Nitrilotriacetate, complexing with

According to R. Brdicka and K. Vesely the carbonyl form of formaldehyde is reduced and the limiting kinetic current is given by the rate of the chemical volume reaction of dehydration. An analogous situation occurs for the equilibria among complexes, metal ions and complexing agents if the rates of complex formation and decomposition are insufficient to preserve the equilibrium. A simple example is the deposition of cadmium at a mercury electrode from its complex with nitrilotriacetic COO"... 

Fig. 21. Volume profile for the reaction of methyl radicals with the nitrilotriacetate complex of Co(II).

Another aminopolycarboxylic acid, closely related to IMDA and forming strong complexes with the lanthanide ions, is nitrilotriacetic acid (NTA). The hy-... 

Electroreduction of Cd(II)-nitrilotriace-tic acid and Cd(II)-aspartic acid systems was studied on DME using SWV [73]. The CE mechanism in which the chemical reaction precedes a reversible electron transfer was established. Also, the rate constants of dissociation of the complexes were determined. Esteban and coworkers also studied the cadmium complexes with nitrilotriacetic acid [74, 75] and fulvic acid [76]. The complexation reaction of cadmium by glycine was investigated by different electrochemical methods using HMDE and mercury microelectrode [77, 78]. 

This effect is shown in Eigure 2.9 for CdSe films deposited from baths containing Cd complexed with NTA (nitrilotriacetate) and Na2SeS03 as a Se source. The nanocrystal size, measured by both XRD and TEM, varied from ca. 3 nm up to 20 nm with increase in temperature and/or change in mechanism from a cluster mechanism to an ion-by-ion deposition. The optical bandgap shifts from 1.8 eV (for bulk, zincblende CdSe) to ca. 2.4 eV for the smallest nanocrystals (ca. 3 nm). 

Fig. 6.2 Scanning electron micrograph of a Cui.2Se film deposited from a selenosul-phate solution of complexed with nitrilotriacetate.

Complexation of chromium(III) by nitrilotriacetic add (H2nta) has been investigated. Values of equilibrium constants (/ = 0, 25 °C) are log K = 10.66 and log K2 — 8.73.1234 A large number of mixed complexes with nta/chromium(III) have been prepared, including mixed aminoad-dates,1235 acetylacetonates, catecholates, oxalates and complexes with 1,10-phenanthroline and 2,2 -bipyridyl.1236 1238... 

Figure 12-4 Structures of analytically useful chelating agents. Nitrilotriacetic acid (NTA) tends to form 2 1 (ligand metal) complexes with metal ions, whereas the others form 1 1 complexes.

Complexes with IMDA and related ligands.—A series of three substituted aminoacetic acids, IMDA, HIMDA and NTA constitute another set of very interesting ligands. The stability constants of the iminodiacetic acid (IMDA) [ 465], N-hydroxyethyliminodiacetic acid (HIMDA) 466 and nitrilotriacetic acid (NTA) complexes are compared in Table 34. Based on log k values the following trend of stability is noted. The... 

The most important ferrous developers, however, are the complexes with ethylenediaminetetraacetic acid (EDTA) and related ligands, such as diethylenetriaminepentaacetic add (DTPA), nitrilotriacetic add (NT A) and JV-hydroxyethylethylenediaminetriacetic add (HETA). Complexes... 

Nitrilotriacetic acid (NTA) is a constituent of various domestic and hospital detergents and is a common water contaminant. NTA forms water-soluble chelate complexes with various metal ions, including iron, at neutral pH. Its iron complex, Fe-NTA, is a known potent nephrotoxic agent. The renal toxicity is assumed to be caused by the elevation of serum free-iron concentration following the reduction of Fe-NTA at the luminal side of the proximal tubule, which generates reactive oxygen species and leads to enhancement of lipid peroxidation. 

The free ion, Cu2+, appears to be the major species of Cu taken up by plants (Graham, 1981 Jones and Jarvis, 1981). Hence Cu complexation will decrease uptake (DeKock and Mitchell, 1957) unless the complex can dissociate and/or diffuse quickly enough to maintain a constant supply of Cu2+ at the root surface. In the case of Zn, the presence of humic acid (Chen and Aviad, 1990) and carboxylic acids (EDTA, diethylenetriamine pentaacetic acid (DTPA), nitrilotriacetic acid (NTA) DeKock and Mitchell, 1957) has been found to decrease absorption but it is not known whether Zn uptake is correlated with Zn2+ in solution because Zn speciation was not estimated. Other work has shown that Zn initially complexed with citrate is taken up by barley from nutrient solutions (Chairidchai and Ritchie, 1993) and the presence of chelates (EDTA, citrate) can speed up the diffusion of Zn to a root surface in soils (Hodgson et al., 1967 Elgawhary et al., 1970). Speciation in solution is particularly important in the uptake of iron because of its extremely low solubility in the absence of complexing anions... 

Nitrilotriacetate (NTA), A-methyliminodiacetate (MIDA) and iminodiacetate (IDA) (116) form a series of 1 1 and 1 2 (metakligand) complexes with Rh111 (and Co111), which have been characterized by H NMR and electronic spectra.1087 On the basis of the NMR and a comparison to the Co analog,... 

Table 3.3 lists the log Pi and the EpTTa of Eu(III) complexes with iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), A -(2-hydroxyethyl)ethlenediamine-A, A, A -triacetic acid (HEDTA), ethylenediamine-A, A, A, A -tetraacetic acid (EDTA),... 

Historically, nitrilotriacetic acid (NTA) is next in importance to EDTA. It forms stable complexes with most metals, even to some extent with the alkali metals (the pJf for sodium is 2.1). Unfortunately, its tendency to form 2 1 complexes causes difficulty with the stoichiometry. 

The ease with which the core of ferritin and bacfer can be reconstituted with Fe and an oxidant has led to work with Fe and other metals. Fe, added as a citrate, oxalate, or nitrilotriacetate complex, to horse holoferritin does enter the core, but only a small amount of Fe is taken up (139). No Fe + was taken up by apoferritin. This work emphasizes the requirement for core formation to occur by the oxidation of Fe +, a subject we discuss in the following section. 

The sonoelectrochemical deposition of CdSe nanopartides is carried out from an aqueous solution of CdS04, complexed with potassium nitrilotriacetate (N(CH2C02K)3) NTA as a source for Cd, and a selenosulfate solution, (Na2SeS03), as source for Se. The CdSe crystal size could be varied from X-ray amorphous up to 9 nm by controlling the various electrodeposition and sonic parameters. The effects of various electrodeposition and sonic parameters on the properties of CdSe nanopartides are presented in Table 6.3. 

Nitrilotriacetate and related ligands form 1 1 V111 complexes with three water molecules completing the coordination sphere (174). When one acetate group is exchanged with a... 

The Cu ion reacts with [OH] to form [CuOH] ", which exhibits a pH-depen-dent absorption with = 300 nm. Copper(III) complexes with NHj, ethylene-diamine and various amino acids are characterized by pulse radiolysis . The [Cu(EDTA)] (EDTA = ethylenediaminetetraacetate) and [Cu(NTA)] (NTA = nitrilotriacetate) ions are oxidized to the corresponding Chj(III) species by [OH] Cu(lII) rearranges and then metal-ligand intramolecular electron transfer yields some Cud) species. ... 

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