A Reversible
Molecular Switch Based on the Biphenyl
Structure
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Abstract
DFT
calculations were performed on a biphenyl-based molecule bonded
to gold nanoleads in order to evaluate its potential as a reversible
molecular switch. The torsion angle (φ) between the aromatic
rings may be controlled by means of reducing a disulfide functionality
that bridges the two rings, giving rise to a “closed”
species (disulfide bridge oxidized, φ ∼ 28°) and
an “opened” species (disulfide bridge reduced, φ
∼ 65°). The mechanical properties of the nanojunction
formed by this molecular species sandwiched between gold cluster pyramids
mimicking metallic electrodes were determined. The thermodynamics
of the reduction reaction was studied on the disulfide bridge as well
as on the potentially competing anchoring sulfur atoms. A highly favorable
product ratio toward the disulfide bridge reduction was found. Conductance
values were calculated by means of non-equilibrium Green functions
techniques. Interestingly, a significant difference between the closed
(high conductance) and opened (low conductance) species was found