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Updated: Mar 14, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Force-induced tautomerization in a single molecule
Janina N Ladenthin1, Thomas Frederiksen2,3, Mats Persson4
1Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
Abstract:
Heat transfer, electrical potential and light energy are common ways to activate chemical reactions. Applied force is another way, but dedicated studies for such a mechanical activation are limited, and this activation is poorly understood at the single-molecule level. Here, we report force-induced tautomerization in a single porphycene molecule on a Cu(110) surface at 5 K, which is studied by scanning probe microscopy and density functional theory calculations. Force spectroscopy quantifies the force needed to trigger tautomerization with submolecular spatial resolution. The calculations show how the reaction pathway and barrier of tautomerization are modified in the presence of a copper tip and reveal the atomistic origin of the process. Moreover, we demonstrate that a chemically inert tip whose apex is terminated by a xenon atom cannot induce the reaction because of a weak interaction with porphycene and a strong relaxation of xenon on the tip as contact to the molecule is formed.
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