Computer simulation of the effect of salt on the hydrophobic effect

Abstract

Molecular dynamics simulations of aqueous solutions containing methane and sodium chloride reveal the existence of a structured hydration shell around the non-polar solutes, although this hydration shell is less well defined than in the case where salt is absent. It was also observed that hydrogen bonds made from the hydration shell across to the bulk are weaker than those in the bulk, with or without salt. Although the geometry of the hydrogen bonds is preserved, there is a larger fraction of broken hydrogen bonds in the hydration shell of the non-polar solutes than in the bulk of the solution, the difference increasing with increasing temperature. The number of broken H bonds is significantly larger in the presence of salt, and should contribute to an increase in the free energy of dissolution and hence to a lowering of the solubility and an increase in the hydrophobic interaction.

References

1. P. L. Privalov and S. J. Gill, Adv. Prot. Chem., 1988, 39, 191.
2. W. Blokzijl and J. B. F. N. Engberts, Angew. Chem., Int. Ed. Engl., 1993, 32, 154.
3. M. Costas, B. Kronberg and R. Silveston, J. Chem. Soc., Faraday Trans., 1994, 90, 1513.
4. B. Kronberg, M. Costas and R. Silveston, Pure Appl. Chem., 1995, 67, 897.
5. D. F. Evans and B. W. Ninham, J. Phys. Chem., 1986, 90, 226.
6. R. Lemieux, Acc. Chem. Res., 1996, 29, 373.
7. K. A. Dill, Biochemistry, 1990, 29, 7133.
8. C. Tanford, The Hydrophobic Effect: Formation of Micelles and Biological Membranes, Wiley, New York, 1973.
9. A. Ben-Naim, Solvation Thermodynamics, Plenum, New York, 1987.
10. D. Mirejovsky and E. M. Arnett, J. Am. Chem. Soc., 1983, 105, 1112.
11. M. Costas and D. Patterson, J. Chem. Soc., Faraday Trans. I, 1985, 81, 2381.
12. S. J. Gill, S. F. Dec, G. Olofsson and I. Wadsö, J. Phys. Chem., 1985, 89, 3758.
13. K. Shinoda and M. Fujihira, Bull. Chem. Soc. Jpn., 1969, 41, 2612.
14. K. Shinoda, J. Phys. Chem., 1977, 81, 1300.
15. N. Muller, Acc. Chem. Res., 1990, 23, 23.
16. R. L. Mancera, B. Kronberg, M. Costas and R. Silveston, Biophys. Chem., 1998, 70, 57.
17. G. Hummer, S. Garde, A. E. García, A. Pohorille and L. R. Pratt, Proc. Natl. Acad. Sci. USA, 1996, 93, 8951.
18. B. J. Berne, Proc. Natl. Acad. Sci. USA, 1996, 93, 8800.
19. S. Garde, G. Hummer, A. E. García, M. E. Paulaitis and L. R. Pratt, Phys. Rev. Lett., 1996, 77, 4966.
20. M. E. Paulaitis, Curr. Opin. Colloid Interface Sci., 1996, 2, 315.
21. R. A. Pierotti, J. Phys. Chem., 1965, 69, 281.
22. F. H. Stillinger, J. Solution Chem., 1973, 2, 141.
23. B. Lee, Biopolymers, 1985, 24, 813.
24. B. Lee, Biopolymers, 1991, 31, 993.
25. L. R. Pratt and A. Pohorille, Proc. Natl. Acad. Sci. USA, 1992, 89, 2995.
26. M. Ikeguchi, S. Shimizu, S. Nakamura and K. Shimizu, J. Phys. Chem. B, 1998, 102, 5891.
27. K. A. T. Silverstein, A. D. J. Haymet and K. A. Dill, J. Am. Chem. Soc., 1998, 120, 3166.
28. H. Liu and E. Ruckenstein, J. Phys. Chem. B, 1998, 102, 1005.
29. J. L. Finney, Faraday Discuss., 1996, 103, 1.
30. V. Y. Bezzabotnov, L. Cser, T. Grósz, G. Jancsó and Y. M. Ostanevich, J. Phys. Chem., 1992, 96, 976.
31. G. Jancsó, L. Cser, T. Grósz and Y. M. Ostanevich, Pure Appl. Chem., 1994, 66, 515.
32. M. Nakahara, C. Wakai, Y. Yoshimoto and N. Matubayasi, J. Phys. Chem., 1996, 100, 1345.
33. J. L. Finney, A. K. Soper and J. Z. Turner, Pure Appl. Chem., 1993, 65, 2521.
34. A. Sacco and M. Holz, J. Chem. Soc., Faraday Trans., 1997, 93, 1101.
35. A. Sacco, F. M. De Cillis and M. Holz, J. Chem. Soc., Faraday Trans., 1998, 94, 2089.
36. W. L. Jorgensen, J. Chandrasekhar, J. D. Madura, R. W. Impey and M. L. Klein, J. Chem. Phys., 1988, 89, 3742.
37. D. E. Smith, L. Zhang and A. D. J. Haymet, J. Am. Chem. Soc., 1992, 114, 5875.
38. D. E. Smith and A. D. J. Haymet, J. Chem. Phys., 1993, 98, 6445.
39. P. Jungwirth and R. Zahradník, Chem. Phys. Lett., 1994, 217, 319.
40. J. Forsman and B. Jönsson, J. Chem. Phys., 1994, 101, 5116.
