Binuclear Gd³⁺ Complex of a 34-Membered Macrocycle with Six Carboxymethyl Arms:  X-ray Structures, Formation Constants, NMR, EPR, and ¹H NMR Relaxivities

Abstract

A 34-membered macrocyclic ligand with six pendant carboxymethyl groups has been synthesized by the coupling of two diethylenetriaminepentaacetate (dtpa) and two 1,4-diaminobutane units: the macrocycle is 2,

Synthesis, structure, and stability studies of dimeric gadolinium(III) complexes containing cyclic polyaminopolycarboxylic bisamide ligands

“…Under such circumstances, it is expected that the softer donors, nitrogens, would be left out, whereas the oxygen atoms would still be preferred. A similar observation has been made in the binuclear Gd complex with a 34-membered macrocycle [9]. The two Gd 3+ ions are separated by a distance of 6.68 Å.…”

Stability and Toxicity of Contrast Agents

“…Exceptionally high selectivity for Gd 3+ over Zn 2+ was found for EDTA-DAM (Chart 4.1) [34]. The [2+2] condensation of DTPA-dianhydride and 1,4-diaminobutane yielded a 34-membered cyclic derivative (34DTPABN, Chart 4.2) that forms both mono-and dinuclear complexes with Gd 3+ [56]. The stability constants of this system (log K Gd(L) = 16.46 and log K Gd2(L) = 30.36) were found to be similar to the log K Gd(L) values of other Gd(DTPA-bisamide) complexes.…”

Structure, Dynamics, and Computational Studies of Lanthanide‐Based Contrast Agents

“…It should be noted that Ln 3+ complexes of similar 16-[187] and 17-membered [184] macrocycles (16-DTPA-PAM, 16-DTPA-HPAM, and 17-DTPA-BAM) crystallized as mononuclear complexes with a syn configuration of the amides. The Gd 3+ complex of a 34-membered macrocycle containing two DTPA units (DTPA-bn-DTPA-bn), however, was monomeric and showed coordination polyhedra with the amide functions in a cis configuration [190].…”