Copper interactions

Many authors have used XPS to investigate the mechanisms by which vapor-deposited metals such as copper interact with the surfaces of polyimides. Chou and Tang [29] observed that only small changes occurred in the XPS line shapes after vapor deposition of copper on polyimide they suggested that no... 

This section demonstrates that (1) free ionic copper (Cu2+) is the most toxic chemical species of copper and that copper bioavailability is modified by many biological and abiotic variables (2) copper metabolism and sensitivity to copper of poikilotherms differs from that of mammals and (3) copper interactions with inorganic and organic chemicals are substantial and must be considered when evaluating copper hazards to natural resources. 

Clarification of copper interactions with molybdenum, sulfate, iron, and zinc in plant and animal metabolisms (NAS 1977 Eisler 1989, 1993)... 

Numerous and disparate copper criteria are proposed for protecting the health of agricultural crops, aquatic life, terrestrial invertebrates, poultry, laboratory white rats, and humans (Table 3.8) however, no copper criteria are now available for protection of avian and mammalian wildlife, and this needs to be rectified. Several of the proposed criteria do not adequately protect sensitive species of plants and animals and need to be reexamined. Other research areas that merit additional effort include biomarkers of early copper stress copper interactions with interrelated trace elements in cases of deficiency and excess copper status effects on disease resistance, cancer, mutagenicity, and birth defects mechanisms of copper tolerance or acclimatization and chemical speciation of copper, including measurement of flux rates of ionic copper from metallic copper. 

Holwerda, D.A. 1991. Cadmium kinetics in freshwater clams. V. Cadmium-copper interaction in metal accumulation by Anodonta cygnea and characterization of the metal-binding protein. Arch. Environ. Contam. Toxicol. 21 432 137. 

One more example demonstrates how to use standard reduction potentials to determine the standard potential of a cell. Let s say you wanted to construct a cell using silver and zinc. This cell resembles the Daniell cell of the previous example except that a silver electrode is substituted for the copper electrode and a silver nitrate solution is used in place of copper sulfate. From Table 14.2, it is determined that when silver and copper interact silver is reduced and copper oxidized. The two relevant reactions are... 

Based on the previously described silver complex [Au2Ag2(Q)f,s)4(MeCN)2 , the same reaction with CuCl in acetonitrile but with addition of an equivalent of pyrimidine leads to the polymeric [CuAu(C6F5)2(MeCN)((J.2-C4H4N2)]n [66]. The polymerization of this complex is produced by covalent copper-pyrimidine bonds. The environment of the copper centers also comprises unsupported gold-copper interactions of 2.8216(6) A and one molecule of acetonitrile, leading to a distorted tetrahedral arrangement (see Figure 6.26). 

The following sections (53.4.4.2-6) attempt to describe the electronic properties of simple mononuclear complexes of the copper(II) ion,47,48 to show how these are related to the different stereochemistries of the copper(II) ion and how these properties are modified by the formation of polynuclear complexes.17,30 Particular emphasis is placed on the appearance of the different types of electronic property and how they may be used to provide qualitative evidence for the different types of copper-copper interactions, and hence for possible polynuclear structure formation, particularly in the solid state. While the main emphasis will be on the electronic properties in the solid state, where X-ray evidence may be obtained for a single magnetic species,10 the measurement of the electronic properties in solution will also be described, although in solution a mixture of complex species may be present in equilibrium and complicate the interpretation of the electronic properties.584,816,817,824... 

When the previous reaction is carried out in the same solvent (acetonitrile) with the addition of one equivalent of pyrimidine, the polymeric species [CuAu(C6F5)2(MeCN)(p,2-C4H4N2)] is obtained in high yield.45 In this case, the chain of metals is different from the previous case, and polymerization is produced by covalent copper-pyrimidine bonds with pairs of gold-copper interactions (2.8216(6) A). The environment of the copper centers is tetrahedral, with one acetonitrile molecule occupying the fourth position (Fig. 14). 

