Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2008. / Title from home page (viewed Oct. 8, 2009). Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 0994. Adviser: Martin F. Jarrold.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4445. Adviser: Jonathan V. Sweedler. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6761. Adviser: Ralph G. Nuzzo. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--Indiana University, Dept. of Chemistry, 2009. / Title from PDF t.p. (viewed on Jul 22, 2010). Source: Dissertation Abstracts International, Volume: 70-12, Section: B, page: 7531. Adviser: James P. Reilly.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3482. Adviser: Neil L. Kelleher. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2005. / Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6578. Adviser: David E. Clemmer. Title from dissertation home page (viewed Oct. 11, 2006).

The research embodied in this text involves the characterization and optimization of novel materials and interfaces critical to the performance of organic electronic devices: Thrust 1. A scheme for elucidating the relative significance of energy vs. charge transfer (ET vs. CT) routes to guest dye emission in organic light-emitting diodes (OLEDs) was developed using near-IR emissive phthalocyanine (Pc) or naphthalocyanine (NPc) dopants. CT processes were observed to occur by an oxidized guest mechanism, which may be predicted from the solution electrochemistry of these materials. Additionally, a new series of quinacridone(QA)-based guest dyes were developed/characterized, modified at the N,N' positions to form four generations of Frechet dendrimers and their t-butyl-terminated analogues. As generation number increases, they exhibited decreased aggregation and increased luminescence efficiencies in the condensed phase. In solution, sharply declining rates of heterogeneous electron transfer were observed. Despite this trend, when these new molecules were doped into OLEDs, ET and CT routes to QA emission were not significantly inhibited. Thrust 2. A series of hybrid metal cluster-organic materials containing between one and seven [Re6(mu3-Se)8] 2+ clusters per molecule were electrochemically characterized. Dimer, trimer, and tetramer assemblies yielded uncoupled cluster oxidations. For cluster 7-mer dendrimers, uncoupled oxidations were observed for unconjugated linking groups, while coupled oxidations were observed with a conjugated linker, suggesting through-bond electrical polarization of the interior cluster. Thrust 3. The first UV-Vis attenuated total reflectance (ATR) method for the simultaneous determination of molecular tilt and azimuthal rotation for ultra-thin films of molecules with circularly-polarized electronic transition dipoles was developed, where a priori assumptions of the mean molecular orientation of either angle are not necessary in order to recover both mean angles. A model Pc-based system was evaluated, where this material is known to form in-plane molecular columns. Assuming a delta distribution in the orientation of each angle, it was determined that the mean tilt of the molecular plane away from the substrate surface is 80 ± 3°, and the mean azimuthal rotation of the molecular plane away from the column direction is 56.9 ± 0.8°. The dependence of molecular orientation on environmental exposure conditions and surface premodifiers was also evaluated.

<p> Conformational heterogeneity and protein dynamics play important roles in molecular recognition, but are experimentally difficult to characterize with sufficient temporal and spatial resolution. Infrared (IR) spectroscopy can probe protein dynamics on sub-ps timescales; and further, the small size of vibrational chromophores combined with site-selective incorporation of spectrally isolated IR probes provides high spatial resolution. Herein, we site-specifically introduce nitrile and carbon-deuterium bonds at distinct sites in the Src-homology 3 (SH3) domain from yeast protein Sho1 and its proline-rich peptide binding partner from Pbs2 to examine the underlying mechanisms of molecular recognition via IR spectroscopy. Further, we present efforts at developing instrumentation aimed at improving characterization of weakly absorbing vibrational probes in strongly absorbing solvent.</p><p> Nitrile probes were introduced at six distinct sites in the SH3 domain via amber codon suppression. Variation between the observed absorbance bands indicates site specific differences in conformational heterogeneity imposed by protein domain. Residue-specific changes upon peptide binding are observed at incorporated nitrile moieties, but are more dramatically observed for deuterated vibrational probes incorporated within the peptide binding partner. Deuterated amino acids were incorporated at highly conserved proline residues within the peptide ligand. Upon binding, absorbance bands are observed which indicate population of multiple conformational states in the bound complex. Only single resonances were observed by characterization of the same labeled bonds by NMR, suggesting rapid interconversion on the NMR timescale. Results suggest that the SH3 domain recognizes its peptide binding partner with at least elements of an induced-fit mechanism.</p><p> Characterization of the vibrational probes used above can be challenging due to the path length limitation imposed by the presence of strongly absorbing solvent water. This places an upper bound on the achievable signal strength which can obscure small (&micro;OD) absorbance bands. To confront this limitation we have constructed an absorbance spectrometer with a quantum cascade laser (QCL) source. The instrument allows characterization of samples of increased path length with similar signal-to-noise ratios as in FT IR measurements. Achievable signal-to-noise ratios are limited by QCL source noise; we present several approaches, one electronic and one interferometric, aimed at limiting the deleterious effect of QCL fluctuations.</p><p>

