Lanthanide ion exchange properties of a coordination polymer consisting of di(2-ethylhexyl) phosphoric acid and trivalent metal ions (Ce3+, Fe3+, or Al3+)

Abstract

Three kinds of coordination polymers ([M(dehp)3], M = Ce, Fe, or Al) were prepared by mixing the sodium form (Na(dehp)) of di(2-ethylhexyl) phosphoric acid and MCl3 in an ethanol-water binary mixture. They have monoclinic crystalline structure with similar lattice parameters. The lanthanide ion (Ln(3+) = La(3+), Sm(3+), Dy(3+), or Yb(3+)) exchange properties were studied in a 20 : 80 vol% ethanol-water binary mixture containing 2 mM Ln(NO3)3 at room temperature. The rate of Ln(3+) adsorption is relatively slow; it requires over 3 weeks to reach equilibrium. [M(dehp)3] has different Ln(3+) affinities depending on the kind of central metal ions: the affinity order at 3 week adsorption is Yb(3+) < La(3+) < Dy(3+) < Sm(3+) for [Ce(dehp)3], La(3+) < Sm(3+) < Dy(3+) < Yb(3+) for [Fe(dehp)3], and La(3+) < Sm(3+), Dy(3+), Yb(3+) for [Al(dehp)3]. The difference in affinity order can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The chemical and structural analyses suggested that the Ln(3+) adsorption progresses first by the central M(3+)/Ln(3+) exchange, followed by a morphological change to a rod-like or fibrous form by a solid phase reaction. In the case of [Fe(dehp)3], the eluted Fe(3+) may be hydrolyzed and precipitated as amorphous iron hydroxide.

In the Bottlebrush Garden: The Structural Aspects of Coordination Polymer Phases formed in Lanthanide Extraction with Alkyl Phosphoric Acids

“…11,[15][16][17][18][19] As shown in previous studies, this material is partially ordered: there are several welldefined peaks in their powder x-ray diffraction pattern (XRD). 15,16,20 Unfortunately, the poor quality of these x-ray data do not allow confident indexing of the unit cell, and different structural models proliferated ( Figure 1). In these structures, the Ln 3+ ion is 7 several structural possibilities for CP and its precursor exist, each having credible single crystal references.…”

“…It is seen that the five strongest Bragg peaks are conserved, and the comparison with the data in the literature15,16,20 suggests that all of the…”

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

“…In fact, most heptadentate Schiff base metal complexes are lanthanides Ln(III) complexes, due to lanthanide atom's large size requiring large coordination numbers and predominantly ionic bonding.Therefore, Ln(III) complexes have been successfully applied for constructing various selfassembled structures, in catalysis, for ion exchange, magnetism, gas adsorption and luminescence[323][324][325][326][327][328][329][330][331][332][333][334][335][336][337][338][339][340][341]. For example, Blakemore et al recently synthesized a series of f-block metal complexes (Ln = Ce, 104; Nd, 105; Eu, 106 and Sm, 107) by the reaction of a tripodal ligand featuring three appended pyrene moieties scaffold and Ln(N(SiMe3)2)3 in THF (Fig.…”

Solvent impregnated carbon nanotube embedded polymeric composite beads: An environment benign approach for the separation of rare earths

“…The most intense band is the PAO stretching, together with PAOAC between 1050 and 970 cm À1 . Other important peaks are PAO stretching at 1250-1210 cm À1 and a low intense band around 1680 cm À1 confirming the presence of PAOH [29]. In Fig.…”