organic compounds
1-Butyl-2,3,3-trimethylindol-1-ium iodide
aGrupo de Pesquisa em Fotoquímica Orgânica Aplicada, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, and bChemistry Institute, University of Campinas, Brazil
*Correspondence e-mail: luis.duarte@iqm.unicamp.br
In the title molecular salt, C15H22N+·I−, the fused-ring system is slightly puckered [dihedral angle between the five- and six-membered rings = 3.43 (8)°]. In the crystal, very weak C—H⋯I interactions link the cations to the anions. Photophysical data for the title salt in different solvents are presented.
Keywords: crystal structure; indole; cyanine precursor.
CCDC reference: 1860832
Structure description
Recent studies have shown the importance of the indole nucleus with respect to its anticancer activities (Singh et al., 2010; Shaveta, 2014) and in its biological applications as biosensors (Saikiran et al., 2017; Guo et al., 2015). As part of our studies of indole derivatives, we report here the and optical properties of the title salt, C15H22N+·I−, bearing a quaternized indolic N atom with a butyl side chain.
The indole ring system (Fig. 1) is slightly puckered [dihedral angle between the rings = 3.43 (8)°]. The key torsion angles of the butyl side chain are N1—C12—C13–C14 = 76.14 (18)° and C12—C13—C14—C15 = 176.26 (16)°. In the crystal, there are possibly some very weak C—H⋯I interactions (Table 1). Given that the van der Waals separation of H and I is 3.18 Å, some of these may barely qualify as directional bonds.
The absorption and emission spectra of the title compound are shown in Fig. 2. The relevant data from UV–Vis absorption spectroscopy in different solvents are presented in Table 2. The compound presents absorption maxima located between 279 and 285 nm related to allowed 1ππ* electronic transitions. The fluorescence emission spectra were obtained by exciting the compounds at the absorption maxima wavelength. The title compound shows emission in the UV-A region (∼365 nm), with a small solvatochromic effect and a higher than 7500 cm−1.
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Synthesis and crystallization
A mixture of phenylhydrazine hydrochloride (5.56 mmol), 3-methylbutan-2-one (6.67 mmol), H2SO4 (9.36 mmol) and 20 ml of a solution of acetone–ethanol (1:1 v/v) was refluxed under stirring for 4 h (Fig. 3). The progress of the reaction was monitored by (TLC). The solvent was partially evaporated and the pH adjusted to 4. The organic layer was separated from the aqueous phase by liquid–liquid extraction with dichloromethane (3 × 30 ml). The organic layer was dried with Na2SO4, filtered and concentrated. It is worth mentioning that it was necessary to perform a salting-out step for the separation of the layers. No additional treatments were performed for the indole quaternization step. The indole quaternization was afforded by addition of indole (1.9 mmol) to an excess of iodobutane (9.9 mmol) in acetonitrile, previously saturated with N2. The reaction was conducted under reflux temperature and stirring under a nitrogen atmosphere for 18 h. The reaction was monitored by TLC. The reaction crude was poured into ethyl acetate (50 ml) and allowed to stir under heating for 30 min. Thereafter, the supernatant was removed and the process was repeated three times. The resulting solid was filtered off and dried (yield 70%). The crystallization was performed with addition of methanol to dissolve the solid followed by the addition of ethyl acetate (m.p. 490 K).
1H NMR (CDCl3, 400 MHz): δ (ppm) 7.65 (m, 1H), 7.56 (m, 3H), 4.65 (t, 2H, J = 8.0 Hz), 3.10 (s, 3H), 1.91 (m, 2H), 1.63 (s, 6H), 1.49 (m, 2H), 0.98 (t, 3H, J = 8.0 Hz). 1H NMR (DMSO-d6, 300 MHz): δ (ppm) 7.74 (m, 1H), 7.61 (m, 1H), 4.67 (t, 2H, J = 7.5 Hz), 3.13 (s, 3H), 1.96 (m, 2H), 1.67 (s, 6H), 1.53 (m, 2H), 1.01 (t, 3H, J = 6.0 Hz) 13C NMR (DMSO-d6, 75 MHz): δ (ppm) 195.5, 141.5, 140.7, 130.0, 129.4, 123.4, 115.3, 54.6, 49.7, 29.8, 23.1, 20.0, 17.0, 13.6.
