Determination of stability constants of selected U(VI) flavonol complexes by absorption and emission spectroscopy

Flavonols are polyphenol compounds, which belong to the class of flavonoids. They are produced by plants and can be segregated by the root into the soil. Flavonols can bind metals, e.g. Co, Fe, Ni, Al, Zn and Pb due to the presence of the carbonyl group on the gamma-pyranone ring and the hydroxyl groups as substituents in different positions of the whole organic molecule. The interactions of these polyphenols with radioactive metals have been studied very rare up to now. In this work first results of spectroscopic investigations of the U(VI) complexation by flavonols with several number of hydroxyl groups and glycosidic substituent are presented and discussed. The flavonols and their U(VI) complexes have specific absorption bands and emission signals in the UV-Vis range, which were used for the calculation of deprotonation constants of organic ligands and of the stability constants of the formed U(VI) flavonol complexes in methanolic solution.