Lanthanide complexes separation

Citric acid and nitriloacetic acid (NTA) lanthanide complexes were used in the earliest ion exchange separations of lanthanides from fission product mixtures (Kf = 3.2 for Ce(H3 Cit.)3 and Kf = 10.8 for CeNTA2) (Sillen and Martell, 1964). More recently such polyamino-polycarboxylic acids as ethylenediaminetetraacetic acid (EDTA), 1,2-diaminocyclohexaneacetic acid (DCTA), and diethylenetriaminepentaacetic acid (DTPA) have been prepared. Their lanthanide complexes are very stable (Table 3) and have been widely used in analysis and separation of lanthanide mixtures. They have also been used experimentally to remove internally-deposited 144Ce and other radioactive lanthanide nuclides from animals and man (Foreman and Finnegan, 1957 Catsch, 1962 Balabukha et al., 1966 Palmer et al., 1968 among others). 

Separation of contact and pseudo-contact contributions in paramagnetic lanthanide complexes 372 (L4 = tris 2-[A -methylcarbamoyl-(6-W,A -diethylcarbamoyl)pyridi-ne-2)ethyl]amine ) 390... 

Lanthanide complexes with inorganic ligands such as Cl, Br, I, SCN, N03 and sulphate can be either inner sphere LnX2+ or outer sphere or solvent separated complexes, Ln(H20)2+X In the case of halides the complexes are thought to be outer sphere Ln(H20) X2+, although there is evidence for the existence of anionic complexes like LnCl. Similarly EuSCN2+ is supposed to have both inner sphere and outer sphere character [23]. 

Kinetics of formation and dissociation of lanthanide complexes [La(III) = Pr, Eu, Tb, Ho, and Yb] with l-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) in toluene-water phase were studied by monitoring the fate of La3+— arsenazo III (AZ) complex (MAZ) in the aqueous phase with the hydrophilic separator. The structures of the ligands and AZ are given below ... 

We will now proceed to a discussion of LIS methodologies, uses of lanthanides in complex NMR spectra, quantitative aspects of the LIS method such as testing and separation of shifts, use of pseudo contact shift in molecular structure, and use of aqueous cations and lanthanide complexes in biological systems. 

It was subsequently found that amine polycarboxylates such as EDTA" gave stronger complexes and much better separations. In practice, some Cu + ions ( retainer ) are added to prevent precipitation of either the free acid H4EDTA or the lanthanide complex... 

Improvement in fractional separations in terms of the var5dng stabilities of lanthanide complex species is a well-known and highly important area of applied chemistry (34) S6). The complex species are often useful in analytical determinations. Certain of them possibly can be applied in constructing amorphous transparent or liquid laser devices. 

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