Interaction of praseodymium (III) ion with various ligands: A preliminary study for the preparation of ¹⁴²Pr(III) complex for therapeutic radiopharmaceutical candidate

Interaction between Pr(III) ion with nitrogen-donor ligands (i.e. dimethylamine; 1,4-diaminobutane; 1,6-diaminohexane; 1,4-phenylenediamine; 2,2’-bipyridine; 1,10-phenanthroline; and 4,7-diphenyl-1, 10- phenanthroline), and oxygen-donor ligands (i.e. succinic acid and trisodium citrate) for complex formation of potential therapeutic radiopharmaceutical candidate, have been studied. The interactions of Pr(III) ion with those various ligands, were studied by reacting Pr(III) ion (as nitrate salt, Pr(NO₃)₃, in methanol) with the ligands and then refluxing the mixture at 60-70°C for 4 hours. The compounds resulted were purified by washing or separating with column chromatography, then characterized using UV-Vis, FTIR and mass spectroscopy. The result showed that Pr(III) ion strongly interacted with nitrogen-donor ligands containing aromatic group, which have Ka of -4.17-4.8. The interaction between Pr(III) ion with nitrogen-donor ligands containing aliphatic group and oxygen-donor ligands, which have pKa of > 10, were also observed. Aliphatic chain length affected the interaction between atom donor and metal ion. (author)