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NMR Transversal Relaxivity of Suspensions of Lanthanide Oxide Nanoparticles
Norek, Małgorzata; Pereira, Giovannia A.; Geraldes, Carlos F. G. C.; Denkova, Antonia; Zhou, Wuzong; Peters, Joop A.Aqueous suspensions of paramagnetic lanthanide oxide nanoparticles have been studied by NMR relaxometry. The observed relaxivities are explained by the static dephasing regime (SDR) theory. The corresponding R2 relaxivities are considerably smaller and are strongly dependent on the interval between the two refocusing pulses. The experimental data are rationalized by assuming the value of the diffusion correlat...
Structure and Dynamics of Lanthanide Complexes of Triethylenetetramine-N,N,N',N...
Zitha-Bovens, Emrin; Muller, Robert N.; Laurent, Sophie; Vander Elst, Luce; Geraldes, Carlos F. G. C.; van Bekkum, Herman; Peters, Joop A.A multinuclear NMR study on [Ln(ttha)]3- and [Lnttha(NHR)2]- complexes (R=Et, CH2(CHOH)4CH2OH) shows that coordinating groups of the organic ligands in these complexes are occupying all coordination sites of the metal ions, leaving no space for coordination of H2O molecules (H6ttha=triethylenetetramine-N,N,Nprime,NPrime,Nprimeprimeprime,Nprimeprimeprime-hexaacetic acid). The lanthanides of the first half of the...
Towards Targeted MRI: New MRI Contrast Agents for Sialic Acid Detection
Frullano, Luca; Rohovec, Jan; Aime, Silvio; Maschmeyer, Thomas; Prata, M. Isabel; Lima, J. J. Pedroso de; Geraldes, Carlos F. G. C.; Peters, Joop A.The detection of sialic acid in living systems is of importance for the diagnosis of several types of malignancy. We have designed and synthesized two new lanthanide ion ligands (L1 and L2) that are capable of molecular recognition of sialic acid residues. The basic structure of these ligands consists of a DTPA-bisamide (DTPA, diethylenetriamine pentaacetic acid) whose amide moieties each bear both a boronic fu...
Lanthanide(III) Complexes of Novel Mixed Carboxylic-Phosphorus Acid Derivatives...
Kotek, Jan; Lebduscaronková, Petra; Hermann, Petr; Elst, Luce Vander; Muller, Robert N.; Geraldes, Carlos F. G. C.; Maschmeyer, Thomas; Lukescaron, IvanThree novel phosphorus-containing analogues of H5DTPA (DTPA = diethylenetriaminepentaacetate) were synthesised (H6L1, H5L2, H5L3). These compounds have a -CH2-P(O)(OH)-R function (R = OH, Ph, CH2NBn2) attached to the central nitrogen atom of the diethylenetriamine backbone. An NMR study reveals that these ligands bind to lanthanide(III) ions in an octadentate fashion through the three nitrogen atoms, a P-O oxyg...
X-ray Crystal Structure of a Sodium Salt of [Gd(DOTP)]5: Implications for Its S...
Avecilla, Fernando; Peters, Joop A.; Geraldes, Carlos F. G. C.The X-ray structure of the sodium salt of [Gd(DOTP)]5- shows two different chelates, [Gd(1)(DOTP)]5- and [Gd(2)(DOTP)]5-, bound at either surface of a sheet formed by a cluster of hydrated Na+ ions. Each [Gd(1)(DOTP)]5- anion binds directly to four Na+ ions of this cluster through the free oxygen atoms of the phosphonate groups of the adjacent ligand, while each [Gd(2)(DOTP)]5- unit is connected to the cluster ...
Interactions Between Cyclodextrins and TmIII Chelates of Polyazamacrocycles as ...
Zitha-Bovens, Emrin; Bekkum, Herman van; Peters, Joop A.; Geraldes, Carlos F. G. C.The interactions between α-, β-, and γ-CD and the TmIII chelates of the macrocyclic polyaminopolycarboxylates DOTA and NOTA were studied with the use of 1H- and 13C-NMR shift and relaxation rate measurements. Interactions were only observed between Tm(DOTA)- and γ-CD. The structure and the stability of the concerning supramolecular structures was elucidated by fitting of the NMR titration curves to a theoretica...
Potentiometric and NMR spectroscopic study of protonations and amide hydrogen e...
Lammers, Hendrik; van der Heijden, Anna M.; van Bekkum, Herman; Geraldes, Carlos F. G. C.; Peters, Joop A.The macroscopic and microscopic protonations of DTPA-GlucA2 (DTPA-bis(glucamide)) have been investigated using potentiometry, 1H and 13C NMR. The protonation behavior appears to be similar to that of the corresponding bis(alkylamides), showing that it is not affected by the presence of the polyhydroxy side chains. Consideration of the various possible protonation pathways leads to the conclusion that the differ...
Multinuclear magnetic resonance study of the structure and dynamics of lanthani...
Geraldes, Carlos F. G. C.; Urbano, Ana M.; Hoefnagel, Mattheus A.; Peters, Joop A.The structure and dynamics of the lanthanide(II1) complexes of the bis(propy1amide) of diethylenetriaminepentaacetate (DTPA-PA3 in aqueous solution have been investigated by I3C and I7O NMR. With the use of the longitudinal 13C relaxation times of the NdlI1 complex it is shown that the organic ligand is bound to the lanthanide(II1) ion in an octadentate fashion via the three nitrogens of the diethylenetriamine ...
Multinuclear NMR study of the interaction of the shift reagent lanthanide(III) ...
Ramasamy, Ravichandran; Freitas, Duarte Mota de; Geraldes, Carlos F. G. C.; Peters, Joop A.The paramagnetic ion-induced relaxation rate enhancements of 6Li in adducts of Li+ and Ln(PPP)J- complexes (Ln = Dy, Tm) in aqueous solution show that up to seven monovalent counterions can coordinate in the second coordination sphere of the Ln(II1) ion to the outer oxygens of the triphosphate ligands. However, the pseudocontact ’Li NMR shift data suggest that in the second coordination sphere some preference o...
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