Hydrogen bonds proton transfer process

Berendsen, H.J.C., Mavri, J. Simulating proton transfer processes Quantum dynamics embedded in a classical environment. In Theoretical Treatments of Hydrogen Bonding, D. Hadzi, ed., Wiley, New York (1997) 119-141. 

Elsaesser TH, Bakker HJ (2002) Ultrafast hydrogen bonding dynamics and proton transfer processes in the condensed phase. Springer, Heidelberg... 

The conclusions reached about proton transfer from phenylazoresorcinol monoanions are quite different from the behaviour which has been described for other hydrogen-bonded acids. For phenylazoresorcinol monoanions, it appears that direct attack by base on the hydrogen-bonded proton is an important process and can compete with two-step proton removal. For two-step proton transfer through an open form of the phenylazoresorcinol monoanion it is found that the rate of proton transfer from the open form is... 

S. Bratos, J.-C. Leicknam, G. Gallot, and H. Ratajczak, Ultrafast Hydrogen Bond Dynamics and Proton Transfer Processes in the Condensed Phase, T. Elsaesser and H.J. Bakker (eds.), Kluwer Academic, Dordrecht, 2002, p. 5. 

On the other hand, among electrode reactions involving bond-breaking steps, theoretical approaches to the hydrogen electrode reaction have been extensively treated in the electrochemical literature [31, 41, 58— 62]. These reactions can be regarded as heterogeneous proton transfer processes. 

Hybrid multiscale models enable us to focus on the relevant part of a system. For example, Leenders et al. studied the proton transfer process in the photoactive yellow protein (Figure 6.3) [9], They used Car-Parrinello molecular dynamics [10], a QM method for dynamics simulations, to describe the chromophore and its hydrogen-bonded network in the protein pocket (middle and right-hand circles). This was combined with a traditional MD force field of 28 600 atoms, simulating the entire protein in water (left-hand circle). 

The 17r<7 states also dominate the photoinduced processes in hydrogen-bonded chromophore-solvent clusters. The photoinduced hydrogen transfer reaction is experimentally and computationally well documented in clusters of phenol and indole with ammonia [14,16,32], There is no clear evidence for the existence of an excited-state proton transfer process in these systems [14], The same conclusion applies to bi functional chromophores solvated in finite clusters, such as 7HQ-ammonia and 7HQ-water clusters [15]. In future work, the photochemistry of larger and biologically relevant chromophores (such as tyrosine, tryptophan, or the DNA bases) should be investigated in a finite solvent environment. 

Intermolecular charge- and proton-transfer processes, that is, the motion of the proton associated with the change of electronic structure in hydrogen-bonded complexes, are involved in many chemical reactions in solution. The study of such processes in small clusters leads to very detailed information on the reactive event. 

Proton transfer (process III) in the excited state, which can be followed by the emission of the ionic form of a hydrogen-bonded phenolate anion [A- - BH+(B) —process V]. A large shift is then expected in the excitation spectrum and the dispersed fluorescence spectra typical of A. ... 

Occasionally, potential energy curves for bond stretching vibrations can be unusually flat as well. One special case is of particular importance in hydrogen-bonded complexes. At infinite intermolecular distance two states are possible in which the proton is either bound to molecule A or to molecule B. The two states are related by a proton transfer process ... 

Zundel, G. (2000) Hydrogen bonds with large proton polarizability and proton transfer processes in electrochemistry and biology, in Prigogine, I. and Rice, S. A. (eds) Adv. Chem. Phys. Ill, John Wiley Sons, Inc. 1-218. 

Zundel, G., Proton polarizability and proton transfer processes in hydrogen bonds and cation polarizabilities of other cation bonds—their importance to understand molecular processes in electrochemistry and biology. Trends Phys. Chem. 3, 129-156 (1992). 

The authors conclude that the emitting state created after excitation of the phenol form is predominantly quinoid but not identical with the excited cls-qulnone. It is speculated that the proton transfer process may not be a simple transfer between two minima of a hydrogen bond but rather involve another minimum In which the proton can be trapped. The same suggestion has been made previously by Shlgorln (84) on the basis of theoretical arguments. 

G. Zundel, Hydrogen Bonds with Large Proton Polarizability and Proton Transfer Process in Electrochemistry and Biology, in Advances in Chemical Physics (Eds. I. Prigogine and S. A. Rice), Vol. Ill, Wiley, New York, 2000. 

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