Tunable Multistate Mechanoresistance in a Single-Molecule Junction Incorporating Energy-Dissipative Structures.

Mechanoresponsive molecular devices are capable of exhibiting dynamic responses to external mechanical stimuli, enabling applications in smart materials, nano-devices, and flexible electronics. However, energy conversion induced by mechanical stimuli requires efficient energy dissipation mechanisms. Traditional methods often involve bond breaking or incomplete energy release, which can lead to device failure during continuous operations. Therefore, ensuring the mechanical stability of molecular devices under cyclic external forces remains a significant challenge. Here, we introduce a pillar[6]arene-like cyclophane (PLC) as an energy-dissipative structure to construct a programmable multistate mechanoswitching at the single-molecule level. We observed that, compared to rigid molecules with low energy dissipation, PLC-based macrocyclic molecular devices not only withstand mechanical stretching up to 6 Å but also exhibit three stable states during the mechanical stretching/compressing processes. Combined with theoretical calculations, we confirm that these three distinct states are related to the charge transport pathways and the strength of the electrode-molecule interface coupling. This work establishes energy dissipation as a core design principle for multistate mechanoelectronic devices.