Luminescence Study on the Inner‐Sphere Hydration Number of Lanthanide(III) Ions in Neutral Organo‐Phosphorus Complexes

Abstract

Time‐resolved laser‐induced fluorescence spectroscopy (TRLFS) was employed to determine the inner‐sphere (i.e., first coordination sphere) hydration number (N _H2O) of lanthanide(III) ions (Ln = Sm, Eu, Tb, and Dy) in the TRPO‐dodecane/HNO₃ (or HNO₃–NaNO₃) system under various conditions. In addition, the N _H2O of Ln(III) in extracted complexes with octyl(phenyl)‐N,N‐diisobutylcarbamoylmethyl phosphine oxide (CMPO), dihexyl‐N,N‐diethylcarbamoylmethyl phosphonate (CMP), trioctyl phosphine oxide (TOPO), and tributyl phosphate (TBP) were also determined. The results show that there is no water molecule in the first coordination sphere of Ln(III) complexes, except for Sm(III) and Dy(III) in CMP complexes.

Keywords:

• Hydration
• Coordination sphere
• TRPO complexes