Proton Coupled Electron Transfer (PCET) and Excited State Proton Transfer reactions (ESPT), are important mechanisms for the charge transfer in a variety of processes of great importance in biochemistry (photosynthesis, enzyme reactions) and electrochemistry (fuel cells, chemical sensors).In this context, a challenge for theoretical approaches regards the accurate description of both the ground and excited state Potential Energy Surface (PES) associated to the reaction under investigation, in order to have a clear definition of the reaction space, including micro and bulk solvation effects. A great contribution to this purpose would be the validation of electronic methods rooted in Density Functional Theory, in both the gas and the liquid phase, and the use of purposely defined density based parameters to effectively characterize stationary points and probable reaction channels.Here we present results regarding the PCET in oligopeptides and the ESPT reaction between a coumarin dye and a base molecule.[1,2,3,4] In the first case, we evaluated the capability of various classes of density functionals to properly describe the PESs involved in the PCET reactions, in both the gas phase and the aqueous solvent, also investigating the influence of the microsolvation on the properties of residues acting as electron donor and acceptor.[2] In the second case we show how, by using ad hoc designed density based indices, it is possible to recover the main photo-physical features of the ESPT reaction and to characterize the stationary points of the excited state PES, thus allowing its full characterization and providing some hints on the most probable reaction channel.[4]References[1] Giese et al J.Org.Chem. 74, 3621 (2009)[2] Raucci et al manuscript in preparation.[3] Papanikolas et al J. Phys. Chem. B 116, 14886 (2012)[4] Savarese et al J. Phys. Chem. B 117, 16165 (2013)

Another brick in the wall of PCET reactions: DFT point of view

248th National Meeting (2014)

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