organic compounds
9-Butyl-3-nitro-9H-carbazole
aDeparment of Chemistry, Anhui Science and Technology University, Fengyang 233100, People's Republic of China, and bDepartment of Chemistry, Anhui Science and Technology University, Fengyang 233100, People's Republic of China
*Correspondence e-mail: songcc@ahstu.edu.cn
The title compound, C16H16N2O2, is a carbazole derivative with the 3-position substituted by a nitro group and the 9-position substituted by an n-butyl group. The nitro group is inclined to the benzene ring to which it is attached by 4.4 (2)°. The n-butyl substituent has an extended conformation and lies almost normal to the plane of the carbozole ring. In the crystal, inversion-related molecules stack along the a axis and are linked via offset π–π interactions, forming columns [shortest intercentroid distance = 3.773 (1) Å].
Keywords: crystal structure; carbazole; offset π–π interactions.
CCDC reference: 1515348
Structure description
Carbazole-based materials are well known for their excellent thermal stability, hole-transporting properties, versatile structural derivatization, and their ability to form amorphous films. Such compounds have also been used to produce high-performance blue phosphorescent organic light-emitting diodes (Ye et al., 2010). When a n-butyl group is introduced into the molecule, it enhances the solubility and film-forming ability. A nitro group can form non-covalent interactions, especially hydrogen bonds, and exhibits a diversity of chemical and biological actions (Trzesowska-Kruszynska, 2015). The synthesis and of the title compound, with both a butyl and a nitro substituent, is described herein.
In the title compound, Fig. 1, the bond lengths and angles are similar to those in the related compound 1-nitro-9H-carbazole (Kautny & Stöger, 2014). The carbazole ring system is, as expected, almost planar (r.m.s. deviation = 0.01 Å) and the nitro group is inclined by 4.4 (2)° to the benzene ring to which it is attached. The n-butyl substituent has an extended conformation and lies almost normal to the plane of the carbozole ring system. Its mean plane is inclined to the central five-membered ring by 77.6 (2) °.
In the crystal, inversion-related molecules stack along the a axis and are linked via offset π–π interactions, forming columns (Fig. 2). The shortest intercentroid distance is Cg1⋯Cg3i = 3.773 (1) Å [Cg1 and Cg3 are the centroids of rings N2/C3/C6/C11/C16 and C11–C16, respectively, interplanar distance = 3.536 (1) Å, slippage = 1.316 Å, symmetry code: (i) −x + 1, −y, −z + 2].
Synthesis and crystallization
The precursor N-(n-butyl)-carbazole was prepared in accord with the literature method (Yang et al., 2005). Carbazole (3.3 g, 20 mmol) was added to a mixture of NaOH (1.3 g, 32 mmol), Bu4NBr (0.3 g) as phase-transfer catalyst in 20 ml CH3COCH3. The mixture was stirred for 1 h and then 1-bromobutane was slowly added. After refluxing for 24 h, no carbazole was present (monitoring by TLC). The solvents were removed under reduced pressure, and 20 ml water was added to the flask and a white solid precipitated out. The white solid was filtered and washed several times with water, dried and recrystallized from ethanol solution giving white needle-shaped crystals (yield: 4.1 g, 90.1%).
The title compound was prepared in accord with the literature methods (Shufen et al., 1995; Zhang et al., 2014). N-(n-butyl)-carbazole (5.6 g, 25 mmol) was dissolved in dichloromethane (50 ml) and the solution cooled (ice–water bath) to 273–275 K. Concentrated nitric acid (65–68%, 2.2 ml, 32 mmol) was added dropwise over one hour with vigorous stirring. Stirring was continued for a further hour at 283 K, after which time all of the N-(n-butyl)-carbazole had reacted. The liquor was steam distilled to remove dichloromethane, then the mixture was cooled and filtered and the product obtained was washed several times with water. The residue was purified by flash on silica gel using dichloroethane as (yield: 5.8 g, 86.5%). Yellow block-like crystals of the title compound, suitable for X-ray were grown from ethanol solution by slow evaporation at room temperature in about one week.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 1Structural data
CCDC reference: 1515348
https://doi.org/10.1107/S2414314616017764/su4073sup1.cif
contains datablocks I, Global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616017764/su4073Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314616017764/su4073Isup3.cml
Data collection: SMART (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C16H16N2O2 | Z = 2 |
Mr = 268.31 | F(000) = 284 |
Triclinic, P1 | Dx = 1.314 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.1948 (9) Å | Cell parameters from 3094 reflections |
b = 9.5630 (11) Å | θ = 2.3–26.8° |
c = 9.7528 (11) Å | µ = 0.09 mm−1 |
α = 68.106 (1)° | T = 296 K |
β = 73.141 (1)° | Block, light yellow |
γ = 85.379 (1)° | 0.18 × 0.17 × 0.16 mm |
V = 678.37 (13) Å3 |
Bruker SMART CCD area detector diffractometer | 2372 independent reflections |
Radiation source: fine-focus sealed tube | 2080 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.014 |
phi and ω scans | θmax = 25.0°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −9→9 |
Tmin = 0.984, Tmax = 0.986 | k = −11→11 |
4867 measured reflections | l = −11→10 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.039 | H-atom parameters constrained |
wR(F2) = 0.113 | w = 1/[σ2(Fo2) + (0.0524P)2 + 0.1519P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
2372 reflections | Δρmax = 0.24 e Å−3 |
183 parameters | Δρmin = −0.15 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.029 (5) |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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. |
x | y | z | Uiso*/Ueq | ||
