Stability constants and <sup>1</sup>H relaxation effects of ternary complexes formed between gd‐dtpa, gd‐dtpa‐bma, gd‐dota, and gd‐edta and citrate, phosphate, and carbonate ions

Burai, László; Hietapelto, Vesa; Király, Róbert; Tóth, Éva; Brücher, Ernő

doi:10.1002/mrm.1910380120

Cited by 59 publications

(80 citation statements)

References 28 publications

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“…The relaxivities r a (s À1 mm À1 ) are defined as the paramagnetic relaxation enhancements (PREs) R ap R a ÀR a0 per mM of added Gd-L complex [Eq. (15)]:…”

Section: Theorymentioning

confidence: 99%

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Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Nonat

Fries

Pécaut

et al. 2007

Chemistry A European J

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The tripodal hexadentate picolinate ligand dpaa3- (H3dpaa=N,N'-bis[(6-carboxypyridin-2-yl)methyl]glycine) has been synthesised. It can form 1:1 and 1:2 lanthanide/ligand complexes. The crystal structure of the bis(aquo) lutetium complex [Lu(dpaa)(H2O)2] has been determined by X-ray diffraction studies. The number of water molecules was determined by luminescence lifetime studies of the terbium and europium complexes. The tris(aquo) terbium complex shows a fairly high luminescence quantum yield (22 %). The [Gd(dpaa)(H2O)3] complex displays a high water solubility and an increased stability (pGd=12.3) with respect to the analogous bis(aquo) complex [Gd(tpaa)(H2O)2] (pGd=11.2). Potentiometric and relaxometric studies show the formation of a soluble GdIII hydroxo complex at high pH values. A unique aquohydroxo gadolinium complex has been isolated and its crystal structure determined. This complex crystallises as a 1D polymeric chain consisting of square-shaped tetrameric units. In heavy water, the [Gd(dpaa)-(D2O)3] complex shows a quite high HOD proton relaxivity at high field (11.93 s(-1) mM(-1) at 200 MHz and 298 K) because of the three inner-sphere water molecules. The formation of ternary complexes with physiological anions has been monitored by relaxometric studies, which indicate that even under conditions favourable to the formation of adducts with oxyanions, the mean relaxivity remains higher than those of most of the currently used commercial contrast agents except for the citrate. However, the measured relaxivity (r1=7.9 s(-1) mM(-1)) in a solution containing equimolar concentrations of [Gd(dpaa)(D2O)3] and citrate is still high. The interaction with albumin has been investigated by relaxometric and luminescence studies. Finally, a new versatile method to unravel the geometric and dynamic molecular factors that explain the high-field relaxivities has been developed. This approach uses a small, uncharged non-coordinating probe solute, the outer-sphere relaxivity of which mimics that of the water proton. Only a routine NMR spectrometer and simple mathematical analysis are required.

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“…The relaxivities r a (s À1 mm À1 ) are defined as the paramagnetic relaxation enhancements (PREs) R ap R a ÀR a0 per mM of added Gd-L complex [Eq. (15)]:…”

Section: Theorymentioning

confidence: 99%

“…The OS relaxivities r OS 1,w and r OS 2,w of the HOD protons are given by Equation (22) or (10) adapted for GdA C H T U N G T R E N N U N G (dpaa) 2 . The total relaxivities r 1,w and r 2,w are obtained from their definition given by Equation (15). The IS relaxivities r (17) or (11).…”

mentioning

confidence: 99%

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Nonat

Fries

Pécaut

et al. 2007

Chemistry A European J

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“…Phosphate coordination has been described previously for Gd-poly(amino carboxylate) complexes, stability constants of logK = 2.16 and 4.8 were reported for the ternary complex formed between PO 4 3À and [ 1.9 ], respectively. [37,38] The interaction of phosphate and [Gd 2 L À has no effect on the 31 P relaxation rate (T 2 = 0.75 s). These results show that phosphate interacts with […”

Section: A C H T U N G T R E N N U N G (H 2 O)mentioning

confidence: 99%

Unexpected Aggregation of Neutral, Xylene‐Cored Dinuclear Gd^III Chelates in Aqueous Solution

