organic compounds
1-Isobutyl-N,N-dimethyl-1H-imidazo[4,5-c]quinolin-4-amine
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and bDepartment of Chemistry, Mangalore University, Karnataka, India
*Correspondence e-mail: hkfun@usm.my
In the title compound, C16H20N4, the 1H-imidazo[4,5-c]quinoline ring system is approximately planar, with a maximum deviation of 0.0719 (15) Å. An intramolecular C—H⋯N hydrogen bond contributes to the stabilization of the molecule, forming an S(6) ring motif. In the crystal, the molecules are stacked along the b axis through weak aromatic π–π interactions between benzene and imidazole and benzene and pyridine rings [centroid–centroid distances = 3.6055 (10) and 3.5342 (10) Å, respectively].
Related literature
For background to quinolines and their microbial activity, see: Jampilek et al. (2005); Gershon et al. (2004); Dardari et al. (2004). For the syntheses of 1H-imidazo[4,5-c]quinolin-4-amines, see: Gabriel (1918); Izumi et al. (2003). For bond-length data, see: Allen et al. (1987). For hydrogen-bond motifs, see: Bernstein et al. (1995).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2009); cell SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supporting information
10.1107/S160053681100153X/is2656sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053681100153X/is2656Isup2.hkl
4-Chloro-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolone (2 g, 0.00771 mole), methanol (30 ml) and 3.3 ml of DMF were heated to reflux for 72 h. The solid formed was separated, filtered off and washed with methanol. Yield, 1.99 g (58.5%). Crystals suitable for x-ray analysis were obtained from ethanol by slow evaporation.
All H atoms were positioned geometrically (C—H = 0.93 to 0.98 Å) and refined using the riding model with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating group model was applied to the methyl groups.
Data collection: APEX2 (Bruker, 2009); cell
SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).C16H20N4 | F(000) = 576 |
Mr = 268.36 | Dx = 1.239 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3031 reflections |
a = 9.2804 (2) Å | θ = 2.2–27.4° |
b = 18.5492 (6) Å | µ = 0.08 mm−1 |
c = 8.5147 (2) Å | T = 296 K |
β = 101.051 (2)° | Block, colourless |
V = 1438.57 (7) Å3 | 0.39 × 0.29 × 0.14 mm |
Z = 4 |
Bruker SMART APEXII CCD area-detector diffractometer | 3456 independent reflections |
Radiation source: fine-focus sealed tube | 2271 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.037 |
ϕ and ω scans | θmax = 28.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −12→12 |
Tmin = 0.971, Tmax = 0.989 | k = −19→24 |
13134 measured reflections | l = −10→11 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.146 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0604P)2 + 0.3608P] where P = (Fo2 + 2Fc2)/3 |
3456 reflections | (Δ/σ)max = 0.001 |