N2 | 0.37033 (15) | 0.13986 (14) | 0.84237 (13) | 0.0458 (3) | |
N1 | −0.13392 (18) | 0.18235 (19) | 1.34577 (17) | 0.0603 (4) | |
O2 | −0.18313 (17) | 0.30664 (17) | 1.34766 (18) | 0.0832 (5) | |
O1 | −0.19381 (19) | 0.06376 (19) | 1.45000 (16) | 0.0867 (5) | |
C11 | 0.37310 (18) | −0.01575 (16) | 0.88088 (16) | 0.0432 (3) | |
C2 | 0.04843 (19) | 0.03728 (17) | 1.20382 (17) | 0.0455 (4) | |
H2 | −0.0023 | −0.0514 | 1.2821 | 0.055* | |
C3 | 0.17430 (17) | 0.03417 (16) | 1.07446 (16) | 0.0410 (3) | |
C6 | 0.24994 (18) | 0.17125 (16) | 0.95749 (16) | 0.0425 (3) | |
C1 | 0.00093 (19) | 0.17611 (18) | 1.21260 (17) | 0.0477 (4) | |
C16 | 0.25369 (17) | −0.08540 (16) | 1.02448 (16) | 0.0413 (3) | |
C4 | 0.0748 (2) | 0.31103 (18) | 1.09844 (19) | 0.0520 (4) | |
H4 | 0.0393 | 0.4021 | 1.1094 | 0.062* | |
C12 | 0.4732 (2) | −0.09885 (19) | 0.79835 (18) | 0.0528 (4) | |
H12 | 0.5521 | −0.0521 | 0.7035 | 0.063* | |
C7 | 0.4756 (2) | 0.24856 (19) | 0.69959 (17) | 0.0533 (4) | |
H7A | 0.5905 | 0.2119 | 0.6782 | 0.064* | |
H7B | 0.4814 | 0.3434 | 0.7130 | 0.064* | |
C5 | 0.2000 (2) | 0.31044 (17) | 0.96963 (18) | 0.0509 (4) | |
H5 | 0.2501 | 0.4001 | 0.8927 | 0.061* | |
C15 | 0.2343 (2) | −0.24194 (17) | 1.08728 (18) | 0.0499 (4) | |
H15 | 0.1560 | −0.2899 | 1.1822 | 0.060* | |
C13 | 0.4502 (2) | −0.2532 (2) | 0.8634 (2) | 0.0591 (4) | |
H13 | 0.5146 | −0.3116 | 0.8107 | 0.071* | |
C8 | 0.4070 (2) | 0.2762 (2) | 0.56171 (17) | 0.0561 (4) | |
H8A | 0.4875 | 0.3420 | 0.4695 | 0.067* | |
H8B | 0.4003 | 0.1809 | 0.5495 | 0.067* | |
C9 | 0.2347 (2) | 0.3454 (2) | 0.5750 (2) | 0.0598 (4) | |
H9A | 0.2426 | 0.4447 | 0.5783 | 0.072* | |
H9B | 0.1551 | 0.2839 | 0.6706 | 0.072* | |
C14 | 0.3336 (2) | −0.32454 (19) | 1.0057 (2) | 0.0575 (4) | |
H14 | 0.3223 | −0.4292 | 1.0465 | 0.069* | |
C10 | 0.1674 (3) | 0.3591 (3) | 0.4412 (2) | 0.0808 (6) | |
H10A | 0.2381 | 0.4300 | 0.3478 | 0.121* | |
H10B | 0.0526 | 0.3935 | 0.4592 | 0.121* | |
H10C | 0.1688 | 0.2625 | 0.4321 | 0.121* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N2 | 0.0465 (7) | 0.0483 (7) | 0.0367 (6) | 0.0007 (5) | −0.0075 (5) | −0.0123 (5) |
N1 | 0.0487 (8) | 0.0790 (10) | 0.0608 (9) | 0.0037 (7) | −0.0083 (7) | −0.0396 (8) |
O2 | 0.0679 (8) | 0.0907 (10) | 0.1034 (11) | 0.0107 (7) | −0.0029 (7) | −0.0669 (9) |
O1 | 0.0833 (10) | 0.0943 (11) | 0.0613 (8) | −0.0012 (8) | 0.0146 (7) | −0.0306 (8) |
C11 | 0.0415 (7) | 0.0503 (8) | 0.0391 (7) | 0.0050 (6) | −0.0145 (6) | −0.0160 (6) |
C2 | 0.0446 (8) | 0.0507 (9) | 0.0396 (7) | −0.0024 (6) | −0.0092 (6) | −0.0159 (6) |
