Surface Modification and Nanojunction Fabrication with Molecular Metal Wires

Abstract : Electron transfer has been a core subject in science and technology. This project focuses on the development of molecular wires with metal-metal bonds. The long-term goals of this research team aim for developing devices taking advantage of the unique electron transporting behaviors across the nano-objects. One of the first steps is to tailor the axial ligands for the molecular wires, specifically, to make contact between molecules and the electrode. We have studied diruthenium wires containing axial ligands of tetrathiafulvalene-acetylide , masked diazoniums , olefins, and phosphonate . Binding with sulfur and phosphonate to gold and silica oxide surface will then be possible. We also showed that the properties of metal string complexes with three or more metal atoms can be tuned by equatorial ligands, such as rigid naphthylridylamide , super rigid anthyridines , and sulfur-containing ligands (e.g., pyridylthiazolylamine) and bulky camphorsulfonyl groups to manifest the chirality of metal strings. With replacement of metal cores or chromatographic purification, heterometallic strings can be prepared. Studies show that the ligands perturb the electronic structures and the electron-transport properties of the metal-metal frameworks. Platforms of conductance measurements for single-molecule studies have been developed. Two mini-reviews were published in 2014 on the synthesis of metal strings and on conductance mechanisms.