185 parameters | Δρmax = 0.26 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C16H20N4 | V = 1438.57 (7) Å3 |
Mr = 268.36 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.2804 (2) Å | µ = 0.08 mm−1 |
b = 18.5492 (6) Å | T = 296 K |
c = 8.5147 (2) Å | 0.39 × 0.29 × 0.14 mm |
β = 101.051 (2)° |
Bruker SMART APEXII CCD area-detector diffractometer | 3456 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 2271 reflections with I > 2σ(I) |
Tmin = 0.971, Tmax = 0.989 | Rint = 0.037 |
13134 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.146 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.26 e Å−3 |
3456 reflections | Δρmin = −0.18 e Å−3 |
185 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.44302 (15) | 0.08084 (8) | 0.74563 (17) | 0.0430 (4) | |
N3 | 0.31258 (17) | 0.18631 (8) | 0.3740 (2) | 0.0512 (4) | |
N2 | 0.51431 (15) | 0.14182 (8) | 0.30069 (17) | 0.0418 (4) | |
N4 | 0.22238 (16) | 0.14021 (9) | 0.68830 (19) | 0.0520 (4) | |
C7 | 0.35046 (18) | 0.12102 (9) | 0.6440 (2) | 0.0400 (4) | |
C6 | 0.57198 (17) | 0.05715 (9) | 0.7062 (2) | 0.0386 (4) | |
C5 | 0.66567 (19) | 0.01562 (10) | 0.8208 (2) | 0.0467 (5) | |
H5A | 0.6387 | 0.0059 | 0.9184 | 0.056* | |
C4 | 0.7957 (2) | −0.01084 (11) | 0.7918 (2) | 0.0500 (5) | |
H4A | 0.8563 | −0.0378 | 0.8698 | 0.060* | |
C3 | 0.8376 (2) | 0.00247 (10) | 0.6460 (2) | 0.0499 (5) | |
H3A | 0.9262 | −0.0155 | 0.6269 | 0.060* | |
C2 | 0.74870 (18) | 0.04200 (9) | 0.5307 (2) | 0.0428 (4) | |
H2A | 0.7771 | 0.0500 | 0.4333 | 0.051* | |
C1 | 0.61517 (17) | 0.07070 (8) | 0.55699 (19) | 0.0358 (4) | |
C9 | 0.51360 (17) | 0.11474 (8) | 0.45202 (19) | 0.0363 (4) | |
C8 | 0.38711 (18) | 0.14192 (9) | 0.4938 (2) | 0.0395 (4) | |
C10 | 0.3921 (2) | 0.18403 (10) | 0.2632 (2) | 0.0510 (5) | |
H10A | 0.3677 | 0.2090 | 0.1670 | 0.061* | |
C11 | 0.61699 (19) | 0.12704 (10) | 0.1942 (2) | 0.0449 (4) | |
H11A | 0.5682 | 0.1362 | 0.0848 | 0.054* | |
H11B | 0.6434 | 0.0764 | 0.2024 | 0.054* | |
C12 | 0.7563 (2) | 0.17189 (10) | 0.2307 (2) | 0.0466 (4) | |
H12A | 0.7980 | 0.1669 | 0.3450 | 0.056* | |
C13 | 0.8672 (2) | 0.14245 (12) | 0.1367 (3) | 0.0684 (6) | |
H13A | 0.8840 | 0.0923 | 0.1609 | 0.103* | |
H13B | 0.9579 | 0.1684 | 0.1657 | 0.103* | |
H13C | 0.8298 | 0.1481 | 0.0242 | 0.103* | |
C14 | 0.7246 (3) | 0.25132 (11) | 0.1958 (3) | 0.0689 (6) | |
H14A | 0.8137 | 0.2785 | 0.2254 | 0.103* | |
H14B | 0.6539 | 0.2680 | 0.2564 | 0.103* | |
H14C | 0.6862 | 0.2576 | 0.0837 | 0.103* | |
C15 | 0.1048 (2) | 0.17851 (13) | 0.5909 (3) | 0.0690 (6) | |
H15A | 0.1212 | 0.1807 | 0.4830 | 0.103* | |
H15B | 0.1002 | 0.2265 | 0.6318 | 0.103* | |
H15C | 0.0139 | 0.1540 | 0.5923 | 0.103* | |
C16 | 0.1954 (2) | 0.11825 (15) | 0.8435 (3) | 0.0716 (7) | |
H16A | 0.2865 | 0.1175 | 0.9193 | 0.107* | |
H16B | 0.1527 | 0.0709 | 0.8355 | 0.107* | |
