Expanding the Scope of Pyclen-Picolinate Lanthanide Chelates to Po-Tential Theranostic Applications

A family of three picolinate pyclen based ligands, previously investigated for the complexation of Y³⁺ and some lanthanide ions (Gd³⁺, Eu³⁺), was studied with ¹⁶¹Tb and ¹⁷⁷Lu in view of potential radiotherapeutic applications. The set of six Tb³⁺and Lu³⁺complexes was synthesized and fully characterized. The coordination properties in the solid state and in solution were thoroughly studied. Potentiometric titrations, corroborated by DFT calculations, showed the very high stability constants of the Tb³⁺ and Lu³⁺ complexes, which are associated to remarkable kinetic inertness. A complete radiolabeling study performed with both¹⁶¹Tb and ¹⁷⁷Lu radionuclides, including experiments with regard to the stability with and without scavengers and kinetic inertness using challenging agents, proved that the ligands could reasonably compete with the DOTA analogue. To conclude, the potential of using the same ligand for both radiotherapy and optical imaging was highlighted for the first time.

Expanding the Scope of Pyclen-Picolinate Lanthanide Chelates to Po-Tential Theranostic Applications

A family of three picolinate pyclen based ligands, previously investigated for the complexation of Y³⁺ and some lanthanide ions (Gd³⁺, Eu³⁺), was studied with ¹⁶¹Tb and ¹⁷⁷Lu in view of potential radiotherapeutic applications. The set of six Tb³⁺and Lu³⁺complexes was synthesized and fully characterized. The coordination properties in the solid state and in solution were thoroughly studied. Potentiometric titrations, corroborated by DFT calculations, showed the very high stability constants of the Tb³⁺ and Lu³⁺ complexes, which are associated to remarkable kinetic inertness. A complete radiolabeling study performed with both¹⁶¹Tb and ¹⁷⁷Lu radionuclides, including experiments with regard to the stability with and without scavengers and kinetic inertness using challenging agents, proved that the ligands could reasonably compete with the DOTA analogue. To conclude, the potential of using the same ligand for both radiotherapy and optical imaging was highlighted for the first time.

Synthesis, thermogravimetric analysis and enthalpy determination of lanthanide β-diketonates

This work reports thermodynamic characterizations of lanthanide β-diketonates for use in nuclear fission product separation. Adsorption and sublimation enthalpies have been shown to be linearly correlated, therefore there is motivation to determine sublimation thermodynamics. An isothermal thermogravimetric analysis method is employed on fourteen lanthanide chelates for the ligands 2,2,6,6-tetramethyl-3,5-heptanedione and 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione to determine sublimation enthalpies. No linear trend is seen across the series; values show a cyclical nature, possibly indicating a greater influence of chemisorption for some complexes and less of a role of physisorption in dictating adsorption differences between lanthanides in the same series. This is in line with previous reports in terms of the chromatographic separation order of the lanthanides. The results reported here can be used to manipulate separations parameters and column characteristics to better separate these lanthanide chelates. Fourteen chelates of the ligand 1,1,1-trifluoro-2,4-pentanedione are also thermally characterized but found to not sublime and be undesirable for this method. Additionally, all chelates are characterized by constant heating thermogravimetric analysis coupled with mass spectrometry, melting point analysis, elemental analysis and FTIR.

Paramagnetic lanthanide chelates for multicontrast MRI

A paramagnetic chelator that serves as a platform for multicontrast MRI is presented. It can be utilized as a T1-weighted, paraCEST or 19F MRI contrast agent.

AMPED: a new platform for picolinate based luminescent lanthanide chelates

Anchoring three picolinate units on a AMPED scaffold affords a strongly pre-organized ligand for the formation of luminescent lanthanide complexes.