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

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ISSN: 2056-9890

4-Chloro-2-[(E)-(4-nitro­phen­yl)diazenyl]phenol

aDepartment of Chemistry, Moscow State University, 119992 Moscow, Russian Federation
*Correspondence e-mail: aslanov@struct.chem.msu.ru

(Received 14 January 2009; accepted 29 January 2009; online 11 February 2009)

The title compound, C12H8ClN3O3, in the crystalline state and in solution, exists in the azo form, as predicted by density functional theory (DFT) calculations. The mol­ecule is approximately planar [the dihedral angle between the rings is 1.83 (8)°], with the nitro group slightly twisted [13.4 (2)°] relative to the benzene ring. Translationally related mol­ecules form stacks along [010] with an inter­planar distance of 3.400 (2) Å. The hydroxy group forms an intramolecular hydrogen bond with the azo N atom.

Related literature

For the crystal structure of a closely related mol­ecule, (1Z)-4-hydroxy­benzo-1,2-quinone-1-[(2-chloro-4-nitro­phen­yl)hydrazone, that crystallizes as a hydrazone tautomer, see: You et al. (2004[You, X.-L., Lu, C.-R., Huang, Z.-L. & Zhang, D.-C. (2004). Dyes Pigm. 63, 217-223.]). For reference structural data, see: Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]). For details of the synthetic procedure, see: Fierz-David & Blangey (1949[Fierz-David, H. E. & Blangey, L. (1949). Fundamental Processes of Dye Chemistry, pp. 236-240. London: Interscience.]). For background on DFT calculations, see: Becke (1993[Becke, A. D. (1993). J. Chem. Phys. 98, 5648-5652.]); Klamt & Schüürmann (1993[Klamt, A. & Schüürmann, G. (1993). J. Chem. Soc. Perkin Trans. 2, pp. 799-805.]); Krishnan et al. (1980[Krishnan, R., Binkley, J. S., Seeger, R. & Pople, J. A. (1980). J. Chem. Phys. 72, 650-654.]); Lee et al. (1988[Lee, C., Yang, W. & Parr, R. G. (1988). Phys. Rev. B37, 785-789.]); Schmidt et al. (1993[Schmidt, M. W., Baldridge, K. K., Boatz, J. A., Elbert, S. T., Gordon, M. S., Jensen, J. J., Koseki, S., Matsunaga, N., Nguyen, K. A., Su, S., Windus, T. L., Dupuis, M. & Montgomery, J. A. (1993). J. Comput. Chem. 14, 1347-1363.]). For the concept of resonance-assisted hydrogen bonds, see: Gilli et al. (1989[Gilli, G., Belucci, F., Ferretti, V. & Bertolasi, V. (1989). J. Am. Chem. Soc. 111, 1023-1028.]).

[Scheme 1]

Experimental

Crystal data
  • C12H8ClN3O3

  • Mr = 277.66

  • Monoclinic, P 21 /c

  • a = 19.008 (5) Å

  • b = 4.817 (2) Å

  • c = 12.862 (4) Å

  • β = 92.65 (2)°

  • V = 1176.4 (7) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.33 mm−1

  • T = 291 (2) K

  • 0.40 × 0.20 × 0.15 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: none

  • 2567 measured reflections

  • 2567 independent reflections

  • 2110 reflections with I > 2σ(I)

  • 3 standard reflections frequency: 90 min intensity decay: 4%

Refinement
  • R[F2 > 2σ(F2)] = 0.037

  • wR(F2) = 0.098

  • S = 1.56

  • 2567 reflections

  • 173 parameters

  • H-atom parameters constrained

  • Δρmax = 0.25 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
O1—H1⋯N2 0.82 1.88 2.5777 (17) 143

Data collection: CAD-4 Software (Enraf–Nonius, 1989[Enraf-Nonius (1989). CAD-4 Software. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 Software; data reduction: PROFIT (Streltsov & Zavodnik, 1989[Streltsov, V. A. & Zavodnik, V. E. (1989). Sov. Phys. Crystallogr. 34, 824-828.]) routine of WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]); 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: PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]); software used to prepare material for publication: PLATON.

