Interaction of metals

Formation of artificial receptors by interaction of metal with macroheterocycles as templates 97CRV1669. 

In the light of what has been said above, little further explanation of the implications of the title of the present work is required. Its treatment of the subject of corrosion will centre round the control of the environmental interactions of metals and alloys used as materials of construction. 

Decompositions of crystalline mixed hydroxides to mixed oxides often occur at temperatures lower than those required to produce the same phases through the direct interaction of metal oxides. This route thus offers an attractive approach for the preparation of catalysts of high area and activity [1147]. Detailed kinetic investigations comparable with those for the dehydroxylations of a number of pure hydroxides (Sect. 2.1) are not, however, available. 

Interaction of Metal Centers Through Sulfur-Containing Ligands (O. Kahn, J.-J. Girerd)... 

The FT-IR spectra of pure of nanocomposites exhibited shift in the absorption frequencies due to the interaction of metal with starch (Fig. 16). 

The interaction of metals with the OH groups in water molecules is attended by a stretching of the H-OH bonds, which raises the donor properties of these water molecules and serves to accelerate electrochemical reactions with a slow step that involves hydrogen. This was confirmed in the electroreduction of anions NOj, BrOj, and the like on metals exhibiting varying degrees of hydrophilicity. 

Damaskin, B.B.andFrumkffiA. N. (1974) Potentials of zero charge, interaction of metals with water and adsorption of organic substances—111. The role of the water dipoles in the structure of the dense part of the electric double layer. Electrochim. Acta, 19, 173-176. 

Interactions of Metal Salts with the Formation. Interactions of metal salts with the formation and distribution of the retained aluminum in a porous medium may significantly affect the location and strength of gels. This interaction was demonstrated with polyacrylamide-aluminum citrate gels [1514]. Solutions were displaced in silica sand. The major findings of this study are that as the aluminum-to-citrate ratio increases, the aluminum retention increases. Furthermore, the amount of aluminum retained by silica sand increases as the displacing rate decreases. The process is reversible, but the aluminum release rate is considerably slower than the retention rate. The amount of aluminum released is influenced by the type and the pH level of the flowing solution. The citrate ions are retained by silica sand primarily as a part of the aluminum citrate complex. Iron, cations, and some divalent cations cannot be used in the brine environment. 

An explanation of the direct 4s contribution to the charge density at the nucleus requires MO calculations. A simple MO diagram for octahedral complexes is shown in Fig. 4.4. The a-interaction of metal /-orbitals and symmetry-adapted ligand orbitals usually yields the major part to the stability of the bonds. According... 

The vibrational spectrum of a metal complex is one of the most convenient and unambigious methods of characterization. However, it has not been possible to study the interactions of metal ions and biological polymers in this way since the number of vibrational bands from the polymer obscure the metal spectrum. The use of laser techniques for Raman spectroscopy now make it very likely that the Raman spectra of metals in the presence of large amounts of biological material will be measured (34). The intensity of Raman lines from metal-ligand vibrations can be... 

V. Interaction of Metal Complexes with Biological Ligands and Macro-molecules... 

The ionic profile of the metal was modeled as a step function, since it was anticipated that it would be much narrower than the electronic profile, and the distance dx from this step to the beginning of the water monolayer, which reflects the interaction of metal ions and solvent molecules, was taken as the crystallographic radius of the metal ions, Rc. Inside the metal, and out to dl9 the relative dielectric constant was taken as unity. (It may be noted that these calculations, and subsequent ones83 which couple this model for the metal with a model for the interface, take the position of the outer layer of metal ion cores to be on the jellium edge, which is at variance with the usual interpretation in terms of Wigner-Seitz... 

For the metal in the electrochemical interface, one requires a model for the interaction between metal and electrolyte species. Most important in such a model are the terms which are responsible for establishing the metal-electrolyte distance, so that this distance can be calculated as a function of surface charge density. The most important such term is the repulsive pseudopotential interaction of metal electrons with the cores of solvent species, which affects the distribution of these electrons and how this distribution reacts to charging, as well as the metal-electrolyte distance. Although most calculations have used parameterized simple functional forms for this term, it can now be calculated correctly ab initio. 

