Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270113001510/sk3473sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113001510/sk3473Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113001510/sk3473IIsup3.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113001510/sk3473IIIsup4.hkl |
CCDC references: 925776; 925777; 925778
For related literature, see: Allen (2002); Bernstein et al. (1995); Davies & Bond (2001); Guckian et al. (2000); Headen et al. (2010); Howie et al. (2010); Hunter & Sanders (1990); Hunter et al. (2001); Kaiser et al. (2009); Lee et al. (2007); Lima et al. (2012); Sinnokrot & Sherrill (2003, 2006); Thomas et al. (2002); Xue et al. (2006); Yu et al. (2006).
The general procedure for the preparation of the title compounds was as follows. Sodium (0.172 g) was added slowly to the appropriate alcohol (15 ml) at 273 K. After the reaction was complete, 4,7-dichloroquinoline (0.5 g) was added and the mixture was refluxed overnight. The reaction mixture was rotary evaporated and water (20 ml) was added to the residue. The aqueous solution was extracted into CH2Cl2 (3 × 10 ml), and the organic extracts were combined, dried over anhydrous Na2SO4 and concentrated under vacuum to leave the desired solid product, which was recrystallized from an appropriate solvent, viz. (I) from MeOH (m.p. 375–377 K), (II) from water (m.p. 410–411 K) and (III) from EtOH (yield 82%; m.p. 371–372 K).
H atoms were treated as riding atoms, with aromatic C—H and terminal C–H2 = 0.95 Å and secondary C—H2 = 0.99 Å, with Uiso = 1.2Ueq(C), and with C–H(methyl) = 0.98 Å, with Uiso = 1.5Ueq(C).
The crystals of (III) were exceedingly small and, as a result, the number of strong reflections is low and the R factor is accordingly greater than 0.10.
For all compounds, data collection: CrystalClear-SM Expert (Rigaku, 2011); cell refinement: CrystalClear-SM Expert (Rigaku, 2011); data reduction: CrystalClear-SM Expert (Rigaku, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: OSCAIL (McArdle et al., 2004) and SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: OSCAIL (McArdle et al., 2004) and SHELXL97 (Sheldrick, 2008).
C12H10ClNO | F(000) = 456 |
Mr = 219.66 | Dx = 1.440 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71075 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 3850 reflections |
a = 3.9370 (9) Å | θ = 2.5–31.2° |
b = 11.977 (3) Å | µ = 0.35 mm−1 |
c = 21.482 (6) Å | T = 100 K |
V = 1013.0 (4) Å3 | Needle, colourless |
Z = 4 | 0.40 × 0.02 × 0.02 mm |
Rigaku Saturn724+ diffractometer | 3087 independent reflections |
Radiation source: Rotating Anode | 2869 reflections with I > 2σ(I) |
Confocal monochromator | Rint = 0.031 |
Detector resolution: 28.5714 pixels mm-1 | θmax = 31.4°, θmin = 1.9° |
profile data from ω–scans | h = −5→3 |
Absorption correction: multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | k = −17→13 |
Tmin = 0.874, Tmax = 0.993 | l = −30→30 |
14640 measured reflections |
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)] = 0.032 | H-atom parameters constrained |
wR(F2) = 0.075 | w = 1/[σ2(Fo2) + (0.0407P)2 + 0.0823P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max = 0.001 |
3087 reflections | Δρmax = 0.28 e Å−3 |
137 parameters | Δρmin = −0.20 e Å−3 |
0 restraints | Absolute structure: Flack (1983), with 1202 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.01 (5) |
C12H10ClNO | V = 1013.0 (4) Å3 |
Mr = 219.66 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 3.9370 (9) Å | µ = 0.35 mm−1 |
b = 11.977 (3) Å | T = 100 K |
c = 21.482 (6) Å | 0.40 × 0.02 × 0.02 mm |
Rigaku Saturn724+ diffractometer | 3087 independent reflections |
Absorption correction: multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | 2869 reflections with I > 2σ(I) |
Tmin = 0.874, Tmax = 0.993 | Rint = 0.031 |
14640 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | H-atom parameters constrained |
wR(F2) = 0.075 | Δρmax = 0.28 e Å−3 |
S = 1.07 | Δρmin = −0.20 e Å−3 |
3087 reflections | Absolute structure: Flack (1983), with 1202 Friedel pairs |
