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2010 Spring
2009 Fall
Tuesday, April 20, 2010
Relationship between Structural and Transport Properties in Organized Soft Matter Systems by NMR
Sergey Vasenkov
Assistant Professor
Department of Chemical Engineering
University of Florida, Gainesville

2:00 - 3:00 PM, Tuesday, April 20, 2010
CEB 218 (810 South Clinton Street)

Room temperature ionic liquids show great promise as a new media for organic synthesis, catalytic reactions, separation processes, and extraction. Formation of polar and unpolar domains is believed to be responsible for many unique properties of these “green” solvents. Aggregation of ions and/or molecules into various types of domains also determines many properties of other types of soft matter systems that include aqueous solution of ionic surfactants and multicomponent lipid bilayers. In particular, translational diffusion can be drastically altered by the formation of domains and aggregates. Fundamental knowledge of an influence of molecular/ion aggregation on transport properties can be obtained by using a novel pulsed field gradient (PFG) NMR option that combines advantages of high field (17.6 T) NMR and high magnetic field gradients (up to 30 T/m). Results of studies of several types of soft matter systems by this new NMR experimental option will be presented and discussed in detail.
Tuesday, April 13, 2010
Catalyst Design Using Pseudomorphic Overlayers
Joseph H. Holles
Assistant Professor
Department of Chemical Engineering
Michigan Technological University

11:00 - 12:00 PM, Tuesday, April 13, 2010
CEB 218 (810 South Clinton Street)

Supported metal catalysts have been the mainstay of the chemical industry for many years. In order to improve the activity of these catalysts, the researcher may change the metal, particle size, support, add dopants or promoters, or even combine metals. All of these approaches serve to change the electronic interaction between the catalyst and the reactants and products. Historically, this catalyst development was done by trial and error similar to the medieval alchemist. Today, we can computationally predict in advance this important electronic interaction using first principles quantum chemical techniques. In particular, the pseudomorphic overlayer of a monolayer of one metal on the bulk structure of another metal has shown tremendous promise for systematically controlling the electronic interaction. However, to date, this work has been limited to computational or single crystal high vacuum studies.

We have developed a synthesis technique to move this catalyst structure into the real world of high surface-area supported catalysts. The directed deposition synthesis technique allows for the controlled deposition of no more than one layer of metal on previously deposited particles of a different metal. A series of Re@Pd (core@shell) catalysts have been synthesized using the directed deposition technique. These catalysts were then characterized using hydrogen chemisorption to determine binding energy and ethylene hydrogenation to determine activity.
Thursday, March 18, 2010
Surface Mineralization, Alignment, and Programmed-Self Assembly of the TMV Biotemplate
Michael T. Harris
School of Chemical Engineering
Purdue University

11:00 Am - 12:00 PM, Thursday, March 18, 2010
CEB 230 (810 South Clinton Street)

This presentation focuses on the use of a well-defined plant virus, Tobacco mosaic virus (TMV) to develop strategies for the assembly, patterning and functionalization of nanoscale surface features and devices. Current and ongoing studies have lead to methodologies for the uniform coating of viral templates with reactive metals as well as techniques for the patterned self-assembly of these bio-templates. Additional efforts have begun to investigate the efficacy of incorporating viral based nanotemplates into functional devices including hydrogen sensors and battery electrodes. The goals of this research are directed at developing and characterizing methods for the hierarchical assembly of virus-based materials onto surfaces and within solutions. Functionalized virus-based assemblies will then be analyzed for their surface and conducting properties. Our goal is to assemble, for the first time, simple patterned structures and circuits from ordered arrays of virus nanotemplates.

