Publication

Ab initio molecular dynamics simulation of redox reactions of transition metal ions in aqueous solution and proteins

Ivano Tavernelli
2005
Conference Papers

Résumé

Redox potentials measure the free energy required to transfer a mol. species (ion) between two states of different total charge. In soln. a major contribution to the redox potential is the hydration free energy difference of the ion in the two oxidn. states which can in principle be computed from classical mol. dynamics (MD) simulation. However, for redox active transition metal ions reliable force fields are in general not available and one has to use quantum chem. methods which are capable of describing large solvent fluctuations. From this point of view Car-Parrinello MD (CPMD) combining 'on the fly' electronic structure calcn. with classical mol. dynamics of the ions is the method of choice for simulation of transition metal ions. In the last years we have been developing novel schemes for the computation of redox properties from first principles. In our approach reactant and product (i.e. the two oxidn. states of an ion) are described by two potential energy surfaces which differ by the no. of electrons. The transformation between the two surfaces can be enforced using geometrical constraints, thermodn. integration techniques or grand canonical methods. In addn. to redox potential the first two methods also yield free energy curves of oxidn. which can be used to test the predictions of Marcus theory of electron transfer. In the talk our computational methods will be explained and results presented for the half reactions Ag(I) -> Ag(II) and Ru(II) -> Ru(III) in aq. soln. and Ru(II) -> Ru(III) in a de-novo designed porphyrine-protein. [on SciFinder (R)]

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https://infoscience.epfl.ch/entities/publication/499d0303-6aab-4f5a-9b8e-6e86ae227828

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Ivano Tavernelli
2005
Conference Papers

Résumé

Source officielle

https://infoscience.epfl.ch/entities/publication/499d0303-6aab-4f5a-9b8e-6e86ae227828

À propos de ce résultat

Concepts associés (32)

Réaction d'oxydoréduction

vignette|L'aluminothermie est une réaction d'oxydoréduction entre l'aluminium et certains oxydes métalliques. Une réaction d'oxydoréduction ou réaction rédox est une réaction chimique au cours de laquelle se produit un transfert d'électrons. Elle consiste en une réaction oxydante couplée à une réaction réductrice. L'espèce chimique qui capte les électrons est l'oxydant et celle qui les cède, le réducteur. La réaction est caractérisée par une variation du nombre d'oxydation (n.o.) de chacune des espèces en jeu.

Potentiel d'oxydoréduction

Le potentiel d'oxydoréduction, ou potentiel redox, est une grandeur empirique exprimée en volts et généralement notée (ou, pour le potentiel redox standard, E(M/M) où M désigne un métal quelconque). Ce potentiel est exprimé par rapport à une référence, souvent mesurée par une électrode normale à hydrogène (ENH, d'où l'unité V/ENH rencontrée dans certains ouvrages). Cette mesure est appliquée aux couples d'oxydoréduction pour prévoir la réactivité des espèces chimiques entre elles.

Standard electrode potential

In electrochemistry, standard electrode potential , or , is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: "the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode". The basis for an electrochemical cell, such as the galvanic cell, is always a redox reaction which can be broken down into two half-reactions: oxidation at anode (loss of electron) and reduction at cathode (gain of electron).

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