137 parameters | Absolute structure parameter: 0.01 (5) |
0 restraints |
Experimental. 4-Allyloxy-7-chloroquinoline 1H NMR (400.0MHz, DMSO-d6, δ, p.p.m.): 8.77 (1H, d, J = 5.2 Hz, H-2), 8.18 (1H, d, J = 8.9 Hz, H-5), 8.00 (1H, d, J = 1.8 Hz, H-8), 7.59 (1H, dd, J = 8.9 and 1.9 Hz, H-6), 7.07 (1H, d, J = 5.3 Hz, H-3), 6.22-6.13 (1H, m, CH═), 5.55 (1H, dd, J = 17.2 and 1.2 Hz) and 5.73 (1H, dd, J = 10.6 and 0.7 Hz) (H2C═), 4.87 (2H, d, J = 5.1 Hz, OCH2). 13C NMR (125 MHz, DMSO-d6, δ, p.p.m.): 160.3, 152.9, 149.2, 134.4, 132.4, 127.3, 126.2,; 123.7, 119.4, 118.2, 102.4, 68.9. MS/ESI: [M+H]: 220.0. IR νmax (cm1; KBr): 1125 (C—O), 922 (C═CH2). |
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 | ||
Cl7 | 0.75315 (9) | 0.16731 (2) | 0.582400 (14) | 0.02439 (9) | |
O4 | 0.3865 (3) | 0.70449 (7) | 0.62487 (4) | 0.0194 (2) | |
N1 | 0.1892 (3) | 0.42768 (9) | 0.73786 (5) | 0.0205 (2) | |
C2 | 0.0973 (4) | 0.52931 (11) | 0.75455 (5) | 0.0215 (3) | |
H2 | −0.0150 | 0.5368 | 0.7935 | 0.026* | |
C3 | 0.1503 (3) | 0.62789 (11) | 0.72000 (5) | 0.0193 (3) | |
H3 | 0.0750 | 0.6982 | 0.7351 | 0.023* | |
C4 | 0.3150 (3) | 0.61873 (10) | 0.66371 (5) | 0.0162 (2) | |
C4a | 0.4229 (3) | 0.51185 (10) | 0.64285 (5) | 0.0160 (2) | |
C5 | 0.5953 (3) | 0.49573 (10) | 0.58558 (5) | 0.0179 (2) | |
H5 | 0.6439 | 0.5581 | 0.5598 | 0.021* | |
C6 | 0.6925 (3) | 0.39105 (10) | 0.56716 (5) | 0.0189 (3) | |
H6 | 0.8067 | 0.3803 | 0.5287 | 0.023* | |
C7 | 0.6204 (4) | 0.29958 (10) | 0.60616 (6) | 0.0187 (2) | |
C8 | 0.4551 (3) | 0.31124 (10) | 0.66182 (5) | 0.0186 (3) | |
H8 | 0.4103 | 0.2477 | 0.6870 | 0.022* | |
C8a | 0.3514 (3) | 0.41873 (11) | 0.68153 (5) | 0.0178 (3) | |
C41 | 0.2780 (4) | 0.81394 (9) | 0.64363 (5) | 0.0190 (2) | |
H41A | 0.3829 | 0.8337 | 0.6840 | 0.023* | |
H41B | 0.0281 | 0.8152 | 0.6487 | 0.023* | |
C42 | 0.3825 (4) | 0.89589 (11) | 0.59509 (6) | 0.0216 (3) | |
H42 | 0.3117 | 0.9710 | 0.6009 | 0.026* | |
C43 | 0.5639 (4) | 0.87434 (12) | 0.54479 (6) | 0.0232 (3) | |
H43A | 0.6408 | 0.8005 | 0.5369 | 0.028* | |
H43B | 0.6176 | 0.9327 | 0.5165 | 0.028* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl7 | 0.02605 (17) | 0.01693 (13) | 0.03019 (14) | 0.00165 (16) | −0.00208 (16) | −0.00393 (11) |
O4 | 0.0246 (5) | 0.0145 (4) | 0.0191 (4) | −0.0001 (4) | 0.0032 (4) | 0.0005 (3) |
N1 | 0.0213 (7) | 0.0226 (5) | 0.0177 (4) | −0.0028 (5) | 0.0007 (4) | 0.0017 (4) |
C2 | 0.0217 (7) | 0.0262 (6) | 0.0166 (5) | −0.0013 (6) | 0.0016 (5) | −0.0004 (5) |
C3 | 0.0183 (7) | 0.0208 (6) | 0.0187 (5) | −0.0010 (5) | 0.0001 (4) | −0.0028 (4) |
C4 | 0.0148 (6) | 0.0168 (5) | 0.0169 (5) | −0.0026 (5) | −0.0022 (4) | 0.0002 (4) |
C4a | 0.0140 (6) | 0.0181 (6) | 0.0160 (5) | −0.0017 (5) | −0.0016 (4) | −0.0001 (4) |
C5 | 0.0188 (6) | 0.0180 (5) | 0.0168 (5) | 0.0000 (5) | −0.0001 (5) | 0.0009 (4) |
C6 | 0.0184 (7) | 0.0199 (5) | 0.0183 (5) | −0.0009 (5) | 0.0000 (4) | −0.0015 (4) |
C7 | 0.0179 (6) | 0.0155 (5) | 0.0227 (5) | 0.0002 (5) | −0.0036 (5) | −0.0028 (4) |
C8 | 0.0178 (6) | 0.0174 (6) | 0.0206 (5) | −0.0027 (5) | −0.0023 (5) | 0.0024 (4) |
C8a | 0.0164 (6) | 0.0201 (6) | 0.0169 (5) | −0.0023 (5) | −0.0029 (4) | 0.0020 (4) |
C41 | 0.0192 (7) | 0.0160 (5) | 0.0218 (5) | 0.0015 (6) | 0.0004 (5) | −0.0019 (4) |
C42 | 0.0199 (6) | 0.0171 (6) | 0.0278 (6) | 0.0009 (5) | −0.0015 (5) | 0.0021 (4) |
C43 | 0.0224 (7) | 0.0227 (6) | 0.0245 (5) | −0.0001 (6) | −0.0009 (5) | 0.0045 (5) |
Cl7—C7 | 1.7446 (13) | C5—H5 | 0.9500 |
O4—C4 | 1.3530 (14) | C6—C7 | 1.4081 (17) |
O4—C41 | 1.4363 (14) | C6—H6 | 0.9500 |
N1—C2 | 1.3194 (17) | C7—C8 | 1.3684 (18) |
N1—C8a | 1.3726 (15) | C8—C8a | 1.4153 (18) |
C2—C3 | 1.4101 (18) | C8—H8 | 0.9500 |
C2—H2 | 0.9500 | C41—C42 | 1.4899 (17) |
C3—C4 | 1.3765 (16) | C41—H41A | 0.9900 |
C3—H3 | 0.9500 | C41—H41B | 0.9900 |
C4—C4a | 1.4213 (17) | C42—C43 | 1.3207 (18) |
C4a—C5 | 1.4185 (16) | C42—H42 | 0.9500 |
C4a—C8a | 1.4189 (16) | C43—H43A | 0.9500 |
C5—C6 | 1.3692 (17) | C43—H43B | 0.9500 |
C4—O4—C41 | 117.26 (9) | C8—C7—Cl7 | 119.39 (10) |
