Synthesis, crystal structures and luminescence properties of lanthanide complexes with a tridentate salicylamide-type ligand

Six lanthanide nitrato complexes [Ln = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Er (6)] with a tridentate salicylamide-type ligand, 2-(2-(diisopropylamino)-2-oxoethoxy)-N-(pyridin-2-ylmethyl)benzamide (L), have been synthesized. All complexes were characterized by elemental analysis, IR, TGA and conductivity measurements. The structures of 2, 3 and 4 were determined by X-ray single-crystal diffraction and their general formulae were shown to be [LnL(NO3)3(H2O)]·CH3CN. These data indicate the tridentate salicylamide-type ligand could effectively chelate the lanthanide ions to conform to a 1:1 metal-to-ligand stoichiometry. The luminescence properties of the europium and terbium complexes were also investigated.