TY - JOUR

T1 - Osmotic second virial coefficients for hydrophobic interactions as a function of solute size

AU - Naito, Hidefumi

AU - Okamoto, Ryuichi

AU - Sumi, Tomonari

AU - Koga, Kenichiro

N1 - Funding Information:
This work was supported by the JSPS KAKENHI (Grant Nos. 18KK0151, 18K03562, and 20H02696). Part of the computation was carried out using the Research Center for Computational Science, Okazaki, Japan (Project No. 21-IMS-C125).
Publisher Copyright:
© ESO 2022 2022 Author(s).

PY - 2022/6/14

Y1 - 2022/6/14

N2 - To gain quantitative insight into how the overall strength of the hydrophobic interaction varies with the molecular size, we calculate osmotic second virial coefficients B for hydrophobic spherical molecules of different diameters σ in water based on molecular simulation with corrections to the finite-size and finite-concentration effects. It is shown that B (<0) changes by two orders of magnitude greater as σ increases twofold and its solute-size dependence is best fit by a power law B ∝ σα with the exponent α ≃ 6, which contrasts with the cubic power law that the second virial coefficients of gases obey. It is also found that values of B for the solutes in a nonpolar solvent are positive but they obey the same power law as in water. A thermodynamic identity for B derived earlier [K. Koga, V. Holten, and B. Widom, J. Phys. Chem. B 119, 13391 (2015)] indicates that if B is asymptotically proportional to a power of σ, the exponent α must be equal to or greater than 6.

AB - To gain quantitative insight into how the overall strength of the hydrophobic interaction varies with the molecular size, we calculate osmotic second virial coefficients B for hydrophobic spherical molecules of different diameters σ in water based on molecular simulation with corrections to the finite-size and finite-concentration effects. It is shown that B (<0) changes by two orders of magnitude greater as σ increases twofold and its solute-size dependence is best fit by a power law B ∝ σα with the exponent α ≃ 6, which contrasts with the cubic power law that the second virial coefficients of gases obey. It is also found that values of B for the solutes in a nonpolar solvent are positive but they obey the same power law as in water. A thermodynamic identity for B derived earlier [K. Koga, V. Holten, and B. Widom, J. Phys. Chem. B 119, 13391 (2015)] indicates that if B is asymptotically proportional to a power of σ, the exponent α must be equal to or greater than 6.

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U2 - 10.1063/5.0097547

DO - 10.1063/5.0097547

M3 - Article

C2 - 35705398

AN - SCOPUS:85132008243

VL - 156

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 22

M1 - 221104

ER -