Quantum-chemical calculations of the hydration energies of organic cations and anions in the framework of a continuum solvent approximation

Abstract We investigate the method of calculation of solvation energies using the continuum solvent model and the semiemperical NDDO quantum-chemical background. The electrostatic part of the calculation is based on the Miertus-Scrocco-Tomasi procedure treating the solvent as a dielectric continuum with a cavity and numerically solving the integral equation for the charge distribution on the cavity surface. Its efficiency was significantly increased by accelerating the convergence of the surface integration procedure and modifying the iterative scheme. The calculated solvation free energies of numerous organic ions agree with the experimental estimates within 2–3 kcal/mol. The specific solute-solvent interactions are shown to be important in several cases and a consistent procedure of calculating their contribution to the solvation energy is elaborated.

[1]  The influence of the basis set on the evaluation of conformational energies for small organic solutes in aqueous solutions , 1986 .

[2]  M. Dewar,et al.  Ground States of Molecules. 38. The MNDO Method. Approximations and Parameters , 1977 .

[3]  Jacopo Tomasi,et al.  Electrostatic interaction of a solute with a continuum. Improved description of the cavity and of the surface cavity bound charge distribution. , 1987 .

[4]  Eamonn F. Healy,et al.  Development and use of quantum mechanical molecular models. 76. AM1: a new general purpose quantum mechanical molecular model , 1985 .

[5]  György G. Ferenczy,et al.  Semiempirical AM1 electrostatic potentials and AM1 electrostatic potential derived charges: A comparison with ab initio values , 1989 .

[6]  S. Miertus,et al.  Dependance of atomic radii and volumes on the electron distribution in solute molecule and on solute-solvent interaction , 1987 .

[7]  R. Constanciel,et al.  On the theory of solvent effects , 1978 .

[8]  S. Miertus,et al.  Approximate methods for solvent effects calculations on biomolecules , 1989 .

[9]  O. Tapia,et al.  An inhomogeneous self‐consistent reaction field theory of protein core effects. Towards a quantum scheme for describing enzyme reactions , 1981 .

[10]  Jacopo Tomasi,et al.  Evaluation of the dispersion contribution to the solvation energy. A simple computational model in the continuum approximation , 1989 .

[11]  R. Bonaccorsi,et al.  On the free energy changes of a solution in light absorption or emission processes , 1983 .

[12]  R. Bonaccorsi,et al.  Theoretical study of reaction mechanisms for the ketonization of vinyl alcohol in gas phase and aqueous solution , 1987 .

[13]  Harold A. Scheraga,et al.  Free energies of hydration of solute molecules. 3. Application of the hydration shell model to charged organic molecules , 1987 .

[14]  Walter Thiel,et al.  A semiempirical model for the two-center repulsion integrals in the NDDO approximation , 1977 .

[15]  Modesto Orozco,et al.  On the use of AM1 and MNDO wave functions to compute accurate electrostatic charges , 1990 .

[16]  R. Bonaccorsi,et al.  Ab initio evaluation of absorption and emission transitions for molecular solutes, including separate consideration of orientational and inductive solvent effects , 1983 .

[17]  S. Miertus,et al.  The extended polarizable continuum model for calculation of solvent effects , 1988 .

[18]  G. G. Hall,et al.  The development of quantum mechanical solvent effect models. Macroscopic electrostatic contributions , 1976 .

[19]  Alan R. Katritzky,et al.  Quantitative predictions of tautomeric equilibria for 2-, 3-, and 4-substituted pyridines in both the gas phase and aqueous solution: combination of AM1 with reaction field theory , 1989 .

[20]  J. Stewart.  Optimization of parameters for semiempirical methods I. Method , 1989 .

[21]  Jacopo Tomasi,et al.  Approximate evaluations of the electrostatic free energy and internal energy changes in solution processes , 1982 .

[22]  Jacopo Tomasi,et al.  Conformational energy of glycine in aqueous solutions and relative stability of the zwitterionic and neutral forms. An ab initio study , 1984 .

[23]  F. J. Luque,et al.  Comparative study of the molecular electrostatic potential obtained from different wavefunctions. Reliability of the semiempirical MNDO wavefunction , 1990 .

[24]  R. Bonaccorsi,et al.  The effect of the solvent in electronic transitions: some recent developments in the continuum model , 1984 .

[25]  P. Kollman,et al.  Atomic charges derived from semiempirical methods , 1990 .

[26]  J. Tomasi,et al.  Electrostatic interaction of a solute with a continuum. A direct utilizaion of AB initio molecular potentials for the prevision of solvent effects , 1981 .

[27]  Vincenzo Mollica,et al.  Group contributions to the thermodynamic properties of non-ionic organic solutes in dilute aqueous solution , 1981 .

[28]  O. Tapia,et al.  Medium polarization effect on proton potential shape S.A SCRF--MO CNDO/2 study of methanol and methanethiol H-bonded to imidazol. , 1978, Biochemical and biophysical research communications.