Hydrogen bonding between ethynyl aromates and triethylamine: IR spectroscopic and computational study

Danijela Bakarić, Josipa Alerić, Tijana Parlić-Risović, Jens Spanget-Larsen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Ethynylpyridines (EPs) and ethynylbenzene (EB) are multifunctional systems able to participate in hydrogen-bonded complexes as both donors and acceptors of the H-atom. Their structures and stabilities are mainly a function of the hydrogen-bonding properties of the partner in the complex and the surroundings in which the complexation occurs. In this paper, IR spectroscopy and quantum chemical calculations are employed to characterize hydrogen-bonded complexes of 2- and 3-EP and EB with triethylamine (TEA) in tetrachloroethene (C2Cl4) solution. The formation of ≡C−H···N hydrogen bonds is experimentally confirmed by the appearance of TEA concentration-dependent signals in the IR spectra of the EPs and EB. Along with the signals due to unassociated ≡C−H and C≡C oscillators (2-EP: 3308 cm–1 and 2120 cm–1; 3-EP: 3308 cm–1 and 2116 cm–1; EB: 3313 cm–1 and 2113 cm–1) weak, red-shifted signals arise at ~3215 ± 5 cm–1 and ~2105 ± 5 cm–1 which are assigned to the stretching vibrations of hydrogen-bonded ≡C−H··· and C≡C··· oscillators, respectively. This result is at variance with those of previous investigations of EB and TEA in the gas phase. In the 2-EP···TEA complex these bands remain at the same position with increasing TEA concentration. However, in the 3-EP···TEA and EB···TEA complexes the ≡C−H··· stretching band demonstrates a slightly reduced red-shift as the TEA concentration increases, whereas the C≡C··· stretching band absorbs at the same wavenumber in the investigated TEA concentration range. The results of B3LYP-D3 calculations indicate that complexes with more or less linear ≡C−H···N intermolecular hydrogen bonds are more stable than other, dispersion-driven complexes. Complexes with the Cs symmetrical TEA conformer are predicted to have larger binding energy than those formed with the C3 and C1 symmetrical conformers. The predicted IR spectral shifts are slightly different for complexes with the three different TEA conformers. Association constants of hydrogen-bonded complexes at 26 °C are estimated to be ~0.1 mol–1 dm3.
OriginalsprogEngelsk
TidsskriftSpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Vol/bind209
Sider (fra-til)288-294
Antal sider7
ISSN1386-1425
DOI
StatusUdgivet - 15 feb. 2019

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    title = "Hydrogen bonding between ethynyl aromates and triethylamine: IR spectroscopic and computational study",
    abstract = "Ethynylpyridines (EPs) and ethynylbenzene (EB) are multifunctional systems able to participate in hydrogen-bonded complexes as both donors and acceptors of the H-atom. Their structures and stabilities are mainly a function of the hydrogen-bonding properties of the partner in the complex and the surroundings in which the complexation occurs. In this paper, IR spectroscopy and quantum chemical calculations are employed to characterize hydrogen-bonded complexes of 2- and 3-EP and EB with triethylamine (TEA) in tetrachloroethene (C2Cl4) solution. The formation of ≡C−H···N hydrogen bonds is experimentally confirmed by the appearance of TEA concentration-dependent signals in the IR spectra of the EPs and EB. Along with the signals due to unassociated ≡C−H and C≡C oscillators (2-EP: 3308 cm–1 and 2120 cm–1; 3-EP: 3308 cm–1 and 2116 cm–1; EB: 3313 cm–1 and 2113 cm–1) weak, red-shifted signals arise at ~3215 ± 5 cm–1 and ~2105 ± 5 cm–1 which are assigned to the stretching vibrations of hydrogen-bonded ≡C−H··· and C≡C··· oscillators, respectively. This result is at variance with those of previous investigations of EB and TEA in the gas phase. In the 2-EP···TEA complex these bands remain at the same position with increasing TEA concentration. However, in the 3-EP···TEA and EB···TEA complexes the ≡C−H··· stretching band demonstrates a slightly reduced red-shift as the TEA concentration increases, whereas the C≡C··· stretching band absorbs at the same wavenumber in the investigated TEA concentration range. The results of B3LYP-D3 calculations indicate that complexes with more or less linear ≡C−H···N intermolecular hydrogen bonds are more stable than other, dispersion-driven complexes. Complexes with the Cs symmetrical TEA conformer are predicted to have larger binding energy than those formed with the C3 and C1 symmetrical conformers. The predicted IR spectral shifts are slightly different for complexes with the three different TEA conformers. Association constants of hydrogen-bonded complexes at 26 °C are estimated to be ~0.1 mol–1 dm3.",
    keywords = "Ethynyl aromates, Triethylamine, Hydrogen bonding, IR spectroscopy, B3LYP-D3 calculations",
    author = "Danijela Bakarić and Josipa Alerić and Tijana Parlić-Risović and Jens Spanget-Larsen",
    note = "Full bibliographic reference: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 209 (2019) 288–294",
    year = "2019",
    month = "2",
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    doi = "10.1016/j.saa.2018.10.058",
    language = "English",
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    pages = "288--294",
    journal = "Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy",
    issn = "1386-1425",
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    Hydrogen bonding between ethynyl aromates and triethylamine : IR spectroscopic and computational study. / Bakarić, Danijela; Alerić, Josipa; Parlić-Risović, Tijana; Spanget-Larsen, Jens.

    I: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Bind 209, 15.02.2019, s. 288-294.

    Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

    TY - JOUR

    T1 - Hydrogen bonding between ethynyl aromates and triethylamine

    T2 - IR spectroscopic and computational study

    AU - Bakarić, Danijela

    AU - Alerić, Josipa

    AU - Parlić-Risović, Tijana

    AU - Spanget-Larsen, Jens

    N1 - Full bibliographic reference: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 209 (2019) 288–294

    PY - 2019/2/15

    Y1 - 2019/2/15

    N2 - Ethynylpyridines (EPs) and ethynylbenzene (EB) are multifunctional systems able to participate in hydrogen-bonded complexes as both donors and acceptors of the H-atom. Their structures and stabilities are mainly a function of the hydrogen-bonding properties of the partner in the complex and the surroundings in which the complexation occurs. In this paper, IR spectroscopy and quantum chemical calculations are employed to characterize hydrogen-bonded complexes of 2- and 3-EP and EB with triethylamine (TEA) in tetrachloroethene (C2Cl4) solution. The formation of ≡C−H···N hydrogen bonds is experimentally confirmed by the appearance of TEA concentration-dependent signals in the IR spectra of the EPs and EB. Along with the signals due to unassociated ≡C−H and C≡C oscillators (2-EP: 3308 cm–1 and 2120 cm–1; 3-EP: 3308 cm–1 and 2116 cm–1; EB: 3313 cm–1 and 2113 cm–1) weak, red-shifted signals arise at ~3215 ± 5 cm–1 and ~2105 ± 5 cm–1 which are assigned to the stretching vibrations of hydrogen-bonded ≡C−H··· and C≡C··· oscillators, respectively. This result is at variance with those of previous investigations of EB and TEA in the gas phase. In the 2-EP···TEA complex these bands remain at the same position with increasing TEA concentration. However, in the 3-EP···TEA and EB···TEA complexes the ≡C−H··· stretching band demonstrates a slightly reduced red-shift as the TEA concentration increases, whereas the C≡C··· stretching band absorbs at the same wavenumber in the investigated TEA concentration range. The results of B3LYP-D3 calculations indicate that complexes with more or less linear ≡C−H···N intermolecular hydrogen bonds are more stable than other, dispersion-driven complexes. Complexes with the Cs symmetrical TEA conformer are predicted to have larger binding energy than those formed with the C3 and C1 symmetrical conformers. The predicted IR spectral shifts are slightly different for complexes with the three different TEA conformers. Association constants of hydrogen-bonded complexes at 26 °C are estimated to be ~0.1 mol–1 dm3.

    AB - Ethynylpyridines (EPs) and ethynylbenzene (EB) are multifunctional systems able to participate in hydrogen-bonded complexes as both donors and acceptors of the H-atom. Their structures and stabilities are mainly a function of the hydrogen-bonding properties of the partner in the complex and the surroundings in which the complexation occurs. In this paper, IR spectroscopy and quantum chemical calculations are employed to characterize hydrogen-bonded complexes of 2- and 3-EP and EB with triethylamine (TEA) in tetrachloroethene (C2Cl4) solution. The formation of ≡C−H···N hydrogen bonds is experimentally confirmed by the appearance of TEA concentration-dependent signals in the IR spectra of the EPs and EB. Along with the signals due to unassociated ≡C−H and C≡C oscillators (2-EP: 3308 cm–1 and 2120 cm–1; 3-EP: 3308 cm–1 and 2116 cm–1; EB: 3313 cm–1 and 2113 cm–1) weak, red-shifted signals arise at ~3215 ± 5 cm–1 and ~2105 ± 5 cm–1 which are assigned to the stretching vibrations of hydrogen-bonded ≡C−H··· and C≡C··· oscillators, respectively. This result is at variance with those of previous investigations of EB and TEA in the gas phase. In the 2-EP···TEA complex these bands remain at the same position with increasing TEA concentration. However, in the 3-EP···TEA and EB···TEA complexes the ≡C−H··· stretching band demonstrates a slightly reduced red-shift as the TEA concentration increases, whereas the C≡C··· stretching band absorbs at the same wavenumber in the investigated TEA concentration range. The results of B3LYP-D3 calculations indicate that complexes with more or less linear ≡C−H···N intermolecular hydrogen bonds are more stable than other, dispersion-driven complexes. Complexes with the Cs symmetrical TEA conformer are predicted to have larger binding energy than those formed with the C3 and C1 symmetrical conformers. The predicted IR spectral shifts are slightly different for complexes with the three different TEA conformers. Association constants of hydrogen-bonded complexes at 26 °C are estimated to be ~0.1 mol–1 dm3.

    KW - Ethynyl aromates

    KW - Triethylamine

    KW - Hydrogen bonding

    KW - IR spectroscopy

    KW - B3LYP-D3 calculations

    U2 - 10.1016/j.saa.2018.10.058

    DO - 10.1016/j.saa.2018.10.058

    M3 - Journal article

    VL - 209

    SP - 288

    EP - 294

    JO - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

    JF - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

    SN - 1386-1425

    ER -