4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s845
chem. Listy 106, s587–s1425 (2012)
solid state Chemistry Materials chemistry/New materials
Novel Materials and Molecular interactions
o - 4 1 4
MAtrix-iSoLAtion And AB initio Study of the
CoMPLex Between forMiC ACid And xenon
q. CAo 1 , L. KhriAChtChev 1 , M. MeLAvuori 1 ,
M. räSänen 1 , J. LundeLL 2
1 Universitty of Helsinki, Chemistry, Helsinki, Finland
2 Universitty of Jyväskylä, Chemistry, Jyväskylä, Finland
Formic acid (HCOOH, FA) is a useful model compound for
understanding the properties of more complicated molecules and
the intermolecular interactions, in particular, of biological interest.
As the simplest organic acid, FA exhibits the conformational
isomerism with respect to the rotation about the single C-O bond,
which is a typical phenomenon in the conformational processes
in carboxylic acids. Light-induced conformational change has
allowed preparing dimers and complexes of the higher-energy
conformer. Since rare-gas matrices are widely used to study
conformational changes, understanding of the interactions
between rare-gas atoms and different conformers is important. In
present work, we study the complexes of trans- and cis-FA with
a Xe atom using IR spectroscopy in an argon matrix. The
geometries, interaction energies, reaction barriers, and vibrational
spectra of the 1:1 FA···Xe complexes are calculated by the ab
initio method at the MP2 level of theory. The calculations reveal
four structures for the trans-FA···Xe complex and four structures
for the cis-FA···Xe complex. In the experiments, two structures
of the trans-FA···Xe complex are observed after deposition of
FA/Xe/Ar matrices, with and without OH···Xe interaction
(H-bonded and non-H-bonded structures). The cis-FA···Xe
complex was synthesized by vibrational excitation of the
non-H-bonded trans-FA···Xe complex. The non-H-bonded and
H-bonded structures of the cis-FA···Xe complex are observed
after the excitation. The decay of the H-bonded and non-H-bonded
cis-FA···Xe complexes in an argon matrix is, respectively,
substantially slower and faster compared to the cis-FA monomer.
This observation is explained by the different tunnelling barriers
for these species. This is the first experimental report of the
non-H-bonded complex for cis-FA. This work is partially
motivated by anaesthetic properties of xenon, which enhances the
importance of research on the interaction between Xe atoms and
organic molecules.
Keywords: Ab initio; formic acid; xenon; Tunnelling; Matrix
isolation;
Novel Materials and Molecular interactions
4 th EucheMs chemistry congress
o - 4 1 5
ioniC nAnoPArtiCLe networKS: new
verSAtiLe hyBrid MAteriALS
M. neouze 1
1 Vienna University of Technology, Institute of Materials
Chemistry, Vienna, Austria
Recently ionic nanoparticle networks (INN) were
reported in the frame of the remarkable development of new
inorganic-organic hybrid materials based on nanoparticle
assembly. The original method we developed to synthesize
3-D networks is based on the functionalization of metal oxide
nanoparticles with ionic linkers, the bridging ligands containing
imidazolium units. Recent publications pointed out the powerful
synergy of ionic species with nanoparticles. Such synergy makes
those new inorganic-organic hybrid materials promising
candidates for many applications such as catalysis or luminescent
devices, as will be exemplified in this communication.
Focusing on catalysis for CO activation reactions, the
2
combination of high imidazolium content with the presence of
metal centers, also able to coordinate to CO molecules, makes
2
the hybrid materials INN highly promising catalysts. In addition
the imidazolium bridging units in the final hybrid material renders
the INN tailorable, while the INN materials are solid, which
allows an easy separation of the catalyst after reaction. Thus, INN
materials, with mono- and di-imidazolium bridging units as well
as with various counter anions, were investigated as catalysts for
the cycloaddition of CO into different starting epoxides.
2
The photoluminescent properties of INN were also studied.
It appears that INN materials are luminescent in the visible range.
The excitation wavelength as well as the wavelength of maximum
emission can be tailored when modifying the imidazolium linker
used to link the nanoparticles. In parallel, the short-range order of
the network was investigated via small-angle X-ray scattering.
This short-range order was interpreted as originating from
self-organization of the aromatic rings of the ligands bridging the
nanoparticles by means of pi-pi stacking. This hypothesis was
validated by luminescence investigations on the hybrid materials.
Keywords: Materials Science; Nanoparticles; Luminescence;
Stacking interactions; Cycloaddition;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc