Physical Sciences and Mathematics Commons^™

Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chien-Hung Chiang

LSU Doctoral Dissertations

Chemo- and biosensors based on fluorescent conjugated polymer benefit from greater detection sensitivity due to amplification of the electronic perturbations produced by analyte binding. This amplification stems from the exciton-transporting properties of conjugated polymers. A conventional design paradigm relies on the analyte binding events which generate sites of lower energy relative to the polymer energy: either fluorescence quenching sites (turn-off sensors) or bathochromically shifted fluorophores (turn-on sensors). In both type sensors, the excitons migrate to the lower-energy site created by analyte binding.

This dissertation primarily focused the investigation of an alternative paradigm when analyte binding creates higher energy gap sites …

Synthesis, Characterization, And Evaluation Of Novel Bodipy Dyes With Theranostic Applications, Jaime Suzanne Hayes

LSU Doctoral Dissertations

Boron dipyrromethene (BODIPY) dyes, have garnered much attention in recent decades due to their enticing photophysical properties and their bioimaging applicability. Despite the progression of this field, the development of BODIPY based anti-cancer agents and radioimaging dyes has seen little progress. The utilization of fluorescent BODIPYs as photosensitizers for photodynamic therapy, and as boron delivery agents for boron neutron capture therapy offers promise as theranostic agents. Additionally, BODIPY derivatives that absorb and emit in the near-IR regions of the electromagnetic spectrum and bear radioisotopes suitable for radioimaging techniques are of great interest. Chapter 1 is a concise overview of the …

Gumbos And Nanogumbos: Applications As Photosensitizers In Dye-Sensitized Solar Cells, Atiya Nicole Jordan

LSU Doctoral Dissertations

Renewable energy is a major concern due to increased world energy consumption. In particular, solar energy is a type of renewable energy source that uses devices known as solar cells to convert sunlight to electricity. Specifically, devices referred to as dye-sensitized solar cells (DSSCs) employ dyes to absorb solar energy. Dyes derived from ruthenium complexes have been typically used in DSSCs. Unfortunately, several disadvantages are associated with current ruthenium complex photosensitizers, which can be attributed to limited supply and expense of metals, as well as reduced absorption in the near-infrared region of the electromagnetic spectrum. Accordingly, this dissertation is a …

Ionic Materials For Applications In Sensing And Optoelectronics, Sergio L. De Rooy

LSU Doctoral Dissertations

Organic salts consist of bulky anions and/or cations whose properties can be tailored for specific purposes. Ionic liquids (ILs) are (semi)organic salts with melting points below 100 ºC. They typically exhibit neglible vapor pressures, high thermal stability, wide liquidus range, and tunable solubility. Moreover specific functions can be built into their respective ions. The first part of the dissertation involves discussions of chiral ionic liquids with additional protic, magnetic, and magneto-luminescent properties, respectively. In addition to their enantioselective sensing capabilities, the ILs may find use in chiral separations and catalysis. The second part of the dissertation involves discussions of fluorescent …

Preparation And Studies Of Ratiometric Fluorescent Chemosensors Based On The Attenuation Of Excitation Energy Transfer, Jiba Raj Acharya

LSU Doctoral Dissertations

Molecular devices possessing pi-electron conjugated scaffold demonstrate unique capabilities as fluorescent chemosensors for the trace detection of analytes in a variety of environments. Important properties of these compounds such as charge transport and exciton migration, emission intensity etc. can be simply attenuated by external stimuli or analyte binding, leading to considerable changes in observable signals. The main goal of this Ph.D. dissertation was to study the possibility to control excitation energy migration in conjugated systems. Towards this goal, we designed surface-immobilized monodispersed oligo(p-phenylene ethynylene)s (OPEs) as a general basis for thin-film ratiometric fluorescent chemosensors. The sensor molecules have been functionalized …

Probing The Association Behavior Of Hydrophobic Organic Compounds With Dissolved Humic Materials, Hadi M. Marwani

