Water-exchange, electronic relaxation, and rotational dynamics of the MRI contrast agent [Gd(DTPA-BMA)(H2O)] in aqueous solution: a variable pressure, temperature, and magnetic field oxygen-17 NMR study

González, Gabriel; Powell, D. Hugh; Tissières, Véronique; Merbach, André E.

doi:10.1021/j100052a010

Cited by 141 publications

(140 citation statements)

References 6 publications

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“…The contribution arising from spin rotation is given by Equation (4), [35] in which dg 2 L is the deviation from the free electron g L value and t R is the rotational correlation time [Eq. (5)]…”

Section: Methodsmentioning

confidence: 99%

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

et al. 1999

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Section: Methodsmentioning

confidence: 99%

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

et al. 1999

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“…[7] The two approaches gave the same results for parameters derived from the 17 ϩ have been analyzed by means of the Swift-Connick equations, according to the method previously described. [7,17,18] For the mole fraction of bound water (P m ), we used a temperature-dependent value calculated on the basis of ∆H 2-3 0 and ∆S 2-3 0 obtained for [Eu-(DO2A)(H 2 O) [2][3] ϩ in the UV/Vis study. In the calculations, the electronic relaxation rates measured by EPR at 0.34 T (X-band) have been fitted simultaneously with the 17 O NMR data.…”

Section: O Nmr and Epr Measurementsmentioning

confidence: 99%

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Yerly

Dunand

Tóth

et al. 2000

Eur. J. Inorg. Chem.

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The hydration state of a series of [Ln(DO2A)(H2O)n]+ complexes in aqueous solution at pH = 6.4–7.0 was studied by measuring the lanthanide‐induced 17O shifts (LIS) of water [Ln includes elements from Ce to Yb; DO2A = 1,7‐bis(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane]. Their contact contribution, obtained from Reilley plots, indicated a decrease in the inner‐sphere water coordination number of the [Ln(DO2A)(H2O)n]+ complexes from n = 3 (Ce–Eu), to n = 2 (Tb–Yb). A temperature‐dependent UV/Vis absorption study of the 578–582 nm 7F0 → 5D0 transition band of [Eu(DO2A)(H2O)n]+ in aqueous solution showed that this complex is present in an equilibrium between eight‐ and nine‐coordinate species with n = 2 and n = 3, respectively. The hydration equilibrium parameters (2 ↔ 3), K2–3298= 4.0 ± 0.2, ΔH2–30 = –12.1 ± 1 kJ mol–1 and ΔS 2–30 = –28.9 ± 3 J mol–1 K–1,correspond to an average hydration number of 2.65–2.85 in the temperature range 273–363 K. A variable temperature, multiple field 17O NMR study combined with direct EPR measurements of the transverse electronic relaxation rates has been used to obtain the parameters characterizing water exchange, rotation and electronic relaxation, all influencing the proton relaxivity of [Gd(DO2A)(H2O)2–3]+. The small increase in the water exchange rate of [Gd(DO2A)(H2O)2–3]+ (k ex298 = (10 ± 5) × 106s–1) relative to that of[Gd(DOTA)(H2O)]– (4.8 × 106 s–1) is a consequence of an unfavorable interplay of charge and hydration equilibria. The value of τ R298 = 40 ± 1 ps is short, and the electronic relaxation rate (1/T2e ≈︁ 1.2 × 1010 s–1) is fast relative to [Gd(DOTA)(H2O)]– (1.3–2.4 × 109 s–1 for B = 0.34 T). These parameters negate to some extent the expected increase in proton relaxivity of the [Gd(DO2A)(H2O)2–3]+ complex.

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“…Relaxivity of PCA is determined by three physicochemical factors: (i) the rotational correlation time (τ R ) of the complex, (ii) the water residence time (τ m ) in the inner sphere, and (iii) the longitudinal electronic spin relaxation time (T1e) of paramagnetic ion. [2][3][4][5][6][7][8][9][10][11] It is worth mentioning that T1e, although provides quite critical information in certain cases, is too short to be directly measured by current EPR techniques. 12 Nevertheless, the decay of the electronic spin magnetization perpendicular to the external field, usually characterized by a transverse electronic relaxation time (T 2e ), allows an estimation of T 1e within the framework of a given model of the electronic relaxation.…”

Section: Introductionmentioning

confidence: 99%

“…Some empirical formulas, initially proposed by Powell to describe both transverse and longitudinal relaxation times, have been applied in a unified model to simultaneously interpret 17 O NMR, 1 H NMR, and EPR. 4,8,9 Yet, Powell's formulas have exhibited some drawbacks in that they not only require an additional factor such as a spin rotation mechanism for the interpretation of data but also the final results thus obtained are generally in a poor agreement with the experimental EPR data. Thus, for the purpose of reasonable prediction of T1e, it is desirable to find a suitable model enabling to describe the underlying mechanism.…”

Section: Introductionmentioning

confidence: 99%

Determination of Correlation Times of New Paramagnetic Gadolinium MR Contrast Agents by EPR and¹⁷O NMR

2009

Bulletin of the Korean Chemical Society

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The work describes EPR and 17 O NMR measurements followed by theoretical calculation of the rotational correlation time (τR), the water residence time (τm), and the longitudinal electronic spin relaxation time (T1e) for two new gadolinium complexes 1 and 2 of the type [Gd(L)(H2O)] (L = tranexamic esters) in order to investigate their efficiency as a paramagnetic contrast agent (PCA). Of three correlation times, τR plays a major and predominant role to the unusually high relaxivity of 1 and 2 as compared with that of clinically approved MR CAs such as, and [Gd(DOTA)(H2O)] -(Dotarem ® ). The presence of bulky tranexamic ester in the ligand seems to be responsible for the conformational rigidity, which in turn causes such great an increase in τR.

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Water-exchange, electronic relaxation, and rotational dynamics of the MRI contrast agent [Gd(DTPA-BMA)(H2O)] in aqueous solution: a variable pressure, temperature, and magnetic field oxygen-17 NMR study

Cited by 141 publications

References 6 publications

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Determination of Correlation Times of New Paramagnetic Gadolinium MR Contrast Agents by EPR and¹⁷O NMR

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Water-exchange, electronic relaxation, and rotational dynamics of the MRI contrast agent [Gd(DTPA-BMA)(H2O)] in aqueous solution: a variable pressure, temperature, and magnetic field oxygen-17 NMR study

Cited by 141 publications

References 6 publications

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

High Relaxivity for Monomeric Gd(DOTA)-Based MRI Contrast Agents, Thanks to Micellar Self-Organization

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Determination of Correlation Times of New Paramagnetic Gadolinium MR Contrast Agents by EPR and17O NMR

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Determination of Correlation Times of New Paramagnetic Gadolinium MR Contrast Agents by EPR and¹⁷O NMR