C3 | 0.0411 (7) | 0.0457 (8) | 0.0377 (7) | 0.0008 (6) | −0.0132 (6) | −0.0152 (6) |
C6 | 0.0431 (8) | 0.0474 (8) | 0.0383 (7) | 0.0014 (6) | −0.0134 (6) | −0.0155 (6) |
C1 | 0.0438 (8) | 0.0598 (9) | 0.0460 (8) | 0.0043 (7) | −0.0116 (6) | −0.0280 (7) |
C16 | 0.0406 (7) | 0.0474 (8) | 0.0387 (7) | 0.0025 (6) | −0.0137 (6) | −0.0171 (6) |
C4 | 0.0559 (9) | 0.0503 (9) | 0.0575 (9) | 0.0081 (7) | −0.0192 (7) | −0.0272 (8) |
C12 | 0.0477 (8) | 0.0665 (11) | 0.0442 (8) | 0.0101 (7) | −0.0112 (7) | −0.0231 (8) |
C7 | 0.0451 (8) | 0.0620 (10) | 0.0426 (8) | −0.0063 (7) | −0.0068 (7) | −0.0103 (7) |
C5 | 0.0570 (9) | 0.0448 (8) | 0.0482 (8) | −0.0009 (7) | −0.0150 (7) | −0.0134 (7) |
C15 | 0.0512 (9) | 0.0485 (9) | 0.0486 (8) | 0.0001 (7) | −0.0135 (7) | −0.0163 (7) |
C13 | 0.0601 (10) | 0.0648 (11) | 0.0615 (10) | 0.0185 (8) | −0.0199 (8) | −0.0347 (9) |
C8 | 0.0540 (9) | 0.0622 (10) | 0.0401 (8) | 0.0013 (7) | −0.0052 (7) | −0.0114 (7) |
C9 | 0.0602 (10) | 0.0641 (11) | 0.0574 (10) | 0.0065 (8) | −0.0157 (8) | −0.0262 (8) |
C14 | 0.0650 (10) | 0.0488 (9) | 0.0645 (10) | 0.0082 (8) | −0.0234 (8) | −0.0247 (8) |
C10 | 0.0859 (14) | 0.0962 (15) | 0.0755 (13) | 0.0283 (12) | −0.0423 (12) | −0.0388 (12) |
N2—C6 | 1.3730 (19) | C12—H12 | 0.9300 |
N2—C11 | 1.3924 (19) | C7—C8 | 1.531 (2) |
N2—C7 | 1.4601 (19) | C7—H7A | 0.9700 |
N1—O1 | 1.225 (2) | C7—H7B | 0.9700 |
N1—O2 | 1.2290 (19) | C5—H5 | 0.9300 |
N1—C1 | 1.458 (2) | C15—C14 | 1.381 (2) |
C11—C12 | 1.393 (2) | C15—H15 | 0.9300 |
C11—C16 | 1.406 (2) | C13—C14 | 1.391 (2) |
C2—C1 | 1.380 (2) | C13—H13 | 0.9300 |
C2—C3 | 1.387 (2) | C8—C9 | 1.502 (2) |
C2—H2 | 0.9300 | C8—H8A | 0.9700 |
C3—C6 | 1.418 (2) | C8—H8B | 0.9700 |
C3—C16 | 1.442 (2) | C9—C10 | 1.517 (2) |
C6—C5 | 1.398 (2) | C9—H9A | 0.9700 |
C1—C4 | 1.391 (2) | C9—H9B | 0.9700 |
C16—C15 | 1.393 (2) | C14—H14 | 0.9300 |
C4—C5 | 1.374 (2) | C10—H10A | 0.9600 |
C4—H4 | 0.9300 | C10—H10B | 0.9600 |
C12—C13 | 1.376 (2) | C10—H10C | 0.9600 |
C6—N2—C11 | 108.59 (12) | N2—C7—H7B | 109.0 |
C6—N2—C7 | 126.97 (13) | C8—C7—H7B | 109.0 |
C11—N2—C7 | 124.40 (13) | H7A—C7—H7B | 107.8 |
O1—N1—O2 | 123.01 (15) | C4—C5—C6 | 118.11 (14) |
O1—N1—C1 | 118.64 (15) | C4—C5—H5 | 120.9 |
O2—N1—C1 | 118.35 (16) | C6—C5—H5 | 120.9 |
N2—C11—C12 | 128.91 (14) | C14—C15—C16 | 118.65 (15) |
N2—C11—C16 | 109.18 (13) | C14—C15—H15 | 120.7 |
C12—C11—C16 | 121.91 (14) | C16—C15—H15 | 120.7 |
C1—C2—C3 | 117.88 (14) | C12—C13—C14 | 122.02 (15) |
C1—C2—H2 | 121.1 | C12—C13—H13 | 119.0 |
