Proton transfer quantum intermolecular

We have examined the proton transfer reaction AH-B A -H+B in liquid methyl chloride, where the AH-B complex corresponds to phenol-amine. The intermolecular and the complex-solvent potentials have a Lennard-Jones and a Coulomb component as described in detail in the original papers. There have been other quantum studies of this system. Azzouz and Borgis performed two calculations one based on centroid theory and another on the Landau-Zener theory. The two methods gave similar results. Hammes-Schiffer and Tully used a mixed quantum-classical method and predicted a rate that is one order of magnitude larger and a kinetic isotope effect that is one order of magnitude smaller than the Azzouz-Borgis results. 

The earliest ideas about proton conduction in aqueous solutions were stimulated by considerations of the electrolytic decomposition of water in 1806. Grotthuss postulated chains of water dipoles along which electricity may be transported. One basic step which is part of any proton conduction mechanism formulated since the early days of physical chemistry had already been described by several authors at the beginning of this century . They recognized that intermolecular proton transfer can lead to charge transport at a rate exceeding that of other species. The first formal theory was attempted by Huckel in 1928 at a time when the existence of a discrete H30 ion had already been suspected. Huckel treated this species as a dipole and tried to calculate its reorientational rates into positions favourable for proton transfer to neighbouring water molecules. A first quantum mechanical theory of intermolecular proton... 

In this chapter, we have described the fundamental parameters that should be obtained when characterising an electronic, singlet or triplet, excited state and how to determine them experimentally including methodologies and required equipment. These characteristics include electronic energy, quantum yields, lifetimes and number and type of species in the excited state. Within this last context, i.e., when excited state reactions give rise to additional species in the excited state we have explored several excited state kinetic schemes, found to be present when excimers, exciplexes are formed and (intra and intermolecular) proton transfer occurs. This includes a complete formalism (with equations) for the steady-state and dynamic approaches for two and three-state systems, from where all the rate constants can be obtained. Additionally, we have explored additional recent developments in photophysics the competition between vibrational relaxation and photochemistry, and the non-discrete analysis (stretched-exponential) of fluorescence decays. 

Noguera, M., Bertran, J., 8c Sodupe, M. (2004). A quantum chemical study of Cu2+ interacting with guanine-cytosine base pair. Electrostatic and oxidative effects on intermolecular proton-transfer processes. The Journal of Physical Chemistry A, 108, 333. 

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