Costa

Balogh

Turcry

et al. 2006

Chemistry A European J

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We have synthesized ditopic ligands L(1), L(2), and L(3) that contain two DO3A(3-) metal-chelating units with a xylene core as a noncoordinating linker (DO3A(3-) = 1,4,7,10-tetraazacyclododecane-1,4,7-triacetate; L(1) = 1,4-bis{[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl]methyl}benzene; L(2) = 1,3-bis{[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl]methyl}benzene; L(3) = 3,5-bis{[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl]methyl}benzoic acid). Aqueous solutions of the dinuclear Gd(III) complexes formed with the three ligands have been investigated in a variable-temperature, multiple-field (17)O NMR and (1)H relaxivity study. The (17)O longitudinal relaxation rates measured for the [Gd(2)L(1-3)(H2O)(2)] complexes show strong field dependence (2.35-9.4 T), which unambiguously proves the presence of slowly tumbling entities in solution. The proton relaxivities of the complexes, which are unexpectedly high for their molecular weight, and in particular the relaxivity peaks observed at 40-50 MHz also constitute experimental evidences of slow rotational motion. This was explained in terms of self-aggregation related to hydrophobic interactions, pi stacking between the aromatic linkers, or possible hydrogen bonding between the chelates. The longitudinal (17)O relaxation rates of the [Gd(2)L(1-3)(H2O)(2)] complexes have been analysed with the Lipari-Szabo approach, leading to local rotational correlation times tau(1)(298) of 150-250 ps and global rotational correlation times tau(g)(298) of 1.6-3.4 ns (c(Gd): 20-50 mM), where tau(1)(298) is attributed to local motions of the Gd segments, while tau(g)(298) describes the overall motion of the aggregates. The aggregates can be partially disrupted by phosphate addition; however, at high concentrations phosphate interferes in the first coordination sphere by replacing the coordinated water. In contrast to the parent [Gd(DO3A)(H2O)(1.9)], which presents a hydration equilibrium between mono- and dihydrated species, a hydration number of q = 1 was established for the [Ln(2)L(1-3)(H2O)(2)] chelates by (17)O chemical shift measurements on Ln = Gd and UV/Vis spectrophotometry for Ln = Eu. The exchange rate of the coordinated water is higher for [Gd(2)L(1-3)(H2O)(2)] complexes k(ex)(298) = 7.5-12.0 x 10(6) s(-1)) than for [Gd(DOTA)(H2O)](-). The proton relaxivity of the [Gd(2)L(1-3)(H2O)(2)] complexes strongly decreases with increasing pH. This is related to the deprotonation of the inner-sphere water, which has also been characterized by pH potentiometry. The protonation constants determined for this process are logK(OH) = 9.50 and 10.37 for [Gd(2)L(1)(H2O)(2)] and [Gd(2)L(3)(H2O)(2)], respectively.

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“…Annual industrial output of EDTA and other complexones is in the thousands of tons [92HE]. The highly stable complexes formed with polyaminopolycarboxylate ligands are of particular importance in biology and medicine [05BC, 01LE, 00BCa, 00HF, 98AB, 97BH,84DMb]. The initial field of complexone biomedical application was chelation therapy [99CT].…”

Section: Introductionmentioning

confidence: 99%

Critical evaluation of stability constants of metal complexes of complexones for biomedical and environmental applications* (IUPAC Technical Report)

Anderegg¹,

Arnaud‐Neu

Delgado

et al. 2005

Pure and Applied Chemistry

263

170

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Available experimental data on stability constants of proton (hydron) and metal complexes for seven complexones of particular biomedical and environmental interest: iminodiacetic acid [2,2'-azanediyldiacetic acid, IDA], (methylimino)diacetic acid [2,2'-(methylazanediyl)diacetic acid, MIDA]; 2,2',2'',2'''-{[(carboxymethyl)azanediyl]bis[(ethane-1,2-diyl)nitrilo]}tetraacetic acid (DTPA), 3,6,9,12-tetrakis(carboxymethyl)-3,6,9,12-tetraazatetradecanedioic acid (TTHA); 2,2',2''-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA); 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA); 2,2',2'',2'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid (TETA), published in 1945-2000, have been critically evaluated. Some typical errors in stability constant measurements for particular complexones are summarized. Higher quality data are selected and presented as “Recommended” or “Provisional”.

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Stability constants and ¹H relaxation effects of ternary complexes formed between gd‐dtpa, gd‐dtpa‐bma, gd‐dota, and gd‐edta and citrate, phosphate, and carbonate ions

Cited by 59 publications

References 28 publications

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Unexpected Aggregation of Neutral, Xylene‐Cored Dinuclear Gd^III Chelates in Aqueous Solution

Critical evaluation of stability constants of metal complexes of complexones for biomedical and environmental applications* (IUPAC Technical Report)

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Stability constants and 1H relaxation effects of ternary complexes formed between gd‐dtpa, gd‐dtpa‐bma, gd‐dota, and gd‐edta and citrate, phosphate, and carbonate ions

Cited by 59 publications

References 28 publications

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Unexpected Aggregation of Neutral, Xylene‐Cored Dinuclear GdIII Chelates in Aqueous Solution

Critical evaluation of stability constants of metal complexes of complexones for biomedical and environmental applications* (IUPAC Technical Report)

Contact Info

Product

Resources

About

Stability constants and ¹H relaxation effects of ternary complexes formed between gd‐dtpa, gd‐dtpa‐bma, gd‐dota, and gd‐edta and citrate, phosphate, and carbonate ions

Unexpected Aggregation of Neutral, Xylene‐Cored Dinuclear Gd^III Chelates in Aqueous Solution