Proton Transfer Reactions in Nanoconfined Solvents

A key component of our efforts to address the fundamental question:

How does a chemical reaction occur differently in a nanoconfined solvent than in a bulk solvent?

are investigations into proton transfer reactions in nanoconfined solvents.  Charge transfer processes are typically strongly coupled to the solvent and are therefore dramatically affected by the limited number of solvent molecules, geometric constraints, and surface hydrophilicity/hydrophobicity.  Thus, proton transfer reactions, which are by themselves a critically important class of reactions, represent an interesting avenue for investigation.  By understanding how reactivity is connected to the pore characteristics, these studies may assist in the development of design principles for microporous and mesoporous catalysts as well as a better understanding of biological processes.

Our work on proton transfer reactions in nanoconfined solvents have so far focused primarily on a model phenol-amine proton transfer reaction in atomically smooth, spherical, hydrophobic nanocavities.  Among the topics we have investigated are:

  • The modified mechanisms, free energy surfaces, and reaction rate constants upon nanoconfinement. See J. Phys. Chem. B 109, 4941 (2005) and J. Phys. Chem. B 109, 18201 (2005).
  • The infrared spectral signatures of a proton transfer complex and how they relate to the equilibrium and dynamical information contained in linear and nonlinear vibrational spectra. See J. Phys. Chem. B 112, 7448 (2008).
  • The role of vibrational nonadiabaticity in the reaction rate constant.  See J. Phys. Chem. B 114, 7535 (2010).
  • Useful definitions of the reaction coordinate for proton transfer reactions in complex environments, where the usual collective solvent coordinate may not represent the full picture.  See J. Phys. Chem. A 116, 832 (2011).

We are continuing to pursue a number of interesting issues associated with proton transfer in nanoconfined solvents including predictions for realistic, experimentally-accessible reaction complexes and confining frameworks.

Relevant References:

Ward H. Thompson,
Annual Reviews of Physical Chemistry, 62, 599-619 (2011). Abstract
``Solvation Dynamics and Proton Transfer in Nanoconfined Liquids”

Being J. Ka and Ward H. Thompson,
Journal of Physical Chemistry A 116, 832-838 (2011). Abstract
``Sampling the Proton Transfer Reaction Coordinate in Mixed Quantum-Classical Molecular Dynamics Simulations"

Being J. Ka and Ward H. Thompson,
Journal of Physical Chemistry B 114, 7535-7542 (2010). Abstract
``Nonadiabatic Effects on Proton Transfer Rate Constants in a Nanoconfined Solvent"

Katie R. Mitchell-Koch and Ward H. Thompson,
Journal of Physical Chemistry B 112, 7448-7459 (2008). Abstract
``Infrared Spectroscopy of a Model Phenol-Amine Proton Transfer  Complex in Nanoconfined CH3Cl"

Ward H. Thompson,
Journal of Physical Chemistry B 109, 18201 - 18208 (2005). Abstract
``Proton Transfer in Nano-confined Polar Solvents. II. Adiabatic Proton Transfer Dynamics"

Shenmin Li and Ward H. Thompson,
Journal of Physical Chemistry B 109, 4941 - 4946 (2005). Abstract
``Proton Transfer in Nano-confined Polar Solvents. I. Free Energies and Solute Position"


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