H16C | 0.1292 | 0.1517 | 0.8784 | 0.107* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0436 (8) | 0.0471 (8) | 0.0387 (8) | 0.0035 (7) | 0.0084 (6) | −0.0017 (7) |
N3 | 0.0483 (8) | 0.0502 (9) | 0.0556 (10) | 0.0094 (7) | 0.0110 (7) | 0.0128 (8) |
N2 | 0.0434 (8) | 0.0424 (8) | 0.0401 (8) | −0.0001 (6) | 0.0093 (6) | 0.0054 (7) |
N4 | 0.0468 (8) | 0.0622 (10) | 0.0497 (10) | 0.0129 (8) | 0.0161 (7) | 0.0038 (8) |
C7 | 0.0396 (9) | 0.0384 (9) | 0.0425 (10) | −0.0003 (7) | 0.0089 (7) | −0.0055 (8) |
C6 | 0.0388 (8) | 0.0368 (9) | 0.0395 (9) | −0.0017 (7) | 0.0058 (7) | −0.0033 (7) |
C5 | 0.0525 (11) | 0.0512 (11) | 0.0354 (10) | 0.0042 (9) | 0.0062 (8) | 0.0028 (8) |
C4 | 0.0479 (10) | 0.0540 (11) | 0.0456 (11) | 0.0095 (9) | 0.0023 (8) | 0.0075 (9) |
C3 | 0.0428 (10) | 0.0512 (11) | 0.0568 (12) | 0.0086 (8) | 0.0126 (8) | 0.0068 (9) |
C2 | 0.0446 (9) | 0.0405 (9) | 0.0453 (10) | 0.0015 (8) | 0.0137 (8) | 0.0049 (8) |
C1 | 0.0376 (8) | 0.0309 (8) | 0.0385 (9) | −0.0022 (7) | 0.0064 (7) | −0.0010 (7) |
C9 | 0.0410 (9) | 0.0311 (8) | 0.0367 (9) | −0.0036 (7) | 0.0069 (7) | 0.0000 (7) |
C8 | 0.0400 (9) | 0.0342 (8) | 0.0432 (10) | 0.0001 (7) | 0.0052 (7) | 0.0016 (8) |
C10 | 0.0502 (10) | 0.0514 (11) | 0.0508 (11) | 0.0071 (9) | 0.0080 (9) | 0.0145 (9) |
C11 | 0.0500 (10) | 0.0485 (10) | 0.0368 (10) | 0.0018 (8) | 0.0100 (8) | 0.0018 (8) |
C12 | 0.0483 (10) | 0.0483 (10) | 0.0449 (10) | 0.0000 (8) | 0.0132 (8) | 0.0083 (8) |
C13 | 0.0610 (13) | 0.0689 (14) | 0.0824 (16) | 0.0028 (11) | 0.0312 (12) | 0.0030 (13) |
C14 | 0.0788 (15) | 0.0514 (12) | 0.0844 (17) | −0.0004 (11) | 0.0352 (13) | 0.0129 (12) |
C15 | 0.0460 (11) | 0.0844 (16) | 0.0790 (16) | 0.0166 (11) | 0.0183 (10) | 0.0156 (13) |
C16 | 0.0606 (13) | 0.1034 (19) | 0.0566 (13) | 0.0146 (12) | 0.0256 (11) | 0.0048 (13) |
N1—C7 | 1.325 (2) | C1—C9 | 1.425 (2) |
N1—C6 | 1.376 (2) | C9—C8 | 1.385 (2) |
N3—C10 | 1.305 (2) | C10—H10A | 0.9300 |
N3—C8 | 1.388 (2) | C11—C12 | 1.519 (3) |
N2—C10 | 1.365 (2) | C11—H11A | 0.9700 |
N2—C9 | 1.384 (2) | C11—H11B | 0.9700 |
N2—C11 | 1.461 (2) | C12—C14 | 1.521 (3) |
N4—C7 | 1.361 (2) | C12—C13 | 1.521 (3) |
N4—C15 | 1.427 (2) | C12—H12A | 0.9800 |
N4—C16 | 1.450 (2) | C13—H13A | 0.9600 |
C7—C8 | 1.439 (2) | C13—H13B | 0.9600 |
C6—C5 | 1.406 (2) | C13—H13C | 0.9600 |
C6—C1 | 1.426 (2) | C14—H14A | 0.9600 |
C5—C4 | 1.368 (2) | C14—H14B | 0.9600 |
C5—H5A | 0.9300 | C14—H14C | 0.9600 |
C4—C3 | 1.393 (3) | C15—H15A | 0.9600 |
C4—H4A | 0.9300 | C15—H15B | 0.9600 |
C3—C2 | 1.368 (2) | C15—H15C | 0.9600 |
C3—H3A | 0.9300 | C16—H16A | 0.9600 |
C2—C1 | 1.405 (2) | C16—H16B | 0.9600 |
C2—H2A | 0.9300 | C16—H16C | 0.9600 |
C7—N1—C6 | 120.37 (15) | N2—C10—H10A | 122.9 |
C10—N3—C8 | 103.93 (14) | N2—C11—C12 | 113.65 (15) |
C10—N2—C9 | 105.91 (14) | N2—C11—H11A | 108.8 |
C10—N2—C11 | 125.01 (15) | C12—C11—H11A | 108.8 |
C9—N2—C11 | 129.00 (14) | N2—C11—H11B | 108.8 |
C7—N4—C15 | 125.46 (16) | C12—C11—H11B | 108.8 |
