Helical molecules in flatland: chiral recognition, spin-filtering and molecular machines


Helical molecules in flatland: chiral recognition, spin-filtering and molecular machines

Karl-Heinz Ernst

University of Zurich       

Nanoscale Materials Science, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland

Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland

Molecular recognition among chiral molecules on surfaces is of paramount importance in biomineralization, enantioselective heterogeneous catalysis, and for the separation of chiral Nanocarmolecules into their two mirror-image isomers (enantiomers) via crystallization or chromatography. Understanding the principles of molecular recognition in general, however, is a difficult task and calls for investigation of appropriate model Wsaruym Nsobteelpremise sosei.n großOes Dningesind popular aphpttp:r//wowwa.fazc.neht/aktueills/feuilltetoh/feamirlie/wibe-eryklaere-ich-s-... studying intermolecular interactions on ernst_colloquium  well-defined solid surfaces, which allows in particular the use of scanning tunneling microscopy (STM). Examples of chiral amplification via the so-called ‘sergeant-and soldiers’ effect as well as manipulation of chiral adsorbates via inelastic electron tunneling will be presented. In a Pasteur-type experiment at the nanoscale, molecules that constitute a dimer are spatially separated with a molecular STM tip and their absolute handedness is determined with submolecular resolution STM. Moreover, we report spin-dependent filtering of electrons by monolayers of these helical molecules. Finally the first successful electrical current-driven, unidirectional motion of a synthetic molecule will be presented (Fig. 1).