  The appealing feature of molecular electronics is the possibility of
exploiting functionality built within a single molecule. This functionality can
be employed, for example, for sensing or switching purposes. Thus, ideally, the
associated conductance changes should be sizable upon application of external
stimuli. Here, we show that a molecular spring can be mechanically compressed
or elongated to tune its conductance by up to an order of magnitude by
controlling the quantum interference between electronic pathways. Oscillations
in the conductance occur when the stress built up in the molecule is high
enough to allow the anchoring groups to move along the surface in a
stick-slip-like fashion. The mechanical control of quantum interference effects
and the resulting large change in molecular conductance open the door for
applications in, e.g., a minute mechanosensitive sensing device functional at
room temperature.
