  Using a first principles approach, we study the electron transport properties
of a new class of molecular wires containing fluorenone units, whose features
open up new possibilities for controlling transport through a single molecule.
We show that the presence of side groups attached to these units leads to Fano
resonances close to the Fermi energy. As a consequence electron transport
through the molecule can be controlled either by chemically modifying the side
group, or by changing the conformation of the side group. This sensitivity,
opens up new possibilities for novel single-molecule sensors. We also show that
transport can be controlled by tilting a molecule with respect to the electrode
surfaces. Our results compare favorably with recent experiments.
