Hydroxypyridinonate

Fig. 1. Common siderophore iron-binding groups catechol (Eq. (4)), hydroxamic acid (Eq. (5)), ot-hydroxycarboxylic acid (Eq. (6)), and hydroxypyridinone (Eq. (7)). Additional siderophore binding groups ...

One donor group that is only rarely observed in nature is hydroxypyridinone (Fig. 17). As mentioned previously, the sole example found in nature is cepabactin, a bidentate l-hydroxy-2-pyridinone siderophore (8 in Fig. 2) (46). The bidentate 1,... 

The exchange of iron from transferrin to desferrioxamine B (4), some catecholate siderophores, and some hydroxypyridinone-based siderophore mimics has been investigated (139,189,190). Turcot et al. found that at concentrations similar to those that would be observed in biological settings or clinical treatments,... 

GFP hopo ICBP IP3 Ln3+ mal memal MLCK nota oxine par pdta pmea py quin-2 green fluorescent protein hydroxypyridinon(at)e intestinal calcium-binding protein inositol 1,4,5-triphosphate a lanthanide(III) cation malonate methylmalonate myosin light chain kinase 1,4,7-triazacyclononane-l,4,7-triacetate 8- hydroxyquinoline pyridine-2-azo-4 -dimethylaniline propylene-1,2-diaminetetraacetate 9- [2-(phosphonomethoxy)ethyl] adenine pjrridine pjrridyl 8-amino-2- [(2-amino-5-methylphenoxy )methyl] -6-methoxyquinoline-ATJV -tetraacetate 2- [ [2-[his(carboxymethyl)amino]-5-methyl-phenoxy] methyl] -6-methoxy-8- [bis(carboxymethyl) amino] quinoline]... 

Hydroxypyranones, Hydroxypyridinones, and their Complexes John Burgess and Maria Rangel... 

Fig. 1. General formulae for hydroxypyranones and hydroxypyridinones 1, 3-hydroxy-2-pyranone 2, 3-hydroxy-4-pyranones 3, 3-hydroxy-2-pyridi-nones 4, 3-hydroxy-4-pyridinones 5, l-hydroxy-2-pyridinone. In each case the ring atoms are numbered anticlockwise, starting with the ring-oxygen or ring-nitrogen atom.

Chelating resins have been prepared in which hydroxypyridinones have been incorporated into sepharose gels (66). These materials were developed, along with desferrioxamine analogues (67), with a particular view to immobilizing iron(III). Other specialty hydroxypyridinones have included several containing alkene units, incorporated for their lipophicity, their potential for use in hydroboration (68), or for their intrinsic interest (69). 

Fig. 4. Capping units (a) bonding through peptide links, (b) to ring-carbon or ring-nitrogen, (c) to give hexadentate hydroxypyridinones, (d) such as 21, tren(3,2-hopo)3.

Once the required ligands have been obtained, the formation of complexes is usually straightforward. Metal complexes can often be prepared by direct reaction in solution between the ligand and a metal salt, generally at pHs above seven so that the hydroxypyranone or hydroxypyridinone is in its anionic form. There can be difficulties with purification, as solubility characteristics of ligands and their respective complexes may be inconveniently similar, but recrystallization is usually effective. In cases of difficulty sublimation may successfully separate unreacted ligand from the complex. 

It is quite often possible to prepare hydroxypyridinone complexes directly by one-pot synthesis from the appropriate hydroxypyranone, amine, and metal salt 90-92). They can also be prepared by reacting complexes such as P-diketonates with hydroxypyridinones (see e.g., Ce, Mo later). Several maltolate complexes, of stoichiometry ML2, ML3, ML4, or MOL2, have been prepared by electrochemical oxidation of the appropriate metal anode, M — a first-row d-block metal (Ti, V, Cr, Mn, Fe, Co, Ni), In, Zr, or Hf, in a solution of maltol in organic solvent mixtures 92). Preparations of, e.g., manganese(III), vanadium(III), or vanadium(V) complexes generally involve oxidation... 

The importance of hydroxypyridinones in connection with the decorporation of plutonium (Section IV.C.7) and the similarities between the coordination chemistries of early actinides and lanthanides... 

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