C2—N1—C8a | 116.05 (11) | C6—C7—Cl7 | 118.17 (10) |
N1—C2—C3 | 126.08 (12) | C7—C8—C8a | 119.43 (11) |
N1—C2—H2 | 117.0 | C7—C8—H8 | 120.3 |
C3—C2—H2 | 117.0 | C8a—C8—H8 | 120.3 |
C4—C3—C2 | 117.73 (12) | N1—C8a—C8 | 117.97 (11) |
C4—C3—H3 | 121.1 | N1—C8a—C4a | 123.17 (11) |
C2—C3—H3 | 121.1 | C8—C8a—C4a | 118.85 (11) |
O4—C4—C3 | 125.40 (11) | O4—C41—C42 | 108.83 (10) |
O4—C4—C4a | 115.29 (10) | O4—C41—H41A | 109.9 |
C3—C4—C4a | 119.31 (11) | C42—C41—H41A | 109.9 |
C5—C4a—C8a | 119.73 (11) | O4—C41—H41B | 109.9 |
C5—C4a—C4 | 122.62 (11) | C42—C41—H41B | 109.9 |
C8a—C4a—C4 | 117.65 (11) | H41A—C41—H41B | 108.3 |
C6—C5—C4a | 120.60 (11) | C43—C42—C41 | 126.38 (12) |
C6—C5—H5 | 119.7 | C43—C42—H42 | 116.8 |
C4a—C5—H5 | 119.7 | C41—C42—H42 | 116.8 |
C5—C6—C7 | 118.96 (11) | C42—C43—H43A | 120.0 |
C5—C6—H6 | 120.5 | C42—C43—H43B | 120.0 |
C7—C6—H6 | 120.5 | H43A—C43—H43B | 120.0 |
C8—C7—C6 | 122.44 (11) | ||
C8a—N1—C2—C3 | 0.1 (2) | C5—C6—C7—Cl7 | −178.90 (11) |
N1—C2—C3—C4 | −0.5 (2) | C6—C7—C8—C8a | −0.1 (2) |
C41—O4—C4—C3 | −0.79 (18) | Cl7—C7—C8—C8a | 179.14 (10) |
C41—O4—C4—C4a | 179.16 (12) | C2—N1—C8a—C8 | 179.89 (12) |
C2—C3—C4—O4 | −179.92 (12) | C2—N1—C8a—C4a | 0.66 (19) |
C2—C3—C4—C4a | 0.13 (19) | C7—C8—C8a—N1 | −179.37 (12) |
O4—C4—C4a—C5 | 0.36 (18) | C7—C8—C8a—C4a | −0.10 (19) |
C3—C4—C4a—C5 | −179.69 (12) | C5—C4a—C8a—N1 | 179.25 (12) |
O4—C4—C4a—C8a | −179.43 (11) | C4—C4a—C8a—N1 | −0.96 (19) |
C3—C4—C4a—C8a | 0.53 (18) | C5—C4a—C8a—C8 | 0.02 (18) |
C8a—C4a—C5—C6 | 0.24 (19) | C4—C4a—C8a—C8 | 179.81 (12) |
C4—C4a—C5—C6 | −179.54 (13) | C4—O4—C41—C42 | 179.63 (11) |
C4a—C5—C6—C7 | −0.4 (2) | O4—C41—C42—C43 | −4.0 (2) |
C5—C6—C7—C8 | 0.3 (2) |
C10H8ClNO | F(000) = 400 |
Mr = 193.62 | Dx = 1.513 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71075 Å |
Hall symbol: -P 2yn | Cell parameters from 12569 reflections |
a = 3.8120 (4) Å | θ = 3.5–27.5° |
b = 10.9801 (11) Å | µ = 0.40 mm−1 |
c = 20.348 (2) Å | T = 100 K |
β = 93.591 (7)° | Needle, colourless |
V = 850.02 (15) Å3 | 0.13 × 0.05 × 0.01 mm |
Z = 4 |
Rigaku Saturn724+ diffractometer | 1929 independent reflections |
Radiation source: Rotating Anode | 1569 reflections with I > 2σ(I) |
Confocal monochromator | Rint = 0.073 |
Detector resolution: 28.5714 pixels mm-1 | θmax = 27.5°, θmin = 3.5° |
profile data from ω–scans | h = −4→4 |
Absorption correction: multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | k = −14→14 |
Tmin = 0.950, Tmax = 0.996 | l = −26→26 |
17170 measured reflections |
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)] = 0.035 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.097 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.056P)2 + 0.0232P] where P = (Fo2 + 2Fc2)/3 |
1929 reflections | (Δ/σ)max < 0.001 |
119 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
C10H8ClNO | V = 850.02 (15) Å3 |
Mr = 193.62 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 3.8120 (4) Å | µ = 0.40 mm−1 |
b = 10.9801 (11) Å | T = 100 K |
c = 20.348 (2) Å | 0.13 × 0.05 × 0.01 mm |
β = 93.591 (7)° |
Rigaku Saturn724+ diffractometer | 1929 independent reflections |
Absorption correction: multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | 1569 reflections with I > 2σ(I) |
Tmin = 0.950, Tmax = 0.996 | Rint = 0.073 |
17170 measured reflections |
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.097 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.30 e Å−3 |
1929 reflections | Δρmin = −0.24 e Å−3 |
119 parameters |
Experimental. 7-Chloro-4-methoxyquinoline 1H NMR (500.0MHz, DMSO-d6, δ, p.p.m.): 8.76 (1H, d, J = 4.1 Hz, H-2), 8.15 (1H, d, J = 7.1 Hz, H-5), 8.00 (1H, d, J = 1.5 Hz, H-8), 7.59 (1H, dd, J = 7.2 and 1.6 Hz, H-6), 7.08 (1H, d, J = 4.2 Hz, H-3), 4.06 (3H, s, Me). 13C NMR (125 MHz, DMSO-d6, δ, p.p.m.): 161.6, 153.1, 149.1,134.4, 127.3, 126.3, 123.7, 119.3,101.6, 56.3. MS/ESI: [M+H]: 193.0. IR νmax (cm1; KBr): 1124 (C—O). |
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 | ||
Cl7 | 0.89892 (10) | 0.08327 (3) | 0.06834 (2) | 0.02916 (15) | |
