Determination of the number of inner-sphere water molecules in lanthanide(III) polyaminocarboxylate complexes

Alpoím, Maria C.; Urbano, Ana M.; Geraldes, Carlos F. G. C.; Peters, Joop A.

doi:10.1039/dt9920000463

Cited by 117 publications

(148 citation statements)

References 28 publications

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“…The distance of closest approach was set to the usual value of 0.36 nm (Laurent et al 2000;Parac-Vogt et al 2004), the relative diffusion constant was fixed to 3.3·10 À9 m 2 s À1 (Vander Elst et al 2005) and the distance for the inner sphere interaction was set to 0.31 nm (Powell et al1996;Laurent et al 2000). The number of coordinated water molecules was assumed to be equal to one, by analogy with other Gd-DTPA bisamide derivatives (Alpoim et al 1992). The parameters describing the electronic relaxation of gadolinium(III) (s SO , the electronic relaxation rate at very low magnetic field and s V , the correlation time modulating the electronic relaxation) as well as the ''effective'' rotational correlation time s R and the residence time of the coordinated water molecule s M were simultaneously fitted.…”

Section: Resultsmentioning

confidence: 99%

Paramagnetic liposomes containing amphiphilic bisamide derivatives of Gd-DTPA with aromatic side chain groups as possible contrast agents for magnetic resonance imaging

et al. 2005

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Three amphiphilic DTPA bisamide derivatives containing long-chain phenylalanine esters (with 14, 16 and 18 carbon atoms in the alkyl chain) were synthesized and their corresponding gadolinium(III) complexes were prepared. The attempts to form paramagnetic micelles carrying the gadolinium(III) complexes yielded unstable or polydisperse micelles implying that the presence of the bulky aromatic side groups in the amphiphilic Gd-DTPA bisamide complexes results in an inefficient packing of the paramagnetic complex into micelles. All complexes were efficiently incorporated into liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), yielding stable and monodisperse paramagnetic liposomes. All liposomes had a comparable size, typically between 120 and 160 nm. As a result of the reduced mobility of the gadolinium(III) complexes, solutions of these supramolecular structures show a higher relaxivity than solutions of Gd-DTPA. However, the relaxivity gain is lower compared to compounds consisting of purely aliphatic chains of the same length, most likely due to the less efficient packing or increased local mobility of the gadolinium(III) complex. In the case of the Gd-DTPA bisamide complex with 18 carbon atoms, the immobilization inside the liposomal structure is less effective, probably because the aliphatic chains of the complex are longer than the alkyl chains of the DPPC host, resulting in a relatively high local mobility. The paramagnetic liposomes containing the Gd-DTPA bisamide complexes with 14 carbon atoms showed the highest relaxivity because the optimal length match between the hydrophobic chains of the DPPC and the ligand allowed very efficient packing of the paramagnetic complex into the liposome.

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Section: Resultsmentioning

confidence: 99%

Paramagnetic liposomes containing amphiphilic bisamide derivatives of Gd-DTPA with aromatic side chain groups as possible contrast agents for magnetic resonance imaging

et al. 2005

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“…For all these complexes, the axial proton, H 4 , has the shortest distance form Yb 3' , followed by the other axial ring proton, H 1 , and the two equatorial ring protons, H 2 and H 3 , which have equal Yb Ã/H distances. Due to their different arrangements of the pendant acetate arms around the Yb ion, the calculated Yb Ã/H distances of the pendant arm protons H 5 Å for all these complexes. This suggests that the conformation of the tetraazacyclododecane ring and the geometry of the pyramid formed by the lanthanide ion and the four nitrogen atoms remain the same in solution.…”

Section: Resultsmentioning

confidence: 99%

“…In most cases, these lanthanide-induced shifts (LIS) are very sensitive to structural changes associated with changes in pH, temperature and counter-ions, allowing the lanthanide complexes to be used for many purposes, such as elucidation of molecular conformation [2,3], resolution of enantiomers [4], detection of coordinated water numbers of lanthanide complexes [5], simplification of NMR spectra [6], separation of transmembrane cation resonances [7,8] and temperature probes in biological systems [9 Á/11].…”

