Sequester transition metal ions

Metal ion assisted electron transfer reactions are important when considering the roles of sequesterants and enzymes in antioxidant protection (8). Compounds like ethylenediaminetetraacetic acid (EDTA), phytic acid, and polyphenols can sequester transition metal ions and thereby inhibit oxidation. Binding the metal ions essentially prevents them from regenerating hydroxy radicals through the Fenton reaction. 

Ethylenediamine is used to synthesize EDTA chelating agent as well as certain fungicides. It is also an antifreeze inhibitor and is used to produce certain lubricants for textile applications. EDTA is widely used as a chelating agent to sequester transition metal ions and reduce their negative effect (that is, catalysis of oxidative degradation) in many applications. 

The presence of salts and additives can have an important influence on the performance of an FBA. Traces of transition-metal ions such as iron and copper have an adverse effect on fluorescence [30], but this can be controlled using conventional polyphosphate or EDTA-type sequestering agents [31]. Other salts, even sodium sulphate or sodium chloride, have been claimed to enhance the fluorescence of FBAs in solution [32]. Apart from the normal... 

These comparisons should be taken into account when substituting lanthanide ions for first-row transition-metal ions in order to induce chemical shifts or change the relaxation behavior of a n.m.r. spectrum to elicit ion sequestering and structural information (see later). 

Thus the ammonia acts to effectively sequester the open shelled transition metal ion, creating a relatively uninteresting classical metal complex that acts as a counterion for a number of complicated sulfosalt frameworks [127,128]. 

Complex Ion Formation. Phosphates form water-soluble complex ions with metallic cations, a phenomenon commonly called sequestration. In contrast to many complexing agents, polyphosphates are nonspecific and form soluble, charged complexes with virtually all metallic cations. Alkali metals are weakly complexed, but alkaline-earth and transition metals form more strongly associated complexes (eg, eq. 16). Quaternary ammonium ions are complexed Htde if at all because of their low charge density. The amount of metal ion that can be sequestered by polyphosphates generally increases... 

D-Glucosamine and either ammonia, 1,2-ethylenediamine, or 1,10-phenanthroline have been shown to form complexes with Co (III) ions, and the cobalt (ethylenediamine. D-glucosamine) complex is formed from the a-pyranose anonoo of the sugar. Aldose oximes on catalytic hydrogenation afford bis(polyhydroxyalkyl)amines. These compounds and their N-carboxymetbyl derivatives react with borate ions to give maciocyclic diborate esters which can sequester Ca, Cu and Cd ions. The coordination of some divalent transition metal imis to 2-amino-2-deoxy-D-g(ycero-D-gu/o-heptonic acid in aqueous solution has beat studied. ... 

---