|
 |
Fig. 1 |
|
  |
Fig. 2 (a) Raman spectra of pure [bmim][PF6] in the 280-900 cm-1 region as a function of pressure. The asterisks represent the frequencies of the PF6 ion. CH2 r represents the CH2 rocking mode. (b) Pressure dependence of the intensity ratio (Igauche/Itrans ) between the conformers of the [bmim]+ cation. |
 |
Fig. 3. Variation of the molecular volume (VM) of the [bmim]+ cation as a function of the NCCC dihedral angle. |
References
[1] H. Hamaguchi and R. Ozawa, Structure of ionic liquids and ionic liquid
compounds: Are ionic liquids genuine liquids in the conventional sense?
Adv. Chem. Phys. 131 (2005), pp. 85-104.
[2] K. Nishikawa, S. Wang, and K. Tozaki, Rhythmic melting and crystallizing of ionic liquid 1-butyl-3-methylimidazolium bromide, Chem. Phys. Lett. 458 (2008), pp. 88-91.
[3] S. Seki, K. Hayamizu, S. Tsuzaki, K. Fujii, Y. Umebayashi, T. Mitsugi, T. Kobayashi, Y. Ohno, Y. Kobayashi, Y. Mita, H. Miyashiro, and S. Ishiguro, Relationship between center atom species (N, P) and ionic conductivity, density, self-diffusion coefficient of quaternary cation room-temperature ionic liquids, Phys. Chem. Chem. Phys. 11 (2009), pp. 3509-3514.
[4] K. Nishikawa, S.Wang, T. Endo, and K. Tozaki, Melting and crystallization behaviors of ionic liquid, 1-isopropyl-3-methylimidazolium bromide, studies by using nanowatt-stabilized differential scanning calorimetry, Bull. Chem. Soc. Jpn 82 (2009), pp. 806-812.
[5] L. Su, L. Li,Y. Hu, C.Yuan, C. Shao, and S. Hong, Phase transition of [Cn-mim][PF6] under high pressure up to 1.0 GPa, J. Chem. Phys. 130 (2009), pp. 184503-1-4.
[6] L. Su, M. Li, X. Zhu, Z. Wang, Z. Chen, F. Li, Q. Zho, and S. Hong, In-situ crystallization of low-melting ionic liquid [BMIM][PF6] under high pressure up to 2 GPa, J. Phys. Chem. B 114 (2010) pp. 5061-5065.
[7] T. Endo, T. Kato, K. Tozaki, and K. Nishikawa, Phase behaviors of room temperature ionic liquid linked with cation conformational changes: 1-Butyl-3-methylimidazolium hexafluorophosphate, J. Phys. Chem. B 114 (2010), pp. 407-411.
[8] H.K. Mao, P.M. Bell, J.W. Shaner, and D.J. Steinberg, Specific volume measurements of Cu, Mo, Pd, and Ag and calibration of the ruby R1 fluorescence pressure gauge from 0.06 to 1 Mbar, J. Appl. Phys. 49 (1978), pp. 3276-3283.
[9] R. Ozawa, S. Hayashi, S. Saha, A. Kobayashi, and H. Hamaguchi, Rotational isomerism and structure of the 1-butyl-3-methylimidazolim cation in the ionic liquid state, Chem. Lett. 32 (2003), pp. 948-949.
[10] T. Takekiyo, N. Hatano, Y. Imai, H. Abe, and Y. Yoshimura, Alkyl-chain length dependence on the stability of pressure-induced conformational change of imidazolium-based ionic liquids, in preparation.
[11] Y.Taniguchi, H.Takaya, P.T.T.Wong, and E.Whaley, Effect of pressure on molecular conformations. II.Trans.gauche equilibrium of 1,2-dichloroethane and 1,2-dibromoethane, J. Chem. Phys. 75 (1981), pp. 4815-4822.
[12] M. Kato and Y. Taniguchi, Effect of pressure on conformational equilibria of liquid 1-chloropropane and 1-bromopropane, J. Chem. Phys. 93 (1990), pp. 4345-4348.
[13] P.E. Schoen, R.G. Proest, J.P. Sheridan, and J.M. Schnur, Pressure induced changes in liquid alkane chain conformation, J. Chem. Phys. 71 (1979), pp. 317-323.
[14] M. Kato andY. Taniguchi, High pressure study on molecular conformational equilibria of n-pentane, J. Chem. Phys. 94 (1991), pp. 4440-4445.
