  Electromechanical coupling through piezoelectric polymer chains allows the
emission of organic molecules in active nanowires to be tuned. This effect is
evidenced by highly bendable arrays of counter-ion dye-doped nanowires made of
a poly(vinylidenefluoride) copolymer. A reversible redshift of the dye emission
is found upon the application of dynamic stress during highly accurate bending
experiments. By density functional theory calculations it is found that these
photophysical properties are associated with mechanical stresses applied to
electrostatically interacting molecular systems, namely to counterion-mediated
states that involve light-emitting molecules as well as charged regions of
piezoelectric polymer chains. These systems are an electrostatic class of
supramolecular functional stress-sensitive units, which might impart new
functionalities in hybrid molecular nanosystems and anisotropic nanostructures
for sensing devices and soft robotics.
