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See detailGadolinium DOTA Chelates Featuring Alkyne Groups Directly Grafted on the Tetraaza Macrocyclic Ring: Synthesis, Relaxation Properties, "Click" Reaction, and High-Relaxivity Micelles
Vanasschen, Christian; Bouslimani, Nouri ULg; Thonon, David ULg et al

in Inorganic Chemistry (2011), 50(18), 8946-8958

This paper reports on the synthesis and relaxivity properties of tetraacetic DOTA-type chelating agents featuring one or two alkyne groups directly grafted on the tetraaza macrocyclic ring and available ... [more ▼]

This paper reports on the synthesis and relaxivity properties of tetraacetic DOTA-type chelating agents featuring one or two alkyne groups directly grafted on the tetraaza macrocyclic ring and available for "click" reactions with azide-bearing substrates. The racemic DOTAma ligand bearing one alkyne group was obtained by a bisaminal template route. The same approach was used to prep. ligand DOTAda substituted by two alkyne groups located on two adjacent carbon atoms. The S,S enantiomer of DOTAda was also prepd. by a "crab-like" condensation. This ligand is the first example of a DOTA deriv. featuring two reactive functions adjacent to each other on the macrocyclic ring. A triacetic monoalkyne ligand (DO3ma) was also synthesized for comparison purposes. NMR studies indicate that the Yb(III) chelates of DOTAma and DOTAda adopt two conformations in solns. in which the tetraaza ring is rigidified. The hydration state of the Eu(III) chelates was detd. by luminescence spectroscopy, and the water exchange time of the Gd(III) complexes was measured by 17O NMR. Ring substitution accelerates the water exchange. These data were used to interpret nuclear magnetic relaxation dispersion curves of the Gd(III) chelates. Two long aliph. chains have been added to DOTAda by a "click" procedure to form the (C18)2DOTAda ligand. The corresponding Gd(III) complex forms micelles of unusually high relaxivity presumably because of the close proximity of the aliph. chains on the macrocyclic ring that ensures a rigid double anchoring into the micelles. [less ▲]

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See detailInteraction of 6,6-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2:6,2-terpyridine (CyMe4-BTTP) with some trivalent ions such as lanthanide(III) ions and americium(III)
Lewis, Frank; Harwood, Laurance; Hudson, Michael J. et al

in Dalton Transactions (2010), 39

The new solvent extraction reagent 6,6’’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2’:6’,2’’-terpyridine (CyMe4-BTTP) has been synthesized in 4 steps from 2,2’:6’,2’’ ... [more ▼]

The new solvent extraction reagent 6,6’’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2’:6’,2’’-terpyridine (CyMe4-BTTP) has been synthesized in 4 steps from 2,2’:6’,2’’-terpyridine. Detailed NMR and mass spectrometry studies indicate that the ligand forms 1:2 complexes with lanthanide(III) perchlorates where the aliphatic rings are conformationally constrained whereas 1:1 complexes are formed with lanthanide(III) nitrates where the rings are conformationally mobile. An optimized structure of the 1:2 solution complex with Yb(III) was obtained from the relative magnitude of the induced paramagnetic shifts. X-ray crystallographic structures of the ligand and of its 1:1 complex with Y(III) were also obtained. The NMR and mass spectra of [Pd(CyMe4-BTTP)]n2n+ are consistent with a dinuclear double helical structure (n = 2). In the absence of a phase-modifier, CyMe4-BTTP in 1-octanol showed a maximum distribution coefficient of Am(III) of 0.039 (±20%) and a maximum separation factor of Am(III) over Eu(III) of 12.0 from nitric acid. From nitric acid, the metal(III) cations are extracted as the 1:1 complex. The generally low distribution coefficients observed compared with the BTBPs arise because the 1:1 complex of CyMe4-BTTP is considerably less hydrophobic than the 1:2 complexes formed by the BTBPs. In M(BTTP)3+ complexes, there is a competition between the nitrate ions and the ligand for the complexation of the metal. [less ▲]

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