A Molecular Switch with Dual Responses to Electrochemical and Mechanical Stimuli

Abstract

Molecular switches capable of responding to two or more orthogonal stimuli are essential for advancing molecular-scale logic, sensing, and memory technologies. However, integrating distinct control mechanisms within a single-molecule architecture remains a fundamental challenge. Here, we report a single-molecule electrochemical-mechanical dual-control switch based on difluoroboron dipyrromethene (BODIPY) molecular junctions. We demonstrate that applying an electrochemical gate voltage threshold (−0.6 V) reduces the BODIPY core to a stable radical anion, effectively serving as a logic enable (EN) signal. Under this electrochemically activated regime, precision mechanical modulation (∼5.0 Å amplitude) via an STM tip cleanly dictates the molecular conformation. Compressive strain drives the formation of a highly conductive asymmetric Au–S/Au−π contact (the SET operation) with a two-order-of-magnitude conductance contrast, while tensile strain physically ruptures the Au−π interfacial coupling to recover the symmetric terminal Au–S anchoring (the RESET operation). This dual-input sliding molecular resistor operates stably at frequencies up to 200 Hz, with density functional theory calculations elucidating the underlying radical-enhanced resonant transport pathway. By seamlessly mapping these synergistic electro-mechanical inputs to digital logic, we successfully transform this molecular junction into a nonvolatile, nanoscale gated RS latch. Ultimately, our work establishes a highly robust and versatile design strategy for constructing complex, multistimuli-responsive molecular circuitry at the single-molecule limit.