A frequency-resolved cavity model (FRCM) for treating equilibrium and non-equilibrium solvation energies. 2: Evaluation of solvent reorganization energies

Abstract The frequency-resolved cavity model (FRCM), a generalized continuum reaction field model, which allows for distinct effective solute cavities pertaining to optical (op) and inertial (in) solvent response, has been implemented and applied to the evaluation of solvent reorganization energy ( E s ) for a number of intramolecular electron transfer (ET) processes in polar media. Specifically, effective radii are defined for the solute atoms: r ∞ = κ · r vdW (where κ is taken as a universal scale factor) and r in = r ∞ + δ (where δ is specific to a particular solvent). Optimal values of κ and δ are determined through the use of solvation free energy data for small atomic and molecular ions, together with the experimental estimates of solvation reorganization energy ( E s ) for intramolecular ET in the steroid-based radical ions studied by Closs, Miller and co-workers [G.L. Closs, L.T. Calcaterra, N.J. Green, K.W. Penfield, J.R. Miller, J. Phys. Chem. 90 (1986) 3673; M.D. Johnson, J.R. Miller, N.S. Green, G.L. Closs, J. Phys. Chem. 93 (1989) 1173; J.R. Miller, B.P. Paulson, R. Bal, G.L. Closs, J. Phys. Chem. 99 (1995) 6923]. With these optimal parameters, E s is then evaluated for a number of other intramolecular ET processes, yielding results which are in generally good agreement with experimentally based estimates, and which give support for some of the assumptions employed in the analysis of the experimental data. Calculations with conventional solute atom radii ( r ∞ = r in , with κ =1.2 and δ =0) fitted to equilibrium solvation data yield E s values exceeding the FRCM results by factors of ≥2.

[1]  D. Matyushov,et al.  OPTICAL AND RADIATIONLESS INTRAMOLECULAR ELECTRON TRANSITIONS IN NONPOLAR FLUIDS : RELATIVE EFFECTS OF INDUCTION AND DISPERSION INTERACTIONS , 1995 .

[2]  Robert J. Cave,et al.  Generalization of the Mulliken-Hush treatment for the calculation of electron transfer matrix elements , 1996 .

[3]  M. V. Basilevsky,et al.  Quantum-chemical calculations of the hydration energies of organic cations and anions in the framework of a continuum solvent approximation , 1992 .

[4]  H. Friedman,et al.  Energetics of charge transfer reactions in solvents of dipolar and higher order multipolar character. I. Theory , 1996 .

[5]  Mark D. Johnson,et al.  Distance dependence of intramolecular hole and electron transfer in organic radical ions , 1989 .

[6]  M. V. Basilevsky,et al.  Quantum-chemical evaluation of energy quantities governing electron transfer kinetics: applications to intramolecular processes , 1996 .

[7]  M. V. Basilevsky,et al.  A frequency-resolved cavity model (FRCM) for treating equilibrium and non-equilibrium solvation energies , 1998 .

[8]  M. Paddon-Row,et al.  Optical and thermal electron transfer in rigid difunctional molecules of fixed distance and orientation , 1987 .

[9]  N. J. Green,et al.  Distance, stereoelectronic effects, and the Marcus inverted region in intramolecular electron transfer in organic radical anions , 1986 .

[10]  M. Newton,et al.  The multi-configurational adiabatic electron transfer theory and its invariance under transformations of charge density basis functions , 1994 .

[11]  M. Newton,et al.  Solvent Reorganization and Donor/Acceptor Coupling in Electron-Transfer Processes: Self-Consistent Reaction Field Theory and ab Initio Applications , 1995 .

[12]  Rudolph A. Marcus,et al.  Chemical and Electrochemical Electron-Transfer Theory , 1964 .

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

[14]  J. Stewart.  Optimization of parameters for semiempirical methods II. Applications , 1989 .

[15]  W. Fawcett,et al.  Estimation of the outer-sphere contribution to the activation parameters for homogeneous electron-transfer reactions using the mean spherical approximation , 1991 .

[16]  P. Eaton,et al.  Long-distance electron transfer through rodlike molecules with cubyl spacers , 1993 .

[17]  Linus Pauling,et al.  The Nature of the Chemical Bond and the Structure of Molecules and Crystals , 1941, Nature.

[18]  Rudolph A. Marcus,et al.  On the Theory of Oxidation‐Reduction Reactions Involving Electron Transfer. I , 1956 .

[19]  M. Newton,et al.  Electron Transfer Reactions in Condensed Phases , 1984 .

[20]  John R. Miller,et al.  Torsional Low-Frequency Reorganization Energy of Biphenyl Anion in Electron Transfer Reactions , 1995 .

[21]  Harold L. Friedman,et al.  Green function theory of charge transfer processes in solution , 1988 .