Nowadays sophisticated time-resolved spectroscopy techniques[1] allow for a deeper understanding of molecular relaxation processes triggered by the electronic excitation, such the forces ruling the solvation dynamics of solvatochromic dyes, excited state proton transfers, and, more in general, photo-reactions.Unfortunately, the experiment itself is often not enough to unveil the detail of the molecular motion hidden behind the spectra. In this context, a theoretical-computational study can be an invaluable support to understand, for example, the driving forces, the mechanism and kinetics of a photoreaction.We combine ab-initio molecular dynamics simulations with a robust and extensively applicable theoretical-computational protocol to perform time-resolved vibrational analysis.[2, 3] Essentially, normal-like modes extracted from trajectories[4] can be analyzed[5-6] to obtain the temporal evolution of the frequencies underlying a signal of both stationary and non-stationary nature. This tool seems to be very promising for a wide range of applications in chemistry. Here we present results regarding the photo-reactivity of Green Fluorescent Protein,[2] and the non-equilibrium solvation dynamics of the solvatochromic dye N-methyl-6-oxyquinolinium betaine in water solution.[3] Perspectives of the method and future developments are also discussed.[1] P. Kukura et al., Annu.Rev.Phys.Chem., 58 , 461 (2007)[2] G. Donati, A. Petrone, N. Rega, manuscript in preparation[3] A. Petrone, G. Donati, N. Rega, manuscript in preparation[4] N. Rega, Theor.Chem.Acc., 116 , 347 (2006)[5] I. Daubechies, IEEE Trans Inf Theory, 36 , 961 (1990)[6] S.G. Mallat, IEEE, 11  , 674 (1989)

Time-resolved vibrational analysis to unveil excited state proton transfer mechanisms: A theoretical-computational protocol

248th National Meeting (2014)

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