41. S. Lüdemann, H. Schreiber, R. Abseher and O. Steinhauser, J. Chem. Phys., 1996, 104, 286.
42. S. Lüdemann, R. Abseher, H. Schreiber and O. Steinhauser, J. Am. Chem. Soc., 1997, 119, 4206.
43. A. Wallqvist and B. J. Berne, J. Phys. Chem., 1995, 99, 2893.
44. A. Geiger, A. Rahman and F. H. Stillinger, J. Chem. Phys., 1979, 70, 263.
45. D. C. Rapaport and H. A. Scheraga, J. Phys. Chem., 1982, 86, 873.
46. K. Watanabe and H. C. Andersen, J. Phys. Chem., 1986, 90, 795.
47. A. Laaksonen and P. Stilbs, Mol. Phys., 1991, 74, 747.
48. A. Wallqvist, J. Phys. Chem., 1991, 95, 8921.
49. N. T. Skipper, Chem. Phys. Lett., 1993, 207, 424.
50. R. L. Mancera and A. D. Buckingham, Chem. Phys. Lett., 1995, 234, 296.
51. N. T. Skipper, C. H. Bridgeman, A. D. Buckingham and R. L. Mancera, Faraday Discuss., 1996, 103, 141.
52. R. L. Mancera, A. D. Buckingham and N. T. Skipper, J. Chem. Soc., Faraday Trans., 1997, 93, 2263.
53. S. K. Shoor and K. E. Gubbins, J. Phys. Chem., 1969, 73, 498.
54. W. L. Masterton and T. P. Lee, J. Phys. Chem., 1970, 74, 1776.
55. M. Kinoshita and F. Hirata, J. Chem. Phys., 1997, 108, 5202.
56. B. E. Conway, Pure Appl. Chem., 1985, 57, 263.
57. R. L. Mancera, Chem. Phys. Lett., 1998, 296, 459.
58. Molecular Dynamics simulation code, Moldy, 1988, 1992, 1993. Keith Refson, Department of Earth Sciences, University of Oxford, UK.
59. M. P. Allen and D. J. Tildesley, Computer Simulation of Liquids, Clarendon Press, Oxford, 1987.
60. W. G. Hoover, Phys. Rev. A, 1985, 31, 1695.
61. W. L. Jorgensen, J. Chandrasekhar, J. D. Madura, R. W. Impey and M. L. Klein, J. Chem. Phys., 1983, 79, 926.
62. W. L. Jorgensen, J. D. Madura and C. J. Swenson, J. Am. Chem. Soc., 1984, 106, 6638.
63. J. Chandrasekhar, D. C. Spellmeyer and W. L. Jorgensen, J. Am. Chem. Soc., 1984, 106, 903.
64. B. G. Rao and U. C. Singh, J. Am. Chem. Soc., 1990, 112, 3803.
65. B. M. Pettitt and P. J. Rossky, J. Chem. Phys., 1986, 84, 5836.
66. M. Parrinello and A. Rahman, J. Appl. Phys., 1981, 52, 7182.
67. D. G. Bounds, Mol. Phys., 1985, 54, 1335.
68. G. Hummer, D. M. Soumpasis and M. Neumann, J. Phys.: Condens. Matter, 1994, 6, 141.
69. D. E. Smith and L. X. Dang, J. Chem. Phys., 1994, 100, 3757.
70. R. A. Friedman and M. Mezei, J. Chem. Phys., 1995, 102, 419.
71. D. H. Powell, G. W. Neilson and J. E. Enderby, J. Phys.: Condens. Matter, 1993, 5, 5723.
72. Y. Wang and Y. Tominaga, J. Chem. Phys., 1994, 101, 3453.
73. M. Yamagami, H. Wakita and T. Yamaguchi, J. Chem. Phys., 1995, 103, 8174.
74. G. Hummer, D. M. Soumpasis and M. Neumann, Mol. Phys., 1994, 81, 1155.
75. J. Gao, J. Phys. Chem., 1994, 98, 6049.
76. A. P. Lyubartsev and A. Laaksonen, J. Phys. Chem., 1996, 100, 16410.
77. I. I. Vaisman, F. K. Brown and A. Tropsha, J. Phys. Chem., 1994, 98, 5559.
78. R. L. Mancera and A. D. Buckingham, J. Phys. Chem., 1995, 99, 14632.
79. P.-L. Chau, T. R. Forester and W. Smith, Mol. Phys., 1996, 89, 1033.
80. R. L. Mancera, J. Chem. Soc., Faraday Trans., 1996, 92, 2547.
81. C. H. Bridgeman, A. D. Buckingham and N. T. Skipper, Chem. Phys. Lett., 1996, 253, 209.
82. R. L. Mancera, J. Comput.-Aided Mol. Des., 1996, 10, 321.
83. K. E. Laidig and V. Daggett, J. Phys. Chem., 1996, 100, 5616.
84. L. Degrève and C. Quintanale Jr., J. Chem. Phys., 1994, 101, 2319.
85. S. Obst and H. Bradaczek, J. Phys. Chem., 1996, 100, 15677.
86. G. Hummer, L. R. Pratt and A. E. García, J. Phys. Chem., 1996, 100, 1206.
87. S. Koneshan, J. C. Rasaiah, R. M. Lynden-Bell and S. H. Lee, J. Phys. Chem. B, 1998, 102, 4193.
88. K. Szornel, P. A. Egelstaff, G. E. McLaurin and E. Whalley, J. Phys.: Condens. Matter, 1994, 6, 8373.
89. A. Geiger and P. Mausbach, in Hydrogen-Bonded Liquids, ed. J. C. Dore and J. Teixeira, NATO ASI Series, Kluwer Academic, Netherlands, 1991, p. 171.
90. F. Sciortino, A. Geiger and H. E. Stanley, Nature (London), 1991, 354, 218.
91. M. Haughney, M. Ferrario and I. R. McDonald, J. Phys. Chem., 1987, 91, 4934.