A series of 9-substituted methylacridinium salts have been devised, chemiluminescent in alkaline hydrogen peroxide solutions. Their relative light intensities correspond to the expected order of reactivity with the nucleophilic hydroperoxide anion, and the mechanistic evidence is consistent with the requirement for a four-membered cyclic peroxide intermediate as the direct precursor to chemiluminescence. In every case, the actual emitter is N-methyl-acridone, λ max 442 mμ The brightest compounds are a series of substituted phenyl esters. They have large rate differences (with a Hammett dependence) but have equal quantum yields, equivalent to that of the closely-related "classical" light producer, lucigenin. / Science, Faculty of / Chemistry, Department of / Graduate

Graduation date: 1992

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Allen J. Bard. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Allen J. Bard. Vita. Includes bibliographical references. Also available from UMI.

Not available / text

Not available / text

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 109-112). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 95-96). Also available via the Internet.

Electrogenerated chemiluminescence (ECL) of new, highly fluorescent molecules was studied. Six novel, highly fluorescent, green emitters were synthesized by incorporating an acceptor group like 2,1,3-Benzothiadiazole between different donor groups. The structural effects on the electrochemical, spectroscopic, and ECL behavior are shown in detail. Stable electrochemistry and high PL quantum yield were observed. Most of the ECL was visible by the naked eye. Well-known, fluorescent, polyaromatic hydrocarbons (PAH), like 9,10-diphenylanthracene derivatives, pyrene, and anthracene were incorporated between two bulky fluorene derivative groups. The fluorene substitutions block the active positions of the PAH cores, permitting the formation of stable radical ions upon electrochemical oxidation or reduction. Such a tailoring led to increase electrochemical reversibility and tuning of the ECL wavelength. Fluorene-based DPA (FDF) is characterized by a highly efficient and stable blue-cyan color. Another interesting type of molecules was star-shaped structures. The effects of structure on the electrochemistry and spectroscopy of a series of star-shaped, rigid molecules was examined. T1-T4 is composed of oligofluorene arms with truxene as a central core basically there were weak donor and weak acceptors. The ECL quantum efficiency was near 80% for the long-arm T4. One of the interesting goals in ECL is to find ECL emitters in aqueous media. Organic nanoparticles (ONPs) were chosen to achieve this goal. An organic nanoparticle (ONPs) is still challenging area in nanoscience. The key factor of such a challenge comes from the difficulty to control the size and shape of the prepared nanoparticles. ONPs of common hydrocarbon ECL emitters like rubrene and 9,10-diphenylanthracene (DPA) were prepared in aqueous solution using a reprecipitation method. ECL of rubrene NPs was observed when tripropylamine (TPrA) was used as a coreactant, and weaker ECL of DPA NPs was observed when the oxalate ion was used as a coreactant. The ECL of ONPs in aqueous media may open a new field in ECL, allowing the exploration of more phenomena in organic nanoscience. Organic nanoparticle ECL (especially if one able to make small size to be diffused easily) has potential application as a tag for the analysis of biologically interesting molecules. / text

The excited state emissions and lifetimes of [Cr(bipy)₃]³⁺, cis – [Cr(bipy)₂Cl₂]⁺, trans – [Cr(py)₄FBr]⁺, cis – [Cr(phen)₂F₂]⁺, and trans – [Cr(py)₄F₂]⁺ were studied in hydroxylic and nonhydroxylic solvents at 77 K and as a function of temperature. The emission characteristics are determined by the relative disposition of ²E and one component of ²T₁. The energy of these two levels is influenced by intramolecular and environmental factors, and solvent-induced level inversion occurs in cis – [Cr(phen)₂F₂]⁺. The influence of temperature and solvent viscosity were studied in several glasses with variable melting ranges. The emission of all of the complexes, except [Cr(bipy)₃]³₊, were found to be influenced by solvent viscosity. This influence is large when ²E and the component of ²T₁ are close in energy, and level inversion upon melting of the solvent occurs in cis –[Cr(phen)₂F₂]⁺. The decay of the emission of Cr(III) complexes normally shows small temperature dependence at lower temperatures and large temperature dependence at higher temperatures. The threshold for the appearance of strong temperature dependence depends on intramolecular and environmental factors. The decays of all the complexes except [Cr(bipy)₃]³⁺ show strong discontinuities in the rigid-fluid transition regions of the solvent glasses which are accompanied by risetimes in the decay profiles when the emission intensity is monitored at long wavelengths. This is attributed to solvent relaxation during the excited state lifetime.