Lanthanide complexes iminodiacetate

Complexes of calixarenes with bipyridyl chromophores can be stabilized by the addition of anionic side arms, such as iminodiacetate units (85). Whilst the lanthanide complexes of ligands [L51]4- and [L52]4- are not soluble in water, their photophysical properties in... 

There are difficulties associated with the use of ordinary electronic absorption spectra of lanthanide complexes in solution to provide detailed information regarding coordination number and geometry. However, difference spectra versus NdCl3 are reported for Nd3+-ligand (L) solutions for the 4/9/2— -4G5/2, 4G7,2 transitions (L = dipicolinate, oxydiacetate, iminodiacet-ate, malate, methyliminodiacetate and Ar,Ar -ethylenebis Af-(o-hydroxyphenyl)glycinate ). Hypersensitive behaviour was examined and transition dipole strengths were discussed in terms of the nature of the complex species present.431... 

Edta-related lanthanide complexes are of course coordinatively unsaturated in the absence of other ligands. In water, they are hydrated and the water of hydration may be displaced by other species. The kinetics of such a process, the reaction of europium 1,2-diaminocyclohexane-tetraacetate, [Eu(dcta)aq] with iminodiacetate ion, ida , to give [Eu(dcta)(ida)] ", have been studied by the elegant method of selective tunable laser excitation of the transition in... 

During the early sixties Thompson and Loraas (77) reported the formation of mixed complexes of reasonable stability (log K 3.0—5.3) between lanthanide—HEDTA and ligands such as EDDA (N,N -ethylenediaminediacetic acid), HIMDA (N-hydroxyethyliminodiacetic acid) and IMDA (iminodiacetic acid). This observation together with the remarkably large formation constants (72) for the bis-EDDA complexes [log A2 =4.73 (La) 8.48 (Lu)] suggested a coordination number larger than six for the tripositive lanthanide ions in aqueous solution, in view of the fact that mixed chelates of the t5q>e M (HEDTA) (IMDA) axe not formed when M =Co(II), Ni(II) or Cd(II). 

No appreciable polymerization occurred in concentrated aqueous solutions of La or Nd hydroxonitrilotriacetates but, with the heavier lanthanides, dimerization, via hydroxo bridges, occurred in dilute solution. A series of mixed ligand chelate complexes was obtained with Ho and Er and 5-sulpho-salicylate (ssa) and edta, iV-hydroxyethylethylenediamine-triacetic acid, 1,2-diaminocyclohexanediamine-tetra-acetic acid (YX i.e. [M(Y)(ssa)], and iminodiacetic acetate, hydroxyethyliminodiacetic acid and nitrilotriacetic acid, [M(Y)(ssa)2] with higher carboxylates, no mixed chelate complexes were produced. In the presence of an excess of hydroxyethylethylenediamine triacetic acid (H3A), [Eu(A)(HA)] was formed. Lanthanum(m) formed 1 1 complexes with nitrilotriacetic acid and 8-hydroxyquinoline, or 2-picolinic acid and 8-hydroxyquinoline-5-sulphonic acid. 

Lanthanides and yttrium have been separated by chelation ion chromatography on a column packed with iminodiacetic acid bonded to silica [19]. The mobile phase contained 16 mM nitric acid and 500 mM potassium nitrate. The high nitrate concentration undoubtedly modified the ion-exchange and chelating action of the stationary phase by the partial formation of soluble nitrate complexes with the lanthanide cations. Post-column detection was used with Arsenazo III, which form intensely colored complexes with the lanthanides. 

The 1 1 complexes between the lanthanides and edta form stable associates with the anions of 8-hydroxyquinoline-5-sulphonic acid (oxs), iminodiacetic acid (ida), and nitrilotriacetic acid (nta) since the characteristic co-ordination number of the Ln ions is generally greater than six. In Figure 6 the free-energy changes associated with the formation of these... 

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