C7—N4—C16 | 119.42 (16) | H11A—C11—H11B | 107.7 |
C15—N4—C16 | 115.06 (16) | C11—C12—C14 | 111.44 (16) |
N1—C7—N4 | 117.22 (16) | C11—C12—C13 | 109.34 (16) |
N1—C7—C8 | 119.85 (15) | C14—C12—C13 | 111.73 (17) |
N4—C7—C8 | 122.93 (16) | C11—C12—H12A | 108.1 |
N1—C6—C5 | 117.17 (15) | C14—C12—H12A | 108.1 |
N1—C6—C1 | 124.58 (15) | C13—C12—H12A | 108.1 |
C5—C6—C1 | 118.24 (15) | C12—C13—H13A | 109.5 |
C4—C5—C6 | 121.37 (17) | C12—C13—H13B | 109.5 |
C4—C5—H5A | 119.3 | H13A—C13—H13B | 109.5 |
C6—C5—H5A | 119.3 | C12—C13—H13C | 109.5 |
C5—C4—C3 | 120.26 (17) | H13A—C13—H13C | 109.5 |
C5—C4—H4A | 119.9 | H13B—C13—H13C | 109.5 |
C3—C4—H4A | 119.9 | C12—C14—H14A | 109.5 |
C2—C3—C4 | 120.10 (17) | C12—C14—H14B | 109.5 |
C2—C3—H3A | 119.9 | H14A—C14—H14B | 109.5 |
C4—C3—H3A | 119.9 | C12—C14—H14C | 109.5 |
C3—C2—C1 | 121.20 (16) | H14A—C14—H14C | 109.5 |
C3—C2—H2A | 119.4 | H14B—C14—H14C | 109.5 |
C1—C2—H2A | 119.4 | N4—C15—H15A | 109.5 |
C2—C1—C9 | 127.93 (15) | N4—C15—H15B | 109.5 |
C2—C1—C6 | 118.81 (15) | H15A—C15—H15B | 109.5 |
C9—C1—C6 | 113.24 (14) | N4—C15—H15C | 109.5 |
N2—C9—C8 | 105.21 (14) | H15A—C15—H15C | 109.5 |
N2—C9—C1 | 132.15 (15) | H15B—C15—H15C | 109.5 |
C8—C9—C1 | 122.60 (15) | N4—C16—H16A | 109.5 |
C9—C8—N3 | 110.77 (15) | N4—C16—H16B | 109.5 |
C9—C8—C7 | 119.13 (15) | H16A—C16—H16B | 109.5 |
N3—C8—C7 | 130.09 (15) | N4—C16—H16C | 109.5 |
N3—C10—N2 | 114.14 (16) | H16A—C16—H16C | 109.5 |
N3—C10—H10A | 122.9 | H16B—C16—H16C | 109.5 |
C6—N1—C7—N4 | 177.51 (15) | C11—N2—C9—C1 | 6.5 (3) |
C6—N1—C7—C8 | −2.0 (2) | C2—C1—C9—N2 | −0.3 (3) |
C15—N4—C7—N1 | −175.07 (19) | C6—C1—C9—N2 | 178.26 (16) |
C16—N4—C7—N1 | 1.9 (3) | C2—C1—C9—C8 | −177.77 (16) |
C15—N4—C7—C8 | 4.4 (3) | C6—C1—C9—C8 | 0.8 (2) |
C16—N4—C7—C8 | −178.62 (18) | N2—C9—C8—N3 | −1.55 (19) |
C7—N1—C6—C5 | 179.12 (15) | C1—C9—C8—N3 | 176.52 (15) |
C7—N1—C6—C1 | −2.1 (3) | N2—C9—C8—C7 | 177.37 (14) |
N1—C6—C5—C4 | 179.43 (17) | C1—C9—C8—C7 | −4.6 (2) |
C1—C6—C5—C4 | 0.5 (3) | C10—N3—C8—C9 | 1.2 (2) |
C6—C5—C4—C3 | −0.6 (3) | C10—N3—C8—C7 | −177.58 (18) |
C5—C4—C3—C2 | −0.1 (3) | N1—C7—C8—C9 | 5.2 (2) |
C4—C3—C2—C1 | 0.8 (3) | N4—C7—C8—C9 | −174.26 (16) |
C3—C2—C1—C9 | 177.63 (17) | N1—C7—C8—N3 | −176.11 (17) |
C3—C2—C1—C6 | −0.8 (3) | N4—C7—C8—N3 | 4.4 (3) |
N1—C6—C1—C2 | −178.65 (15) | C8—N3—C10—N2 | −0.4 (2) |
C5—C6—C1—C2 | 0.1 (2) | C9—N2—C10—N3 | −0.6 (2) |
N1—C6—C1—C9 | 2.7 (2) | C11—N2—C10—N3 | 176.48 (16) |
C5—C6—C1—C9 | −178.54 (15) | C10—N2—C11—C12 | 100.8 (2) |
C10—N2—C9—C8 | 1.26 (18) | C9—N2—C11—C12 | −82.9 (2) |
C11—N2—C9—C8 | −175.65 (16) | N2—C11—C12—C14 | −67.1 (2) |
C10—N2—C9—C1 | −176.54 (18) | N2—C11—C12—C13 | 168.91 (16) |
Experimental details
Crystal data | |
Chemical formula | C16H20N4 |
Mr | 268.36 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 9.2804 (2), 18.5492 (6), 8.5147 (2) |
β (°) | 101.051 (2) |
