A series of dinuclear lanthanide(iii) complexes constructed from Schiff base and β-diketonate ligands: synthesis, structure, luminescence and SMM behavior

Abstract

A series of new isostructural lanthanide(III) complexes are reported which are constructed from Schiff base and β-diketonate ligands, namely, [Ln₂(DBM)₆(L)] (Ln = Sm (1), Eu (2), Gd (3), Dy (4), Yb (5); L = N,N′-bis(pyridin-2-ylmethylene)ethane-1,2-diamine, DBM = dibenzoylmethanide). The structures of the isomorphous complexes 1–5 were determined by single-crystal X-ray crystallography. The two Ln(III) ions in the molecules of 1–5 are bridged by a Schiff base ligand that displays a curved configuration. Complexes 1, 2 and 5 exhibit lanthanide ion-based luminescence not only in the solid state but also in methanol solution. The lifetimes and quantum yields of luminescence were also determined. The magnetic analysis reveals that complexes 4 and 5 exhibit field-induced single-molecule magnet behavior with energy barriers (U_eff/k_B) of 46.8 and 23.0 K at direct current fields of 2000 Oe, respectively.