4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s746
chem. Listy 106, s587–s1425 (2012)
Nanochemistry / Nanotechnology / Molecular machines, Carbon tubes, sheets, balls
Nanochemistry, nanotechnology and nanostructured
materials – iV
o - 3 5 3
SeLf-ASSeMBLy of ChArGed nAnoPArtiCLeS At
fLuid interfACeS
v. SAShuK 1 , M. fiALKowSKi 1
1 Institute of Physical Chemistry, Soft Condensed Matter and
Fluids, Warsaw, Poland
Inspired by nature, self-assembly phenomena are currently
the subject of intensive studies in modern science. Autonomous
organization of individual elements into complex structures is
increasingly considered the best “bottom-up” approach to
fabricating novel materials.
Herein we present self-assembly of charged nanoparticles
(NPs) into hexagonally close-packed lattices at fluid interfaces. [1]
We employ gold NPs covered with a mixture of ionic (charged)
and hydrophobic ligands. At a certain ligand ratio, the NPs display
a property to absorb spontaneously at fluid interfaces producing
monolayers. We found that such self-assembled NPs exhibit
Janus-type amphiphilic structure and possess well defined and
constant charge. At oil-water interface, the NPs autonomously
form hexagonally packed lattices as a result of a fine balance
between repulsive electrostatic and attractive hydrophobic forces.
In turn, at air-water interface, the NPs arrange into sparse
monolayers which then can be readily compressed to give dense
films by using Langmuir-Blodgett technique. The NP monolayers
squeezed into such films can be used for coating of various
materials.
references:
1. Sashuk et al., Chem. Eur. J. 2012, 18, 2235
Keywords: Nanoparticles; Self-assembly; Interfaces;
Monolayers;
4 th EucheMs chemistry congress
Nanochemistry, nanotechnology and nanostructured
materials – iV
o - 3 5 4
CheMiStry in nAno-SCALe oPtiCAL CAvitieS
J. A. hutChiSon 1 , t. SChwArtz 1 , e. devAux 1 ,
C. Genet 1 , t. w. eBBeSen 1
1 Université de Strasbourg and CNRS, ISIS, Strasbourg, France
Chemistry is normally controlled by reaction conditions
such as the type of solvent, the concentration of reactants, and
temperature. The reaction barrier can be lowered by the use of
catalysts or bypassed by the absorption of thermal or photonic
energy by one of the reactants. In this contribution we explore the
notion that one can influence a chemical reaction via a very
different path: by the strong coupling of molecules and photons
to form new, hybrid light/molecule states.
Strong coupling phenomena are most familiar to chemists
in the exchange of electron density between atomic orbitals to
form molecular bonding and anti-bonding orbitals. Physical
chemists are likewise familiar with the strong coupling of resonant
transitions of molecules in aggregates (exchange of excitation
energy) generating hybrid states of higher and lower energy,
sometimes labelled H- and J-aggregate bands respectively
depending on their geometry. Less intuitive is that strong coupling
can also be found at the level of molecules exchanging photons
with a resonant optical cavity, forming hybrid light/matter states
(or cavity polaritons). [1, 2]
We will present studies of molecular systems inside
nano-scale optical cavities formed by two metallic mirrors,
demonstrating clearly that molecular reactivity is modified by
strong interaction with cavity optical fields.
references:
1. Hutchison, J.A., Schwartz, T., Devaux, E., Genet, C.,
Ebbesen, T.W. Modifying chemical landscapes by
coupling to vacuum fields. Angew. Chem. Int. Ed., 2012,
51, 1592-1596.
2. Schwartz, T., Hutchison, J.A., Genet, C., Ebbesen, T.W.
Reversible switching of ultra-strong light-molecule
coupling. Physical Review Letters, 2011, 106, 196405(4).
Keywords: Nanostructures; Reaction mechanisms;
Photophysics; Energy transfer; Photochromism;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc