Journal of the Iranian Chemical Society

, Volume 10, Issue 4, pp 733–744 | Cite as

Electronic and topological properties of interactions between imidazolium-based ionic liquids and thiophenic compounds: a theoretical investigation

Original Paper


To deepen the understanding the interactions of thiophenic compounds in ionic liquids, we have performed a systemic study on the electronic structures, and topological properties of interactions between N-ethyl-N-ethylimidazolium diethyl phosphate ([EEIM][DEP]) ionic liquid and 3-methylthiophene (3-MT), benzothiophene (BT), or dibenzothiophene (DBT) using density functional theory. From NBO atomic charges and electrostatic potential analyses, most of the positive charge is located on C2–H2 in the [EEIM] cation, and the negative charge is focused on oxygen atoms in [DEP] anion, implying oxygen atoms in [DEP] should easily attack C2–H2 in [EEIM]. The electrostatic interaction between anion and cation may be dominant for the formation of the [EEIM]–[DEP] ion pair. The large stabilizing effect is due to the strong orbital interactions between the antibonding orbital of proton donor σ*(C2–H2) in [EEIM] cation and the lone pairs of proton acceptor LP(O) in [DEP] anion. A common feature of [EEIM][DEP], [EEIM][DEP]-3-MT/BT/DBT complexes is the presence of hydrogen bonds between [EEIM] cation and [DEP] anion. This work has also given the interacting mechanism of 3-MT, BT, and DBT adsorption on [EEIM][DEP] ionic liquid. Both [EEIM] cation and [DEP] anion are shown to play important roles in interactions between 3-MT, BT, DBT and [EEIM][DEP], which has been corroborated by NBO and AIM analyses. The π···π, π···C–H and hydrogen bonding interactions occur between [EEIM][DEP] and 3-MT, BT, DBT. The strength of sulfur involved interactions between 3-MT, BT, DBT and [EEIM][DEP] follows the order of 3-MT > BT > DBT. The order of interaction energies between [EEIM][DEP] and 3-MT, BT, DBT is 3-MT < BT < DBT, in agreement with the order of extractive selectivity from fuel oils (DBT > BT > 3-MT) in terms of sulfur partition coefficients.


Ionic liquid Desulfurization Density functional theory Electronic properties NBO analyses Topological properties 


