Lecture Erik T.J. Nibbering
|19 May 2005||FWN-Building 5118.-152, Nijenborgh 4, 9747 AG, Groningen|
|Speaker:||Dr. Erik T.J. Nibbering|
|Affiliation:||Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin|
|Title:||Sequential proton transfer through water bridges in acid-base reactions|
|Date:||Thu May 19, 2005|
|Telephone:||+31 50 363 4369|
Aqueous proton transfer is one of the most fundamental chemical reactions. For instance, water mediates the transfer of a proton in membrane protein proton channels. These proton channels function by a sequential hopping of protons through proton wires consisting of amino acid side groups and water molecules. A sequential proton transfer is also at the heart of the von Grotthuss mechanism of anomalous high proton mobility in water. Water is considered to play a key role in aqueous acid-base neutralization reactions, where a proton is exchanged between an acid and a base, forming the conjugated base and conjugated acid respectively. Theoretical considerations have shown that water facilitates an efficient charge separation when the proton leaves the acid.
In this work we show compelling experimental evidence that water in addition functions as a bridge between an acid and a base, by both providing and stabilizing the proton transfer pathway. For optical triggering the proton transfer reaction we use a photoacid [1,2]. In particular we detect the transient behaviour of the IR-active marker mode of the hydrated proton to be correlated with the transient reactant and product bands. The hydrated proton in our acid-base neutralization experiment turns out to be similar to the Eigen cation and not the Zundel cation for solvated protons in water.
 M. Rini, B. Magnes, E. Pines, E. T. J. Nibbering, Science 301, 349 (2003).
 M. Rini, D. Pines, B. Z. Magnes, E. Pines, E. T. J. Nibbering, J. Chem. Phys. 121, 9593 (2004)
|Last modified:||22 October 2012 2.30 p.m.|