O4 | 0.5718 (3) | 0.67284 (10) | 0.10505 (5) | 0.0244 (3) | |
N1 | 0.4436 (3) | 0.38168 (12) | 0.23375 (6) | 0.0237 (3) | |
C2 | 0.3598 (4) | 0.49420 (14) | 0.24930 (8) | 0.0240 (3) | |
H2 | 0.2707 | 0.5061 | 0.2914 | 0.029* | |
C3 | 0.3894 (4) | 0.59811 (14) | 0.20972 (8) | 0.0235 (3) | |
H3 | 0.3195 | 0.6760 | 0.2244 | 0.028* | |
C4 | 0.5223 (4) | 0.58330 (13) | 0.14927 (8) | 0.0205 (3) | |
C5 | 0.7544 (4) | 0.44119 (14) | 0.06716 (8) | 0.0227 (3) | |
H5 | 0.7868 | 0.5068 | 0.0377 | 0.027* | |
C6 | 0.8388 (4) | 0.32556 (14) | 0.04902 (8) | 0.0236 (3) | |
H6 | 0.9299 | 0.3104 | 0.0074 | 0.028* | |
C7 | 0.7883 (4) | 0.22947 (14) | 0.09307 (8) | 0.0232 (3) | |
C8 | 0.6607 (4) | 0.24774 (14) | 0.15333 (7) | 0.0227 (3) | |
H8 | 0.6311 | 0.1808 | 0.1820 | 0.027* | |
C4a | 0.6201 (4) | 0.46452 (14) | 0.12884 (7) | 0.0203 (3) | |
C8a | 0.5723 (4) | 0.36699 (14) | 0.17291 (7) | 0.0209 (3) | |
C41 | 0.4611 (4) | 0.79300 (14) | 0.12217 (9) | 0.0283 (4) | |
H41A | 0.2108 | 0.7917 | 0.1306 | 0.042* | |
H41B | 0.4991 | 0.8489 | 0.0858 | 0.042* | |
H41C | 0.5978 | 0.8204 | 0.1618 | 0.042* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0222 (6) | 0.0282 (7) | 0.0209 (7) | −0.0002 (5) | 0.0034 (5) | 0.0004 (5) |
C2 | 0.0217 (7) | 0.0308 (8) | 0.0200 (8) | −0.0014 (6) | 0.0045 (6) | −0.0026 (6) |
C4 | 0.0166 (7) | 0.0225 (7) | 0.0221 (8) | −0.0029 (5) | −0.0005 (6) | 0.0018 (6) |
O4 | 0.0287 (6) | 0.0214 (5) | 0.0237 (6) | −0.0004 (4) | 0.0052 (4) | 0.0014 (4) |
C3 | 0.0211 (7) | 0.0258 (8) | 0.0238 (8) | 0.0003 (6) | 0.0021 (6) | −0.0035 (6) |
C5 | 0.0205 (7) | 0.0258 (8) | 0.0220 (8) | −0.0017 (6) | 0.0029 (6) | 0.0010 (6) |
C7 | 0.0191 (7) | 0.0241 (8) | 0.0261 (8) | −0.0015 (6) | 0.0004 (6) | −0.0031 (6) |
Cl7 | 0.0307 (2) | 0.0243 (2) | 0.0329 (3) | 0.00209 (15) | 0.00552 (16) | −0.00465 (15) |
C6 | 0.0214 (7) | 0.0285 (8) | 0.0212 (8) | −0.0020 (6) | 0.0036 (6) | −0.0029 (6) |
C8 | 0.0203 (7) | 0.0244 (7) | 0.0234 (8) | −0.0001 (6) | 0.0013 (6) | 0.0015 (6) |
C8a | 0.0151 (7) | 0.0259 (7) | 0.0218 (8) | −0.0012 (6) | 0.0002 (5) | 0.0005 (6) |
C4a | 0.0157 (7) | 0.0247 (7) | 0.0204 (8) | −0.0010 (5) | 0.0000 (5) | −0.0001 (6) |
C41 | 0.0284 (8) | 0.0234 (8) | 0.0333 (9) | 0.0005 (6) | 0.0046 (7) | −0.0010 (7) |
N1—C2 | 1.3195 (19) | C5—H5 | 0.9500 |
N1—C8a | 1.370 (2) | C7—C8 | 1.362 (2) |
C2—C3 | 1.405 (2) | C7—C6 | 1.405 (2) |
C2—H2 | 0.9500 | C7—Cl7 | 1.7420 (15) |
C4—O4 | 1.3540 (18) | C6—H6 | 0.9500 |
C4—C3 | 1.369 (2) | C8—C8a | 1.415 (2) |
C4—C4a | 1.426 (2) | C8—H8 | 0.9500 |
O4—C41 | 1.4348 (18) | C8a—C4a | 1.416 (2) |
C3—H3 | 0.9500 | C41—H41A | 0.9800 |
C5—C6 | 1.366 (2) | C41—H41B | 0.9800 |
C5—C4a | 1.408 (2) | C41—H41C | 0.9800 |
C2—N1—C8a | 115.64 (13) | C5—C6—H6 | 120.6 |
N1—C2—C3 | 126.42 (14) | C7—C6—H6 | 120.6 |
N1—C2—H2 | 116.8 | C7—C8—C8a | 119.63 (14) |
C3—C2—H2 | 116.8 | C7—C8—H8 | 120.2 |
O4—C4—C3 | 125.85 (14) | C8a—C8—H8 | 120.2 |
O4—C4—C4a | 114.87 (13) | N1—C8a—C8 | 117.93 (13) |
C3—C4—C4a | 119.27 (14) | N1—C8a—C4a | 123.44 (14) |
C4—O4—C41 | 116.81 (12) | C8—C8a—C4a | 118.62 (14) |
C4—C3—C2 | 117.77 (14) | C5—C4a—C8a | 119.69 (14) |
C4—C3—H3 | 121.1 | C5—C4a—C4 | 122.86 (14) |
C2—C3—H3 | 121.1 | C8a—C4a—C4 | 117.44 (14) |
C6—C5—C4a | 120.97 (14) | O4—C41—H41A | 109.5 |
C6—C5—H5 | 119.5 | O4—C41—H41B | 109.5 |
C4a—C5—H5 | 119.5 | H41A—C41—H41B | 109.5 |
C8—C7—C6 | 122.30 (14) | O4—C41—H41C | 109.5 |
C8—C7—Cl7 | 120.16 (12) | H41A—C41—H41C | 109.5 |
C6—C7—Cl7 | 117.54 (12) | H41B—C41—H41C | 109.5 |
C5—C6—C7 | 118.78 (15) | ||
C8a—N1—C2—C3 | 0.2 (2) | C7—C8—C8a—N1 | 179.77 (13) |
C3—C4—O4—C41 | −2.7 (2) | C7—C8—C8a—C4a | 0.0 (2) |
C4a—C4—O4—C41 | 177.06 (12) | C6—C5—C4a—C8a | 0.2 (2) |
O4—C4—C3—C2 | −179.46 (13) | C6—C5—C4a—C4 | −178.76 (13) |
C4a—C4—C3—C2 | 0.7 (2) | N1—C8a—C4a—C5 | 179.96 (13) |
N1—C2—C3—C4 | −1.0 (2) | C8—C8a—C4a—C5 | −0.2 (2) |
C4a—C5—C6—C7 | 0.2 (2) | N1—C8a—C4a—C4 | −1.0 (2) |
C8—C7—C6—C5 | −0.5 (2) | C8—C8a—C4a—C4 | 178.75 (12) |
Cl7—C7—C6—C5 | −179.97 (11) | O4—C4—C4a—C5 | −0.7 (2) |
