Imine Linkers Enable the Formation of Robust Single Molecule Junctions

While imine (C=N) groups are renowned for their role in dynamic chemistry, whether imine binds to Au electrodes for forming single-molecule junctions and their electronic properties remain elusive. We demonstrate that imine groups work as chemical anchors for reliable formation of single-molecule junctions with gold electrodes. Scanning tunneling microscope-based break junction measurements and density functional theory calculations reveal that imine-terminated wires exhibit slightly higher conductance than amine-terminated analogs. Critically, in the presence of a nearby phenyl ring substituent, junction formation is suppressed with amine anchors but not with imines, indicating expanded molecular designs attained with imine linkers. We further find that in addition to the structures terminated with one imine and one thiomethyl linkers, dual-imine terminated molecules can also form stable molecular junctions. Our findings highlight that imines can be used as linkers with slightly reduced contact resistance than commonly used amines, offering new molecular designs for constructing molecular devices.