Uranium(VI) complexes with phospholipid model compounds--a laser spectroscopic study.
We present the complex formation of the uranyl ion (UO(2)(2+)) in the aqueous system with phosphocholine, O-phosphoethanolamine and O-phosphoserine. These phosphonates (R-O-PO(3)(2-)) represent the hydrophilic head groups of phospholipids. The complexation was investigated by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at pH=2-6. An increase of the fluorescence intensity, connected with a strong red-shift of about 8 nm compared to the free uranyl ion, indicates a complex formation between UO(2)(2+) and the phosphonates already at pH=2. Even at pH=6 these complexes prevail over the uranyl hydroxide and carbonate species, which are generated naturally at this pH. At pH=4 and higher a 1:2 complex between uranyl and O-phosphoserine was found. Complexes with a metal-to-ligand ratio of 1:1 were observed for all other ligands. Fluorescence lifetimes, emission maxima and complex stability constants at T=22+/-1 degrees C are reported. The TRLFS spectra of uranyl complexes with two phosphatidic acids (1,2-dimyristoyl-sn-glycero-3-phosphate and 1,2-dipalmitoyl-sn-glycero-3-phosphate), which represent the apolaric site of phospholipids, show in each case two different species.
Koban
A
A
Forschungszentrum Dresden-Rossendorf e.V., Institute of Radiochemistry, P.O. Box 510119, D-01314 Dresden, Germany. a.koban@fzd.de
Bernhard
G
G
D013856:Acidithiobacillus thiooxidans / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000138:chemical synthesis / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000138:chemical synthesis / Q000737:chemistry; D010718:Phosphatidylserines / Q000138:chemical synthesis / Q000737:chemistry; D010743:Phospholipids / Q000138:chemical synthesis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014501:Uranium / Q000737:chemistry*
D009942:Organometallic Compounds; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D014501:Uranium