C6—C7—C8—C8a | 0.4 (2) | C3—C4—C4a—C5 | 179.15 (14) |
Cl7—C7—C8—C8a | 179.89 (11) | O4—C4—C4a—C8a | −179.64 (12) |
C2—N1—C8a—C8 | −178.94 (13) | C3—C4—C4a—C8a | 0.2 (2) |
C2—N1—C8a—C4a | 0.9 (2) |
C11H10ClNO | F(000) = 432 |
Mr = 207.65 | Dx = 1.404 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71075 Å |
Hall symbol: -P 2yn | Cell parameters from 3850 reflections |
a = 3.932 (10) Å | θ = 2.5–31.2° |
b = 11.98 (3) Å | µ = 0.35 mm−1 |
c = 20.86 (6) Å | T = 100 K |
β = 90.56 (6)° | Needle, colourless |
V = 983 (5) Å3 | 0.05 × 0.01 × 0.01 mm |
Z = 4 |
Rigaku Saturn724+ diffractometer | 491 reflections with I > 2σ(I) |
Radiation source: Rotating Anode | Rint = 0.251 |
Confocal monochromator | θmax = 25.0°, θmin = 2.6° |
Detector resolution: 28.5714 pixels mm-1 | h = −4→3 |
profile data from ω–scans | k = −14→14 |
8971 measured reflections | l = −24→24 |
1719 independent reflections |
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)] = 0.109 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.324 | H-atom parameters constrained |
S = 0.82 | w = 1/[σ2(Fo2) + (0.1364P)2] where P = (Fo2 + 2Fc2)/3 |
1719 reflections | (Δ/σ)max < 0.001 |
128 parameters | Δρmax = 0.55 e Å−3 |
0 restraints | Δρmin = −0.47 e Å−3 |
C11H10ClNO | V = 983 (5) Å3 |
Mr = 207.65 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 3.932 (10) Å | µ = 0.35 mm−1 |
b = 11.98 (3) Å | T = 100 K |
c = 20.86 (6) Å | 0.05 × 0.01 × 0.01 mm |
β = 90.56 (6)° |
Rigaku Saturn724+ diffractometer | 491 reflections with I > 2σ(I) |
8971 measured reflections | Rint = 0.251 |
1719 independent reflections |
R[F2 > 2σ(F2)] = 0.109 | 0 restraints |
wR(F2) = 0.324 | H-atom parameters constrained |
S = 0.82 | Δρmax = 0.55 e Å−3 |
1719 reflections | Δρmin = −0.47 e Å−3 |
128 parameters |
Experimental. 7-Chloro-4-ethoxyquinoline 1H NMR (500.0MHz, DMSO-d6, δ, p.p.m.): 8.75 (1H, d, J = 5.2 Hz, H-2), 8.16 (1H, d, J = 8.9 Hz, H-5), 7.99 (1H, d, J = 2.0 Hz, H-8), 7.59 (1H, dd, J = 8.9 and 2.1 Hz, H-6), 7.05 (1H, d, J = 5.3 Hz, H-3), 4.32 (2H, q, J = 7.0 Hz, CH2), 1.48 (3H, t, J = 7.0 Hz, Me). 13C NMR (125 MHz, DMSO-d6, δ, p.p.m.): 160.7, 153.1, 149.2, 134.3, 127.3, 126.2, 123.8, 119.4, 102.1, 64.4, 14.2. MS/ESI: [M+H]: 208.2. IR νmax (cm1; KBr): 1123 (C—O). |
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 | ||
Cl7 | 0.9928 (5) | 0.1086 (2) | 0.07330 (11) | 0.0616 (9) | |
O4 | 0.5920 (14) | 0.6502 (6) | 0.1167 (3) | 0.0596 (18) | |
N1 | 0.4553 (17) | 0.3701 (7) | 0.2368 (3) | 0.059 (2) | |
C2 | 0.356 (2) | 0.4683 (9) | 0.2547 (4) | 0.062 (3) | |
H2 | 0.2535 | 0.4746 | 0.2956 | 0.074* | |
C3 | 0.3905 (19) | 0.5687 (7) | 0.2173 (4) | 0.048 (2) | |
H3 | 0.3127 | 0.6384 | 0.2333 | 0.057* | |
C4 | 0.540 (2) | 0.5615 (9) | 0.1571 (4) | 0.055 (2) | |
C4a | 0.647 (2) | 0.4548 (8) | 0.1354 (4) | 0.051 (2) | |
C5 | 0.7964 (19) | 0.4349 (8) | 0.0751 (4) | 0.054 (3) | |
H5 | 0.8253 | 0.4960 | 0.0467 | 0.065* | |
C6 | 0.901 (2) | 0.3308 (9) | 0.0560 (4) | 0.056 (2) | |
H6 | 1.0014 | 0.3204 | 0.0151 | 0.067* | |
C7 | 0.8573 (19) | 0.2393 (9) | 0.0979 (4) | 0.056 (2) | |
C8 | 0.7075 (19) | 0.2521 (9) | 0.1561 (4) | 0.061 (3) | |
H8 | 0.6752 | 0.1889 | 0.1829 | 0.073* | |
C8a | 0.599 (2) | 0.3593 (10) | 0.1771 (4) | 0.066 (3) | |
C41 | 0.485 (2) | 0.7596 (8) | 0.1381 (4) | 0.057 (3) | |
H41A | 0.6133 | 0.7819 | 0.1771 | 0.068* | |
H41B | 0.2391 | 0.7595 | 0.1480 | 0.068* | |
C42 | 0.5575 (19) | 0.8378 (8) | 0.0839 (4) | 0.061 (3) | |
H42A | 0.5083 | 0.9145 | 0.0972 | 0.091* | |
H42B | 0.4143 | 0.8184 | 0.0469 | 0.091* | |
H42C | 0.7976 | 0.8318 | 0.0722 | 0.091* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl7 | 0.0517 (14) | 0.0729 (19) | 0.0603 (16) | 0.0029 (12) | 0.0078 (11) | −0.0022 (12) |
O4 | 0.047 (3) | 0.084 (5) | 0.048 (4) | 0.000 (3) | 0.014 (3) | 0.003 (3) |
N1 | 0.047 (4) | 0.089 (7) | 0.043 (4) | 0.009 (4) | 0.011 (4) | −0.006 (4) |
C2 | 0.046 (5) | 0.091 (9) | 0.048 (6) | −0.012 (5) | 0.006 (4) | −0.003 (6) |
C3 | 0.050 (5) | 0.046 (6) | 0.047 (5) | 0.003 (4) | 0.012 (4) | −0.011 (4) |
C4 | 0.045 (5) | 0.083 (7) | 0.038 (5) | 0.003 (5) | 0.008 (4) | −0.008 (5) |
C4a | 0.041 (5) | 0.079 (7) | 0.035 (5) | −0.005 (5) | 0.008 (4) | 0.002 (5) |
C5 | 0.042 (5) | 0.085 (8) | 0.035 (4) | 0.003 (5) | 0.003 (4) | 0.009 (5) |
C6 | 0.047 (5) | 0.075 (8) | 0.046 (5) | 0.003 (5) | 0.006 (4) | −0.017 (5) |
C7 | 0.036 (5) | 0.083 (8) | 0.051 (5) | 0.002 (5) | 0.009 (4) | 0.009 (5) |
C8 | 0.036 (5) | 0.105 (9) | 0.041 (5) | 0.001 (5) | −0.003 (4) | −0.008 (5) |
C8a | 0.041 (5) | 0.124 (10) | 0.034 (5) | 0.002 (6) | 0.003 (4) | −0.010 (5) |
C41 | 0.037 (5) | 0.094 (8) | 0.039 (5) | 0.016 (5) | 0.004 (4) | −0.013 (5) |
C42 | 0.042 (5) | 0.096 (8) | 0.044 (5) | −0.013 (5) | 0.008 (4) | −0.001 (5) |
Cl7—C7 | 1.733 (10) | C5—H5 | 0.9500 |
O4—C4 | 1.373 (10) | C6—C7 | 1.414 (12) |
O4—C41 | 1.448 (10) | C6—H6 | 0.9500 |
N1—C2 | 1.296 (11) | C7—C8 | 1.364 (11) |
N1—C8a | 1.378 (10) | C8—C8a | 1.423 (13) |
C2—C3 | 1.441 (12) | C8—H8 | 0.9500 |
C2—H2 | 0.9500 | C41—C42 | 1.498 (11) |
C3—C4 | 1.395 (11) | C41—H41A | 0.9900 |
C3—H3 | 0.9500 | C41—H41B | 0.9900 |
C4—C4a | 1.422 (12) | C42—H42A | 0.9800 |
C4a—C5 | 1.414 (11) | C42—H42B | 0.9800 |
C4a—C8a | 1.450 (13) | C42—H42C | 0.9800 |
C5—C6 | 1.374 (12) | ||
C4—O4—C41 | 117.7 (7) | C8—C7—Cl7 | 120.1 (8) |
C2—N1—C8a | 118.3 (9) | C6—C7—Cl7 | 118.5 (7) |
N1—C2—C3 | 124.9 (9) | C7—C8—C8a | 120.5 (10) |
N1—C2—H2 | 117.6 | C7—C8—H8 | 119.7 |
C3—C2—H2 | 117.6 | C8a—C8—H8 | 119.7 |
C4—C3—C2 | 118.6 (8) | N1—C8a—C8 | 119.3 (10) |
C4—C3—H3 | 120.7 | N1—C8a—C4a | 121.6 (10) |
C2—C3—H3 | 120.7 | C8—C8a—C4a | 119.1 (8) |
O4—C4—C3 | 124.9 (9) | O4—C41—C42 | 106.0 (7) |
O4—C4—C4a | 117.0 (7) | O4—C41—H41A | 110.5 |
C3—C4—C4a | 118.1 (9) | C42—C41—H41A | 110.5 |
C5—C4a—C4 | 124.1 (8) | O4—C41—H41B | 110.5 |
C5—C4a—C8a | 117.3 (9) | C42—C41—H41B | 110.5 |
C4—C4a—C8a | 118.6 (8) | H41A—C41—H41B | 108.7 |
C6—C5—C4a | 122.7 (9) | C41—C42—H42A | 109.5 |
C6—C5—H5 | 118.7 | C41—C42—H42B | 109.5 |
C4a—C5—H5 | 118.7 | H42A—C42—H42B | 109.5 |
C5—C6—C7 | 119.0 (8) | C41—C42—H42C | 109.5 |
C5—C6—H6 | 120.5 | H42A—C42—H42C | 109.5 |
C7—C6—H6 | 120.5 | H42B—C42—H42C | 109.5 |
C8—C7—C6 | 121.4 (9) | ||
C8a—N1—C2—C3 | −1.2 (12) | C5—C6—C7—C8 | 1.4 (12) |
N1—C2—C3—C4 | 0.1 (13) | C5—C6—C7—Cl7 | −179.6 (6) |
C41—O4—C4—C3 | 0.3 (11) | C6—C7—C8—C8a | −1.8 (12) |
C41—O4—C4—C4a | −179.9 (7) | Cl7—C7—C8—C8a | 179.2 (6) |
C2—C3—C4—O4 | −179.3 (7) | C2—N1—C8a—C8 | −179.5 (7) |
C2—C3—C4—C4a | 0.8 (12) | C2—N1—C8a—C4a | 1.3 (12) |
O4—C4—C4a—C5 | −1.1 (12) | C7—C8—C8a—N1 | −178.6 (7) |
C3—C4—C4a—C5 | 178.7 (7) | C7—C8—C8a—C4a | 0.6 (12) |
O4—C4—C4a—C8a | 179.5 (7) | C5—C4a—C8a—N1 | −179.8 (7) |
C3—C4—C4a—C8a | −0.7 (12) | C4—C4a—C8a—N1 | −0.4 (12) |
C4—C4a—C5—C6 | 179.2 (7) | C5—C4a—C8a—C8 | 1.0 (11) |
C8a—C4a—C5—C6 | −1.5 (12) | C4—C4a—C8a—C8 | −179.6 (7) |
C4a—C5—C6—C7 | 0.3 (12) | C4—O4—C41—C42 | −177.6 (6) |
Experimental details
(I) | (II) | (III) | |
Crystal data | |||
Chemical formula | C12H10ClNO | C10H8ClNO | C11H10ClNO |
Mr | 219.66 | 193.62 | 207.65 |
Crystal system, space group | Orthorhombic, P212121 | Monoclinic, P21/n | Monoclinic, P21/n |
Temperature (K) | 100 | 100 | 100 |
a, b, c (Å) | 3.9370 (9), 11.977 (3), 21.482 (6) | 3.8120 (4), 10.9801 (11), 20.348 (2) | 3.932 (10), 11.98 (3), 20.86 (6) |
α, β, γ (°) | 90, 90, 90 | 90, 93.591 (7), 90 | 90, 90.56 (6), 90 |
V (Å3) | 1013.0 (4) | 850.02 (15) | 983 (5) |
Z | 4 | 4 | 4 |
Radiation type | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 0.35 | 0.40 | 0.35 |
Crystal size (mm) | 0.40 × 0.02 × 0.02 | 0.13 × 0.05 × 0.01 | 0.05 × 0.01 × 0.01 |
Data collection | |||
Diffractometer | Rigaku Saturn724+ diffractometer | Rigaku Saturn724+ diffractometer | Rigaku Saturn724+ diffractometer |
Absorption correction | Multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | Multi-scan (CrystalClear-SM Expert; Rigaku, 2011) | – |
Tmin, Tmax | 0.874, 0.993 | 0.950, 0.996 | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14640, 3087, 2869 | 17170, 1929, 1569 | 8971, 1719, 491 |
Rint | 0.031 | 0.073 | 0.251 |
(sin θ/λ)max (Å−1) | 0.732 | 0.649 | 0.595 |
Refinement | |||
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.075, 1.07 | 0.035, 0.097, 1.07 | 0.109, 0.324, 0.82 |
No. of reflections | 3087 | 1929 | 1719 |
No. of parameters | 137 | 119 | 128 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.28, −0.20 | 0.30, −0.24 | 0.55, −0.47 |
Absolute structure | Flack (1983), with 1202 Friedel pairs | ? | ? |
Absolute structure parameter | 0.01 (5) | ? | ? |
Computer programs: CrystalClear-SM Expert (Rigaku, 2011), SHELXS97 (Sheldrick, 2008), OSCAIL (McArdle et al., 2004) and SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).
Compound | CgI | CgJ | Distance between ring centroids (Å) | Perpendicular distance between rings (Å) | Offset (Å) |
(I) | Cg1 | Cg1i | 3.9370 (13) | 3.4633 (5) | 1.872 |
(I) | Cg2 | Cg2ii | 3.9370 (14) | 3.4547 (5) | 1.888 |
(I) | Cg1 | Cg2i | 3.5968 (12) | 3.4588* | 0.987* |
(II) | Cg1 | Cg1i | 3.8120 (9) | 3.4431 (6) | 1.636 |
(II) | Cg2 | Cg2ii | 3.8120 (10) | 3.4594 (6) | 1.601 |
(II) | Cg1 | Cg2i | 3.6151 (9) | 3.4525* | 1.072* |
(III) | Cg1 | Cg1i | 3.932 (12) | 3.530 (3) | 1.732 |
(III) | Cg2 | Cg2ii | 3.932 (12) | 3.529 (3) | 1.734 |
(III) | Cg1 | Cg2i | 3.652 (12) | 3.536* | 0.913* |
Notes: Cg1 and Cg2 are the centroids of the rings containing
atoms N1 and C5, respectively. The dihedral angles between the rings denoted by Cg1 and Cg2 are 0.38 (7), 1.02 (7) and 0.4 (4)° for (I), (II) and (III), respectively. The offsets for these Cg1 and Cg2 distances are based on the average value of the perpendicular distances between the planes denoted by an asterisk (*). Symmetry codes: (i) x - 1, y, z; (ii) x + 1, y, z. |
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The study of the nature and geometry of aromatic interactions has become an important field of research since they have been found as custom motifs in molecular recognition. Their significance as recognition elements has been investigated by statistical analysis (Thomas et al., 2002) and theoretical calculations (Hunter et al., 2001; Hunter & Sanders, 1990). The main forces defining the nature of an attractive aromatic interaction seem to be electrostatic, van de Waals and hydrophobic, the extent of these components depending on the type of interaction. Although the nature of C—H···π and face-to-face stacking interactions due to aromatic quadruple moments has been satisfactorily assessed by models involving electrostatic force models, the offset stacked orientation is still under intensive investigation since here van der Waals interactions appear to play the dominant role (Guckian et al., 2000; Lee et al., 2007). The influence of covalently bonded substituents and heteroaromatic rings on the energetics and geometry of π–π complexes is still being actively debated in the literature (Sinnokrot & Sherrill, 2003, 2006; Lima et al., 2012). The difficulty of building a model for π–π interactions arises from the fact that, firstly, theoretical calculations have to be performed at high levels of theory in order to assess the electronic correlation energy, and secondly the experimental data have to be highly accurate, due to the small amount of energy involved in the establishment of the π–π interaction. The latter also conditions the assessment of the geometry of the interaction in the solid state. Usually, stabilization of the solid state in organic molecules is preferentially achieved by classical hydrogen bonds or C—H···π interactions that overcome the π–π stacking energetically. Nevertheless, recent results on the structure of benzene in the liquid phase obtained by high-resolution neutron diffraction suggest that benzene has a preference for π–π parallel displacement micro-aggregation, rather than C—H···π interaction (Headen et al., 2010). Thus, reports of structures stabilized mainly by π–π interactions are relevant contributions to the clarification of the geometry of the interaction, as well as opening the field for further investigations with respect to the energetics of those interactions.
