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Mechanically Activated Molecular Switch through Single-Molecule Pulling

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journal contribution
posted on 2011-02-23, 00:00 authored by Ignacio Franco, Christopher B. George, Gemma C. Solomon, George C. Schatz, Mark A. Ratner
We investigate a prototypical single-molecule switch marrying force spectroscopy and molecular electronics far from the thermodynamic limit. We use molecular dynamics to simulate a conducting atomic force microscope mechanically manipulating a molecule bound to a surface between a folded state and an unfolded state while monitoring the conductance. Both the complexity and the unique phenomenology of single-molecule experiments are evident in this system. As the molecule unfolds/refolds, the average conductance reversibly changes over 3 orders of magnitude; however, throughout the simulation the transmission fluctuates considerably, illustrating the need for statistical sampling in these systems. We predict that emergent single-molecule signatures will still be evident with conductance blinking, correlated with force blinking, being observable in a region of dynamic bistability. Finally, we illustrate some of the structure−function relationships in this system, mapping the dominant interactions in the molecule for mediating charge transport throughout the pulling simulation.