[Todos] Seminario INQUIMAE - DQIAQF Lunes 30 de septiembre 13hs

[andrea en qi.fcen.uba.ar]

Lunes 30 de septimebre, 13 hs
Lugar: Aula de seminarios INQUIMAE, 3er piso
Orador: Gautam R. Desiraju

 Solid State and Structural Chemistry Unit, Indian Institute of Science,
C. V. Raman Avenue, Bangalore 560 012, India
desiraju en sscu.iisc.ernet.in

Resumen de la charla:

THE SUPRAMOLECULAR SYNTHON IN CRYSTAL ENGINEERING


The concept of the supramolecular synthon in crystal engineering is a
simplifying one and synthons relate molecular structure with crystal
structure. A synthon is a structural unit that is found often enough in
certain molecules, so that one may reasonably predict that it will occur
again in a new molecule that contains the same critical molecular
functionalities that are found in the precursor molecule. In short, one
tries to identify certain critical regions of the molecule that will
influence and determine the stable crystal structure. The synthon,
however, goes beyond being a static descriptor of crystal structure. It is
not a pattern, a building block or a motif, all terms that are used often
enough in the crystal engineering literature. The synthon is a kinetic
descriptor that accurately reflects modularity. In its repeated appearance
in crystal structures is a hint that there are preferred strong and weak
intermolecular interactions that serve as kinetic routes to crystal
structures. This is in contrast to the most stable crystal structures that
can be formed for a given molecule, in the limit the global minimum or the
thermodynamic structure. The latter structures minimize energy and
ideally, optimize close packing and maximize crystal density. They are the
kinds of structures that emerge in computational predictions of unknown
crystal structures. So we have a trade-off between structures that show
the best packing (thermodynamic) and those that show the best interactions
(kinetic). Systems in which both kinds of crystals can be isolated are
typically polymorphic.


References.
[1]     G. R. Desiraju, Angew. Chem. Int. Ed., 2007, 46, 8342-8356.
[2]     G. R. Desiraju, J. Am. Chem. Soc., 2013, 135, 9952-9967.



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