If copper interactions were minimized in real seawater, abundant metals of lesser sulfide affinity would take up some of the slack. ITiis is partially evident from analyses of the type in Table III. For example, nickel has mixed layer concentrations on the order of nanomolar (22), and its sulfide equilibria and inorganic seawater speciations may resemble those of zinc (lv-19.31.32). Titration, however, should only lower free sulfide to a Table m SH equivalence point, or, to roughly picomolar. In a follow up to 1Z, Dyrssen and coworkers treat Cu(II) as a variable parameter, and find that in its absence, nickel, zinc and lead can all become sulfides while the bisulfide ion still hovers well above pM (18). Again, it must be emphasized that error margins in the various equilibria remain to be investigated. 

This chapter focuses on the chemistry ofbiomimetic copper nitrosyl complexes relevant to the NO-copper interactions in proteins that are central players in dissimilatory nitrogen oxide reduction (denitrification). The current state of knowledge of NO-copper interactions in nitrite reductase, a key denitrifying enzyme, is briefly surveyed the syntheses, structures, and reactivity of copper nitrosyl model complexes prepared to date are presented and the insight these model studies provide into the mechanisms of denitrification and the structures of other copper protein nitrosyl intermediates are discussed. Emphasis is placed on analysis of the geometric features, electronic structures, and biomimetic reactivity with NO or NOf of the only structurally characterized copper nitrosyls, a dicopper(II) complex bridged by NO and a mononuclear tris(pyrazolyl)hydroborate complex having a Cu(I)-NO formulation. 

By analyzing the XPS intensities for normal and grazing exit of electrons from the sample surface it was concluded that the pim molecules are lying approximately flat on the copper surface. Note that this orientation of the pim molecule in principle allows for a considerable interaction between the benzene ring and the copper surface. However, it is known from earlier studies that the benzene UPS valence band remains essentially unaltered when benzene is deposited on a copper surface (12) No evidence for a strong 7t-electron-copper interaction is thus observed despite the fact that the benzene molecule is believed to lie flat on the copper surface. Hence, the observation of only minor chemical shifts in the Is levels of the benzene ring carbons is consistent with the proposed orientation (12) of pim on the copper surface. 

Electron spectroscopy for chemical analysis (ESCA) studies were undertaken in order to characterize the PEEK/copper interactions that occur on Cu(0), Cu(I), and Cu(II) surfaces. 

Studies by Cox and collaborators showed that a 0.4% zinc enrichment of maternal rat rations during gestation (21,22,23) or lactation (24,25,26) would reduce copper content and cytochrome C oxidase activity In the tissues of fetuses and pups and the copper content of the milk (25). Adding 0.2% copper to the diet reversed this effect. Whether the zinc copper Interaction Is mediated exclusively at the maternal gut, or at other foci of mineral transport In the dam or offspring cannot be determined. 

Tsuchiya H and Bates CJ (1997) Vitamin C and copper interactions in guinea-pigs and a study of collagen cross-links. British Journal of Nutrition 77,315-25. 

To check the validity of the concept that polished copper interacts with titanium during polishing, titanium films (with no copper present on the wafers) were polished in a slurry containing Cu ions introduced as Cu(N03)2- Figure 4.43 shows the dependence of the polish rate of titanium on Cu(N03)2 concentration in the slurry. The polish rate of titanium increased with the addition of copper, supporting the hypothesis that Cu ions in the polishing... 

This wealth of copper CMP data has not narrowed the focus of developing an abrasive particle-copper interaction model, but actually expanded it. Copper can be polished with various abrasives, in the presence of various suppressants and with a wide range of oxidants over a wide pH range. Because of the very rigorous demands of copper damascene CMP, and the incomplete current understanding, the research effort focussed on copper is still growing. 

The mechanism of this eflFect is not known. Hill and Starcher (49) postulated that reduction of copper from its divalent (cupric) state to its monovalent (cuprous) state accounted for the impaired absorption of copper in the presence of ascorbic acid they produced the same effect with another reducing agent, dimercaptopropanol (BAL). This explanation has been accepted by others (56), although the oxidation state of copper for maximum intestinal absorption has not been established. An intramucosal competition of ascorbic acid for sulfhydryl sites on metallo-thioneins was demonstrated (57). If this ligand has any regulatory role in copper uptake, this alternative mechanism of ascorbic acid-copper interaction could explain the mechanism. Experimental confirmation of an ascorbic-acid-induced inhibition of copper absorption in the human intestine has not been presented. 

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