Supporting information


Comment top

The present work was fulfilled in the course of study of the hydroxyazo-ketohydrazone tautomerism in phenylazophenols. The title compound, (I), exists in crystals as the azo form (Fig. 1). It is evidenced, firstly, by the fact that the H atom was found and refined in the vicinity of O atom, and secondly, by comparison of the molecular geometry with numerous structures of azo tautomers found in the Cambridge Structural Database (Allen, 2002). Since the UV–visible spectra of the crystalline title compound resemble its spectra in solutions, the azo tautomer has to predominate in solutions as well.

However, recently it has been reported that (1Z)-4-hydroxybenzo-1,2-quinone 1-[(2-chloro-4-nitrophenyl)hydrazone (II), the compound closely related to (I), exists in crystals as the hydrazone tautomer (You et al., 2004).

The azo–hydrazone equilibrium is known to be shifted by the effect of donor and acceptor substituents and also by intra- and intermolecular hydrogen bonds. In order to evaluate the relative importance of these factors, we have performed the DFT calculations of azo and hydrazone tautomers of (I) and (II). Calculations were carried out using GAMESS (Schmidt et al., 1993) with B3LYP exchange-correlation functional (Becke, 1993; Lee et al., 1988) and 6-311G** basis set (Krishnan et al., 1980). After geometry of an isolated molecule has been optimized, molecular structure was fixed, and the effect of nonspecific intermolecular interactions was accounted by COSMO method (Klamt & Schüürmann, 1993), taking the dielectric permeability equal to 10. The results indicate that for 2-phenyldiazenylphenol (III), the azo form is by 10.5 kJ/mol more stable than the hydrazone form. For compound (I), this difference decreases to 7.5 kJ/mol and for (II) - to 6.8 kJ/mol, but nonetheless the azo form is still preferable.

Thus, the difference between (I) and (II) most probably arises from specific intermolecular interactions. In (I), there is the only worthnoting intermolecular contact C15—H15···O2 (-x, -1 - y, -z) (H15···O2 2.56 Å, C15···O2 3.452 (2) Å, C15—H15···O2 161°), which cannot have any effect on the relative stability of tautomers. In (II), the keto group forms a strong hydrogen bond with the hydroxy group of a neighboring molecule (O···H 1.74 Å, O···O 2.581 (2) Å, O—H···O 173°). This interaction stabilizes the hydrazone tautomer, according to the conception of resonance-assisted hydrogen bonds (Gilli et al., 1989). So, the shift of tautomeric equilibrium in (II) towards the hydrazone form should be most probably rationalized by formation of intermolecular hydrogen bonds.

Related literature top

For the crystal structure of a closely related molecule, (1Z)-4-hydroxybenzo-1,2-quinone-1-[(2-chloro-4-nitrophenyl)hydrazone, that crystallizes as a hydrazone tautomer, see: You et al., 2004). For reference structural data, see: Allen (2002). For details of the synthetic procedure, see: Fierz-David & Blangey (1949). For background on DFT calculations, see: Becke (1993); Klamt & Schüürmann (1993); Krishnan et al. (1980); Lee et al. (1988); Schmidt et al. (1993). For the concept of resonance-assisted hydrogen bonds, see: Gilli et al. (1989).

Experimental top

The title compound was prepared by coupling of p-nitrophenyldiazonium chloride with p-chlorphenol. For details of the synthetic procedure, see Fierz-David & Blangey (1949). Single crystals were grown by slow evaporation of ethanol solution.

Refinement top

H atoms were located in a difference map and refined freely, but at final stage they were positioned geometrically and refined using a riding model with C—H = 0.93 Å, O—H = 0.82 Å and with Uiso(H) = 1.2 times Ueq(C), Uiso(H) = 1.5 times Ueq(O)

