Reactions in single-molecule junctions

Developing new materials is a long-standing goal that extends across the fields of synthesis, catalysis, nanotechnology and materials science. Transforming one compound or material into another involves the gaining, losing and sharing of electrons at a molecular level. Investigating single-molecule reactions - and understanding how they provide information about or differ from reactions in the bulk - will deepen our understanding of chemical reactions and establish new frameworks in materials science. In this Review, we survey state-of-the-art chemical reactions occurring in single-molecule junctions. We explore the advantages of real-time testbeds that deliver detailed information about reaction dynamics, intermediates, transition states and solvent effects. We provide a quantitative perspective of the charge transport phenomena associated with chemical reactions at molecular tunnelling junctions, and we compare the behaviour of single-molecule reactions and those taking place in ensemble states. Finally, we explore the possibility of leveraging single-molecule catalysis for large-scale production of materials.