Single-Molecule Junction Origami

Abstract

Stimuli-responsive molecular junctions, where the conductance can be altered by an external perturbation, are an important class of nanoelectronic devices. These have recently attracted interest as large effects can be introduced through exploitation of quantum phenomena. We show here that significant changes in conductance can be attained as a molecule is repeatedly compressed and relaxed, resulting in molecular folding along a flexible fragment and cycling between an <i>anti</i> and a <i>syn </i>conformation. Power spectral density analysis and DFT transport calculations show that through-space tunnelling between two phenyl fragments is responsible for the conductance increase as the molecule is mechanically folded to the <i>syn</i> conformation. This phenomenon represents a novel class of mechanoresistive molecular devices, where the functional moiety is embedded in the conductive backbone and exploits intramolecular nonbonding interactions, in contrast to most studies where mechanoresistivity arises from changes in the molecule-electrode interface.