4th EucheMs chemistry congress

thursday, 30-Aug 2012
s753
chem. Listy 106, s587–s1425 (2012)
Nanochemistry / Nanotechnology / Molecular machines, Carbon tubes, sheets, balls
Nanoscale particles, cages, sheets and tubes – Vi
o - 4 7 7
intrinSiCALLy ChirAL thioLAte-ProteCted
GoLd CLuSterS: enAntioSePArAtion,
ChiroPtiCAL ProPertieS And fLexiBiLity of
Au38
t. BürGi 1
1 University of Geneva, Department of Physical Chemistry,
Geneva, Switzerland
Bestowing chirality to metal surfaces and nanoparticles has
become an intensive field of research. Such systems are promising
candidates for enantioselective catalysis and for other applications
in chiral technology in general.
Chirality in metal nanoparticles leads to optical activity, i.e.
the differential absorption of left- and right-circularly polarized
light. [1, 2] The origin of this optical activity is still debated, as
several competing mechanisms may be responsible for it. Up to
now optical activity was only observed for particles that are
covered by chiral thiols. However, from X-ray structural analysis
it became clear very recently that even particles covered by achiral
thiols can be chiral due to the arrangement of the ligands in their
surface. [3, 4] The importance of this type of surface chirality for the
observed optical activity could not be studied yet, because all the
samples prepared up to now were racemic and were therefore not
optically active.
In our contribution we demonstrate for the first time the
separation of a gold particle or cluster, Au (SCH2CH2Ph) ,
38 24
covered by achiral thiols into its enantiomers using chiral HPLC. 5
The optical activity of the separated enantiomers is very strong
and the observed anisotropy factors are the largest ever observed
for gold nanoclusters. This demonstrates the importance of the
surface structure of the particles for their optical activity.
references:
1. Schaaff, T. G.; Knight, G.; Shafigullin, M. N.; Borkman,
R. F.; Whetten, R. L. J. Phys. Chem. B 1998, 102, 10643.
2. Gautier, C.; Burgi, T. ChemPhysChem 2009, 10, 483.
3. Jadzinsky, P. D.; Calero, G.; Ackerson, C. J.; Bushnell, D. A.;
Kornberg, R. D. Science 2007, 318, 430.
4. Qian, H.; Eckenhoff, W. T.; Zhu, Y.; Pintauer, T.; Jin, R.
J. Am. Chem. Soc. 2010, 132, 8280.
5. Dolamic, I; Knoppe, S.; Dass, A.; Bürgi, T. Nature Commun.
2012, 3, 798.
Keywords: chirality; optical activity; gold nanoparticles;
enantioseparation;
4 th EucheMs chemistry congress
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc