Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 7 October 2005:
Vol. 310. no. 5745, pp. 83 - 86
DOI: 10.1126/science.1117756
Prev | Table of Contents | Next

Reports

Sequential Proton Transfer Through Water Bridges in Acid-Base Reactions

Omar F. Mohammed,1 Dina Pines,2 Jens Dreyer,1 Ehud Pines,2* Erik T. J. Nibbering1*

The proton transfer mechanism between aqueous Brønsted acids and bases, forming an encounter pair, has been studied in real time with ultrafast infrared spectroscopy. The transient intermediacy of a hydrated proton, formed by ultrafast dissociation from an optically triggered photoacid proton donor ROH, is implicated by the appearance of an infrared absorption marker band before protonation of the base, B–. Thus, proton exchange between an acid and a base in aqueous solution is shown to proceed by a sequential, von Grotthuss–type, proton-hopping mechanism through water bridges. The spectra suggest a hydronium cation H3O+ structure for the intermediate, stabilized in the Eigen configuration in the ionic complex RO–···H3O+···B–.

1 Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, D-12489 Berlin, Germany.
2 Department of Chemistry, Ben-Gurion University of the Negev, Post Office Box 653, Beer-Sheva 84125, Israel.

* To whom correspondence should be addressed. E-mail: epines{at}bgumail.bgu.ac.il (E.P.); nibberin{at}mbi-berlin.de (E.T.J.N.)

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Structural Evidence of Substrate Specificity in Mammalian Peroxidases: STRUCTURE OF THE THIOCYANATE COMPLEX WITH LACTOPEROXIDASE AND ITS INTERACTIONS AT 2.4 A RESOLUTION.
I. A. Sheikh, A. K. Singh, N. Singh, M. Sinha, S. B. Singh, A. Bhushan, P. Kaur, A. Srinivasan, S. Sharma, and T. P. Singh (2009)
J. Biol. Chem. 284, 14849-14856
   Abstract »    Full Text »    PDF »
Acid-base analysis: a critique of the Stewart and bicarbonate-centered approaches.
I. Kurtz, J. Kraut, V. Ornekian, and M. K. Nguyen (2008)
Am J Physiol Renal Physiol 294, F1009-F1031
   Abstract »    Full Text »    PDF »
Trapped water molecules are essential to structural dynamics and function of a ribozyme.
M. M. Rhodes, K. Reblova, J. Sponer, and N. G. Walter (2006)
PNAS 103, 13380-13385
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)