Chemistry Commons^™

Copper Complexation And Speciation In The Western South And Equatorial Atlantic Ocean, John A. Consolvo

Chemistry & Biochemistry Theses & Dissertations

Presented here are the first data on copper complexation and speciation in the South Atlantic Ocean. Samples were collected at six vertical profile stations and along the surface (1m) transect during the 1996 IOC Baseline Contaminant Survey. Copper complexation measurements were made for the surface transect (1m) samples and three of the six vertical profile stations (1m - ~500m) using differential pulse anodic stripping voltammetry (DPASV) with a thin mercury film, rotating glassy carbon disk electrode (TMFRGCDE).

A strong organic copper complexing ligand (L₁; log K' _cuL1/cu2+ > 11. 8 ± 0 .4) was detected in 57% of all …

3-Hydroxykynurenine And 3-Hydroxyanthranilic Acid Generate Hydrogen Peroxide And Promote Α-Crystallin Cross Linking By Metal Ion Reduction, Lee E. Goldstein, Michael C. Leopold, Xudong Huang, Craig S. Atwood, Aleister J. Saunders, Mariana Hartshorn, James T. Lim, Et Al.

Chemistry Faculty Publications

The kynurenine pathway catabolite 3-hydroxykynurenine (3HK) and redox-active metals such as copper and iron are implicated in cataractogenesis. Here we investigate the reaction of kynurenine pathway catabolites with copper and iron, as well as interactions with the major lenticular structural proteins, the R-crystallins. The o-aminophenol kynurenine catabolites 3HK and 3-hydroxyanthranilic acid (3HAA) reduced Cu(II)>Fe(III) to Cu(I) and Fe(II), respectively, whereas quinolinic acid and the nonphenolic kynurenine catabolites kynurenine and anthranilic acid did not reduce either metal. Both 3HK and 3HAA generated superoxide and hydrogen peroxide in a copper-dependent manner. In addition, 3HK and 3HAA fostered copper-dependent R-crystallin cross-linking. 3HK- …

Cu(Ii) Potentiation Of Alzheimer A Neurotoxicity, Xudong Huang, Math P. Cuajungco, Craig S. Atwood, Mariana A. Hartshorn, Joel D. A. Tyndall, Graeme R. Hanson, Karen C. Stokes, Michael C. Leopold, Et Al.

Chemistry Faculty Publications

Oxidative stress markers as well as high concentrations of copper are found in the vicinity of Aβ amyloid deposits in Alzheimer's disease. The neurotoxicity of Aβ in cell culture has been linked to H2O2generation by an unknown mechanism. We now report that Cu(II) markedly potentiates the neurotoxicity exhibited by Aβ in cell culture. The potentiation of toxicity is greatest for Aβ1–42 > Aβ1–40 ≫ mouse/rat Aβ1–40, corresponding to their relative capacities to reduce Cu(II) to Cu(I), form H2O2 in cell-free assays and to exhibit amyloid pathology. The copper complex of Aβ1–42 has a highly positive formal reduction potential (≈+500–550 mV versus …

Oxidation Of Benzoins To Benzils Using Bismuth(Iii) Nitrate-Copper(Ii) Acetate, Ram Mohan, Steven Tymonko, Bryce Nattier

Scholarship

Benzoins are oxidized to benzils in excellent yields by 0.4 equivalents of Bi(NO₃)3.5H₂0 and 4 mol% of Cu(OAc)₂₃)₃.5H₂0 is a stable, inexpensive, commercially available solid. The relatively low cost and low toxicity of bismuth(Ill) nitrate makes this procedure a particularly attractive method for oxidation of benzoins.

