Selectivity in single-molecule reactions by tip-induced redox chemistry

Selective and reversible bond formation and dissociation can be controlled by tip-induced reduction-oxidation reactions on a surface. Molecular rearrangements leading to different constitutional isomers are selected by the polarity and magnitude of applied voltage pulses from the tip of a combined scanning tunneling microscope (STM) / atomic force microscope (AFM). Combining STM, AFM and Kelvin probe force microscopy data and measurements of reaction yields as a function of voltage and current, we obtain insights into the reaction mechanism and find that the energy landscape of the isomers in different charge states is important to rationalize the selectivity of the reactions.