The metal-carbenoid intermediates, especially ones derived from a-diazocarbonyl compounds, are electrophilic, and electron-rich olefins in general react more easily with the carbenoid intermediates than electron-deficient olefins. For the interaction of metal carbenoid and olefin, three different mechanisms have been proposed, based on the stereochemistry of the reactions and the reactivity of the substrates (Figure 12) 21 (i) a nonconcerted, two-step process via a metallacyclobutane 226,264... 

Almela, A. Elizalde, M. P. Interactions of metal extractant reagents. Part VIII. Comparative aggregation equilibria of Cyanex 302 and Cyanex 301 in heptane. Anal. Proc. 1995, 32, 145-147. 

Behroozi, F., Orman, M., Reese, R., Stockton, W., Calvert, J., Rachford, F. and Schoen, P. (1990) Interaction of metallized tubules with electromagnetic-radiation. Journal of Applied Physics, 68, 3688-3693. 

FIGURE 21.13 The interaction of metal (/orbitals with the molecular orbitals on the allyl group. Note how the symmetry of the (/orbital on the metal matches that of the allyl orbital with which it interacts. 

Thermodynamic aspects of the interaction of metal ions with macrocyclic ligands have been well studied. In many instances such studies have involved a comparison of the behaviour of cyclic ligand systems with that of their open-chain analogues. In this manner, information concerning the thermodynamic consequences arising from the cyclic nature of the macrocyclic ligand has been obtained. Frequently these studies have been restricted to stability constant (log K) measurements and, for such studies, a variety of techniques has been employed (Izatt etal., 1985). 

Carbonaceous species on metal surfaces can be formed as a result of interaction of metals with carbon monoxide or hydrocarbons. In the FTS, where CO and H2 are converted to various hydrocarbons, it is generally accepted that an elementary step in the reaction is the dissociation of CO to form surface carbidic carbon and oxygen.1 The latter is removed from the surface through the formation of gaseous H20 and C02 (mostly in the case of Fe catalysts). The surface carbon, if it remains in its carbidic form, is an intermediate in the FTS and can be hydrogenated to form hydrocarbons. However, the surface carbidic carbon may also be converted to other less reactive forms of carbon, which may build up over time and influence the activity of the catalyst.15... 

Metal Ions in Biological Systems. Volume 32. Interactions of Metal Ions with Nucleotides, Nucleic Acids, and their Constituents Ed. Sigel, A. Sigel, H. Marcel Dekker New York, 1996. 

The nervous system contains an unusually diverse set of intermediate filaments (Table 8-2) with distinctive cellular distributions and developmental expression [21, 22]. Despite their molecular heterogeneity, all intermediate filaments appear as solid, rope-like fibers 8-12 nm in diameter. Neuronal intermediate filaments (NFs) can be hundreds of micrometers long and have characteristic sidearm projections, while filaments in glia or other nonneuronal cells are shorter and lack sidearms (Fig. 8-2). The existence of NFs was established long before much was known about their biochemistry or properties. As stable cytoskeletal structures, NFs were noted in early electron micrographs, and many traditional histological procedures that visualize neurons are based on a specific interaction of metal stains with NFs. 

Lansdown, A. B., Physiological and Toxicological Changes in the Skin Resulting from the Action and Interaction of Metal Ions, Crit. Rev. Toxicol., 25, 397, 1995. 

Interaction of Metal Species with Biological Interphases. 241... 

On the other hand, the presence of hydrophobic complexes is a prerequisite for partitioning and diffusion of metals into the lipid bilayer. In the following paragraphs, various types of metal complexes will be discussed, which are relevant to the interactions of metals in aquatic systems. The role of these various types of metal complexes with respect to interactions at the biological interphases will be systematically examined. 

Metal speciation is discussed here from the perspective of the speciation occurring in natural freshwater environments. This speciation is relevant for interactions of metals with aquatic organisms. 

INTERACTION OF METAL SPECIES WITH BIOLOGICAL INTERPHASES... 

M. Rodriguez and and A.J. Bard, Electrochemical studies of the interactions of metal chelates with DNA, Anal. Chem., 62 (1990) 2658-2662. 

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