One potential method for aligning the coated TMV nanorods involves the evaporation of sessile drops of colloidal dispersions. The ability to control the deposition pattern can be achieved by understanding how evaporation of the liquid affects the fluid flow inside the drop and how the fluid flow affects the particle deposition profile. The second part of this presentation will describe the use of computational fluid dynamics to solve numerically the evaporation dynamics along the drop interface, the induced fluid flow profile inside the drop and its effect on the deposition pattern of the particles on the substrate. Future plans involve the use of a modified version of this computer code to model the application of external fields in the controlled deposition of particles on a substrate during the evaporation of a sessile drop.
Tuesday, January 26, 2010
Bioanalysis in Poly(dimethyl siloxane)-Based Microchannels
Bo Zheng
Assistant Professor
Department of Chemistry
Chinese University of Hong Kong

11:00 Am - 12:00 PM, Tuesday, January 26, 2010
CEB 218 (810 South Clinton Street)

Cross linked poly(dimethyl siloxane) (PDMS) is a transparent rubber and is the most often used material in fabricating microfluidic devices. A unique property of PDMS is the relatively large solubility of air in PDMS. Small molecules, including oxygen and nitrogen, diffuse in PDMS at a similar rate as they do in water. As a result, degassed PDMS can be used as a vacuum source with proper microfluidic design. Two applications in bioanalysis based on the degassed PDMS will be presented. First, a nanoliter liquid dispenser was developed and applied to protein crystallization. Second, PDMS microchannel-based viscometers for Newtonian fluid and for power law non-Newtonian fluid were developed using degassed PDMS to drive the flow of the fluid. In both applications, only nanoliter to microliter volume of the sample fluid was needed, and the analysis process was simple and robust.
Thursday, January 21, 2010
Supported metal oxide catalysts using grafted multidentate complexes
Justin Notestein
Assistant Professor
Department of Chemical & Biological Engineering
Northwestern University

11:00 Am - 12:00 PM, Thursday, January 21, 2010
CEB 230 (810 South Clinton Street)

Supported metal oxide catalysts are ubiquitous materials covering the range of acid, base, and redox chemistry, but they can exhibit complex relationships between reactivity and surface coverage (loading) due to the prevalence of structure-sensitive catalyst mechanisms. In general, structures tend to evolve from isolated cations at low surface coverage to polymeric surface species at intermediate loadings, and crystallites with properties akin to the bulk material at higher loadings. However, even within these broad classifications, it is challenging to control the precise nature of the atomic connectivity to the surface and within the metal oxide domain. A further challenge with supported metal oxide catalysts is the absence of universal methods for evaluating the number of surface sites, such as via scanning microscopy or volumetric and spectroscopic chemisorption measurements for supported metal nanoparticles. Thus, some of the significant design goals in the area of metal oxide catalyst synthesis include: 1) development of methods for creating uniform, isolated surface species, 2) development of methods that specifically form the intermediate, polymeric structures, and 3) creation of synthetic handles beyond metal content and support type, which will allow for fine-tuning of catalyst structure and function and a priori knowledge of the number of surface sites. Developing atomically-precise supported metal oxides, in particular using earth-abundant oxides, promises to usher in new forms of selective catalysis. Three research foci will be discussed that tackle the synthesis of supported metal oxide catalysts for selective oxidation of aromatics to phenolics and the epoxidation / dihydroxylation / allylic oxidation of alkenes. All areas share the use of organic ligands to control the structure of the final supported oxide catalyst. In the first area, supported iron oxides are synthesized from highly chelating precursor complexes. In particular, a chelating acid ligand allows the resulting supported metal oxide to retain the characteristics of an isolated cation at much higher surface densities than observed for more common metal halides. In the second area, small manganese oxide clusters are pre-formed in solution with cyclic amine ligands and subsequently supported using traditional exchange or impregnation techniques or via the formation of new clusters on suitably-modified hybrid solids. These clusters allow direct access to the intermediate, polymeric oxide structures and possess unusual reactivity in epoxidation / dihydroxylation. Finally, cyclic phenol ligands are used to create site-isolated Ta cations on various supports. The structure of the ligand predictably controls the selectivity of the catalyst towards C=C oxidation or allylic CH oxidation. All catalytic oxidations are carried out in the l iquid phase with suspended solid catalysts and aqueous H2O2 as the oxidant. Tests for heterogeneity of the catalysis are included as this is often a concern in l iquid phase oxidations. Surface structures are probed using temperature programmed techniques, diffuse reflectance UV-visible-NIR spectroscopy, solid state 13C NMR spectroscopy, and X-ray absorption spectroscopy where applicable.