Poly metal chelating ability

A further application of TLRC in the biochemical field is in the assessment of the activity of enzymes, where TLRC can be used to monitor and quantitate the products during the course of an enzyme reaction such as deiodination. Other examples of the use of TLRC in biochemical studies are the qualitative assessment of the complex-forming ability of metals and ligands in biological systems and the complex formation of heavy metal chelates, such as molybdenum species with poly-aminocarboxylic acids. 

Phenolics are one of the major groups of non-essential dietary components that have been associated with the inhibition of atherosclerosis and cancer. The bioactivity of phenolics may be related to their antioxidant behavior, which is attributed to their ability to chelate metals, inhibit lipoxygenase, and scavenge free radicals. However, phenolics can also function as prooxidants by chelating metals in a manner that maintains or increases their catalytic activity (Fig. 6). Also, poly-phenolics reduce metals, thereby increasing their ability to form free radicals from peroxide. 

Crown thioethers prompt attempts to impose poly(thioether) coordination upon metal ions, even those for which few thioether complexes were previously known. As a class, simple thioethers (e.g. MejS) are not particularly good ligands for both electronic and steric reasons. Thioethers exhibit weaker a-donor and 7t-acceptor ability than, for example, phosphines. Consequently they also show less binding affinity. In addition, the appreciable bulk of their terminal alkyl groups further hinders complexation. This latter factor is partially circumvented in acyclic polythioethers, and such ligands display respectable chelate effects. 

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