Synthesis, characterization, and crystal structure of the gadolinium(III) chelate of (1R,4R,7R)-.alpha.,.alpha.',.alpha.''-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3MA)

Kang, Sang Ihn; Ranganathan, Rama S.; Emswiler, John; Kumar, Krishan; Gougoutas, Jack Z.; Malley, Mary F.; Tweedle, Michael F.

doi:10.1021/ic00065a019

Cited by 102 publications

(93 citation statements)

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“…In 0.1 M NaCl the first two protonation constants are lower somewhat (log K 1 H =10.82, log K 2 H =8.42) than the value measured in 0.1 M Me 4 NCl (log K 1 H =13.38, log K 2 H =9.15). 41 In those cases where a higher concentration of background electrolyte was used, this difference will be even higher and the values will probably be close to the values measured for the ligand PCTA (Table 1.). The rate constants obtained for Gd(DO3MA) are k 1 =3.7×10 -5 s -1 , k 2 =5.2×10 -4 s -1 , K 2 =5 M -1 , characterizing the direct dissociation, proton catalyzed dissociation of the monoprotonated complex and the protonation constant of the complex, respectively.…”

Section: Kinetics Of Dissociationsupporting

confidence: 61%

Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes

Tircsó¹,

Sherry

2006

Inorg. Chem.

156

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The protonation constants (K i H ) of 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9,-triacetic acid (PCTA) and stability constants of complexes formed between this pyridine containing macrocycle and several different metal ions have been determined in 1.0 M KCl, 25°C and compared to previous literature values. The first protonation constant was found to be 0.5-0.6 log units higher than the value reported previously and a total five protonation steps were detected (log K i H = 11.36, 7.35, 3.83, 2.12 and 1.29). The stability constants of complexes formed between PCTA and Mg 2+ , Ca 2+ , Cu 2+ and Zn 2+ were also somewhat higher than those previously reported but this difference could be largely attributed to the higher first protonation constant of the ligand. Stability constants of complexes formed between PCTA and the Ln 3+ series of ions and Y 3+ were determined by using an "out-of-cell" potentiometric method. These values ranged from log K = 18.15 for Ce(PCTA) to log K = 20.63 for Yb(PCTA), increasing along the lanthanide series in proportion to decreasing Ln 3+ cation size. The rates of complex formation for Ce(PCTA), Eu(PCTA), Y(PCTA) and Yb(PCTA) were followed by conventional UV-VIS spectroscopy in the pH range pH=3.5 -4.4. First order rate constants (saturation kinetics) obtained for different ligand / metal ion ratios were consistent with rapid formation of a diprotonated intermediate, Ln(H 2 PCTA) 2+ . The stabilities of the intermediates as determined from the kinetic data were 2.81, 3.12, 2.97 and 2.69 log K units for Ce(H 2 PCTA), Eu(H 2 PCTA), Y(H 2 PCTA) and Yb(H 2 PCTA), respectively. Rearrangement of these intermediates to the fully chelated complexes was the rate determining step and the rate constant (k r ) for this process was found to be inversely proportional to the proton concentration. The formation rates (k OH ) increased with a decrease in lanthanide ion size (9.68×10 7 M -1 s -1 , 1.74×10 8 M -1 s -1 , 1.13×10 8 M -1 s -1 and 1.11×10 9 M -1 s -1 for Ce(PCTA), Eu(PCTA), Y(PCTA) and Yb(PCTA), respectively). These data indicate that the Ln(PCTA) complexes exhibit the fastest formation rates among all lanthanide macrocyclic ligand complexes studied to date. The acid catalyzed dissociation rates (k 1 ) varied with cation from 9.61×10 -4 M -1 s -1 , 5.08×10 -4 M -1 s -1 , 1.07×10 -3 M -1 s -1 and 2.80×10 -4 M -1 s -1 for Ce(PCTA), Eu(PCTA), Y(PCTA) and Yb(PCTA), respectively.

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Section: Kinetics Of Dissociationsupporting

confidence: 61%

Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes

Tircsó¹,

Sherry

2006

Inorg. Chem.