V (Å3) | 1438.57 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.39 × 0.29 × 0.14 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.971, 0.989 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13134, 3456, 2271 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.146, 1.02 |
No. of reflections | 3456 |
No. of parameters | 185 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.26, −0.18 |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
Acknowledgements
HKF and WSL thank Universiti Sains Malaysia (USM) for the Research University Grant (1001/PFIZIK/811160). WSL also thanks the Malaysian Government and USM for the award of a Research Fellowship.
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Compounds bearing a quinoline moiety are well known due to their broad biological activity (Jampilek et al., 2005). For example, hydroxyquinoline and its derivatives were introduced as antifungal agents in clinical practice and the novel compounds of this type are still being investigated (Gershon et al., 2004; Dardari et al., 2004). 1H-imidazo[4,5-c]quinolin-4-amines were synthesized by using two main synthetic routes. The first route started with 4-hydroxy-3-nitro-1H-quinolin-2-one, employing a modification of the method of Gabriel (Gabriel, 1918) to give 2,4-dichloro-3-nitroquinoline. Alternatively, the chlorination can be accomplished using phenylphosphonicdichloride (Izumi et al., 2003). Reaction of the N-oxide with POCl3 in dichloromethane gave the 4-chloro-1H-imidazo[4,5-c]quinoline analogue, which was converted to 1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-4-amine by treatment with NH3 in methanol at 150 °C. 1H-Imidazo-[4,5-c]quinolines are potential antiviral agents and also induce the production of cytokines, especially interferon (IFN). This promoted us to react 4-chloro-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolone with dimethylformide to give 1-isobutyl-N,N-dimethyl-1H-imidazo[4,5-c]quinolin-4-amine.
In the title compound (Fig. 1), the 1H-imidazo[4,5-c]quinoline ring system (C1–C6/N1/C7/C8/N3/C10/N2/C9) is approximately planar with a maximum deviation of 0.0719 (15) Å at atom N3. The torsion angle, C10—N2—C11—C12, formed between this ring system and the isobutyl unit is 100.8 (2)°. An intramolecular C15—H15A···N3 hydrogen bond (Table 1) contributes to the stabilization of the molecule, forming an S(6) ring motif (Bernstein et al., 1995). Bond lengths (Allen et al., 1987) and angles are within the normal ranges.
There is no significant intermolecular hydrogen bond observed in the crystal packing (Fig. 2). The molecules are stacked along the b axis by way of weak aromatic π–π interactions of the benzene C1–C6 ring (centroid Cg3) with the imidazole N2/C9/C8/N3/C10 (centroid Cg1) and pyridine N1/C6/C1/C9/C8/C7 (centroid Cg2) rings [Cg3···Cg1 separation = 3.6055 (10) Å; Cg3···Cg2 separation = 3.5342 (10) Å].