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

Schmidt, Sebastian W.; Kersch, Alfred; Beyer, Martin K. und Clausen-Schaumann, Hauke (2011): Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis. In: Physical Chemistry Chemical Physics, Vol. 13: pp. 5994-5999

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 × 102 s−1 to 3.6 × 103 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.

• Item Type: Journal article
• Form of publication: Publisher's Version
• Faculties: Physics
• Subjects: 500 Science > 530 Physics; 500 Science > 540 Chemistry
• Alliance/National Licence: This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
• Language: English