Effects of metal ions

J. G. Groppo and B. K. Parekh, Effect of Metal Ions on Vacuum Filtration of Coal, Society for Mining, Metallurgy and Exploration, Annual Meeting,... 

The Effect of Metal Ions on the Free Energy of Hydrolysis of ATP... 

The presence of an azo group as a side group in the polymer structure can be used to produce a macroradical via its decomposition under the effect of metallic ions [3,4]. This macroradical reacts with vinyl monomers leading to grafting with a minimum amount of homopolymers. This reaction was first applied to a polymer by Chapman et al. [5]. The reaction proceeds as follows (See structure below.)... 

The effect of metal-ion catalysis (especially that of cadmium ion) in the above reaction has been studied628, and in Table 201 are listed the first-order rate coefficients for protodeboronation of 2,6-dimethoxybenzeneboronic acid in malonic acid-sodium malonate buffer or perchloric acid, observed in the absence ( ) or presence ( ) of cadmium ion, together with the second-order rate coefficients (k2) obtained by dividing the difference of these values by the cadmium ion concentration. The data of the first ten rows of Table 201 are plotted in Fig. 4 and the... 

Finally, the relative effectiveness of metal ions in catalysing this reaction has been measured628 and the first-order coefficients together with the derived second-order coefficients are given in Table 203 for the protodeboration of 2,6-dimethoxybenzeneboronic acid at 90 °C, p = 0.14 and pH = 6.70. 

CATALYTIC EFFECT OF METAL IONS ON THE REACTION OF 2,6-(MeO)2C6H3B(OH)2 WITH MALONATE BUFFERS AT 90 C AND pH 6.70628... 

Electrochemical effects of metal ion coordination to non-innocent biologically important molecules. M. J. Clarke, Comments Inorg. Chem., 1984, 3,133-151 (57). 

Pentasodium pentetate, tetrasodium etidronate, and tetra-sodium EDTA are added as water softeners and to protect the dyes and perfumes from the effects of metal ions in the mixtures. These compounds lock up calcium and magnesium in the water, preventing them from reacting with the soap to form insoluble soap scum. 

Chamay, D. Nari, J. Noat, G. 1992. Regulation of plant cell-wall pectin methyl esterase by polyamines -Interactions with the effects of metal ions. Eur. J. Biochem. 205 711-714. 

Fig. 25. The effect of metal ion size on porphyrin ruffling. Very small metal ions [P(V) with an ideal P-N bond length of 1.84 A and low-spin Ni(II) with an ideal Ni-N length of 1.90 A in (a) and (b)) cause extensive S4 ruffling. Metal ions close to the right size (M-N = 2.035 A) give planar structures [Zn(II) in (c)]. Metal ions that are too large [Pb(II) at (d) with ideal Pb-N of 2.39 A] are extruded from the plane of the porphyrin and cause it to dome. For clarity, substituents on the porphyrins such as phenyl or ethyl groups have been omitted. Modified after Ref. (77).

A dramatic illustration of the effect of metal ions on DNA structure is seen in the STM images of DNA circles in the presence of either MgCl2 or ZnBr2 (46). The shape of the DNA circles of 168-base-pair (bp) length... 

The effect of metal ions in promoting certain cyclization reactions has been recognized for a very long time. Thus the first synthetic... 

Figure 1 has shown that the maximum chemisorption of oxygen on chars from untreated wood occurs at HTT 450°-500°C. However, in order to understand better the effect of metal ions on the total process consisting of pyrolysis and subsequent chemisorption and oxidation of wood char, it was necessary to carry out pyrolysis, isothermal chemisorption and oxidation reactions in a single experiment. A typical overall pyrolysis, isothermal chemisorption (140°C) and oxidation curve is shown in Figure 2. The temperature program is (1) heat from 25° to 500°C at 5°C/min, (2) cool at...