156

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“…This species is favoured, in aqueous solution, by a temperature increase and by anion binding. The proposed model, based on isomers A and B~ [9,11] has recently got support from the observation, by X-ray crystallographic studies, of both structures A and B~ in the same crystal of Gd(DO3MA) (DO3MA = (1R,4R,7R)-a,a',a"-trimethyl-l,4,7,10-tetraazacyclododecane-l,4,7-triacetic acid) [20] and of a B~-type coordination mode in the Eu(THP) complex (THP = 1,4,7,10-tetraazacyclododecane-N,N',N",N'-tetrakis(2-hydroxypropyl) [21].…”

Section: Resultsmentioning

confidence: 82%

NMR conformational study of the lanthanide(III) complexes of DOTA in aqueous solution

Marques

Geraldes

Sherry

et al. 1995

Journal of Alloys and Compounds

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Variable temperature NMR spectroscopy studies of lanthanide(III) complexes with 1,4,7,10-tetraazacyclododecane-N,N',N",N'-tetraacetic acid (DOTA) provide evidence of the presence of two isomeric forms in aqueous solution. An NMR study was performed in order to gain structural information on the two isomeric species, using a fitting procedure of calculated to experimental dipolar contributions to the paramagnetic shifts. The two isomers show to have identical macrocyclic ring conformations and differ only in the coordination or orientation of the acetate arms of the ligand, yielding either square prismatic and square anti-prismatic coordination geometries, or octadentate and heptadentate coordinations of the ligand relative to the lanthanide ion. Analysis of the dipolar shifts is consistent with both types of acetate conformational equilibria.

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“…The remaining secondary amino groups in compound 14 were alkylated with triflate 10 in MeCN to Scheme 2. "Clickable" DOTA derivatives 5 and 6. give the target compound (15). The yield of isolated compound 15 corresponded to about 80 % yield and the compound was clearly identified by HRMS.…”

Section: Introductionmentioning

confidence: 90%

“…The latter approach is synthetically less demanding and is feasible through the alkylation of cyclen with appropriately functionalized acid derivatives. The resulting side-chain-substituted DOTA derivatives, such as DOTMA and P730 (Scheme 1 a), retain the excellent metal-binding properties of DOTA [15] and, in the case of P730, allow the conjugation of additional functional molecules through amide formation. [16] To make full use of the DOTA scaffold, herein, we propose modular DOTA derivatives 5 and 6 (Scheme 2, hereafter termed "DOTAZA derivatives").…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 1,4,7,10‐Tetra‐azacyclododecan‐1,4,7,10‐tetra‐azidoethylacetic Acid (DOTAZA) and Related “Clickable” DOTA Derivatives

Kriemen

Ruf

Behrens

et al. 2014

Chemistry An Asian Journal

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Herein, we report the synthesis of two enantiomeric DOTAZA esters and a related DOT3AZA ester. These compounds are tunable analogues of the well-known chelator DOTA and can be easily functionalized through click chemistry of the side-chain azide groups. Like DOTA, DOTAZA forms complexes with various di- and trivalent metals, as demonstrated in the synthesis and structural analysis of CuDOTAZA and the preparation of GdDOTAZA.

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Synthesis, characterization, and crystal structure of the gadolinium(III) chelate of (1R,4R,7R)-.alpha.,.alpha.',.alpha.''-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3MA)

Cited by 102 publications

References 0 publications

Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes

Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes

NMR conformational study of the lanthanide(III) complexes of DOTA in aqueous solution

Synthesis of 1,4,7,10‐Tetra‐azacyclododecan‐1,4,7,10‐tetra‐azidoethylacetic Acid (DOTAZA) and Related “Clickable” DOTA Derivatives

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Synthesis, characterization, and crystal structure of the gadolinium(III) chelate of (1R,4R,7R)-.alpha.,.alpha.',.alpha.''-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3MA)

Cited by 102 publications

References 0 publications

Equilibrium and Formation/Dissociation Kinetics of Some LnIIIPCTA Complexes

Equilibrium and Formation/Dissociation Kinetics of Some LnIIIPCTA Complexes

NMR conformational study of the lanthanide(III) complexes of DOTA in aqueous solution

Synthesis of 1,4,7,10‐Tetra‐azacyclododecan‐1,4,7,10‐tetra‐azidoethylacetic Acid (DOTAZA) and Related “Clickable” DOTA Derivatives

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Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes

Equilibrium and Formation/Dissociation Kinetics of Some Ln^IIIPCTA Complexes