[Todos] Seminario INQUIMAE / DQIAQF: Miercoles 8 de Agosto, 13hs.

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Seminarios DQIAQF - INQUIMAE, miércoles 8 de agosto- 13 hs.

Aula de Seminarios INQUIMAE - DQIAQF
Facultad de Ciencias Exactas y Naturales
Ciudad Universitaria - Pab. 2  -  Piso 3



*Adventures with Liquid Crystals: Non covalency, Phosphorescence and
Heterogeneous Catalysis*

Duncan W. Bruce

*Department of Chemistry, University of York, Heslington, YORK YO10 4PF,
UK; duncan.bruce en york.ac.uk*


While liquid crystals are known to the world as the archetypal materials in
flat panel displays, a technology that commands >95% of the market and will
do so for many years to come, in addition they offer very much more
relating to self organisation. For example, the ultra-strong polymers
Kevlar®
and spider silk owe their strength to fabrication from the liquid crystal
phase, while many of the lipids that constitute cell membranas are liquid
crystalline in nature.
In this lecture, the intention is to use a series of *N*-heterocyclic
compounds and some of their metal complexes to illustrate some of what is
possible. Of necessity, the view will be little 'broad brush', but in so
doing it is hoped that everyone will take something from what is presented.
*Non Covalency**: *Halogen bonding is a non-covalent interaction first
described >100 years ago but brought into contemporary chemical vocabulary
as a new interaction in supramolecular chemistry by the Milan group. We
described the first examples of halogen-bonded liquid crystals and have
made comparisons with related hydrogen-bonded materials. This work will be
discussed and the increased lability of halogen Bonds compared to hydrogen
bonds will be proposed.
*Phosphorescence**: *OLEDs represent an alternative flat-panel display
technology based on electroluminescent materials. Spin statistics allow
formation of singlet and triplet excitons in devices in a 1 : 3 ratio, but
in organic materials, emission from the triplet manifold does not generally
occur limiting inherent efficiency. Spin-orbit coupling in heavy-metal
complexes of, for example, Pt and Ir, facilitates triplet emission and
indeed 2- phenylpyridine (ppy) complexes of IrIII are used in commercial
fabrications. We have prepared liquidcrystalline ppy complexes of PtII and
IrIII to try to combine enhanced emission efficiency with other advantages
of liquid-crystalline fabrication and the results to date will be described.
*Heterogeneous Catalysis**: *High-surface-area, mesoporous silicas may be
obtained by templating on the liquid crystal phases of surfactants. We have
approached this subject by using metallosurfactants, the result of which is
porous silicas containing nanoparticulate metals and their oxides in the
pores, some of which are shown to have great catalytic activity. This
approach is then extended to include the use of generic surfactants and
soluble metal salts. Synthesis, structure, catalysis and magnetism will all
be discussed


*Lead References*
H. L. Nguyen, P. N. Horton, M. B. Hursthouse, A. C. Legon and D. W. Bruce,
*J. Am. Chem. Soc.*, 2004, *126*,
16; V. N. Kozhevnikov, B. Donnio and D. W. Bruce, *Angew. Chem. Int. Ed.*,
2008, *47*, 6286; A. Santoro, A. M.
Prokhorov, A. C. Whitwood, B. Donnio, J. A. G. Williams and D. W. Bruce *J.
Am. Chem. Soc.*, 2011, *133*,
5248; A. M. Prokhorov, A. Santoro, J. A. G. Williams and D. W. Bruce,
*Angew. Chem. Int. Ed.*, 2012, *51*, 95;
N. C. King, R. A. Blackley, W. Zhou and D. W. Bruce, *Chem. Commun.*, 2006,
3411; N. C. King, R. A.
Blackley, M. L. Wears, D. M. Newman, W. Zhou and D. W. Bruce *Chem.
Commun.*, 2006, 3414; C. M. A.
Parlett, D. W. Bruce, N. S. Hondow, A. F. Lee and K. Wilson, *ACS Catal.*,
2011, *1*, 636.