High Molecular Conductance and Inverted Conductance Decay over 3 nm in Aminium-Terminated Carbon-Bridged Oligophenylene-Vinylenes

With the progressing miniaturization of electronic device components to improve circuit density while retaining or even reducing spatial requirements, single molecules employed as electric components define the lower limit of accessible structural width. To circumvent the typical exponential conductance decay for increasing length in molecule-based wires, topological states, which describe the occurrence of discontinuities of a bulk material's electronic structure confined to its surface, can be realized for molecules by the introduction of unpaired spins at the molecular termini. The resulting high conductance and reversed conductance decay are typically only observed for shorter molecules, as the terminal spins must be within the electronic coupling range to produce the desired effects. We expand the realm of long and exceptionally conductive molecular wires by employing highly conjugated, planarized carbon-bridged oligo(phenylene-vinylene)s as conduits between readily oxidizable diarylamine termini. This yields molecular wires of already decent conductance values and small conductance decay in the neutral state. Upon the introduction of topological states, the conductance can be increased by a factor of up to 1800 for a 3 nm long molecule, and the conductance decay becomes inverted, together with an excellent signal intensity at concentrations as low as 0.01 mM.