Single Dynamic Covalent Bond Tailored Responsive Molecular Junctions

Responsive molecular devices are one of the core units for molecular electronics, and dynamic covalent bonds (DCBs) provide the opportunity for the fabrication of responsive molecular devices. Herein we employ a single dynamic acyl hydrazone bond to fabricate tailored molecular devices using the scanning tunneling microscopy break-junction technique (STM-BJ) and the eutectic Ga-In technique (EGaIn). We found that the single-DCB-tailored molecular devices exhibited acid-base and/or photo-thermal response with three well-defined molecular conductance states. The reversible switching has the ON/OFF ratio of approximate to 10 between each state for single-molecule junctions and approximate to 3 for the SAMs-based molecular junctions. Combined with the density functional theory calculations, we revealed that the multiple conductance states of these molecular junctions originate from the dynamic acyl hydrazone bond exchange and C=N isomerization. Our work opens the avenue towards the design of tailored single-molecule electrical devices by implanting dynamic covalent bonds in molecular architectures.

Automated summary

In this study, responsive molecular devices with acid-base and photo-thermal responses were fabricated using a single dynamic acyl hydrazone bond. The devices exhibited three well-defined molecular conductance states, with reversible switching and distinct ON/OFF ratios. Density functional theory calculations revealed that the multiple conductance states were due to the dynamic acyl hydrazone bond exchange and C=N isomerization. This work opens up new possibilities for designing tailored single-molecule electrical devices.