Section: Introductionmentioning

confidence: 99%

Analysis of lanthanide induced NMR shifts using a crystal field independent method: application to complexes of tetraazamacrocyclic ligands

Ren

Zhang

Sherry

et al. 2002

Inorganica Chimica Acta

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The linear graphical analysis of the LIS NMR data available for the axially symmetric complexes [Ln(DOTA)] ( (M and m isomers), [Ln(DOTP)] 5( (pH 10.0, 7.0 and 3) and [Ln(DOTEA)] 3' using the classical crystal field dependent method and a crystal field independent method were compared. As the second method provides ratios of geometric structural terms G rather than G values, the effect of lanthanide contraction was reduced. Thus, the large breaks in plots observed for all nuclei of those systems using the classical method are still present in the plots of the second method, only in a few of the nuclei and much reduced. This shows that the large breaks at the middle of the lanthanide series present in plots of the classical method as well as the anomalies often present for those plots for the Tm and Yb ions are mostly due to changes of the crystal field coefficient A 2 0 r 2 along the lanthanide series, while both the hyperfine coupling constants and the ratios of geometric terms also change as a result of the lanthanide contraction, leading to small breaks at the middle of the lanthanide series. Analysis of the proton shifts of [Ln(DOTP)] complexes at pH 10, 7 and 3 indicates that protonation of the complexes results in a decrease on the crystal field coefficient. The dipolar shift ratios and absolute shifts obtained were also interpreted in terms of the structural models for those complexes in solution and their available Xray crystal structures. #

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“…The qF values are proportional to the inverse of the temperatures, as should be expected for contact shifts. 31 It may be concluded that the q value remains fairly constant along the lanthanide series and does not change much with the temperature. However, we cannot exclude that a small and gradual change in the hydration number occurs along the lanthanide series, which cannot be detected in the plots according to eqn.…”

Section: -34mentioning

confidence: 99%

Stability, structure and dynamics of cationic lanthanide(iii) complexes of N,N′-bis(propylamide)ethylenediamine-N,N′-diacetic acid

et al. 2003

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The cationic [Ln(EDTA-PA 2 )] ϩ complexes (EDTA-PA 2 = EDTA-bispropylamide) have been characterised by a multinuclear NMR study.89 Y and 13 C NMR data indicate the formation of 1 : 1 and 1 : 2 (Ln : ligand) complexes in aqueous solution. The stability constants of these complexes, as determined by potentiometric measurements, are log K GdL = 10.3 and log K GdL 2 = 14.3. 13C Relaxation times of the Nd 3ϩ complex show hexadentate binding of the organic ligand via the two amines, the two carboxylates and the two amide oxygen atoms. The complexes are present in solution as a mixture of three isomers: two trans forms and a cis one. Luminescence measurements demonstrate that both Eu 3ϩ and Tb 3ϩ complexes are nona-coordinated at low concentrations (∼10 Ϫ3 M). Three water molecules then complete the coordination sphere. At higher concentrations, the complexes exist in solution as a mixture of nona-and octa-coordinated species, the relative concentration of the latter increases with increasing concentration as a consequence of intermolecular interactions operating in aqueous solutions. Data sets obtained from variabletemperature 17O NMR at 7.05 T and variable-temperature 1 H nuclear magnetic relaxation dispersion (NMRD) on the Gd 3ϩ complex were fitted simultaneously to give insight into the parameters governing the water 1 H relaxivity. Fast rotation limits the relaxivity at 10-40 MHz.

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Determination of the number of inner-sphere water molecules in lanthanide(III) polyaminocarboxylate complexes

Cited by 117 publications

References 28 publications

Paramagnetic liposomes containing amphiphilic bisamide derivatives of Gd-DTPA with aromatic side chain groups as possible contrast agents for magnetic resonance imaging

Paramagnetic liposomes containing amphiphilic bisamide derivatives of Gd-DTPA with aromatic side chain groups as possible contrast agents for magnetic resonance imaging

Analysis of lanthanide induced NMR shifts using a crystal field independent method: application to complexes of tetraazamacrocyclic ligands

Stability, structure and dynamics of cationic lanthanide(iii) complexes of N,N′-bis(propylamide)ethylenediamine-N,N′-diacetic acid

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