4th EucheMs chemistry congress

Poster Session 1
s860
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - Physical, theoretical chemistry
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theoretiCAL StudieS of MetALLoPhiLiC
interACtionS throuGh the uSe of LoCAL
CorreLAtion MethodS
M. AndreJiC 1 , r. MAtA 1
1 Georg-August-Universität Göttingen, Institute of Physical
Chemistry, Göttingen, Germany
It has long been observed that cationic Au(I)d10 complexes
can establish weak metal-metal interactions. This effect is
somewhat curious, since it involves centers with the same charge
and completely filled electronic shells. Similar interactions are
found in complexes with Ag and Cu, but with a much smaller
magnitude. This effect has come to be known as aurophilicity, and
is strongly linked to electron correlation with a further
strengthening by relativistic effects. [1] Previous theoretical works
have shown that high levels of theory are required to reproduced
this effect quantitatively (e.g. CCSD(T)). [2]
We have performed a series of calculations on inorganic
complex dimers of the type (Cl-M-X) , with M = Au, Ag.
2
Comparison is made to density functional theory (DFT), including
empirical dispersion corrections, and state of the art wave
function-based methods. Local approximations have also been
used to treat the metal sites at the highest level of theory in a
QM/QM hybrid scheme. [3] We show some of the challenges in the
theoretical treatment of aurophilic interactions, with prospects on
the treatment of further metal-metal interactions in bioinorganic
complexes.
references:
1. L. Magnko, M. Schweizer, G. Rauhut, M. Schütz, H. Stoll
and H. Werner, Phys. Chem. Chem. Phys. 2002, Vol. 4,
1006-1013.
2. S. Riedel, P. Pyykkö, R. Mata, Chemical Physics Letters,
2005, Vol. 405, 148-152.
3. R. Mata, H. Werner, M. Schütz, The Journal of Chemical
Physics 128, 144106, 2008.
Keywords: Ab initio calculations; Aurophilicity; Electronic
structure;
4 th EucheMs chemistry congress
P - 0 0 0 4
MoLeCuLAr dynAMiCS SiMuLAtionS of
BioACtive GLASS nAnoPArtiCLeS
t. Antonio 1
1 University College London, Chemistry, London, United Kingdom
Bioactive glasses such as the 45S5 composition (BG45) are
clinically employed as bone defect fillers in orthopaedic and
dental applications. Their potential in regenerative medicine has
also been highlighted but not exploited as yet, due to the lack of
fundamental understanding of their composition-structure-activity
relations. For instance, nanosized BG45 particles have shown
enhanced biological activity and antibacterial properties, which
could be the key towards developing a new generation of
biomaterials for regenerative medicine. However, the rational
development of these materials requires a better understanding of
the origin of the superior properties of BG45 nanoparticles.
Molecular dynamics simulations of a Bioglass spherical
nanoparticle (approximately 6 nm diameter) have been carried out
to investigate how the reduced size affect structural and dynamical
features, which could enhance the bioreactivity of these systems.
Compared to the bulk glass or to the 2D-flat surface of BG45, the
simulations reveal that the reduced size leads to a further slight
reduction in the already low silicate connectivity on the
nanoparticle surface, to a ring size distribution shifted towards
three-membered rings, and to a higher Na + /Ca2+ ratio in close
proximity of the surface. A higher mobility of Na cations in the
external regions of the nanoparticle has also been detected. The
possible ways in which these effects can translate into higher
bioreactivity of BG45 nanoparticles are discussed.
Keywords: Molecular dynamics; Nanoparticles; Glasses;
Surface chemistry; Structure-activity relationships;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc