Dual-Site Engineering Unlocks Spin Modulation and Local Field-Controlled Charge Switching in Triangulenes

Open-shell nanographenes, featuring highly tunable and correlated magnetic states, constitute a promising platform for engineering graphene nanomagnets towards molecular-scale spintronics and quantum information technologies. However, their magnetic states are largely dictated by topological constraints and strong electronic correlations, limiting independent control of spin and charge degrees of freedom. Here, we introduce a structural dual-site engineering strategy that integrates intrinsic spin modulation with adsorption- and field-controlled charge state tuning in a single magnetic nanographene, enabling a level of multifunctional control not previously demonstrated. We design and synthesize nitrogen, sulfur-co-engineered [3]triangulene (N,S-Tri), incorporating a central nitrogen dopant and an edge sulfur substitution with complementary functions. The central nitrogen modifies the occupation of the frontier π states and thereby tunes the molecular spin configuration, while the edge sulfur site weakly participates in the low-energy π-state and simultaneously acts as a tunable chemical anchor that regulates molecule-substrate coupling and charge transfer. Using low-temperature scanning probe microscopy, we directly visualize switching from neutral to cationic states, driven by adsorption-site variation on Au(111), or reversible switching by local electrostatic gating. This dual-functional design moves beyond static doping or interface charge transfer in graphene nanomagnets, enabling field-controlled dynamic modulation of spin and charge states, and opening new opportunities for device-oriented applications where molecule-electrode interactions and electrostatic field control play central roles.