Potentiometric, luminescence and NMR study of the interaction of EuIII with glyceryl phosphates

André, João P.; Geraldes, Carlos F. G. C.; Miguel, Maria G.; Teixeira, M. H. S. F.; Boas, L. F. Vilas

doi:10.1016/0277-5387(96)00241-0

Cited by 3 publications

(3 citation statements)

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“…Upon addition of either Eu(III) or Tb(III), shifts of the proton and carbon resonances to higher magnetic fields and signal broadening were observed, as shown in Figure forthe 1 H NMR spectrum of Tb(III)−PCR4. The induced shifts are higher for Tb(III) than for Eu(III), in agreement with the weaker paramagnetism of the latter species 2 PCR4 (a) and Tb(III)−PCR4 (b) 1 H NMR spectra.…”

Section: Resultssupporting

confidence: 69%

“…It is well established that lanthanide-induced shifts in NMR signals can have two contributions: a pseudocontact one coming from the through-space dipolar interactions and a contact contribution coming from direct delocalization of unpaired electron spin density from the metal. , Both contributions are expected to be largest for those atoms nearest the lanthanides and smallest for those which are most remote…”

Section: Resultsmentioning

confidence: 99%

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Lanthanide Ion Interaction with a Crown Ether Methacrylic Polymer, Poly(1,4,7,10-tetraoxacyclododecan-2-ylmethyl methacrylate), as Seen by Spectroscopic, Calorimetric, and Theoretical Studies

Tapia

García

et al. 2004

Macromolecules

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The interaction between trivalent lanthanide ions and the polymer poly(1,4,7,10-tetraoxacyclododecan-2-ylmethyl methacrylate) (PCR4) containing pendant 1,4,7,10-tetraoxacyclododecane (12crown-4) groups has been studied by various spectroscopic techniques, calorimetry and theoretical calculations. Evidence for the binding of Eu(III), Tb(III), and Ce(III) ions and PCR4 in solution was obtained by the lanthanide-induced 1 H and 13 C NMR shifts and the decay of Tb(III) luminescence. From the isotope effect observed on the decay of luminescence of Tb(III) bound to PCR4 in H2O and D2O solutions, it is suggested that complexation leads to a decrease in the number of water molecules from 8 or 9 to 7. In the solid state, studies by differential scanning calorimetry (DSC) show that the interaction between Ce(III), Tb(III), and Li(I) ions and PCR4 leads to an increase in the glass transition temperature (Tg) of the polymer. Electron paramagnetic resonance (EPR) spectra of Gd(III) in the presence of the polymer are quite similar to those in aqueous solution, while Tb(III) emission is quenched by Ce(III) with nearly the same rate constants in water and aqueous PCR4 solutions, and the Ce(III) emission maxima are only very slightly shifted in the presence of the polymer, all suggesting relatively weak dynamic interaction between the cations and the crown ether. However, isotope effects on the Tb(III) luminescence lifetime confirm complexation. From the lanthanide-induced 1 H and 13 C NMR shifts the stability constants of the 1:1 complexes formed have been calculated for both Tb(III) and Eu(III), yielding values 22.5 and 1.9, respectively. The agreement between the constants calculated from 1 H and 13 C NMR shifts are very good and the low values of the calculated stability constants confirm the weak binding of the lanthanide ions by the crown ether. Results of ab initio calculations are also reported, where the interactions are modeled for 12-crown-4/La(III) complex and bond energies determined.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Lanthanide Ion Interaction with a Crown Ether Methacrylic Polymer, Poly(1,4,7,10-tetraoxacyclododecan-2-ylmethyl methacrylate), as Seen by Spectroscopic, Calorimetric, and Theoretical Studies

Tapia

García

et al. 2004

Macromolecules

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show abstract

“…Lanthanides are "hard" acceptors, characterized by ionic interactions with a preference for oxygen donors (5). Ionic binding to Eu(III) may result either in the quenching of fluorescence, as with chloride, thiocyanate, and nitrate ions (6), or in the enhancement of fluorescence, as with phosphate ions (7). Sulfate ions interact with Eu(III) through one or two oxygen atoms, forming a strong inner-sphere complex due to the dinegative anionic charge (8) and increasing the intensity of the 5 D 0 to 7 F 2 fluorescent transition peak (9).…”

Section: Figmentioning

confidence: 99%