 (10)0.0065 (9)0.0093 (8)0.0051 (9)
C260.0854 (14)0.0546 (12)0.0503 (11)0.0078 (10)0.0199 (10)0.0104 (9)
C270.0706 (12)0.0402 (10)0.0548 (11)0.0014 (9)0.0160 (9)0.0023 (8)
C280.0490 (11)0.0698 (14)0.0991 (17)0.0021 (10)0.0219 (11)0.0089 (12)
C290.0626 (12)0.0446 (10)0.0609 (11)0.0092 (9)0.0110 (9)0.0070 (8)
Geometric parameters (Å, º) top
F1—C251.355 (2)C19—C201.433 (2)
N1—C201.3745 (19)C21—C221.466 (2)
N1—C211.314 (2)C22—C231.387 (2)
N2—C31.4376 (19)C22—C271.384 (2)
N2—C71.3871 (18)C23—C241.373 (3)
N2—C211.380 (2)C24—C251.359 (3)
C1—C21.384 (2)C25—C261.358 (3)
C1—C61.387 (2)C26—C271.377 (3)
C1—C291.500 (2)C2—H20.9300
C2—C31.379 (2)C4—H40.9300
C3—C41.374 (2)C6—H60.9300
C4—C51.386 (2)C9—H90.9300
C5—C61.385 (2)C10—H100.9300
C5—C281.507 (2)C11—H110.9300
C7—C81.438 (2)C12—H120.9300
C7—C201.370 (2)C15—H150.9300
C8—C91.405 (2)C16—H160.9300
C8—C131.420 (2)C17—H170.9300
C9—C101.364 (3)C18—H180.9300
C10—C111.380 (3)C23—H230.9300
C11—C121.363 (3)C24—H240.9300
C12—C131.406 (3)C26—H260.9300
C13—C141.460 (2)C27—H270.9300
C14—C151.403 (3)C28—H28A0.9600
C14—C191.405 (2)C28—H28B0.9600
C15—C161.363 (4)C28—H28C0.9600
C16—C171.378 (3)C29—H29A0.9600
C17—C181.368 (3)C29—H29B0.9600
C18—C191.401 (2)C29—H29C0.9600
C20—N1—C21105.06 (13)C23—C24—C25118.82 (17)
C3—N2—C7127.18 (12)F1—C25—C24118.82 (17)
C3—N2—C21126.16 (12)F1—C25—C26118.79 (16)
C7—N2—C21106.41 (12)C24—C25—C26122.40 (17)
C2—C1—C6118.25 (15)C25—C26—C27118.46 (17)
C2—C1—C29120.14 (15)C22—C27—C26121.37 (17)
C6—C1—C29121.60 (15)C1—C2—H2120.00
C1—C2—C3119.71 (14)C3—C2—H2120.00
N2—C3—C2119.45 (13)C3—C4—H4120.00
N2—C3—C4119.00 (13)C5—C4—H4120.00
C2—C3—C4121.56 (14)C1—C6—H6119.00
C3—C4—C5119.85 (15)C5—C6—H6119.00
C4—C5—C6118.13 (15)C8—C9—H9119.00
C4—C5—C28120.42 (16)C10—C9—H9119.00
C6—C5—C28121.45 (16)C9—C10—H10120.00
C1—C6—C5122.49 (15)C11—C10—H10120.00
N2—C7—C8131.64 (14)C10—C11—H11120.00
N2—C7—C20105.12 (12)C12—C11—H11120.00
C8—C7—C20123.21 (13)C11—C12—H12119.00
C7—C8—C9124.93 (15)C13—C12—H12119.00
C7—C8—C13115.67 (14)C14—C15—H15119.00
C9—C8—C13119.38 (15)C16—C15—H15119.00
C8—C9—C10121.32 (17)C15—C16—H16119.00
C9—C10—C11119.83 (18)C17—C16—H16119.00
C10—C11—C12120.1 (2)C16—C17—H17120.00
C11—C12—C13122.54 (18)C18—C17—H17120.00
C8—C13—C12116.76 (16)C17—C18—H18120.00
C8—C13—C14121.27 (15)C19—C18—H18120.00
C12—C13—C14121.97 (16)C22—C23—H23119.00
C13—C14—C15122.53 (17)C24—C23—H23119.00
C13—C14—C19120.65 (15)C23—C24—H24121.00
C15—C14—C19116.82 (17)C25—C24—H24121.00
C14—C15—C16121.47 (19)C25—C26—H26121.00
C15—C16—C17121.3 (2)C27—C26—H26121.00
C16—C17—C18119.4 (2)C22—C27—H27119.00
C17—C18—C19120.32 (18)C26—C27—H27119.00
C14—C19—C18120.78 (16)C5—C28—H28A109.00
C14—C19—C20117.35 (15)C5—C28—H28B110.00
C18—C19—C20121.87 (15)C5—C28—H28C109.00
N1—C20—C7111.40 (13)H28A—C28—H28B109.00
N1—C20—C19126.79 (14)H28A—C28—H28C109.00
C7—C20—C19121.81 (14)H28B—C28—H28C109.00
N1—C21—N2112.01 (14)C1—C29—H29A109.00
N1—C21—C22123.78 (14)C1—C29—H29B109.00
N2—C21—C22124.20 (14)C1—C29—H29C109.00
C21—C22—C23118.68 (14)H29A—C29—H29B109.00
C21—C22—C27123.46 (15)H29A—C29—H29C109.00
C23—C22—C27117.85 (16)H29B—C29—H29C109.00
C22—C23—C24121.09 (16)
