Thesis (Ph. D.)--University of Pennsylvania, 1902. / Includes bibliographical references.

Thesis (M.Sc.(Chemistry))--University of Pretoria, 2000. / Includes abstract in English and Afrikaans. Includes bibliographical references.

Thesis (Ph. D.)--University of Pennsylvania.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed April 26, 2007). PDF text: 232 p. : ill. UMI publication number: AAT 3230060. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.A.)--Boston University

Redox films are a broad class of electrochemically active films with many potential uses. In the present work, Prussian Blue and carbon coated electrodes have been investigated as possible electrochemical sensors for ascorbic acid and pH, respectively. The potential of Prussian Blue as an optical sensor has also been investigated. In the case of Prussian Blue, it has been discovered that up to 100 monolayers can be systematically deposited on gold electrodes by a new technique that we have called "directed assembly". This provides control of layer thickness with nanometer precision. In the case of carbon coated electrodes, we have developed a mechanical coating technique for quartz crystals, which allows them to be used in electrochemical cells, simultaneously as working electrodes and as mass sensors in a quartz crystal microbalance. This opens up the possibility of developing a variety of new sensor technologies, including pH-sensitive microelectrodes.

No description available.

Methods are presented here for the determination of nitrate by electrochemical techniques. The reaction of nitrate with various organic reagents was studied by differential pulse polarography and a method described based on the nitration of benzoic acid. A rectilinear response was obtained over a 10-6 to 5x10-3M concentration range with reproducibility of < 2% at higher nitrate concentrations.

The electrochemical oxidation and reduction of galena (PbS) was studied in aqueous solutions of perchloric acid between pH 0 and 4. The wide variation of rest potential as reported in the literature was explained on the basis of stoichiometric variations of this material as well as the activities of ionic and molecular species involved in the PbS equilibria. The stoichiometry of the anodic and cathodic reactions was determined to be primarily PbS ↦ Pb⁺⁺+ S° + 2e⁻ and PbS + 2H⁺ + 2e⁻↦ Pb° + H₂S respectively. The irreversibility of anodic oxidation to lead sulphate was observed, with no sulphate produced below about 0.7 to 1.0 volt, depending on the pH. Polarization experiments revealed that ohmic, concentration, and activation polarization effects all contributed to the non-equilibrium behavior of PbS. Reaction of Pb0₂ and MnO₂ with PbS was rapid and interpreted as a "galvanic" effect, relying on the conductivity of the reactants as a necessary condition for its success. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

<p> Dinitrosyliron complexes have gained importance as a result of their biological and chemical relevance. Their biological significance stems from the roles exhibited by nitric oxide, including its ability to regulate blood pressure, to act as a biological messenger and because of its involvement in memory storage. Other functions that these dinitrosyliron-based complexes have displayed include their ability to transfer molecular oxygen to alkenes or phosphines, and its use in the polymerization of olefins. One area not yet extended to iron dinitrosyl complexes involves the synthesis of polymeric materials containing a conjugated backbone in the polymer. Thus, the next logical approach was to apply this idea, while investigating their potential to demonstrate unique properties such as optical, redox, and/or conducting behaviour exemplified by other inorganic and organometallic polymeric species. Hence, reactions involving Fe(NO)2(CO)2 and bidentate diphosphine ligands, bis(diphenylphosphino)methane (DPPM), trans-1,2-bis(diphenylphosphino)ethylene (t-DPPEN), 1,1 '-bis(diphenylphosphino) ferrocene (FcP2), bis(diphenylphosphino)acetylene (DPPA) and 1,4- bis(diphenylphosphino)benzene (DPPB) have been investigated. Three types of compounds arose from these reactions: the monometallic system Fe(DPPM)(N0)2(CO) 9, linear dimetallic molecules of the type Fe2(μ-L)(N0)4(CO)2 (L = PPh2CHzPPh2 10, PPh2C≡CPPh2 11, PPh2(p -6H4)PPh2 12, PPhzCH=CHPPhz 13, and PPh2((C5H4)2Fe) PPh2 14), and cyclic dimetallic species of the type Fe2(μ-L)(NO)4 (L = PPh2(p-C6H4)PPh2 15, PPh2CH2PPh2 16, and PPh2C≡CPPh2 17). These systems were isolated and characterized by the use of NMR and IR spectroscopy. The structures of compounds 10, 11, 16 and 17 were also determined by X-ray crystallography. The linear dimetallic compounds, 11, 13 and 14, were treated with tetracyanoethylene (TCNE) to afford compounds of the type Fe2(μ-L)(N0)4(TCNE)2 (L = PPhzC≡CPPh2 18 and PPh2((C5H4)2- Fe)PPh2 19) and [(TCNE)(NO)2Fe(μ-L)[Fe(NO)2(CO)] (L = PPh2CH=CHPPh2 20). These TCNE adducts were probed by means of cyclic voltammetry to investigate their potential redox properties; only compound 18 revealed communication between the two iron centres. </p> <p> Dinitrosyldicarbonyliron, Fe(NO)2(CO)2 and other four-coordinate dinitrosyliron systems have been extensively examined in terms of nucleophilic substitution, including the effects of both hard and soft bases. These findings prompted us to ask whether electrophiles attack dinitrosyliron complexes. Hence, Fe(NO)2(CO)2 1, and also the phosphine complexes Fe(NO)2(CO)(PPh3) 21, and Fe(NO)2(PPh3)2 22, have been treated with a variety of electrophiles (HCl, SiMe3Cl, Et30^+SbCl6-, trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid (TFSA)) to probe the nucleophilic character of the iron centres. Moreover, another approach involved examining the nucleophilic nature of the iron nitrosyl salts, [PPN^+][Fe(CO)3(NO)], 24 and [N(Bu)4+][Fe(C0)3(NO)], 25. </p> / Thesis / Master of Science (MSc)