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Chemically and mechanically controlled single-molecule switches using spiropyrans

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Mark C. Walkey, Chandramalika R. Peiris, Simone Ciampi, Albert C. Aragonès, Ruth B. Domínguez-Espíndola, David Jago, Thea Pulbrook, Brian W. Skelton, Alexandre N. Sobolev, Ismael Díez Pérez, Matthew J. Piggott, George A. Koutsantonis, Nadim Darwish

Original languageEnglish
Pages (from-to)36886-36894
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number40
Published9 Oct 2019

King's Authors


Developing molecular circuits that can function as the active components in electrical devices is an ongoing challenge in molecular electronics. It demands mechanical stability of the single-molecule circuit while simultaneously being responsive to external stimuli mimicking the operation of conventional electronic components. Here, we report single-molecule circuits based on spiropyran derivatives that respond electrically to chemical and mechanical stimuli. The merocyanine that results from the protonation/ring-opening of the spiropyran form showed single-molecule diode characteristics, with an average current rectification ratio of 5 at ±1 V, favoring the orientation where the positively charged end of the molecule is attached to the negative terminal of the circuit. Mechanical pulling of a single spiropyran molecule drives a switch to a more conducting merocyanine state. The mechanical switching is enabled by the strong Au-C covalent bonding between the molecule and the electrodes, which allows the tensile force delivered by the STM piezo to break the molecule at its spiropyran C-O bond.

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