LSU Doctoral Dissertations

The association mechanism between hydrophobic organic compounds (HOC) and dissolved humic materials (DHM) has continued to be one of the interesting areas in environmental applications. The goal of the research reported in this dissertation is to investigate the association behavior of HOC with DHM. The first part of this research involves steady-state fluorescence measurements of these multi-component systems to study the effect of DHM content on the association mechanism of HOC, in particular using pyrene as a model. Results showed that steady-state fluorescence alone may not provide enough information about the quenching mechanism of pyrene with DHM. Lifetime based fluorescence …

Stereochemical And Regiochemical Trends In The Selective Spectrophotometric Detection Of Biological Molecules, Shan Jiang

LSU Doctoral Dissertations

Useful mechanistic studies to date concerning sugar detection by arylboronic acid chemosensors have mainly involved the elucidation of equilibrium constants and the role of boron-nitrogen interactions in signal transduction. However, several discreet sugarboronate complexes exist in solution. This is due to the complex equilibria between isomeric species of even the simplest monosaccharides. Relatively few reports have been devoted to a systematic study of the structures of each of the corresponding individual sugar-boronate complexes. We have investigated some of the precise regio- and stereochemical features of the various equilibrating sugar isomers that induce selective signal transduction. As a result of this …

Synthesis, Characterization, And Application Of Water-Soluble Chiral Calix[4]Arene Derivatives In Spectroscopy And Capillary Electrokinetic Chromatography, Kim Hamilton

LSU Doctoral Dissertations

This dissertation is an account of the synthesis, characterization, and application of novel water-soluble chiral calixarenes in spectroscopy and capillary electrophoresis. It is divided into four sections. The first part describes the synthesis and nuclear magnetic resonance (NMR) characterization of four p-t-butylcalix[4]arenes bearing L-amino acid moieties on their lower rims (CX4-AA). The structure and conformation of the derivatives have been determined using one- and two-dimensional NMR techniques. Proton and carbon-13 spectra show that the derivatives are tetra-substituted and adopt a cone conformation. The preparation and characterization of silica-bonded calixarene stationary phases for capillary electrochromatography is also reported in Chapter 2. …

Solid-Phase Dna Sequencing Reactions Performed In Micro-Capillary Reactors And Solid-Phase Reversible Immobilization In Microfluidic Chips For Purification Of Dye-Labeled Dna Sequencing Fragments, Yichuan Xu

LSU Doctoral Dissertations

The research presented in this dissertation involves micro-capillary reactors for solid phase DNA sequencing, the identification of dye terminator sequencing fragments with time-resolved methods, and purification of dye-labeled DNA fragments using solid- phase reversible immobilization in microfluidic chips. Solid-phase micro-reactors have been prepared for DNA sequencing applications using slab gel electrophoresis. A PCR product was immobilized to the interior wall of a fused-silica capillary tube via a biotin-streptavidin linkage. Solid-phase sequencing was carried out in micro-capillary reactors using a four-lane, single color dye primer chemistry strategy. The read length was found to be 589 bases. The complementary DNA fragments generated …

Analysis Of Near-Infrared Dye-Labeled Sanger Sequencing Fragments With Gel Electrophoresis Using The Time-Resolved Flourescence Lifetime Indentification Methods, Suzanne Jeanel Lassiter

LSU Doctoral Dissertations

The research presented in this dissertation involves the identification of sequencing fragments with time-resolved methods. For this application, near-infrared heavy-atom tricarbocyanine dyes were developed in our laboratory, which can be excited with a single laser and emission collected using a single detection channel. The dyes have four spectroscopically unique, but relatively short lifetimes that can be altered by the intramolecular heavy-atom they contain. The work described here involves the optimization of dye-primer chemistry for preparing Sanger sequencing reactions for longer reads and the optimization of the separation matrix for capillary gel electrophoresis that produces favorable statistical analysis of the aforementioned …