X-ray crystallographic, luminescence and NMR studies of phenacyldiphenylphosphine oxide with the Ln(<scp>iii</scp>) 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.