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

TL;DR

This paper demonstrates how tip-induced redox reactions can reversibly and selectively control bond formation and dissociation at the single-molecule level, advancing understanding of molecular selectivity and mechanisms.

Contribution

It introduces a method for controlling molecular reactions via tip-induced redox chemistry, revealing the role of charge states and energy landscapes in selectivity.

Findings

Reversible and selective bond formation/dissociation achieved by voltage pulses.

Reaction rates and voltage dependence characterized and analyzed.

Density functional theory supports the role of charge states in selectivity.

Abstract

Controlling selectivity of reactions is a quest in chemistry. Here, we demonstrate reversible and selective bond formation and dissociation promoted 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 and atomic force microscope. Characterization of voltage dependence of the reactions and determination of reaction rates demonstrate selectivity in constitutional isomerization reactions and provide insight into the underlying mechanisms. With support of density functional theory calculations, we find that the energy landscape of the isomers in different charge states is important to rationalize the selectivity. Tip-induced selective single-molecule reactions increase our understanding of redox chemistry and could lead to novel molecular machines.