Refinement
Crystal data, data collection and structure . The H atoms were refined as riding on their attached C atoms; the methyl groups were allowed to rotate, but not to tip, to best fit the electron density. The constraint Uiso(H) = kUeq(C), with k = 1.2 for CH and CH2 groups and k = 1.5 for methyl groups was applied.
details are summarized in Table 3
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Structural data
CCDC reference: 1860832
https://doi.org/10.1107/S2414314618011306/hb4247sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618011306/hb4247Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314618011306/hb4247Isup3.cml
Data collection: APEX (Bruker, 2013); cell
SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).C15H22N+·I− | Dx = 1.480 Mg m−3 |
Mr = 343.23 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 9006 reflections |
a = 15.631 (12) Å | θ = 2.6–28.2° |
b = 11.614 (8) Å | µ = 2.06 mm−1 |
c = 16.976 (11) Å | T = 150 K |
V = 3082 (4) Å3 | Needle, light brown |
Z = 8 | 0.37 × 0.10 × 0.09 mm |
F(000) = 1376 |
Bruker APEX CCD detector diffractometer | 3166 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.037 |
Absorption correction: multi-scan (SADABS; Bruker, 2015) | θmax = 28.3°, θmin = 2.4° |
Tmin = 0.637, Tmax = 0.746 | h = −8→20 |
41973 measured reflections | k = −15→15 |
3784 independent reflections | l = −22→22 |
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.019 | H-atom parameters constrained |
wR(F2) = 0.047 | w = 1/[σ2(Fo2) + (0.0198P)2 + 1.6747P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
3784 reflections | Δρmax = 0.49 e Å−3 |
158 parameters | Δρmin = −0.37 e Å−3 |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.30279 (12) | 0.35676 (13) | 0.65813 (9) | 0.0198 (3) | |
C2 | 0.21170 (11) | 0.31229 (14) | 0.65947 (9) | 0.0199 (3) | |
C3 | 0.21293 (11) | 0.23111 (13) | 0.59009 (9) | 0.0179 (3) | |
C4 | 0.29095 (10) | 0.24303 (13) | 0.55103 (9) | 0.0165 (3) | |
C5 | 0.31022 (11) | 0.18740 (14) | 0.48120 (9) | 0.0201 (3) | |
H5 | 0.362745 | 0.199361 | 0.454265 | 0.024* | |
C6 | 0.24721 (12) | 0.11220 (14) | 0.45275 (9) | 0.0222 (4) | |
H6 | 0.257625 | 0.070940 | 0.405389 | 0.027* | |
C7 | 0.16967 (12) | 0.09619 (14) | 0.49194 (10) | 0.0229 (4) | |
H7 | 0.129118 | 0.043056 | 0.471549 | 0.028* | |
C8 | 0.15075 (11) | 0.15720 (15) | 0.56079 (10) | 0.0218 (3) | |
H8 | 0.097231 | 0.148388 | 0.586626 | 0.026* | |
C9 | 0.18792 (12) | 0.25620 (17) | 0.73851 (10) | 0.0286 (4) | |
H9A | 0.230985 | 0.198271 | 0.752297 | 0.043* | |
H9B | 0.131775 | 0.219254 | 0.733967 | 0.043* | |
H9C | 0.185859 | 0.315308 | 0.779666 | 0.043* | |
C10 | 0.15024 (14) | 0.41470 (17) | 0.64136 (12) | 0.0337 (4) | |
H10A | 0.154360 | 0.472001 | 0.683564 | 0.050* | |
H10B | 0.091326 | 0.386260 | 0.637986 | 0.050* | |
H10C | 0.166415 | 0.450183 | 0.591146 | 0.050* | |
C11 | 0.34125 (13) | 0.42907 (15) | 0.72083 (10) | 0.0280 (4) | |
H11A | 0.365790 | 0.379431 | 0.761679 | 0.042* | |
H11B | 0.297002 | 0.478211 | 0.744126 | 0.042* | |
H11C | 0.386361 | 0.477354 | 0.698117 | 0.042* | |
C12 | 0.43452 (11) | 0.34915 (14) | 0.57497 (10) | 0.0204 (3) | |
H12A | 0.447583 | 0.428413 | 0.592736 | 0.024* | |
H12B | 0.440974 | 0.346896 | 0.516979 | 0.024* | |