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: PROFIT (Streltsov & Zavodnik, 1989) routine of WinGX (Farrugia, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with atomic labels and 50% probability displacement ellipsoids for non-H atoms.
[Figure 2] Fig. 2. Chemical diagrams of (II) and (III).
4-Chloro-2-[(E)-(4-nitrophenyl)diazenyl]phenol top
Crystal data top
C12H8ClN3O3F(000) = 568
Mr = 277.66Dx = 1.568 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 19.008 (5) Åθ = 16.8–18.8°
b = 4.817 (2) ŵ = 0.33 mm1
c = 12.862 (4) ÅT = 291 K
β = 92.65 (2)°Prism, red
V = 1176.4 (7) Å30.40 × 0.20 × 0.15 mm
Z = 4
Data collection top
Enraf–Nonius CAD-4
diffractometer
Rint = 0.0
Radiation source: fine-focus sealed tubeθmax = 27.0°, θmin = 1.1°
Graphite monochromatorh = 2424
nonprofiled ω scansk = 06
2567 measured reflectionsl = 016
2567 independent reflections3 standard reflections every 90 min
2110 reflections with I > 2σ(I) intensity decay: 4%
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)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.098H-atom parameters constrained
S = 1.56 w = 1/[σ2(Fo2) + (0.04P)2]
where P = (Fo2 + 2Fc2)/3
2567 reflections(Δ/σ)max = 0.001
173 parametersΔρmax = 0.25 e Å3
0 restraintsΔρmin = 0.14 e Å3
Crystal data top
C12H8ClN3O3V = 1176.4 (7) Å3
Mr = 277.66Z = 4
Monoclinic, P21/cMo Kα radiation
a = 19.008 (5) ŵ = 0.33 mm1
b = 4.817 (2) ÅT = 291 K
c = 12.862 (4) Å0.40 × 0.20 × 0.15 mm
β = 92.65 (2)°
Data collection top
Enraf–Nonius CAD-4
diffractometer
Rint = 0.0
2567 measured reflections3 standard reflections every 90 min
2567 independent reflections intensity decay: 4%
2110 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.098H-atom parameters constrained
S = 1.56Δρmax = 0.25 e Å3
2567 reflectionsΔρmin = 0.14 e Å3
173 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
Cl10.463076 (19)1.28010 (9)0.16237 (3)0.06275 (16)
O10.27449 (6)0.7166 (3)0.14202 (8)0.0703 (4)
H10.24910.60450.11380.105*
O20.00077 (6)0.4250 (3)0.11633 (9)0.0665 (3)
O30.05796 (6)0.4261 (2)0.26393 (8)0.0592 (3)
N10.27334 (5)0.5696 (2)0.07974 (9)0.0436 (3)
N20.23136 (6)0.4462 (2)0.01583 (9)0.0450 (3)
N30.04760 (6)0.3453 (2)0.17452 (10)0.0468 (3)
C10.31710 (7)0.8384 (3)0.07021 (11)0.0496 (4)
C20.31686 (6)0.7693 (3)0.03656 (10)0.0420 (3)
C30.36225 (7)0.9076 (3)0.10740 (11)0.0444 (3)
H30.36200.86420.17780.053*
C40.40705 (7)1.1065 (3)0.07365 (12)0.0475 (3)
C50.40778 (8)1.1751 (3)0.03104 (12)0.0556 (4)
H50.43871.30970.05340.067*
C60.36281 (8)1.0440 (4)0.10150 (12)0.0589 (4)
H60.36291.09350.17140.071*
C110.18678 (6)0.2481 (3)0.06134 (10)0.0402 (3)
C120.18713 (7)0.1938 (3)0.16816 (11)0.0472 (3)
H120.21770.28840.21430.057*
C130.14144 (7)0.0020 (3)0.20368 (10)0.0473 (3)
H130.14120.04280.27430.057*
C140.09613 (6)0.1372 (3)0.13447 (10)0.0401 (3)
C150.09456 (7)0.0863 (3)0.02927 (10)0.0456 (3)
H150.06340.18010.01610.055*
C160.14084 (7)0.1087 (3)0.00691 (11)0.0469 (3)
H160.14110.14650.07780.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0544 (2)0.0552 (3)0.0784 (3)0.00993 (18)0.00095 (19)0.0052 (2)
O10.0844 (8)0.0812 (9)0.0452 (6)0.0262 (7)0.0024 (5)0.0036 (6)