Polymeric pseudocrown ether networks have been generated in situ by the photopolymerization of poly(ethylene glycol) diacrylate transition metal complexes <00CM633>, and the effect of metal ion templation was evaluated. The 1,6,13,18-tetraoxa[6.6]paracyclophane-3,15-diyne (termed pyxophanes) was prepared from hydroquinone and l,4-dichlorobut-2-yne it forms size-selective 7i-complexes with alkali metal cations <00CC2377>. Dibenzo[ ]crown-m have been used in numerous elegant studies in which they were the needles that were threaded by diverse reagents the resultant... 

Timourian, H. and G. Watchmaker. 1977. Assay of sperm motility to study the effects of metal ions. Pages 523-536 in H. Drucker and R.E. Wildung (eds.). Biological Implications of Metals in the Environment. Proceedings of the Fifteenth Annual Hanford Life Sciences Symposium at Richland, Washington, September 29-October 1, 1975. Energy Res. Develop. Admin. Sympos. Ser. 42, CONF-750929. 

Ghanmi, Z., M. Rouabhia, O. Othmane, and P.A. Deschaux. 1989. Effects of metal ions on cyprinid fish immune response in vitro effects of Zn2+ and Mn2+ on the mitogenic response of carp pronephros lymphocytes. Ecotoxicol. Environ. Safety 17 183-189... 

O. A. Zadvomy, N. A. Zorin, I. N. Gogotov (2000) The effect of metal ions on hydrogenase of purple sulfur bacterium Thiocapsa roseopersicina. Biokhimiya. (Russ.), 65 1525-1529... 

Aqvist, J. and Warshel, A. Free energy relationship in metalloenzyme-catalyzed reactions. Calculations of the effects of metal ion substitutions in staphylococcal nuclease, J.Am.Chem.Soc., 112 (1990), 2860-2868... 

Malaney GW, Sheets WD, Quillin R. 1959. Toxic effects of metallic ions on sewage microorganisms. Sewage Ind Wastes 31 1909-1915. 

The effects of metal ions on the alcoholysis and hydrolysis of esters containing crown ether functionalities have also been studied (Cacciapaglia et al., 1989, 1992 Hedderwick et al., 1991a,b). In the former case, transition state binding was considered explicitly, in the same manner as did Ercolani and Mandolini (1990). 

Effect of Metal Ion. To the hematite suspension already characterized one adds Pb(II). The surface complex formation is characterized by... 

In ester hydrolysis, rate-limiting formation of the tetrahedral intermediate usually apphes (Sec. 6.3.1) since the alkoxide group is easily expelled. In contrast, amide hydrolysis at neutral pH involves rate-limiting breakdown of the tetrtihedral intermediate, because RNH is a poor leaving group. The catalytic effect of metal ions on amide hydrolysis has been ascribed to accelerated breakdown of the tetrahedral intermediate. 

Kanai, H., Navarrete, R.C., Macisko, C.W. Scriven, L.E. (1992) Rheol. Acta 31 333 Kandori, K. Ishikawa,T. (1991) Selective adsorption of water on amorphous ferric oxide hydroxide. Langmuir 7 2213-2218 Kandori, K. Aoki,Y. Yasukawa, A. Ishikawa, T. (1998) Effects of metal ions on the morphology and structure of hematite particles produced from forced hydrolysis reaction. 

In a number of classes of systems, the catalytic and other chemical effects of metal ions on reactions of organic and inorganic molecules are generally recognized the catalysis of nucleophilic reactions such as ester hydrolysis the reactions of alkenes and alkynes in the presence of metal carbonyls (8, 9, 69) stereospecific polymerization in the presence of Ziegler catalysts (20, 55, 56) the activation of such small molecules as H2 (37), 02 (13), H202 (13), and possibly N2 (58) and aromatic substitution reactions of metal-cyclopentadienyl compounds (59, 63). 

A number of topics have not been tendered the attention due them enzyme processes, catalytic effects of metal ions in oxidation-reduction reactions, and the activation of small molecules such as H2, 02, and H202 by metal ions. This can be justified only by preoccupation with less well explored groups of reactions, which, it is to be hoped, will receive increased attention in future years. 

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