PMID- 23027503
OWN - NLM
STAT- MEDLINE
DCOM- 20130401
LR  - 20131121
IS  - 1477-9234 (Electronic)
IS  - 1477-9226 (Linking)
VI  - 41
IP  - 45
DP  - 2012 Dec 7
TI  - Curium(III) citrate speciation in biological systems: a europium(III) assisted 
      spectroscopic and quantum chemical study.
PG  - 13969-83
LID - 10.1039/c2dt31480k [doi]
AB  - Citrate complexes are the dominant binding form of trivalent actinides and 
      lanthanides in human urine at pH < 6. Hence, an accurate prediction of the 
      speciation of these elements in the presence of citrate is crucial for the 
      understanding of their impact on the metabolism of the human organism and the 
      corresponding health risks. We studied the complexation of Cm(III) and Eu(III), 
      as representatives of trivalent actinides and lanthanides, respectively, in 
      aqueous citrate solution over a wide pH range using time-resolved laser-induced 
      fluorescence spectroscopy. Four distinct citrate complexes were identified and 
      their stability constants were determined, which are MHCit(0), M(HCitH)HCit(2-), 
      M(HCit)(2)(3-), and M(Cit)(2)(5-) (M = Cm, Eu). Additionally, there were also 
      indications for the formation of MCit(-) complexes. Structural details on the 
      EuHCit(0) and EuCit(-) complexes were obtained with FT-IR spectroscopy in 
      combination with density functional theory calculations. IR spectroscopic 
      evidence for the deprotonation of the hydroxyl group of the citrate ion in the 
      EuCit(-) complex is presented, which also revealed that the complexation of the 
      Eu(3+) ion takes place not only through the carboxylate groups, like in 
      EuHCit(0), but additionally via the hydroxylate group. In both EuHCit(0) and 
      EuCit(-) the carboxylate binding mode is mono-dentate. Under a very low 
      metal : citrate ratio that is typical for human body fluids, the Cm(III) and 
      Eu(III) speciation was found to be strongly pH-dependent. The Cm(III) and Eu(III) 
      citrate complexes dominant in human urine at pH < 6 were identified to be 
      Cm(HCitH)HCit(2-) and a mixture of Eu(HCitH)HCit(2-) and EuHCit(0). The results 
      specify our previous in vitro study using natural human urine samples (Heller et 
      al., Chem. Res. Toxicol., 2011, 24, 193-203).
FAU - Heller, Anne
AU  - Heller A
AD  - Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Germany. 
      a.heller@hzdr.de
FAU - Barkleit, Astrid
AU  - Barkleit A
FAU - Foerstendorf, Harald
AU  - Foerstendorf H
FAU - Tsushima, Satoru
AU  - Tsushima S
FAU - Heim, Karsten
AU  - Heim K
FAU - Bernhard, Gert
AU  - Bernhard G
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20121001
PL  - England
TA  - Dalton Trans
JT  - Dalton transactions (Cambridge, England : 2003)
JID - 101176026
RN  - 0 (Organometallic Compounds)
RN  - 2968PHW8QP (Citric Acid)
RN  - 444W947O8O (Europium)
RN  - M5LL84MZ2W (Curium)
SB  - IM
MH  - Citric Acid/*chemistry/urine
MH  - Curium/*chemistry/urine
MH  - Europium/*chemistry/urine
MH  - Humans
MH  - Hydrogen-Ion Concentration
MH  - Molecular Structure
MH  - Organometallic Compounds/*chemistry
MH  - *Quantum Theory
MH  - Spectroscopy, Fourier Transform Infrared
MH  - Thermodynamics
EDAT- 2012/10/03 06:00
MHDA- 2013/04/02 06:00
CRDT- 2012/10/03 06:00
PHST- 2012/10/03 06:00 [entrez]
PHST- 2012/10/03 06:00 [pubmed]
PHST- 2013/04/02 06:00 [medline]
AID - 10.1039/c2dt31480k [doi]
PST - ppublish
SO  - Dalton Trans. 2012 Dec 7;41(45):13969-83. doi: 10.1039/c2dt31480k. Epub 2012 Oct 
      1.