  1. 1.
    A. Stanislaus, A. Marafi, M.S. Rana, Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production. Catal. Today 153, 1–68 (2010)CrossRefGoogle Scholar
  2. 2.
    P.S. Kulkarni, C.A.M. Afonso, Deep desulfurization of diesel fuel using ionic liquids: current status and future challenges. Green Chem. 12, 1139–1149 (2010)CrossRefGoogle Scholar
  3. 3.
    A. Bosmann, L. Datsevich, A. Jess, A. Lauter, C. Schmitz, P. Wasseerscheid, Deep desulfurization of diesel fuel by extraction with ionic liquids. Chem. Commun. 2494–2495 (2001)Google Scholar
  4. 4.
    W. Lo, H. Yang, G. Wei, One-pot desulfurization of light oils by chemical oxidation and solvent extraction with room temperature ionic liquids. Green Chem. 5, 639–642 (2003)CrossRefGoogle Scholar
  5. 5.
    Y. Nie, C. Li, A. Sun, H. Meng, Z. Wang, Extractive desulfurization of gasoline using imidazolium-based phosphoric ionic liquids. Energy Fuels 20, 2083–2087 (2006)CrossRefGoogle Scholar
  6. 6.
    Y. Nie, C. Li, Z. Wang, Extractive desulfurization of fuel oil using alkylimidazole and its mixture with dialkylphosphate ionic liquids. Ind. Eng. Chem. Res. 46, 5108–5112 (2007)CrossRefGoogle Scholar
  7. 7.
    X. Jiang, Y. Nie, C. Li, Z. Wang, Imidazolium-based alkylphosphate ionic liquids—a potential solvent for extractive desulfurization of fuel. Fuel 87, 79–84 (2008)CrossRefGoogle Scholar
  8. 8.
    R. Anantharaj, T. Banerjee, Phase behavior of 1-ethyl-3-methylimidazolium thiocyanate ionic liquid with catalytic deactivated compounds and water at several temperatures: experiments and theoretical predictions. Int. J. Chem. Eng. 2011, 1–13 (2011)CrossRefGoogle Scholar
  9. 9.
    S. Potdar, R. Anantharaj, T. Banerjee, Aromatic extraction using mixed ionic liquids: experiments and COSMO-RS predictions. J. Chem. Eng. Data 57, 1026–1035 (2012)CrossRefGoogle Scholar
  10. 10.
    A.A.P. Kumar, T. Banerjee, Thiophene separation with ionic liquids for desulphurization: a quantum chemical approach. Fluid Phase Equilib. 278, 1–8 (2009)CrossRefGoogle Scholar
  11. 11.
    R. Anantharaj, T. Banerjee, Liquid–liquid equilibria for quaternary systems of imidazolium based ionic liquid + thiophene + pyridine + iso-octane at 298.15 K: experiments and quantum chemical predictions. Fluid Phase Equilib. 312, 20–30 (2011)CrossRefGoogle Scholar
  12. 12.
    R.S. Santiago, G.R. Santos, M. Aznar, UNIQUAC correlation of liquid–liquid equilibrium in systems involving ionic liquids: the DFT-PCM approach. Fluid Phase Equilib. 278, 54–61 (2009)CrossRefGoogle Scholar
  13. 13.
    C.G. Hanke, A. Johansson, J.B. Harper, R.M. Lynden-Bell, Why are aromatic compounds more soluble than aliphatic compounds in dimethylimidazolium ionic liquids? A simulation study. Chem. Phys. Lett. 374, 85–90 (2003)CrossRefGoogle Scholar
  14. 14.
    K. Kedra-Krolik, M. Fabrice, J. Jaubert, Extraction of thiophene or pyridine from n-heptane using ionic liquids, gasoline and diesel desulfurization. Ind. Eng. Chem. Res. 50, 2296–2306 (2011)CrossRefGoogle Scholar
  15. 15.
    R. Anantharaj, T. Banerjee, Quantum chemical studies on the simultaneous interaction of thiophene and pyridine with ionic liquids. AIChE J. 57, 749–764 (2011)CrossRefGoogle Scholar
  16. 16.
    J. Zhou, J. Mao, S. Zhang, Ab initio calculations of the interaction between thiophene and ionic liquids. Fuel Process. Technol. 89, 1456–1460 (2008)CrossRefGoogle Scholar
  17. 17.
    J. Martinez-Magadan, R. Oviedo-Roa, P. Garcia, R. Martinez-Palou, DFT study of the interaction between ethanethiol and Fe-containing ionic liquids for desulfurization of natural gasoline. Fuel Process. Technol. 97, 24–29 (2012)CrossRefGoogle Scholar
  18. 18.
