Conformational Gating of Many-Body Kondo Resonance in a Topologically Confined Radical Macrocycle

Abstract

The on-demand, reversible manipulation of many-body spin states in single-molecule junctions is a central challenge in molecular electronics. Here, we report the on-surface synthesis and localized gating of a highly symmetric, covalent macrocyclic hexamer composed of stable Blatter radicals on Au(111). Benefiting from the topological confinement of the rigid macrocyclic framework, the individual radical units exhibit exceptional structural and electronic stability. Scanning tunneling spectroscopy reveals distinct Spin-1/2 Kondo resonances localized at each triazinyl core. By applying local voltage pulses from an STM tip, we achieve high-fidelity, reversible switching between two conformational states via the rotation of a phenyl substituent, which significantly modulates the molecule–substrate hybridization and reduces the Kondo line width by nearly half. Crucially, due to the synergistic topological confinement provided by the intrinsically localized spin distribution and the destructive quantum interference inherent in the meta-phenylene linkages, adjacent spin centers remain magnetically isolated, allowing independent, single-site addressing with zero cross-talk. Comparison with a strained, non-planar pentamer underscores the vital role of macrocyclic configuration in preserving manipulation stability. This work provides a robust chemical platform for the spatial-selective control of localized strong-correlation phenomena in covalent radical nanostructures.