Chemical responsivity of the charge transport through molecular junctions is vital towards the sensing applications at the single‐molecule scale, and quantum interference effect in charge transport offers a unique chance to enhance the chemical responsivity of single‐molecule junctions. Here, we investigate the chemical responsive quantum interference in the charge transport through single molecules dithienoborepin (DTB) junctions with specific coordination of fluoride ion in solution. The single‐molecule conductance of two DTB isomers is measured using scanning tunnelling microscopy break‐junction (STM‐BJ) before and after fluoride ion exposure. We find that the conductance responsibility to fluoride ions in the conjugation of two isomers of DTB molecules depends on the position of the boron atom, and the switching ratios can be up to four orders of magnitudes for the isomer with quantum interference, suggest quantum interference leads to significant conductance difference after the boron‐fluoride coordination. Quantum chemical calculations are in agreement with the experimental data and indicate that destructive quantum interference is the origin of the observed large switching ratios.

go back