In this article, the structures of three 4-alkoxy-7-chloroquinolines are reported, namely 4-allyloxy-7-chloroquinoline, (I) (Fig. 1), 7-chloro-4-methoxyquinoline, (II) (Fig. 2), and 7-chloro-4-ethoxyquinoline, (III) (Fig. 3). These compounds form part of a series being studied because of an interest in their potential biological activity, and thus an investigation of their intermolecular interactions is important in elucidating this activity. In all three cases, the supramolecular structures are stabilized by π–π stacking of the quinoline ring systems.
The bond lengths and angles in (I)–(III) are all within the expected ranges [Standard reference?]. An analysis of the molecular structures of these compounds shows that they are essentially planar: the maximum deviations from the mean plane of the quinoline ring system are 0.067 (2) Å for atom C43 in (I), 0.086 (2) Å for atom C41 in (II) and 0.044 (2) Å for atom C41 in (III). In (I), the planarity is reinforced by an intramolecular hydrogen bond between the terminal atom C43 and atom O4 [H···O = 2.43 Å, C···O = 2.753 (2) Å and C—H···O = 100°], which forms an R(5) ring (Bernstein et al., 1995). Excluding the aromatic rings, the molecules have two potential acceptors for H atoms, the pyridinic N atom and the methoxy O atom. In (I), as described above, atom C43 forms an intramolecular C—H···O interaction with atom O4. In (I), (II) and (III), neither the O nor the N atoms act as acceptors for intermolecular hydrogen bonds. Although the heterocyclic ring is a potential acceptor for a C—H···π interaction, such an interaction is not observed. The planarity of the molecules favours a stacking arrangement of the rings in the supramolecular structures but, usually, does not preclude the establishment of other interactions. Nevertheless, in all three title compounds, the only intermolecular interactions are π–π stacking interactions between the quinoline ring systems, making the structures presented here unusual in the sense that the geometry of those interactions is not conditioned by the presence of other types of intermolecular interaction. In each structure, the molecules stack with unit-cell translations along the a axis. Fig. 4 shows the stacking of molecules of (I) along the a axis and Fig. 5 shows a view perpendicular to the quinoline ring system in (II), showing the offset of one molecule with respect to the other. The details of these interactions are given in Table 1, which shows that the stacking parameters are very similar for all three compounds.
Diagrams of the Cg1···Cg2 (centroid-to-centroid, pyridine–benzene) stacking and offsets for (I)–(III) and the parallel displacement stacking of the benzene dimer (geometries of the lowest energy, gas-phase structure) are shown in Fig. 6. The offsets of the rings in (I)–(III) are shorter than those observed for the benzene dimer in the gas phase. The centroids of the pyridine rings are directed towards the C8—C8a bonds in (I)–(III), while in the benzene dimer the centroids are directed towards a C—H bond.
Searches made of the Cambridge Structural Database (CSD, Version?; Allen, 2002) for quinoline structures similar to those reported here having an –O–R group at position 4 and with or without a halogen atom at position 7 (excluding fluorine), surprisingly only found two hits, namely 3-(quinolin-4-yloxy)phthalonitrile (CSD refcode GEPKUI; Xue et al., 2006) and 4-(quinolin-4-yloxy)phthalonitrile (CSD refcode XEBGAN; Yu et al., 2006). In these structures, which are not planar, the main interactions are C—H···N interactions, involving the pyridine N atom and a nitrile N atom in the former, and a nitrile N atom in the latter. Neither has any π–π stacking interactions between the quinoline ring systems. Thus, no comparison can be made between these structures and those presented here. In the structure of quinoline (CSD refcode EDAVUA; Davies & Bond, 2001), there are two molecules in the asymmetric unit and the molecules are linked solely by C—H···π interactions.
In 7-Cl-quinolines having a nitrogen donor at position 4, as in 7-Cl-4-hydrazonylquinolines (Howie et al., 2010) and 4-amino-7-chloroquinoline derivatives (Kaiser et al., 2009), the crystal packing is mediated by N—H···N(heteroatom) hydrogen bonds that make chains. However, in all those structures, π–π interactions are still observed. Together with C—H···π interactions, these contribute to the aggregation of the primary chains into layers and/or stacking into a three-dimensional arrangement. This clearly shows the importance of the π–π interactions of the quinoline ring system in the overall supramolecular arrangement, even in the presence of classical hydrogen bonds. As stated above, C—H···π interactions are governed essentially by electrostatic contributions, while dispersion forces appear to be predominant in the π–π stacking. Theoretical and experimental results obtained with substituted benzenes suggest that the strength of the π–π interaction does not correlate with Hammett constants (Sinnokrot & Sherrill, 2006; Lima et al., 2012). Heterocycles are activated towards electrostatic-based interactions when the lone pair on the heteroatom is incorporated into the aromatic system. Conversely, when the lone pair does not contribute to the aromaticity, the electronegativity of the heteroatom prevails and weakens the quadrupole moment of the ring. This may favour π–π stacking over C—H···π, but further investigations should be carried out in order to elucidate the role of the heteroatom in the π–π interaction.