Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Charged Soft Matter, Polyelectrolytes and Ionic Liquids I

CPP 32.7: Vortrag

Mittwoch, 3. April 2019, 11:00–11:15, H13

Kinetic Pathways of Water Exchange in the First Hydration Shell of Magnesium — •Nadine Schwierz — Max Planck Institute of Biophysics

Water exchange between coordination shells of metal cations in aqueous solutions is fundamental in understanding the reactivity of the ions and their binding kinetics. Simulating water exchange with atomistic resolution is challenging due to the broad range of timescales involved ranging from picoseconds to milliseconds. Here, we apply a combination of transition path sampling and Umbrella sampling to accurately determine the exchange rates and to gain atomistic insight into the molecular pathways of water exchange. Using a recently developed atomistic model for Magnesium, water molecules remain in the first hydration shell for 10 ms on average, a time considerably longer compared to the 0.1 ms predicted by transition state theory using a single ion-water distance as order parameter. The discrepancy between these time scales arises from neglected degrees of freedom of other solvent molecules which play a decisive role in the reaction mechanism of water exchange.