Molecular switches from benzene derivatives adsorbed on metal surfaces

Transient precursor states are often experimentally observed for molecules adsorbing on surfaces. However, such precursor states are typically rather short-lived, quickly yielding to more stable adsorption configurations. Here we employ first-principles calculations to systematically explore the interaction mechanism for benzene derivatives on metal surfaces, enabling us to selectively tune the stability and the barrier between two metastable adsorption states. In particular, in the case of the tetrachloropyrazine molecule, two equally stable adsorption states are identified with a moderate and conceivably reversible barrier between them. We address the feasibility of experimentally detecting the predicted bistable behaviour and discuss its potential usefulness in a molecular switch. Short-lived precursors typically occur before molecules chemisorb on surfaces. Liu et al. predict that for benzene derivatives on metal surfaces, the precursors can be long-lived and the transition to chemisorption states can be reversible, which may be useful in molecular switch applications.