Formation and Evolution of Molecular Junctions Containing Metal Ions and Organic Radicals

Creating single molecule-metal junctions containing metal ions or organic radicals is a promising route to achieving functional molecular devices. Here I discuss our recent advances in understanding formation and evolution of molecular junctions formed with organometallic molecules and organic radicals. Our work indicates that the atomic structure of the electrodes can influence charge transfer at the metal-molecule interface and affect junction evolution characteristics. With organic radicals, controlling charge transfer is critical to preserving radical properties. We measure the conductance of indenoindenodibenzothiophene (IIDBT) diradicaloid, an organic molecule with a stable singlet diradical-like character in its ground state, using Scanning Tunneling Microscope Break Junction technique. We incorporate thioanisole linkers into the molecule to decouple the electronic state from the electrode and to anchor it in place. We find reproducible conductance signatures using these molecules in ambient conditions in organic solvents. A combination of experimental and theoretical work using DFT suggests this family of stable diradicaloid organic molecules is a promising choice for studying and understanding electron transport through diradicaloid molecule-metal junctions.