Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis.

Schmidt, S. W., Kersch, A., Beyer, M. K. and Clausen-Schaumann, H. (2011) Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis. Physical Chemistry Chemical Physics, 13 (13). pp. 5994-5999. DOI 10.1039/c0cp02827d.

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Abstract

We have used temperature-dependent single molecule force spectroscopy to stretch covalently anchored carboxymethylated amylose (CMA) polymers attached to an amino-functionalized AFM cantilever. Using an Arrhenius kinetics model based on a Morse potential as a one-dimensional representation of covalent bonds, we have extracted kinetic and structural parameters of the bond rupture process. With 35.5 kJ mol(-1), we found a significantly smaller dissociation energy and with 9.0 X 10(2) s(-1) to 3.6 X 10(3) s(-1) also smaller Arrhenius pre-factors than expected for homolytic bond scission. One possible explanation for the severely reduced dissociation energy and Arrhenius pre-factors is the mechanically activated hydrolysis of covalent bonds. Both the carboxylic acid amide and the siloxane bond in the amino-silane surface linker are in principle prone to bond hydrolysis. Scattering, slope and curvature of the scattered data plots indicate that in fact two competing rupture mechanisms are observed.

Document Type: Article
Keywords: catalyzed amide hydrolysis chair-boat transitions aqueous-solution molecular-dynamics quartz dissolution formamide kinetics energy water mechanochemistry
Research affiliation: Kiel University
Refereed: Yes
DOI etc.: 10.1039/c0cp02827d
ISSN: 1463-9076
Date Deposited: 01 Nov 2012 04:59
Last Modified: 23 Jan 2013 10:04
URI: http://oceanrep.geomar.de/id/eprint/18571

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