C20—N1—C21—C22178.64 (14)C7—C8—C13—C141.7 (2)
C20—N1—C21—N20.33 (17)C9—C8—C13—C122.2 (2)
C21—N1—C20—C70.17 (17)C8—C9—C10—C110.3 (3)
C21—N1—C20—C19179.41 (15)C9—C10—C11—C121.4 (3)
C3—N2—C21—C223.7 (2)C10—C11—C12—C130.6 (4)
C7—N2—C21—C22178.27 (14)C11—C12—C13—C14178.1 (2)
C3—N2—C7—C20175.21 (13)C11—C12—C13—C81.2 (3)
C21—N2—C7—C200.74 (16)C8—C13—C14—C15179.38 (18)
C7—N2—C3—C499.85 (18)C12—C13—C14—C150.2 (3)
C21—N2—C3—C473.6 (2)C12—C13—C14—C19179.18 (18)
C21—N2—C7—C8176.95 (16)C8—C13—C14—C190.0 (3)
C21—N2—C3—C2106.97 (18)C13—C14—C15—C16178.9 (2)
C7—N2—C21—N10.70 (17)C19—C14—C15—C160.5 (3)
C7—N2—C3—C279.61 (19)C13—C14—C19—C18179.21 (16)
C3—N2—C21—N1175.24 (13)C13—C14—C19—C200.8 (2)
C3—N2—C7—C82.5 (3)C15—C14—C19—C180.2 (3)
C2—C1—C6—C50.5 (3)C15—C14—C19—C20179.75 (17)
C29—C1—C6—C5178.91 (16)C14—C15—C16—C170.5 (4)
C6—C1—C2—C30.1 (2)C15—C16—C17—C180.3 (4)
C29—C1—C2—C3179.29 (15)C16—C17—C18—C190.0 (3)
C1—C2—C3—N2178.84 (14)C17—C18—C19—C20179.97 (18)
C1—C2—C3—C40.6 (2)C17—C18—C19—C140.0 (3)
N2—C3—C4—C5178.51 (14)C14—C19—C20—N1179.08 (15)
C2—C3—C4—C50.9 (2)C18—C19—C20—N11.0 (3)
C3—C4—C5—C28178.70 (16)C18—C19—C20—C7179.86 (15)
C3—C4—C5—C60.6 (2)C14—C19—C20—C70.1 (2)
C4—C5—C6—C10.1 (3)N1—C21—C22—C2334.4 (2)
C28—C5—C6—C1179.37 (17)N1—C21—C22—C27143.96 (17)
N2—C7—C8—C13179.98 (16)N2—C21—C22—C23144.46 (16)
C20—C7—C8—C9176.01 (16)N2—C21—C22—C2737.2 (2)
C20—C7—C8—C132.7 (2)C21—C22—C23—C24179.86 (15)
N2—C7—C20—N10.58 (17)C27—C22—C23—C241.4 (2)
N2—C7—C20—C19179.87 (14)C21—C22—C27—C26179.74 (18)
C8—C7—C20—N1177.36 (14)C23—C22—C27—C261.4 (3)
N2—C7—C8—C91.3 (3)C22—C23—C24—C250.3 (3)
C8—C7—C20—C191.9 (2)C23—C24—C25—F1178.82 (16)
C9—C8—C13—C14177.08 (16)C23—C24—C25—C261.0 (3)
C7—C8—C9—C10179.91 (17)F1—C25—C26—C27178.79 (18)
C13—C8—C9—C101.5 (3)C24—C25—C26—C271.0 (3)
C7—C8—C13—C12179.11 (17)C25—C26—C27—C220.2 (3)
Hydrogen-bond geometry (Å, º) top
Cg1 and Cg2 are the centroids of the C7/C8/C13/C14/C19/C20 and C8–C13 rings, respectively.
D—H···AD—HH···AD···AD—H···A
C9—H9···Cg10.93002.97003.8433156.00
C6—H6···Cg2i0.93002.97003.6994155.00
Symmetry code: (i) x+1/2, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
Cg1 and Cg2 are the centroids of the C7/C8/C13/C14/C19/C20 and C8–C13 rings, respectively.
D—H···AD—HH···AD···AD—H···A
C9—H9···Cg10.93002.97003.8433156.00
C6—H6···Cg2i0.93002.97003.6994155.00
Symmetry code: (i) x+1/2, y+1/2, z+1/2.
references
References top

Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.

Hara, K., Sugihara, H., Tachibana, Y., Islam, A., Yanagida, M., Sayama, K., Arakawa, H., Fujihashi, G., Horiguchi, T. & Kinoshita, T. (2001). Langmuir, 17, 5992–5999.

Lehn, J. M. (1996). In WSupramolecular Chemistry: Concepts and Perspectives. CITY OF PUBLICATION???: Wiley-VCH Verlag GmbH

Nebert, D. W. & Gonzalez, F. J. (1987). Annu Rev. Biochem. 56, 945–993.

Peng, Z., Gharavi, A. R. & Yu, L. J. (1997). J. Am. Chem. Soc. 119, 4622–4632.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Walters, K. A., Trouillet, L., Guillerez, S. & Schanze, K. S. (2000). Inorg. Chem. 39, 5496–5509.

Yamada, M., Tanaka, Y., Yoshimoto, T., Kuroda, S. & Shimao, I. (1992). Bull. Chem. Soc. Jpn, 65, 1006–1011.