Multidentate extracting agents based on calix[4]arene scaffold – UVI/EuIII separation studies

Production of no-carrier-added 89Zr at an 18 MeV cyclotron, its purification and use in investigations in solvent extraction

The chemical separation of zirconium from lanthanides by liquid–liquid extraction is challenging but critical for medical and technological applications. Using the example of 89Zr, we optimize the liquid–liquid-extraction process by means of the radiotracer technique. We produced 89Zr by proton irradiation of a metallic yttrium target at a cyclotron. The purification of the radionuclide was performed by a UTEVA resin. 89Zr was separated in no-carrier-added form in a sulfuric acid solution. 89Zr was successfully used in solvent extraction tests with calixarenes for the separation of zirconium from lanthanides. This reaction is suitable for the efficient extraction and purification of lanthanides.

Synthesis, Crystal Structure, and Biological Activity of a Multidentate Calix[4]arene Ligand Doubly Functionalized by 2-Hydroxybenzeledene-Thiosemicarbazone

The design and synthesis of a novel tert-butyl-calix[4]arene functionalized at 1, 3 positions of the lower rim with two terminal 2-hydroxybenzeledene-thiosemicarbazone moieties is reported. The new ligand with multi-dentate chelating properties was fully characterized by several techniques: ESI-Mass spectroscopy, FT-IR, 1H-NMR, and single crystal X-ray diffraction. The solid state structure confirms that the calix[4]arene macrocycle has the expected open cone conformation, with two opposite phenyl rings inclined outwards with large angles. The conformation of the two alkoxythiosemicarbazone arms produces a molecule with a C2 point group symmetry. An interesting chiral helicity is observed, with the two thiosemicarbazone groups oriented in opposite directions like a two-blade propeller. A water molecule is encapsulated in the center of the two-blade propeller through multiple H-bond coordinations. The antibacterial, antifungal, anticancer, and cytotoxic activities of the calix[4]arene-thiosemicarbazone ligand and its metal derivatives (Co2+, Ni2+, Cu2+, and Zn2+) were investigated. A considerable antibacterial activity (in particular against E. coli, MIC, and MBC = 31.25 μg/mL) was observed for the ligand and its metal derivatives. Significant antifungal activities against yeast (C. albicans) were also observed for the ligand (MIC = 31.25 μg/mL and MBC = 125 μg/mL) and for its Co²⁺ derivative (MIC = 62.5 μg/mL). All compounds show cytotoxicity against the tested cancerous cells. For the Saos-2 cell line, the promising anticancer activity of ligand L (IC₅₀ < 25 μg/mL) is higher than its metal derivatives. The microscopic analysis of DAPI-stained cells shows that the treated cells change in morphology, with deformation and fragmentation of the nuclei. The hemo-compatibility study demonstrated that this class of compounds are suitable candidates for further in vivo investigations.