C13 | 0.49862 (11) | 0.26586 (14) | 0.61218 (10) | 0.0213 (3) | |
H13A | 0.556043 | 0.301760 | 0.610894 | 0.026* | |
H13B | 0.482947 | 0.254517 | 0.668152 | 0.026* | |
C14 | 0.50385 (13) | 0.14869 (16) | 0.57259 (11) | 0.0285 (4) | |
H14A | 0.516312 | 0.159241 | 0.515870 | 0.034* | |
H14B | 0.447852 | 0.109433 | 0.577200 | 0.034* | |
C15 | 0.57325 (15) | 0.0730 (2) | 0.60951 (15) | 0.0459 (6) | |
H15A | 0.574132 | −0.002022 | 0.583103 | 0.069* | |
H15B | 0.561002 | 0.062175 | 0.665637 | 0.069* | |
H15C | 0.629065 | 0.110399 | 0.603421 | 0.069* | |
N1 | 0.34412 (9) | 0.32083 (11) | 0.59593 (8) | 0.0172 (3) | |
I1 | 0.42439 (2) | 0.38097 (2) | 0.32579 (2) | 0.02455 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0245 (9) | 0.0142 (7) | 0.0206 (7) | 0.0005 (7) | 0.0002 (7) | 0.0011 (6) |
C2 | 0.0207 (8) | 0.0199 (7) | 0.0190 (7) | 0.0025 (7) | 0.0021 (7) | −0.0027 (6) |
C3 | 0.0187 (8) | 0.0179 (7) | 0.0171 (7) | 0.0019 (6) | −0.0002 (6) | 0.0010 (6) |
C4 | 0.0167 (8) | 0.0145 (7) | 0.0183 (7) | 0.0003 (6) | −0.0029 (6) | 0.0008 (5) |
C5 | 0.0209 (8) | 0.0220 (8) | 0.0175 (7) | 0.0011 (7) | 0.0021 (7) | 0.0009 (6) |
C6 | 0.0275 (9) | 0.0223 (8) | 0.0168 (7) | 0.0034 (7) | −0.0052 (7) | −0.0024 (6) |
C7 | 0.0234 (9) | 0.0214 (8) | 0.0240 (8) | −0.0029 (7) | −0.0080 (7) | −0.0002 (6) |
C8 | 0.0166 (8) | 0.0256 (8) | 0.0231 (8) | −0.0009 (7) | −0.0012 (7) | 0.0017 (6) |
C9 | 0.0289 (10) | 0.0345 (9) | 0.0223 (8) | −0.0065 (8) | 0.0055 (8) | −0.0006 (7) |
C10 | 0.0342 (11) | 0.0331 (9) | 0.0337 (10) | 0.0159 (9) | −0.0002 (9) | −0.0058 (8) |
C11 | 0.0369 (11) | 0.0229 (8) | 0.0242 (8) | −0.0073 (8) | 0.0005 (8) | −0.0061 (7) |
C12 | 0.0190 (8) | 0.0192 (7) | 0.0229 (8) | −0.0051 (7) | 0.0015 (7) | 0.0021 (6) |
C13 | 0.0180 (8) | 0.0243 (8) | 0.0216 (8) | −0.0032 (7) | 0.0010 (7) | 0.0017 (6) |
C14 | 0.0268 (10) | 0.0278 (8) | 0.0309 (9) | 0.0041 (8) | −0.0046 (8) | −0.0028 (7) |
C15 | 0.0403 (13) | 0.0395 (12) | 0.0580 (14) | 0.0189 (11) | −0.0151 (11) | −0.0138 (10) |
N1 | 0.0183 (7) | 0.0146 (6) | 0.0186 (6) | −0.0018 (5) | −0.0004 (6) | −0.0001 (5) |
I1 | 0.02565 (7) | 0.02731 (7) | 0.02070 (6) | −0.00322 (5) | 0.00032 (5) | −0.00084 (4) |
C1—C2 | 1.515 (3) | C10—H10A | 0.9800 |
C1—C11 | 1.483 (2) | C10—H10B | 0.9800 |
C1—N1 | 1.306 (2) | C10—H10C | 0.9800 |
C2—C3 | 1.509 (2) | C11—H11A | 0.9800 |
C2—C9 | 1.537 (2) | C11—H11B | 0.9800 |
C2—C10 | 1.560 (3) | C11—H11C | 0.9800 |
C3—C4 | 1.395 (2) | C12—H12A | 0.9900 |
C3—C8 | 1.389 (2) | C12—H12B | 0.9900 |
C4—C5 | 1.383 (2) | C12—C13 | 1.529 (2) |
C4—N1 | 1.445 (2) | C12—N1 | 1.494 (2) |
C5—H5 | 0.9500 | C13—H13A | 0.9900 |
C5—C6 | 1.402 (2) | C13—H13B | 0.9900 |
C6—H6 | 0.9500 | C13—C14 | 1.520 (2) |
C6—C7 | 1.395 (3) | C14—H14A | 0.9900 |
C7—H7 | 0.9500 | C14—H14B | 0.9900 |
C7—C8 | 1.398 (2) | C14—C15 | 1.530 (3) |
C8—H8 | 0.9500 | C15—H15A | 0.9800 |
C9—H9A | 0.9800 | C15—H15B | 0.9800 |
C9—H9B | 0.9800 | C15—H15C | 0.9800 |
C9—H9C | 0.9800 | ||
C11—C1—C2 | 124.28 (15) | H10A—C10—H10B | 109.5 |
N1—C1—C2 | 111.60 (14) | H10A—C10—H10C | 109.5 |
N1—C1—C11 | 124.09 (17) | H10B—C10—H10C | 109.5 |
C1—C2—C9 | 112.64 (14) | C1—C11—H11A | 109.5 |
C1—C2—C10 | 108.42 (15) | C1—C11—H11B | 109.5 |
C3—C2—C1 | 100.91 (13) | C1—C11—H11C | 109.5 |
C3—C2—C9 | 114.81 (15) | H11A—C11—H11B | 109.5 |
C3—C2—C10 | 109.30 (14) | H11A—C11—H11C | 109.5 |
C9—C2—C10 | 110.27 (15) | H11B—C11—H11C | 109.5 |
C4—C3—C2 | 108.68 (14) | H12A—C12—H12B | 107.8 |
C8—C3—C2 | 131.06 (16) | C13—C12—H12A | 109.1 |
C8—C3—C4 | 120.19 (15) | C13—C12—H12B | 109.1 |
C3—C4—N1 | 108.31 (14) | N1—C12—H12A | 109.1 |
C5—C4—C3 | 123.46 (15) | N1—C12—H12B | 109.1 |
C5—C4—N1 | 128.23 (15) | N1—C12—C13 | 112.46 (14) |
C4—C5—H5 | 122.2 | C12—C13—H13A | 108.6 |
C4—C5—C6 | 115.67 (16) | C12—C13—H13B | 108.6 |
C6—C5—H5 | 122.2 | H13A—C13—H13B | 107.6 |
C5—C6—H6 | 119.0 | C14—C13—C12 | 114.77 (14) |
C7—C6—C5 | 121.94 (16) | C14—C13—H13A | 108.6 |
C7—C6—H6 | 119.0 | C14—C13—H13B | 108.6 |
C6—C7—H7 | 119.5 | C13—C14—H14A | 109.3 |
C6—C7—C8 | 120.99 (16) | C13—C14—H14B | 109.3 |
C8—C7—H7 | 119.5 | C13—C14—C15 | 111.80 (16) |
C3—C8—C7 | 117.67 (16) | H14A—C14—H14B | 107.9 |
C3—C8—H8 | 121.2 | C15—C14—H14A | 109.3 |
C7—C8—H8 | 121.2 | C15—C14—H14B | 109.3 |
C2—C9—H9A | 109.5 | C14—C15—H15A | 109.5 |
C2—C9—H9B | 109.5 | C14—C15—H15B | 109.5 |
C2—C9—H9C | 109.5 | C14—C15—H15C | 109.5 |
H9A—C9—H9B | 109.5 | H15A—C15—H15B | 109.5 |
H9A—C9—H9C | 109.5 | H15A—C15—H15C | 109.5 |
H9B—C9—H9C | 109.5 | H15B—C15—H15C | 109.5 |
C2—C10—H10A | 109.5 | C1—N1—C4 | 109.97 (14) |
C2—C10—H10B | 109.5 | C1—N1—C12 | 126.15 (14) |
C2—C10—H10C | 109.5 | C4—N1—C12 | 123.79 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···I1 | 0.95 | 3.18 | 3.899 (2) | 134 |
C12—H12A···I1i | 0.99 | 3.29 | 4.186 (3) | 151 |
C12—H12B···I1 | 0.99 | 3.28 | 4.249 (3) | 167 |
C13—H13B···I1ii | 0.99 | 3.24 | 4.172 (3) | 158 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, −y+1/2, z+1/2. |
Solvent | λabs | ε | λem | SS |
Dichloromethane | 285 | 0.79 | 363 | 7540 |
Ethanol | 279 | 2.70 | 367 | 8594 |
Acetonitrile | 281 | 0.89 | 370 | 8560 |
Acknowledgements
The authors acknowlege the agencies CAPES, FAPERGS, CNPq and FAPESP for financial support and fellowships. We thank Professor Dr Teresa Dib Zambon Atvars and the Chemistry Institute of the University of Campinas for the infrastructure and Dr Deborah de A. Simoni for all the valuable discussions.
Funding information
Funding for this research was provided by: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior ; Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (award No. 470529/2012-1); Fundação de Amparo à Pesquisa do Estado de São Paulo (award Nos. 2009/51605-5 and 2013/16245-2).
References
Bruker (2013). APEX and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2015). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Guo, L., Chan, M. S., Xu, D., Tam, D. Y., Bolze, F., Lo, P. K. & Wong, M. S. (2015). ACS Chem. Biol. 10, 1171–1175. Web of Science CrossRef Google Scholar
Saikiran, M., Sato, D., Pandey, S. S., Ohta, T. & Hayase, S. (2017). Dyes Pigm. 140, 6–13. Web of Science CrossRef Google Scholar
Shaveta, S. P. (2014). Eur. J. Med. Chem. 74, 440–450. Web of Science CrossRef Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Singh, P., Kaur, M. & Holzer, W. (2010). Eur. J. Med. Chem. 45, 4968–4982. Web of Science CrossRef Google Scholar
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