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SUMMARY:Stereochemistry in flatland: 2D crystals and unidirectional molecu
 lar motion
DTSTART:20160303T163000
DTEND:20160303T173000
DTSTAMP:20260610T151642Z
UID:50bc8176e5edf58f27f1175ee01313e94b888b561931098d2d0b9bd7
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr. Karl-Heinz Ernst\nNanoscale Materials Science\, Empa
 \, Swiss Federal Laboratories for Materials Science and Technology\, Über
 landstrasse 129\, CH-8600 Dübendorf\, Switzerland\nDepartment of Chemistr
 y\, University of Zurich\, Winterthurerstr. 190\, CH-8057 Zürich\, Switze
 rland\nMany objects in our world have the property that they are incongrue
 nt with their mirror image. Such objects are called chiral or enantiomorph
 ous. Examples are quartz crystals\, shoes\, snail shells\, screws\, etc. T
 he most significant manifestation of chirality is the appearance of left- 
 and right-handed molecules\, so-called enantiomers. Chirality is ubiquitou
 s in the biological world\, but handedness comes unbalanced. That is\, mol
 ecules of life\, like sugars\, proteins\, and their building blocks the am
 ino acids\, appear basically in only one handedness. This has dramatic con
 sequences\, because the biological and pharmaceutical activity of enantiom
 ers is directly related to their handedness and causes different physiolog
 ical effects.\nAfter presenting few examples of chirality in the physical 
 and sociological sciences and a brief introduction into the history of mol
 ecular chirality and the important role it played for understanding the sp
 atial structure of molecules\, various aspects of surface chirality will b
 e discussed:\nMolecular recognition among chiral molecules on surfaces is 
 of paramount importance in biomineralization\, enantioselective heterogene
 ous catalysis\, and for the separation of chiral molecules 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 sy
 stems. One popular approach is thereby studying intermolecular interaction
 s on well-defined solid surfaces\, which allows in particular the use of s
 canning tunneling microscopy (STM). We present an elucidation of chiral re
 cognition of helical hydrocarbons at the single molecule level\, in monola
 yers and in multi-layers. In a Pasteur-type experiment at the nanoscale\, 
 molecules that constitute a dimer are separated with a molecular STM tip a
 nd the subsequent determination of their absolute handedness with a metal 
 tip. Moreover\, we will present examples of chiral amplification via the s
 o-called 2D ‘sergeant-and-soldiers’ effect\, chiral restructuring of a
  copper surface by prochiral molecules and discuss role of chirality in el
 ectrical current-driven molecular machines.
LOCATION:CH G1 495 https://plan.epfl.ch/?room==CH%20G1%20495
STATUS:CONFIRMED
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