Transition Metal Based Spin‐Tuned Charge Transfer in Single‐Molecule Junctions

Investigating the correlation between metal coordination and molecular conductivity in single-molecule systems is essential for advancing our knowledge of molecular electronics, particularly in the realm of spintronics. In the present study, we developed two complex wires utilizing the bipyridine ligand and two transition metal ions, Co²⁺ and Zn²⁺, aiming to study the impact of different spin characters on single-molecule charge transport properties. Single-molecule conductance was investigated using scanning tunnelling microscope breaking junctions (STM-BJ) technique and the underlying mechanism was analysed by density functional theory (DFT) calculations. We demonstrated that the conductance predominantly increases after inserting Zn²⁺, indicating a conducting channel has been constructed. In contrast, the conductance of the analogue coordinated with Co²⁺ does not change significantly, this can be explained by distinct disparities between spin-up and spin-down channels, in which destructive quantum interference in spin-down state counteracts the enhancement of molecular conductance. Our study establishes the groundwork for a systematic approach to the design, fabrication, and implementation of single-complex conductance explorations.