Behavior Of Copper In Hydrogen Storage Alloy Microencapsulated By Copper, Dawei Zhang, Huatang Yuan, Huabin Yang, Zuoxiang Zhou, Yunshi Zhang

Journal of Electrochemistry

Negative electrode made from Cu microencapsulated hydrogen storage alloy was studied by using cyclic voltammetry method. The results showed that copper as a coating material was of a certain stability in 5 mol/L KOH solution within the range of charge and discharge voltage. But when expanding the sweep voltage, the CV curve showed a pair of distinct oxidation reduction current peaks of Cu₂O formation at E = -0.3 V and Cu₂O reduction at E =-0.6 V. With charging discharging cycles, copper is liable to be oxidized to Cu₂O and further oxidized into CuO_{2 …}

Corrosion Behaviour Of Copper Covered With Ion Selective Phenolic Coatings By Eis, Zhoucheng Wang, Yingzhou Zhang, Shaomin Zhou

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS) technique was employed to study the corrosion behaviour of copper painted with the anion selective, cation selective and bipolar phenolic coatings in 3% NaCl solution. From the impedance spectrum characteristics, the models of equivalent circuit for these different coating systems were established, and the methods for the analysis of experimental impedance diagrams in terms of coating and interface properties were discussed. The research results show that the composition and structure of ion selective coatings have significant influence on corrosion behaviour of copper. The bipolar coating consisting of an anion selective inner layer and a cation selective outer …

Electrochemical Studies On Chemical Polishing Of Copper, Keping Han, Jingli Fang

Journal of Electrochemistry

Changes in specular reflectivity,weight loss,surface topograph and potential with time and current-potential curves during chemical polishing were determined. The results showed that chemical polishing was composed of the etching, polishing and pitting stage. The passivating film theory also applied to the chemical polishing.

Electrochemical Study Of The Corrosion Behavior Of Coalesced Copper And Sw-206 Stainless Steel In The Acetic-Acid Solution, Rongzong Hu, Changjian Lin, Jianguang Tan, Zhanmei Sun, Xueqin Wu, Biao Wang

Journal of Electrochemistry

In order to provide a theoretic and experimental consideration for the material selection and anit-corrosion in the petrochemical industries the corrosion behavior of coalesced copper and sw-206 stainless steel in the acetic acid solution was studied by electrochemical impedance spectroscopy and polarization techniques. The effects of the temperature, acetic acid concentration and solubilized oxygen in the acetic acid solution on the corrosion process of this two metals were analyzed. It was found that these effects obviously accelerate corrosion process for the coalesced copper, but no apparent influnce for the sw-206 stainless steel.In the the acetic acid solution, containing water and …

Cyclic Voltammetric Calorimetry Studying The Deposition Of Copper Of Pt Electrodes, Yongchun Zhu, Robin. H. J. Clark

Journal of Electrochemistry

In the present paper, cyclic voltammetric calorimetry has been used to study thedeposition of copper on platinum electrode from LiClO₄ aqueous solution. Cyclic voltammetric thermogram and cyclic voltammetric differential thermogram show that the deposition of copper on theelectrode is an exothermal process with a strong interaction between copper and platinum layer (-3227.0 kJ /mol). The electrochemical oxidation of the deposited copper is composed of twoprocesses: an endothermal activation process with 747.0 kJ/mol of activation enthalpy, and an exothermal oxidation reaction with -189.9 kJ/mol of the reaction enthalpy, which are accord with the data from the theoritical estimation and thermodynamic …

Electrochemically Modified Glassy Carbon Electrode And Determination Of Copper By Anodic Stripping Voltammetry, Jinrui Xu, Yie Liu, Xiurun Zhuang, Tomoo Miwa, Toyohide Takeuchi

Journal of Electrochemistry

This paper reported the glassy carbon electrode modified by cyclic voltammetrybetween -0.1 and +1.5 V (vs. SCE) in an aqueous solution containing catechol, for maldehyde and talium hydroxide. The modified electrode can be applied to the determination of copper(Ⅱ) in water, and its sensitivity is about 35 times higher than that of unmedified glassy carbon electrode, The quantitative limit with this modified electrode is 0.1 ng/ml.

Characterization And Implementation Of A Continuos Flow Trace Metal Preconcentration System For Inductively Couples Plasma Atomic Emission Spectrometry, Robert N. Sibley

Senior Scholar Papers

A continuous flow pre-concentration system for analysis of trace metals in natural waters was characterized and used to determine the copper(II) and lead(II) concentrations in seawater from Penobscot Bay, Maine. Pre-concentrated samples were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). System characterization involved elucidation of the thermodynamic complexation constants, KCu(II) and KPb(II), for Cu(II) and Pb(II) with the pre-concentration column chromatographic material. This was done in aqueous media of known pH and ionic strength. The column contained 8-hydroxyquinoline immobilized on Toyopearl HW-75 fractogel chromatographic resin. The buffer system used for metal binding experiments was an equimolar mixture of …

Photochemical Energy Storage (Photosensitized Isomerization Of Norbornadiene To Quadricyclane By Copper(I) Complexes), Dennis J. Fife

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research has focused on the sensitized photoisomerization step of a solar energy storage system based on the interconversion of norbornadiene (NBD) and quadricyclane (Q). Sensitizers studied in the photoisomerization were arylphosphine complexes of copper(I) halides [(Ph₃P)₃CuX, (MePh₂P)₃CuX, (DIPHOS)CuCl; X = Cl, Br, I and DIPHOS = Ph₂P(CH₂)₂PPh₂]. The lowest electronic excited state of the complexes can be an effective triplet energy sensitizer as evidenced by a maximum quantum yield of 1.0 with (MePh₂P)₃CuX. The sensitization mechanism of the L …

An Fe (Iii) - Initiated Oxidase Reaction With Ferroxidase-Ii, Glenn Alexander Hegamyer

Master's Theses

A reaction involving iron as an intermediary electron carrier for the coupling of electron transfer from an endogenous substrate to ferroxidase-I has been proposed.

The enzymic nature of the reacti on has been established and studies with iron chelating agents have demonstrated the involvement of Fe(III). The kinetic parameters of ferroxidase-11 with Fe (lll) were found to be quite similar to those previously established for Fe(Il). The participation by the copper associated with ferroxi dase-11 was ascertained by use of the copper chelating agent, diethyl -di thio-carbamate .

A variety of substances normally found in blood were surveyed as possible …

Benzohydroxamic Acid As A Reagent For The Determination Of Aluminum And Copper, William E. West

Masters Theses

No abstract provided.

Control Of Copper, Zinc And Manganese Deficiencies In Fruit Trees, N J. Halse

Journal of the Department of Agriculture, Western Australia, Series 4

THE three elements copper, zinc and manganese are plant nutrients of the type often referred to as minor or trace elements.

Although essential elements for plant growth, they are required in comparatively small quantities.

The Chelation Of Cu(Ii) With 1, 3-Bis(Tris(Hydroxymethyl)Methylamino)-2-Propanol And 1, 3-Bis (2-Hydroxyethylamino)-2-Propanol, David Andrew Jackson Jr.

Master's Theses

The chelating agent 1, 3-bis(2-hydroxyethylamino)-2-propanol dihydro­chloride was prepared and preliminary examinations of the Cu(ll) and Fe(lll) complexes were carried out spectrophotometrically. This dihydrochloride as well as 1, 3 bis(tris(hydroxymethyl)methylamino)-2-propanol dihydrochloride. were converted from the chloride salts to their corresponding ammonium bases. The conversion was carried out by passing an aqueous solution of each chloride salt through an ion exchange column containing Amberlite XE-78 resin.

Solutions of these bases were standardized for use in potentiometric titration&. Each ammonium base was titrated with standard perchloric acid at 20°C, 30°C, and 40°C. The dissociation constants. were calculated using these data. Aqueous solutions of …

Gravimetric Analysis, Walter M. Lauer

Chemistry Honors Papers

This 16 page thesis examines gravimetric quantitative analyses of various metals.