Magnetic Signature in Graphene Using Adsorbed Metal–Organic Networks

The interaction of a 2D metal–organic network (MON) stacked on graphene has been studied with the help of first-principles density functional theory (DFT) and DFT + U calculations. By varying the length of a polyphenyl-dicarbonitrile linker, we have evaluated the influence of the metal–metal distance on the electronic and magnetic properties of the MON complexes. Although MON composed of small molecules shows a moderately stable ferromagnetic phase, this magnetic order drops with the size of the complex. After the adsorption of MON on graphene, this last becomes n-doped due to an important charge transfer that improves with the molecular unit size. The MON–graphene interaction contributes to drastically reduce the overall stability of any magnetic order, but the local charge transfer remains strongly spin-polarized-dependent. Hence, the adsorption of magnetic MON on graphene leads to the modification of the electronic and magnetic properties of graphene, mostly in a closed proximity region to the active metal atoms of the MON. Spin-polarized scanning tunneling microscopy simulations reveal a magnetic signature in graphene that originates from its interaction with the MONs and that could be experimentally observed

Manipulating the Conformation of Single Organometallic Chains on Au(111)

The conformations of organometallic polymers formed via the bottom-up assembly of monomer units on a metal surface are investigated, and the relationship between the adsorption geometry of the individual monomer units, the conformational structure of the chain, and the overall shape of the polymer is explored. Iodine-functionalized monomer units deposited on a Au(111) substrate are found to form linear chain structures in which each monomer is linked to its neighbors via a Au adatom. Lateral manipulation of the linear chains using a scanning tunneling microscope allows the structure of the chain to be converted from a linear to a curved geometry, and it is shown that a transformation of the overall shape of the chain is coupled to a conformational rearrangement of the chain structure as well as a change in the adsorption geometry of the monomer units within the chain. The observed conformational structure of the curved chain is well-ordered and distinct from that of the linear chains. The structures of both the linear and curved chains are investigated by a combination of scanning tunneling microscopy measurements and theoretical calculations

UHV-STM Investigations and Numerical Calculations of a Ruthenium β-Diketonato Complex with Protected Ethynyl Ligand: [Ru(dbm)₂(acac-TIPSA)]

The quest of molecular electronic devices necessitates addressing model molecular systems as starting points. Among the targeted functions, electron transfer between specific moieties inside a molecule is expected to play a fundamental role for ultimate logical gates. Here we propose a coordination complex exhibiting two inorganic centers (Ru and Si) that constitutes a step toward a more complex architecture. Starting from the complex <b>1</b> [Ru­(dbm)₂(acac-I)] (dbm = dibenzoylmethanate ion, acac-<i>I</i> = 3-iodo-2,4-pentanedionate ion), the complex <b>2</b> [Ru­(dbm)₂(acac-TIPSA)] (acac-TIPSA = 3-(triisopropylsilyl)­acetylene-2,4-pentanedionate ion) was obtained through Sonogashira cross coupling reaction under classical conditions. This complex <b>2</b> was characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, UV–vis, cyclic voltammetry, mass spectroscopy as well as X-ray single-crystal diffraction. It crystallized with empirical formula of C₄₆H₄₉O₆Ru₁Si₁ in a monoclinic crystal system and space group <i>P</i>2₁/<i>c</i> with <i>a</i> = 21.077(3) Å, <i>b</i> = 9.5130(7) Å, <i>c</i> = 21.8790(12) Å, β = 94.125(7)°, <i>V</i> = 4375.5(7) ų and <i>Z</i> = 4. Additionally, scanning tunneling microscopy measurements at liquid He temperature and in an ultrahigh vacuum (UHV-STM) were conducted on complex <b>2</b> on a Ag(111) surface. The STM images, supported by adsorption and STM image calculations, demonstrate that the molecules exist in two stable forms when adsorbed on the metallic surface