[15] Y. Taniguchi, Effect of pressure on rotational isomers in solution: Infrared and Raman spectroscopies, J. Mol. Struct., 126 (1985), pp. 241-250.
[16] T. Takekiyo andY.Yoshimura, Raman spectroscopic study on the hydration structures of tetraethylammonium cation in water, J. Phys. Chem. A 110 (2007), pp. 10829-10833.
[2] K. Nishikawa, S. Wang, and K. Tozaki, Rhythmic melting and crystallizing of ionic liquid 1-butyl-3-methylimidazolium bromide, Chem. Phys. Lett. 458 (2008), pp. 88-91.
[3] S. Seki, K. Hayamizu, S. Tsuzaki, K. Fujii, Y. Umebayashi, T. Mitsugi, T. Kobayashi, Y. Ohno, Y. Kobayashi, Y. Mita, H. Miyashiro, and S. Ishiguro, Relationship between center atom species (N, P) and ionic conductivity, density, self-diffusion coefficient of quaternary cation room-temperature ionic liquids, Phys. Chem. Chem. Phys. 11 (2009), pp. 3509-3514.
[4] K. Nishikawa, S.Wang, T. Endo, and K. Tozaki, Melting and crystallization behaviors of ionic liquid, 1-isopropyl-3-methylimidazolium bromide, studies by using nanowatt-stabilized differential scanning calorimetry, Bull. Chem. Soc. Jpn 82 (2009), pp. 806-812.
[5] L. Su, L. Li,Y. Hu, C.Yuan, C. Shao, and S. Hong, Phase transition of [Cn-mim][PF6] under high pressure up to 1.0 GPa, J. Chem. Phys. 130 (2009), pp. 184503-1-4.
[6] L. Su, M. Li, X. Zhu, Z. Wang, Z. Chen, F. Li, Q. Zho, and S. Hong, In-situ crystallization of low-melting ionic liquid [BMIM][PF6] under high pressure up to 2 GPa, J. Phys. Chem. B 114 (2010) pp. 5061-5065.
[7] T. Endo, T. Kato, K. Tozaki, and K. Nishikawa, Phase behaviors of room temperature ionic liquid linked with cation conformational changes: 1-Butyl-3-methylimidazolium hexafluorophosphate, J. Phys. Chem. B 114 (2010), pp. 407-411.
[8] H.K. Mao, P.M. Bell, J.W. Shaner, and D.J. Steinberg, Specific volume measurements of Cu, Mo, Pd, and Ag and calibration of the ruby R1 fluorescence pressure gauge from 0.06 to 1 Mbar, J. Appl. Phys. 49 (1978), pp. 3276-3283.
[9] R. Ozawa, S. Hayashi, S. Saha, A. Kobayashi, and H. Hamaguchi, Rotational isomerism and structure of the 1-butyl-3-methylimidazolim cation in the ionic liquid state, Chem. Lett. 32 (2003), pp. 948-949.
[10] T. Takekiyo, N. Hatano, Y. Imai, H. Abe, and Y. Yoshimura, Alkyl-chain length dependence on the stability of pressure-induced conformational change of imidazolium-based ionic liquids, in preparation.
[11] Y.Taniguchi, H.Takaya, P.T.T.Wong, and E.Whaley, Effect of pressure on molecular conformations. II.Trans.gauche equilibrium of 1,2-dichloroethane and 1,2-dibromoethane, J. Chem. Phys. 75 (1981), pp. 4815-4822.
[12] M. Kato and Y. Taniguchi, Effect of pressure on conformational equilibria of liquid 1-chloropropane and 1-bromopropane, J. Chem. Phys. 93 (1990), pp. 4345-4348.
[13] P.E. Schoen, R.G. Proest, J.P. Sheridan, and J.M. Schnur, Pressure induced changes in liquid alkane chain conformation, J. Chem. Phys. 71 (1979), pp. 317-323.
[14] M. Kato andY. Taniguchi, High pressure study on molecular conformational equilibria of n-pentane, J. Chem. Phys. 94 (1991), pp. 4440-4445.
[15] Y. Taniguchi, Effect of pressure on rotational isomers in solution: Infrared and Raman spectroscopies, J. Mol. Struct., 126 (1985), pp. 241-250.
[16] T. Takekiyo andY.Yoshimura, Raman spectroscopic study on the hydration structures of tetraethylammonium cation in water, J. Phys. Chem. A 110 (2007), pp. 10829-10833.
Last Modified: April 1, 2011