Towards Unified Mechanism of Bias-dependent Switching in Reactive Self-assembly Systems

Reversible transitions of surface-adsorbed molecules under external stimuli hold great promise for advancing nanotechnology. Among various stimuli, electric fields have demonstrated remarkable potential in modulating the molecular assembly and reactivity. Despite extensive studies, the mechanism governing bias-induced phase transitions in surface- confined systems, particularly those involving neutral molecules like boronic acids remains ambiguous. Addressing this gap is crucial for the rational design of tunable molecular assemblies. Here, we employ a competitive adsorption strategy to investigate the electric field- mediated switching of multicomponent systems comprising boronic acids and a non-polar reference compound at the liquid-solid interface. Using scanning tunneling microscopy (STM), we uncovered distinct bias-dependent behaviors, including reversible dynamic exchange and phase transitions. Our findings identify partial ionization as a key mechanism driving the dynamic exchange and structural transformations of boronic acids.