Electrochemical gating of single osmium molecules tethered to Au surfaces
The electrochemical study of electron transport between Au electrodes and the redox molecule Os[(bpy)2(PyCH2 NH2CO-]ClO4 tethered to molecular linkers of different length (1.3 to 2.9 nm) to Au surfaces has shown an exponential decay of the rate constant kET 0 with a slope β = 0.53 consistent with th...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_14328488_v20_n4_p957_Herrera |
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| Sumario: | The electrochemical study of electron transport between Au electrodes and the redox molecule Os[(bpy)2(PyCH2 NH2CO-]ClO4 tethered to molecular linkers of different length (1.3 to 2.9 nm) to Au surfaces has shown an exponential decay of the rate constant kET 0 with a slope β = 0.53 consistent with through bond tunneling to the redox center. Electrochemical gating of single osmium molecules in an asymmetric tunneling nano-gap between a Au(111) substrate electrode modified with the redox molecules and a Pt-Ir tip of a scanning tunneling microscope was achieved by independent control of the reference electrode potential in the electrolyte, Eref − Es, and the tip-substrate bias potential, Ebias. Enhanced tunneling current at the osmium complex redox potential was observed as compared to the off resonance set point tunneling current with a linear dependence of the overpotential at maximum current vs. the Ebias. This corresponds to a sequential two-step electron transfer with partial vibration relaxation from the substrate Au(111) to the redox molecule in the nano-gap and from this redox state to the Pt-Ir tip according to the model of Kuznetsov and Ulstrup (J Phys Chem A 104: 11531, 2000). Comparison of short and long linkers of the osmium complex has shown the same two-step ET (electron transfer) behavior due to the long time scale in the complete reduction-oxidation cycle in the electrochemical tunneling spectroscopy (EC-STS) experiment as compared to the time constants for electron transfer for all linker distances, kET 0. © 2015, Springer-Verlag Berlin Heidelberg. |
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