X-ray crystallographic, luminescence and NMR studies of phenacyldiphenylphosphine oxide with the Ln(iii) ions Sm, Eu, Gd, Tb and Dy

Abstract

We report here the characterization in solution (NMR, luminescence, MS) and the solid-state (X-ray crystallography, IR) of complexes between phenacyldiphenylphosphine oxide and five Ln(III) ions (Sm, Eu, Gd, Tb, Dy). Four single crystal X-ray structures are described here showing a 1 : 2 ratio between the Ln³⁺ ions Eu, Dy, Sm and Gd and the ligand, where the phosphine oxide ligands are bound in a monodentate manner to the metal center. A fifth structure is reported for the 1 : 2 Eu(NO₃)₃-ligand complex showing bidentate binding between the two ligands and the metal center. The solution coordination chemistry of these metal complexes was probed by ¹H, ¹³C and ³¹P NMR, mass spectrometry, and luminescence experiments. The title ligand has the capability to sensitize Tb³⁺, Dy³⁺, Eu³⁺ and Sm³⁺ leading to metal-centered emission in solutions of acetonitrile and methanol and in the solid state.