C3—C2—H2 | 121.1 | C14—C13—H13 | 119.0 |
C2—C3—C6 | 119.72 (13) | C9—C8—C7 | 114.26 (14) |
C2—C3—C16 | 133.72 (14) | C9—C8—H8A | 108.7 |
C6—C3—C16 | 106.56 (12) | C7—C8—H8A | 108.7 |
N2—C6—C5 | 129.60 (14) | C9—C8—H8B | 108.7 |
N2—C6—C3 | 109.16 (13) | C7—C8—H8B | 108.7 |
C5—C6—C3 | 121.24 (14) | H8A—C8—H8B | 107.6 |
C2—C1—C4 | 122.71 (14) | C8—C9—C10 | 111.91 (15) |
C2—C1—N1 | 118.87 (14) | C8—C9—H9A | 109.2 |
C4—C1—N1 | 118.42 (15) | C10—C9—H9A | 109.2 |
C15—C16—C11 | 119.52 (14) | C8—C9—H9B | 109.2 |
C15—C16—C3 | 133.98 (14) | C10—C9—H9B | 109.2 |
C11—C16—C3 | 106.50 (12) | H9A—C9—H9B | 107.9 |
C5—C4—C1 | 120.34 (15) | C15—C14—C13 | 120.85 (15) |
C5—C4—H4 | 119.8 | C15—C14—H14 | 119.6 |
C1—C4—H4 | 119.8 | C13—C14—H14 | 119.6 |
C13—C12—C11 | 117.05 (15) | C9—C10—H10A | 109.5 |
C13—C12—H12 | 121.5 | C9—C10—H10B | 109.5 |
C11—C12—H12 | 121.5 | H10A—C10—H10B | 109.5 |
N2—C7—C8 | 112.79 (13) | C9—C10—H10C | 109.5 |
N2—C7—H7A | 109.0 | H10A—C10—H10C | 109.5 |
C8—C7—H7A | 109.0 | H10B—C10—H10C | 109.5 |
C6—N2—C11—C12 | 179.28 (14) | N2—C11—C16—C3 | 0.38 (15) |
C7—N2—C11—C12 | 1.2 (2) | C12—C11—C16—C3 | −179.68 (13) |
C6—N2—C11—C16 | −0.79 (16) | C2—C3—C16—C15 | −0.2 (3) |
C7—N2—C11—C16 | −178.82 (13) | C6—C3—C16—C15 | −179.70 (15) |
C1—C2—C3—C6 | 0.4 (2) | C2—C3—C16—C11 | 179.60 (15) |
C1—C2—C3—C16 | −179.01 (14) | C6—C3—C16—C11 | 0.15 (15) |
C11—N2—C6—C5 | −179.23 (14) | C2—C1—C4—C5 | 0.4 (2) |
C7—N2—C6—C5 | −1.3 (2) | N1—C1—C4—C5 | −178.75 (14) |
C11—N2—C6—C3 | 0.89 (16) | N2—C11—C12—C13 | −179.99 (14) |
C7—N2—C6—C3 | 178.85 (13) | C16—C11—C12—C13 | 0.1 (2) |
C2—C3—C6—N2 | 179.82 (12) | C6—N2—C7—C8 | −99.63 (18) |
C16—C3—C6—N2 | −0.64 (15) | C11—N2—C7—C8 | 78.03 (18) |
C2—C3—C6—C5 | −0.1 (2) | C1—C4—C5—C6 | 0.0 (2) |
C16—C3—C6—C5 | 179.47 (13) | N2—C6—C5—C4 | −179.98 (14) |
C3—C2—C1—C4 | −0.5 (2) | C3—C6—C5—C4 | −0.1 (2) |
C3—C2—C1—N1 | 178.57 (13) | C11—C16—C15—C14 | −0.1 (2) |
O1—N1—C1—C2 | 4.2 (2) | C3—C16—C15—C14 | 179.74 (15) |
O2—N1—C1—C2 | −175.23 (14) | C11—C12—C13—C14 | −0.5 (2) |
O1—N1—C1—C4 | −176.61 (15) | N2—C7—C8—C9 | 63.5 (2) |
O2—N1—C1—C4 | 3.9 (2) | C7—C8—C9—C10 | −175.61 (15) |
N2—C11—C16—C15 | −179.74 (12) | C16—C15—C14—C13 | −0.3 (2) |
C12—C11—C16—C15 | 0.2 (2) | C12—C13—C14—C15 | 0.6 (3) |
Acknowledgements
We are grateful to the Natural Science Foundation of Anhui Province (1508085QB41) and the key discipline construction of Anhui Science and Technology University (grant No. AKZDXK2015A01) for supporting this study.
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