Optical molecular switches
We have reported the electron-transport properties of a new photoaddressable molecular switch. The switching process relies on a new concept based on linear π-conjugated dynamic systems, in which the geometry and, hence, the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans−cis isomerization of an azobenzene unit fixed in a lateral loop. [S. Lenfant et al., J. Phys. Chem. C (2017)].
We have also designed and synthesized a new azobenzene-thiophene molecular switch exhibiting a high “on/off” conductance ratio up to 7,000 (C-AFM on SAMs). [K. Smaali et al., ACS Nano (2010)].
Main coll. : P. Blanchard, J. Roncali (CNRS, Moltech-Anjou, U. Angers); J. Cornil (LCNM, U. Mons, Belgium); C. van Dyck (Dept. Chem., Northwestern Univ., Evanston, USA); A. Rochefort (Ecole Polytechnique Montréal, Quebec, Canada).
Chemical molecular switches
We demonstrate that the conductance switching of benzo-bis(imidazole) molecules upon protonation depends on the lateral functional groups. The protonated H-substituted molecule shows a higher conductance than the neutral one, explained by a reduction of the LUMO-HOMO gap. The opposite is observed for a molecule laterally functionalized by amino-phenyl groups, consistent with a shift of HOMO, which reduces the density of states at the Fermi energy [H. Audi et al., Nanoscale (2020)].
Main coll. : O. Siri, H. Klein (CINAM, CNRS, Marseille, France), I.M. Grace, C.J. Lambert (Physics Dept., Lancaster Univ. UK).