Invitación a Seminario Dr. Rudy Martín-Trasanco

noviembre 26, 2015 by · Deja un Comentario
Categoría: Sin categoría 

Seminarios del Departamento de Ciencias Químicas 

Invita a la comunidad universitaria a la charla titulada

Crosslinked polymer of b-cyclodextrin-epichlorohydrin as capping agent for nanoparticles containing metals

por

 

Dr. Rudy Martín-Trasanco

Centro de Nanociencias Aplicadas (CENAP), Doctorado de Fisicoquímica Molecular, UNAB 

ruquim@gmail.com

Resumen

Cyclodextrins are a family of cyclic oligosaccharide compounds with a torus shape hydrophobic cavity capable to form inclusion complexes with a great variety of guests. The crosslinking ofbCD with epiclorohydrin in a basic media lead to the formation of a highly water soluble b-cyclodextrin-epichlorohydrin polymer (bCDP).  In this work the bCDP polymer was used as capping agent in the synthesis of water soluble gold (AuNPs) and silver (AgNPs) nanoparticles as well as in the preparation of cadmium telluride quantum dots (CdTeQDs) in aqueous media. In all cases, the bCD polymer conferred a high water solubility and stability to the nanoparticles, even at high concentrations permitting their precipitation and further redispersion in water, a process that did not affected their optical properties.

Fecha:  Miércoles  25 de noviembre de 2015

Hora:   11:30 am

Lugar:  Sala 301-R2 en República 252, Santiago

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Invitación Seminario Dr. Diego Oyarzún Jerez

Seminarios del Departamento de Ciencias Químicas 
Invita a la comunidad universitaria a la charla titulada
Anodic nanostructures: 
Synthesis, characterization and applications
 
Por
Dr. Diego Oyarzún Jerez 
Centro de Nanociencias Aplicadas (CENAP)
Facultad de Ciencias Exactas, UNAB
Resumen
The present work gives an overview of the highlights of research on synthesis, characterization and applications of ordered oxide structures (nanotube layers, hexagonal pore arrangements, nanospheres) that are formed by self-organizing anodization of metals. Mainly we address to anodizing of titanium and copper, addition evaluate some factors that lead to the spectacular self-ordering during the growth of anodic oxides that finally yield morphologies such as highly ordered TiO2 nanotube arrays and some similar structures Cu2O nanoporous layers.
 
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Invitación Seminario Dr. Jorge Martinez

Seminarios del Departamento de Ciencias Químicas 
Invita a la comunidad universitaria a la charla titulada
Catalytic activity in ethylene polymerization processes understood through the local hyper-softness  

por
Dr. Jorge Martínez
Departamento de Ciencias Químicas (DCQ), UNAB
Resumen
Metallocene cations of group IV B have allowed an increase of plastic market since 1977 when Walter Kaminsky discovered the use of these organometallic compounds in this field.  Besides, the mechanism proposed by Cossee and Arlman has helped to understand the entire process of ethylene polymerization catalyzed by these organometallic compounds and the same mechanism is used as a guide to understand the catalytic effect exerted by new catalysts that have been used in similar polymerization reactions like cationic complexes based on iron coordinated to ligands of type bis(imino)pyridine. A pure experimental parameter that characterizes these organometallic compounds within the polymerization context is the so called catalytic activity that measures the mass of polyethylene produced per unit of gram or mol of catalyst, per unit of temperature and per unit of pressure of monomer. Values of catalytic activity are usually explained in terms of steric hindrance induced by the respective catalyst, however electronic effects exerted by substituent groups attached on the catalyst are often explained in terms of net electric charges localized on the catalytic sites of the catalyst. This talk will expose that local hyper-softness is a theoretical parameter that has demonstrated to be more suitable to rationalize the aforementioned electronic effects rather than the net electric charges. In consequence there is a link between catalytic activity and local hyper-softnesss that would lead to a more rational computational design of new catalysts.

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Invitación Seminario Dr. Dayan Paez

noviembre 4, 2015 by · Deja un Comentario
Categoría: Sin categoría 
Seminarios del Departamento de Ciencias Químicas 
Invita a la comunidad universitaria a la charla titulada

 Theoretical determination of magnetic properties in f-elements 

Old tools New systems 

por
​Dr. Dayán Páez​

Doctorado en Fisicoquímica Molecular, UNAB​

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Resumen
 
Magnetic properties of f elements represent a challenging for both, experimental and theoretical chemistry, due to the well known complicated electronic structure and the strong multirreference character of the wavefunction. The crystal field and effective Hamiltonian theories developed in the 40s and 50s are useful tools to interpret and rationalize the magnetic properties in these kind of compounds. Recently, organolanthanide and actinide complexes have attracted considerably the attention thanks to their significant contribution at the frontier of single molecule magnets (SMMs). The design of SMMs based on the phenomenon of blocking of magnetization at low temperatures has become a hot area of research due to the potential application of such compounds in new storage and information-processing technologies. In our work we describe at CASSCF/CASPT2 level of theory the magnetic response of different actinide and lanthanide compounds using the spin-Hamiltonian techniques. Also we are interested in the mechanism of the magnetization blocking in molecules with a potential SMMs behaviour.

dayanpaez