4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s820
chem. Listy 106, s587–s1425 (2012)
Physical, theoretical and Computational Chemistry
Computational Chemistry – i
o - 3 9 4
theoretiCAL ChArACterizAtion And
identifiCAtion of eLeCtrideS
e. MAtito 1 , v. PoStiLS 1 , M. GArCiA 1 , M. SoLA 1 ,
J. M. LuiS 1
1 Institut de Química Computacional Universitat de Girona,
Department of Chemistry, Girona, Spain
The electrides [1-2] are intriguing chemical species with an
electron not formally assigned to any atom. This situation is,
however, completely different to that given in a metal where the
electrons are delocalized between positively charged metal ions.
The electron in an electride acts as a formal anion, which is
bonded to positively charged species in the molecule. This
particular feature of electrides prompts very particular chemical
and physical properties: they are powerful reducing reagents,
exhibit exalted electric linear and non-linear optical properties as
well as a particular magnetic behavior.
In this work, we analyze the electronic structure and the
identification of several electride structures by means of the
Quantum Theory of Atoms in Molecules (QTAIM) and the
Electron Localization Function (ELF). [3] Our results show that
these tools make possible the classification of candidate species
as electrides or not. It was already proved that one could
distinguish the electride behavior in insulating high-pressure
forms of alkali metals from ELF analysis [4] but now we show that
with QTAIM and ELF is possible to characterize the electride
behavior in all sorts of molecules.
references:
1. Dye, J. L. Science, 2003, 301, 607-608.
2. Dye, J. L. Science, 1990, 247, 663
3. Matito, E.; Sola, M. Coord. Chem. Rev., 2009, 253,
647–665
4. Marqués et al., Phys Rev. Lett. 103, 115501 (2009)
Keywords: electronic structure; ELF; Nonlinear optics; bond
theory; Density functional calculations;
Computational Chemistry – i
4 th EucheMs chemistry congress
o - 3 9 5
underStAndinG the diffuSion of SMALL GASeS
throuGh PorouS orGAniC CAGe
nAnoCryStALS viA MoLeCuLAr dynAMiCS
d. hoLden 1 , t. hASeLL 1 , A. trewin 1 , h. ShePherd 1 ,
A. CooPer 1
1 University of Liverpool, Chemistry, Liverpool, United Kingdom
Email: abbiet@liv.ac.uk, aicooper@liv.ac.uk
Most organic molecules pack in such a way to minimise free
space therefore exhibiting minimal void volume and hence
permanent porosity is rare. However, previously we have shown
that tetrahedral organic cages can be synthesized and then
desolvated to generate porous crystals that adsorb small guest
molecules such as nitrogen, hydrogen, methane and carbon
dioxide. [1] We have also shown that it is possible to control the
particle size of these systems by altering the building blocks used
within the makeup of the material. [2] These all exhibit a
3D-diamondoid pore network and by altering the modulus there
is an impact on the pore size; as a result the diffusion of gases
through them changes.
Upon the generation of a bespoke force field, it has been
possible to simulate how the diffusion of small gases alter
dependant on their particle size. Using molecular dynamic
simulations we have unlocked phenomena such as gas selectivity,
rare-event hopping and displacement of gases to regions
previously considered inaccessible; all of which help to rationalize
experimental observations. The aim here is to predict materials
which show good selectivity to one gas over another.
references:
1. Tozawa, T.; Jones, J. T. A.; Swamy, S. I.; Jiang, S.;
Adams, D. J.; Shakespeare, S.; Clowes, R.; Bradshaw, D.;
Hasell, T.; Chong, S. Y.; Tang, C.; Thompson, S.; Parker, J.;
Trewin, A.; Bacsa, J.; Slawin, A. M. Z.; Steiner, A.;
Cooper, A. I. Nat. Mater.2009, 8, 973.
2. Hasell, T.; Chong, S. Y.; Jelfs, K. E.; Adams, D. J.;
Cooper, A. I. Journal of the American Chemical Society
2012, 134, 588.
Keywords: Molecular dynamics; Nanostructures; Microporous
materials; Cage compounds; Computational chemistry;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc