Characterization of Lanthanide(III) DOTP Complexes: Thermodynamics, Protonation, and Coordination to Alkali Metal Ions

A. Sherry , J. Ren , J. Huskens , E. Brücher , Éva Tóth (1) , C.F.C.G Geraldes , M.M.C.A. Castro , W.P Cacheris

1 UNIL - Université de Lausanne = University of Lausanne

Lanthanide complexes of the tetraazatetrakis(methylenephosphonate) ligand DOTP8- have been examined by spectrophotometry, potentiometry, osmometry, and 1H, 31P, and 23Na NMR spectroscopy. The LnDOTP5- complexes undergo four protonations between pH 9 and 3, and their stability constants (log KML) range from 27.6 to 29.6 across the lanthanide series. TmDOTP5- acts as a particularly good aqueous shift reagent, inducing paramagnetic shifts in 23Na nuclei of over 400 ppm. 23Na NMR titrations and osmometry measurements indicated that a single Na+ was bound to each TmDOTP5- at low Na+/TmDOTP5- ratios, while three Na+ ions were bound at high Na+/TmDOTP5- ratios.

Domaines: Sciences du Vivant [q-bio]

A. Sherry, J. Ren, J. Huskens, E. Brücher, Éva Tóth, et al.. Characterization of Lanthanide(III) DOTP Complexes: Thermodynamics, Protonation, and Coordination to Alkali Metal Ions. Inorganic Chemistry, 1996, 35 (16), pp.4604-4612. ⟨10.1021/ic9600590⟩. ⟨hal-02080958⟩