Mechanically controlled quantum interference in graphene break junctions.

The ability to detect and distinguish quantum interference signatures is important for both fundamental research and for the realization of devices such as electron resonators, interferometers and interference-based spin filters. Consistent with the principles of subwavelength optics, the wave nature of electrons can give rise to various types of interference effects, such as Fabry-Pérot resonances, Fano resonances and the Aharonov-Bohm effect. Quantum interference conductance oscillations have, indeed, been predicted for multiwall carbon nanotube shuttles and telescopes, and arise from atomic-scale displacements between the inner and outer tubes.

Electric-field induced bistability in single-molecule conductance measurements for boron coordinated curcuminoid compounds.

We have studied the single-molecule conductance of a family of curcuminoid molecules (CCMs) using the mechanically controlled break junction (MCBJ) technique. The CCMs under study contain methylthio (MeS-) as anchoring groups: MeS-CCM (), the free-ligand organic molecule, and two coordination compounds, MeS-CCM-BF () and MeS-CCM-Cu (), where ligand coordinates to a boron center (BF group) and to a Cu moiety, respectively. We found that the three molecules present stable molecular junctions allowing detailed statistical analysis of their electronic properties.

Robust Organic Radical Molecular Junctions Using Acetylene Terminated Groups for C-Au Bond Formation.

Organic paramagnetic and electroactive molecules are attracting interest as core components of molecular electronic and spintronic devices. Currently, further progress is hindered by the modest stability and reproducibility of the molecule/electrode contact. We report the synthesis of a persistent organic radical bearing one and two terminal alkyne groups to form Au-C σ bonds.

Synthesis and Single-Molecule Conductances of Neutral and Cationic Indenofluorene-Extended Tetrathiafulvalenes: Kondo Effect Molecules.

Development of molecules that can switch between redox states with paired and unpaired electrons is important for molecular electronics and spintronics. In this work, a selection of redox-active indenofluorene-extended tetrathiafulvalenes (IF-TTFs) with thioacetate end groups was prepared from a readily obtainable dibromo-functionalized IF-TTF building block using palladium-catalyzed cross-coupling reactions, such as the Suzuki reaction. The end groups served as electrode anchoring groups for single-molecule conductance studies, and the molecules were subjected to mechanically controlled break-junction measurements with gold contacts and to low-bias charge transport measurements in gated three-terminal electromigration junctions.

C-Au Covalently Bonded Molecular Junctions Using Nonprotected Alkynyl Anchoring Groups.

We report on an approach to realize carbon-gold (C-Au) bonded molecular junctions without the need for an additive to deprotect the alkynyl carbon as endstanding anchor group. Using the mechanically controlled break junction (MCBJ) technique, we determine the most probable conductance value of a family of alkynyl terminated oligophenylenes (OPA(n)) connected to gold electrodes through such an akynyl moiety in ambient conditions. The molecules bind to the gold leads through an sp-hybridized carbon atom at each side.