Please cite this article in press as: K. Petukhov, et al., Coord. Chem. Rev. (2009), doi:10.1016/j.ccr.2009.01.024 ARTICLE IN PRESS G Model CCR-111023; No. of Pages 12 Coordination Chemistry Reviews xxx (2009) xxx–xxx Contents lists available at ScienceDirect Coordination Chemistry Reviews journal homepage: www.elsevier.com/locate/ccr Review STM spectroscopy of magnetic molecules K. Petukhov a , M.S. Alam a , H. Rupp a , S. Strömsdörfer a , P. Müller a,∗ , A. Scheurer b , R.W. Saalfrank b , J. Kortus c , A. Postnikov d , M. Ruben e , L.K. Thompson f , J.-M. Lehn g a Department für Physik, Universität Erlangen-Nürnberg, Erwin-Rommel-Str. 1, D-91058 Erlangen, Germany b Department für Chemie und Pharmazie, Universität Erlangen-Nürnberg, Germany c Institut für Theoretische Physik, TU Bergakademie Freiberg, Germany d Laboratoire de Physique des Milieux Denses, Université Paul Verlaine, Metz, France e Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Germany f Department of Chemistry, Memorial University, St. John’s, Newfoundland, Canada g ISIS, Université Louis Pasteur, Strasbourg, France Contents 1. Introduction ........................................................................................................................................... 00 2. Scanning tunneling microscopy and spectroscopy .................................................................................................. 00 3. Addressing the metal centers of grid-type supramolecular transition-metal assemblies ........................................................... 00 4. Star-like supramolecular metal-ion assemblies (single-molecule magnets) ........................................................................ 00 5. Conclusions ........................................................................................................................................... 00 Acknowledgements .................................................................................................................................. 00 References ............................................................................................................................................ 00 article info Article history: Received 31 July 2008 Accepted 18 January 2009 Available online xxx Keywords: Scanning tunneling microscopy Current-imaging tunneling spectroscopy Scanning tunneling spectroscopy Single-molecule magnets Grid-like and star-like supramolecular assemblies abstract We have investigated a series of magnetic supramolecular complexes involving coordinated metal ions. Using the current-imaging tunneling spectroscopy mode of a STM, we mapped isolated single molecules. By comparing with DFT calculations, we confirmed that the weakest bonds, i.e. the supramolecular coor- dination interactions, dominate the molecular orbitals near the Fermi-level of the molecule. Thus, STM spectroscopy can address directly the metal centers in a rather complex molecular entity. Our method allows a selective mapping of the functional units within the supramolecular architecture, even if these units are embedded into a complex set of organic ligands. We observed this behavior in all of our inves- tigated molecules. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Coordinated metal ions are the essential centers of chemical activity in various molecules. Beyond any chemical application, metal complexes embedded into a supramolecular entity are potential building blocks for molecular electronics [1]. Therefore, attaching the functional molecules to a substrate and investigating their behavior and properties is a primary requirement for poten- tial applications. Progress and possibilities of metal complexes in molecular electronics have been reviewed recently, highlighting that the electronic state of metal complexes is attractive for con- structing highly integrated, functional molecular components [2]. ∗ Corresponding author. E-mail address: phm@physik.uni-erlangen.de (P. Müller). Therefore, it is natural to investigate single magnetic molecules which can be envisaged as building blocks for such type of elec- tronics. Scanning tunneling microscopy (STM) has been proved to be a powerful tool to study various surfaces at the atomic and molec- ular level. Although STM is capable of atomic resolution when imaging solid surfaces, mapping of large and complex molecules with submolecular resolution is still a difficult task. An STM image contains both geometric and electronic information about the sam- ple in a complex way [3–5]. Even highly resolved STM topography images cannot provide information about specific features of large molecules. However, the spectroscopic possibilities of STM allow us to probe electronic states of the molecules as a function of energy within a range of few eV around the Fermi-level [6–8]. If there were subunits of the molecule exhibiting a special type of chemical bond- ing, STM spectroscopy would allow filtering out special features of 0010-8545/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ccr.2009.01.024