O20.0716 (7)0.0648 (8)0.0636 (7)0.0297 (6)0.0068 (6)0.0067 (6)
O30.0716 (7)0.0500 (6)0.0570 (7)0.0031 (5)0.0129 (5)0.0118 (5)
N10.0437 (6)0.0373 (6)0.0502 (6)0.0005 (5)0.0071 (5)0.0018 (5)
N20.0460 (6)0.0406 (6)0.0486 (6)0.0002 (5)0.0054 (5)0.0021 (5)
N30.0548 (7)0.0348 (6)0.0518 (7)0.0001 (5)0.0128 (5)0.0031 (5)
C10.0523 (8)0.0494 (8)0.0477 (8)0.0001 (7)0.0095 (6)0.0004 (7)
C20.0418 (6)0.0367 (7)0.0482 (8)0.0030 (6)0.0092 (6)0.0027 (6)
C30.0452 (7)0.0382 (7)0.0502 (7)0.0040 (6)0.0072 (6)0.0035 (6)
C40.0432 (7)0.0373 (7)0.0626 (9)0.0023 (6)0.0067 (6)0.0042 (7)
C50.0551 (8)0.0473 (9)0.0663 (10)0.0056 (7)0.0214 (7)0.0042 (8)
C60.0663 (9)0.0596 (10)0.0522 (9)0.0060 (8)0.0176 (7)0.0075 (8)
C110.0402 (6)0.0351 (7)0.0456 (7)0.0033 (5)0.0055 (5)0.0018 (6)
C120.0478 (7)0.0485 (8)0.0451 (8)0.0054 (6)0.0000 (6)0.0017 (6)
C130.0537 (8)0.0501 (8)0.0384 (7)0.0021 (7)0.0041 (6)0.0024 (6)
C140.0419 (6)0.0296 (6)0.0492 (7)0.0025 (5)0.0081 (5)0.0005 (6)
C150.0505 (7)0.0426 (8)0.0432 (7)0.0058 (6)0.0015 (6)0.0025 (6)
C160.0540 (8)0.0472 (8)0.0395 (7)0.0023 (6)0.0030 (6)0.0053 (6)
Geometric parameters (Å, º) top
Cl1—C41.7387 (16)C4—C51.387 (2)
O1—C11.3358 (17)C5—C61.371 (2)
O1—H10.8200C5—H50.9300
O2—N31.2203 (15)C6—H60.9300
O3—N31.2214 (15)C11—C161.3831 (18)
N1—N21.2670 (16)C11—C121.3983 (19)
N1—C21.4001 (17)C12—C131.3743 (19)
N2—C111.4203 (17)C12—H120.9300
N3—C141.4712 (17)C13—C141.3741 (19)
C1—C61.389 (2)C13—H130.9300
C1—C21.413 (2)C14—C151.3741 (19)
C2—C31.3949 (19)C15—C161.3823 (19)
C3—C41.3660 (19)C15—H150.9300
C3—H30.9300C16—H160.9300
C1—O1—H1109.5C5—C6—C1121.06 (14)
N2—N1—C2115.52 (11)C5—C6—H6119.5
N1—N2—C11114.69 (11)C1—C6—H6119.5
O2—N3—O3124.14 (12)C16—C11—C12120.47 (12)
O2—N3—C14117.79 (12)C16—C11—N2115.84 (12)
O3—N3—C14118.06 (12)C12—C11—N2123.69 (12)
O1—C1—C6118.70 (13)C13—C12—C11118.72 (13)
O1—C1—C2122.63 (13)C13—C12—H12120.6
C6—C1—C2118.67 (14)C11—C12—H12120.6
C3—C2—N1115.33 (12)C14—C13—C12119.79 (12)
C3—C2—C1119.50 (13)C14—C13—H13120.1
N1—C2—C1125.17 (13)C12—C13—H13120.1
C4—C3—C2120.21 (13)C13—C14—C15122.53 (12)
C4—C3—H3119.9C13—C14—N3118.73 (12)
C2—C3—H3119.9C15—C14—N3118.75 (12)
C3—C4—C5120.66 (14)C14—C15—C16117.88 (12)
C3—C4—Cl1120.05 (12)C14—C15—H15121.1
C5—C4—Cl1119.29 (11)C16—C15—H15121.1
C6—C5—C4119.88 (14)C15—C16—C11120.61 (12)
C6—C5—H5120.1C15—C16—H16119.7
C4—C5—H5120.1C11—C16—H16119.7
C2—N1—N2—C11178.90 (10)N1—N2—C11—C16179.47 (11)
N2—N1—C2—C3179.08 (11)N1—N2—C11—C121.27 (18)
N2—N1—C2—C10.30 (19)C16—C11—C12—C130.5 (2)
O1—C1—C2—C3179.22 (13)N2—C11—C12—C13179.77 (12)
C6—C1—C2—C30.1 (2)C11—C12—C13—C140.7 (2)
O1—C1—C2—N10.1 (2)C12—C13—C14—C150.4 (2)
C6—C1—C2—N1179.24 (13)C12—C13—C14—N3179.82 (12)
N1—C2—C3—C4179.97 (11)O2—N3—C14—C13166.51 (12)
C1—C2—C3—C40.6 (2)O3—N3—C14—C1313.07 (17)
C2—C3—C4—C50.4 (2)O2—N3—C14—C1513.72 (18)
C2—C3—C4—Cl1179.53 (10)O3—N3—C14—C15166.71 (12)
C3—C4—C5—C60.5 (2)C13—C14—C15—C160.1 (2)
Cl1—C4—C5—C6178.60 (12)N3—C14—C15—C16179.63 (11)
C4—C5—C6—C11.3 (2)C14—C15—C16—C110.3 (2)
O1—C1—C6—C5179.81 (14)C12—C11—C16—C150.0 (2)
C2—C1—C6—C51.1 (2)N2—C11—C16—C15179.28 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N20.821.882.5777 (17)143

