Protonation states environmental effects

The empirical valence bond (EVB) approach introduced by Warshel and co-workers is an effective way to incorporate environmental effects on breaking and making of chemical bonds in solution. It is based on parame-terizations of empirical interactions between reactant states, product states, and, where appropriate, a number of intermediate states. The interaction parameters, corresponding to off-diagonal matrix elements of the classical Hamiltonian, are calibrated by ab initio potential energy surfaces in solu-fion and relevant experimental data. This procedure significantly reduces the computational expenses of molecular level calculations in comparison to direct ab initio calculations. The EVB approach thus provides a powerful avenue for studying chemical reactions and proton transfer events in complex media, with a multitude of applications in catalysis, biochemistry, and PEMs. 

We also studied protonation state of GFP chromophore [103] and environmental effect [35],... 

Even though rapid tautomerization is observed in an isolated system, it is not necessarily the case in the solid state, in which the symmetrical proton potential is sometimes deformed by an environmental effect. Therefore, the... 

Sampogna, R. and B. Honig. (1994). Environmental effects on the protonation states of active site residues in bacteriorhodopsin. Biophysical J. 66 1341-52. 

Interactions between adjacent particles of condensed phases can lead to quantum correlations, quantum interference, entanglement and decoherence, delocalization and "Schrodinger s cat" states. Such effects are theoretically expected to be extremely short-lived, due to environmental disturbances. Therefore, it has been widely believed that they cannot be experimentally detected. However, based on previous theoretical work (cf. [Chatzidimitriou-Dreismann 1995 Chatzidimitriou-Dreismann 1997 (b)]), we proposed to detect QE in condensed systems by means of sufficiently "fast" scattering techniques. Particularly suitable for this purpose is the NCS method. Our NCS investigations (on liquid H2O - D2O mixtures [Chatzidimitriou-Dreismann 1997 (a)]) started 1995 and have provided, for the first time, direct experimental evidence of attosecond QE between a proton and its adjacent particles. 

Environmental effects, especially changes in solvent polarity, on the photophysical properties of dyes have been described. Likewise, solvation dynamics have been measured for dyes that undergo a substantial increase in dipole moment following excitation.Light-induced intramolecular proton transfer is an important route for non-radiative deactivation of an excited state and has been studied extensively in recent times. Double proton transfer has been reported for [2,2 -bipyridyl]-3,3 -diol ° and for 7-azaindole. ... 

Therefore, it has been postulated that in any reaction the reacting partners form a molecular complex of some kind before they reach the transition state [38, 55]. This must be taken into account when environmental effect on chemical reactivity is interpreted. Many literature data (9, 39, 40, 42] seem to support this postulate. Even diffusion controlled proton transfer is preceded by the formation of a hydrogen-bridged species [50] Let us mention finally that the most fruitful theory of chemical reactivity (intermolecular perturbation) presents charge-transfer between reacting partners as an indispensable and unavoidable step in the overall reaction [51]. 

Environmental Effects on Excited-State Proton Transfer Reactions.56... 

Environmental effects on excited-state proton transfer reactions... 

ENVIRONMENTAL EFFECTS ON EXCITED-STATE PROTON TRANSFER REACTIONS... 

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