Phosphonated chelates for nuclear imaging.

A series of bis-, tris- and tetra-phosphonated pyridine ligands is presented. In view of their potential use as chelates for radiopharmaceutical applications, the physico-chemical properties of the ligands and of their Co(II), Ni(II), Cu(II), and Zn(II) complexes were studied by means of potentiometry and UV-Vis absorption spectroscopy. The pKa values of the ligands and of the complexes, as well as the stability constants for the formation of the complexes, are presented.

Synthesis of an activated phosphonated bifunctional chelate with potential for PET imaging and radiotherapy.

The synthesis of a phosphonated acyclic bifunctional chelate L* for the labeling of biomaterial is described. L* is based on a pyridine backbone, functionalized in ortho positions by aminomethyl-bis-methylphosphonic acids, and, in the para position, by a side chain containing a reactive NHS carbamate function. The stability of L* in aqueous solutions at different pH values was studied by mass spectrometry, showing the activated function to be sensitive to hydrolysis above neutral pH.

Thermodynamic insight into the origin of the inclusion of monosulfonated isomers of triphenylphosphine into the beta-cyclodextrin cavity.

Formation of inclusion complexes between the beta-cyclodextrin and the potassium salt of o-, m-, and p-substituted monosulfonated triphenylphosphine derivatives was investigated in aqueous solution by NMR spectroscopy. Titration and continuous variation plots obtained from 31P and 1H NMR data indicate the formation of a 1:1 inclusion complex for the three phosphine isomers. T-ROESY NMR experiments show that in all cases a non-sulfonated aromatic ring was included into the hydrophobic cavity of beta-cyclodextrin from the secondary hydroxyl groups side.