Experimental details

Crystal data
Chemical formulaC12H8ClN3O3
Mr277.66
Crystal system, space groupMonoclinic, P21/c
Temperature (K)291
a, b, c (Å)19.008 (5), 4.817 (2), 12.862 (4)
β (°) 92.65 (2)
V3)1176.4 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.33
Crystal size (mm)0.40 × 0.20 × 0.15
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2567, 2567, 2110
Rint0.0
(sin θ/λ)max1)0.638
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.098, 1.56
No. of reflections2567
No. of parameters173
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.25, 0.14

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), PROFIT (Streltsov & Zavodnik, 1989) routine of WinGX (Farrugia, 1999), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N20.821.882.5777 (17)143
 

Acknowledgements

KAP and AVY thank the ICDD for financial assistance (grant No. 93-05).

References

First citationAllen, F. H. (2002). Acta Cryst. B58, 380–388.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationBecke, A. D. (1993). J. Chem. Phys. 98, 5648–5652.  CrossRef CAS Web of Science Google Scholar
First citationEnraf–Nonius (1989). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationFierz-David, H. E. & Blangey, L. (1949). Fundamental Processes of Dye Chemistry, pp. 236–240. London: Interscience.  Google Scholar
First citationGilli, G., Belucci, F., Ferretti, V. & Bertolasi, V. (1989). J. Am. Chem. Soc. 111, 1023–1028.  CrossRef CAS Web of Science Google Scholar
First citationKlamt, A. & Schüürmann, G. (1993). J. Chem. Soc. Perkin Trans. 2, pp. 799–805.  CrossRef Google Scholar
First citationKrishnan, R., Binkley, J. S., Seeger, R. & Pople, J. A. (1980). J. Chem. Phys. 72, 650–654.  CrossRef CAS Web of Science Google Scholar
First citationLee, C., Yang, W. & Parr, R. G. (1988). Phys. Rev. B37, 785–789.  CrossRef Web of Science Google Scholar
First citationSchmidt, M. W., Baldridge, K. K., Boatz, J. A., Elbert, S. T., Gordon, M. S., Jensen, J. J., Koseki, S., Matsunaga, N., Nguyen, K. A., Su, S., Windus, T. L., Dupuis, M. & Montgomery, J. A. (1993). J. Comput. Chem. 14, 1347–1363.  Web of Science CrossRef CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2003). J. Appl. Cryst. 36, 7–13.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationStreltsov, V. A. & Zavodnik, V. E. (1989). Sov. Phys. Crystallogr. 34, 824–828.  Google Scholar
First citationYou, X.-L., Lu, C.-R., Huang, Z.-L. & Zhang, D.-C. (2004). Dyes Pigm. 63, 217–223.  Web of Science CSD CrossRef CAS Google Scholar

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