A Reversible Molecular Switch Based on the Biphenyl Structure

MARTIN E. ZOLOFF MICHOFF; M. EZEQUIEL CASTILLO; EZEQUIEL P. M. LEIVA

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 117 p. 25724 - 25732

1932-7447

DFT calculations were performed on a biphenyl-based molecule bonded to old 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 ~ 28º) and an ?opened? species (disulfide bridge reduced, ϕ ~ 65º). The mechanical properties of the nanojunction formed by this molecular species sandwiched between gold clusters 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 towards the disulfide bridge reduction was found. Conductance values were calculated by means of non-equilibrium Green functions (NEGFC) techniques. Interestingly, a significant difference between the ?closed? (high conductance) and ?opened? (low conductance) species was found.