    X. Liu, G. Zhou, X. Zhang, S. Zhang, Molecular dynamics simulation of desulfurization by ionic liquids. AIChE J. 56, 2983–2996 (2010)CrossRefGoogle Scholar
  19. 19.
    J. Gui, D. Liu, Z. Sun, D. Liu, D. Min, B. Song, X. Peng, Deep oxidative desulfurization with task-specific ionic liquids: an experimental and computational study. J. Mol. Catal. A: Chem. 331, 64–70 (2010)CrossRefGoogle Scholar
  20. 20.
    Y. Nie, X. Yuan, Theoretical study on interaction between ionic liquids and aromatic sulfur compounds. J. Theor. Comput. Chem. 10, 31–40 (2011)CrossRefGoogle Scholar
  21. 21.
    B. Delley, An all-electron numerical method for solving the local density functional for polyatomic molecules. J. Chem. Phys. 92, 508–517 (1990)CrossRefGoogle Scholar
  22. 22.
    B. Delley, From molecules to solids with the DMol3 approach. J. Chem. Phys. 113, 7756–7764 (2000)CrossRefGoogle Scholar
  23. 23.
    J.P. Perdew, Y. Wang, Accurate and simple analytic representation of the electron-gas correlation energy. Phys. Rev. B 45, 13244–13249 (1992)CrossRefGoogle Scholar
  24. 24.
    O. Castellano, R. Gimon, H. Soscun, Theoretical study of the σ–π and π–π interactions in heteroaromatic monocyclic molecular complexes of benzene, pyridine, and thiophene dimers: implications on the resin-asphaltene stability in crude oil. Energy Fuels 25, 2526–2541 (2011)CrossRefGoogle Scholar
  25. 25.
    A.E. Reed, L.A. Curtiss, F. Weinhold, Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint. Chem. Rev. 88, 899–926 (1988)CrossRefGoogle Scholar
  26. 26.
    F. Biegler-König, J. Schönbohm, Update of the AIM2000 program for atoms in molecules. J. Comput. Chem. 23, 1489–1494 (2002)CrossRefGoogle Scholar
  27. 27.
    F. Biegler-König, J. Schönbohm, D. Bayles, AIM2000—a program to analyze and visualize atoms in molecules. J. Comput. Chem. 22, 545–559 (2001)CrossRefGoogle Scholar
  28. 28.
    Y. Inada, H. Orita, Efficiency of numerical basis sets for predicting the binding energies of hydrogen bonded complexes: evidence of small basis set superposition error compared to Gaussian basis sets. J. Comput. Chem. 29, 225–232 (2008)CrossRefGoogle Scholar
  29. 29.
    A. Bondi, Van der Waals volumes and radii. J. Phys. Chem. 68, 441–451 (1964)CrossRefGoogle Scholar
  30. 30.
    P.A. Hunt, B. Kirchne, T. Welton, Characterizing the electronic structure of ionic liquids: an examination of the 1-butyl-3-methylimidazolium chloride ion pair. Chem. Eur. J. 12, 6762–6775 (2006)CrossRefGoogle Scholar
  31. 31.
    M.O. Sinnokrot, E.F. Valeev, C.D. Sherrill, Estimates of the ab initio limit for π–π interactions: the benzene dimer. J. Am. Chem. Soc. 124, 10887–10893 (2002)CrossRefGoogle Scholar
  32. 32.
    C.A. Hunter, J.K.M. Sanders, The nature of π–π interactions. J. Am. Chem. Soc. 112, 5525–5534 (1990)CrossRefGoogle Scholar
  33. 33.
    M.J. Rashkin, M.L. Waters, Unexpected substituent effects in offset π–π stacked interactions in water. J. Am. Chem. Soc. 124, 1860–1861 (2002)CrossRefGoogle Scholar
  34. 34.
    R.W.F. Bader, A quantum theory of molecular structure and its applications. Chem. Rev. 91, 893–928 (1991)CrossRefGoogle Scholar
  35. 35.
    U. Koch, P.L.A. Popelier, Characterization of C-H-O hydrogen bonds on the basis of the charge density. J. Phys. Chem. 99, 9747–9754 (1995)CrossRefGoogle Scholar
  36. 36.
    P.L.A. Popelier, Characterization of a dihydrogen bond on the basis of the electron density. J. Phys. Chem. A 102, 1873–1878 (1998)CrossRefGoogle Scholar

Copyright information

© Iranian Chemical Society 2012

Authors and Affiliations

  1. 1.College of ScienceChina University of Petroleum (East China)QingdaoChina
  2. 2.College of Chemical EngineeringChina University of Petroleum (East China)QingdaoChina

Personalised recommendations