<p> Electrokinetic chromatography is a variation of capillary electrophoresis that allows for the separation of nonionic analytes by selective interaction with an ionic pseudostationary phase dissolved in the background electrolyte. The utility of electrokinetic chromatography to characterize pseudostationary phases and pseudostationary phase&ndash;solute interactions has been recognized since its introduction. The objective of this dissertation was to use electrokinetic chromatography and copolymer stabilized lipid bilayer nanodiscs as a pseudostationary phase to characterize small molecule-lipid bilayer interactions. </p><p> Styrene-maleic acid copolymers were used to stabilize cylindrical sections of lipid bilayer in solution, forming nanodiscs. The nanodiscs are formed based on strong hydrophobic interactions between the styrene moiety, on the copolymer, and the alkyl tails of the lipids. Using the nanodisc pseudostationary phase, the affinity of the bilayer structure for probe solutes was characterized. Linear solvation energy relationship analysis was employed to characterize the changes in solvent environment of the nanodiscs of varied copolymer to lipid ratio, copolymer chemistry and molecular weight, and lipid composition. Increases in the lipid to copolymer ratio resulted in smaller, more cohesive nanodiscs with greater electrophoretic mobility. Nanodisc structures with copolymers of different chemistry and molecular weight were compared and showed changes in solvent characteristics and selectivity. Seven phospholipid and sphingomyelin nanodiscs of different lipid composition were characterized. Changes in lipid head group structure had a significant effect on bilayer?solute interactions. In most cases, changes in alkyl tail structure had no discernible effect on solvation environment. </p><p> The nanodisc pseudostationary phase was also used to study sphingomyelin stereochemistry. Various studies have produced conflicting results regarding whether interactions with lipid bilayers are or can be stereoselective. Using sphingomyelin nanodiscs stereoselective interactions between a pair of atropisomers, R-(+)/(S)-(&ndash;) 1,1'-Bi-2-naphthol, were demonstrated. </p><p> Finally the dissociation constants between sphingomyelin nanodiscs and solvochromatic analytes were measured and then validated using steady state fluorescence. Using nanodisc affinity capillary electrophoresis, dissociation constants were derived on the same order of magnitude as the dissociation constants derived using the fluorescent technique. Future directions of this project will be to study peptide and protein interactions with lipid bilayers of interest.</p><p>

<p> N-nitrosodimethylamine is a carcinogenic disinfection byproduct which can be reformed after wastewater treatment if appropriate conditions are present. In this study various NDMA formation precursors over a range of conditions have been studied to attempt to quantify this NDMA reformation potential. Efforts were made in this study to demonstrate the effect of time, pH, and multiple different precursor chemicals on the reformation process. Dimethylamine (DMA) has been demonstrated to be a precursor chemical, and was chosen as a standard for initial experiments. The concentration of this precursor was kept constant at 100 ppt (parts per trillion) and solutions at three different pH&rsquo;s were tested over a 24-hour time period to see if any significant NDMA formation occurred. The impacts of various treated wastewater constituent chemicals including H₂O₂, monochloramine, dimethylhydrazine, etc. were also performed in this study. Significant difficulties occurred for the analysis of these samples, with large background interferences occurring in the method of analysis. Based on the data obtained, it appears that the formation potential of NDMA with DMA as a precursor was found to be the most efficient compound at basic pH (pH 9) and very basic (pH 13). This is consistent with the last step in wastewater remediation, where quicklime is added to the water to regulate the pH and for protection of distribution system. In addition, preliminary experiments were conducted using Ranitidine as a NDMA reformation precursor.</p><p>