title: Substitution of gadolinium ethylenediaminetetraacetate with phosphites: towards gadolinium deposit in nephrogenic systemic fibrosis.
abstract: In neutral media, reactions of gadolinium ethylenediaminetetraacetates with phosphorous acid result in the formation of the mixed-ligand polymeric complex K3n[Gd(EDTA)(HPO3)]n·7nH2O () and dimeric complex Na6[Gd2(EDTA)2(HPO3)2]·2.5NaCl·21H2O () (H4EDTA = ethylenediaminetetraacetic acid) in warm solution. Further substitution with citric acid gives the monomeric gadolinium citrate with EDTA (NH4)2Na[Gd(EDTA)(H2cit)]·4H2O (). The compounds were characterized by elemental analysis, single crystal X-ray diffraction, FT-IR, ESI-MS and thermogravimetric analysis. Structural analysis indicates that three coordinated water molecules in the gadolinium ethylenediaminetetraacetate trihydrates are replaced by phosphite ions (HPO3(2-)) in the compounds and . Gadolinium atoms are octa-coordinated by EDTA and the phosphite ion, the latter links adjacent Gd-EDTA units to generate an infinite one-dimensional chain in compound and a dimeric octatomic ring in . In complex , coordinated water molecules were substituted by the α-hydroxy, α-carboxy and β-carboxy groups of citrate. Citrate is favourable for inhibiting the formation of Gd-EDTA phosphite. All the complexes are very easily soluble in water. The solution behavior of the isostructural lanthanum complexes was probed with (13)C and (31)P NMR spectra in D2O for comparison. ESI-MS analysis and recrystallization proved that complexes and dissociate to the monomeric unit of Gd-EDTA and free HPO3(2-) in aqueous solution. Substitutions of gadolinium ethylenediaminetetraacetates to and are attributed to be the cause of nephrogenic systemic fibrosis in some way.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen, 361005, China. zhzhou@xmu.edu.cn.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Mao-Long
authors.initials: ML
authors.lastname: Chen
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Zhou
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004492:Edetic Acid / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D054989:Nephrogenic Fibrosing Dermopathy / Q000175:diagnosis*; D009942:Organometallic Compounds / Q000737:chemistry*; D017905:Phosphites / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D017905:Phosphites; D004492:Edetic Acid; D005682:Gadolinium