Single-molecule contact switching electro-inductive effects.

The non-faradaic application of electric fields generated at the surface of charged electrodes to polarize bound molecules, also termed as electro-inductive effects, have recently attracted increasing attention in modifying the chemical reactivity of molecules in electrosynthesis. Herein, we applied this electro-inductive effect to control the Lewis adduct formation and dissociation between BF and pyridine N of heterocycles to realize single-molecule contact switching. single-molecule conductance measurements, Raman analysis and theoretical calculations clearly show that the outward electric field along the positively-charged electrode surface polarizes adsorbed molecules to withdraw electron density from the terminal pyridine N, which weakens the N-BF Lewis bond for dissociation upon applied positive potentials. The released unbounded pyridine N can connect the molecule into a molecular circuit for electron transfer (considered as the "ON" state). Meanwhile, the inward electric field along the negatively charged electrode surface promotes the formation of an N-BF Lewis bond, leading to breaking of the molecular circuit (considered as the "OFF" state). Combined with the optimization of BF concentration from the equilibrium BF ⇌ BF + F, the electro-inductive effect can reversibly switch single-molecule conductance in conductance measurements and tunnelling currents in - measurements.