04-Nov-2019 - Institute for Basic Science

Sponge-like 2D material with interesting electrical conductivity and magnetic properties

New 2D Metal Organic Framework with an ever-growing list of possible applications

Chemists at the Center for Multidimensional Carbon Materials (CMCM), within the Institute for Basic Science (IBS, South Korea), have reported the synthesis of a novel type of 2D metal organic framework (MOF) with interesting electrical conductivity and magnetic properties. Published in the Journal of the American Chemical Society, this new material may potentially contribute to optoelectronics, photovoltaics, (photo)electrocatalysis, and energy storage.

Also known as sponge-like or Swiss-cheese-like materials, MOFs are made of metal ions connected to organic ligands and are characterized by nano-sized holes. IBS researchers in collaboration with the School of Materials Science at the Ulsan National Institute of Science and Technology (UNIST) designed and synthesized Ni(II) tetraaza[14]annulene-linked MOF (NiTAA-MOF), where the metal component is nickel and the nickel tetraaza[14]annulene molecules are used as MOF building blocks for the first time.

The researchers discovered that doping this MOF with iodine changes its conductivity and magnetism. Pristine NiTAA-MOF conducts poorly. It is actually an insulator with an electrical conductivity smaller than 10-10 Siemens per centimeter. However, when it is chemically oxidized by iodine, the same measurement rises to 0.01 Siemens per centimeter (the larger this number, the better the conductor). This result shows the vital role of ligand oxidation in the electrical conductivity of some 2D MOFs, expanding the understanding of the origin of electrical conductivity in this type of MOFs.

In addition, the team checked how this material becomes magnetized in an applied magnetic field. Magnetization measurements performed by the researchers of the School of Materials Science showed that iodine-doped NiTAA-MOF is paramagnetic, that is it is weakly attracted by an external magnetic field, and becomes antiferromagnetic at very low temperatures. This means that it could become useful as a polarizing agent in dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR) that is used in experiments for material characterization.

The 2D MOF structure was also modeled through detailed calculations and analyzed by a variety of methods, such as X-ray diffraction, infrared, X-ray photoelectron, diffuse reflectance UV-vis, electron paramagnetic resonance, and Raman spectroscopies.

"Our work can contribute to the fundamental understanding of structure-property relationships in 2D electrically conductive MOFs, and may pave the way to develop new electrically conductive MOFs," says Professor Ruoff, one of the corresponding authors of this study and UNIST professor. "Besides, the as-synthesized and iodine-doped NiTAA-MOF might be applicable in catalase mimics, catalysis, and energy storage."

Facts, background information, dossiers
More about Institute for Basic Science
  • News

    Seeing chemical reactions with music

    Albert Einstein once said, "I see my life in terms of music." Perhaps inspired by his words, scientists at the Center for Self-assembly and Complexity (CSC), within the Institute for Basic Science (IBS, South Korea) now see chemical reactions in the presence of music. The IBS research team ... more

    Growing carbon nanotubes with the right twist

    In a recently published paper in Science Advances, Feng Ding of the Center for Multidimensional Carbon Materials, within the Institute of Basic Science (IBS, South Korea) and colleagues, have achieved the creation of a specific type of carbon nanotubes (CNTs) with a selectivity of 90%, and ... more

    Graphenes now go monolayer and single crystalline

    Director Rodney Ruoff's research group from the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS) at the Ulsan National Institute of Science and Technology (UNIST) has reported a truly single layer (i.e., adlayer-free) large area graphene film ... more

  • Videos

    Multiresponsive nanosurfactant integrates functions of molecular surfactants

    (0:00) Droplets coated with nanosurfactants are hit with a laser which clumps the droplets into a two-dimensional hexagonal structure and rotates them much like gears. (0:17) Droplets are randomly distributed and then a laser is turned on which attracts them together into a bilayer aggregat ... more