Nickel(II)-lanthanide(III) complexes of the dinucleating ligand N,N'-bis(3-hydroxysalicylidene)ethylenediamine

Heteronuclear nickel(II)-lanthanide(III) complexes, NiLn(dhbaen)(NO₃)(H₂O)₂ (Ln = La, Eu or Gd), and a mononuclear Eu(III) complex, Eu(Hdhbaen)(H₂O)₃, were synthesized, where H₄dhbaen denotes N,N′-bis(3-hydroxysalicylidene) ethylenediamine. IR spectra shows that Ni(II) and Ln(III) ions are located at the endogenous N₂O₂- and exogenous O₄-coordination sites of ligand, respectively. Based on CD spectra, it was concluded that amino alcohols are specifically bound at the Ni(II)-Ln(III) heterometal centre, through the nitrogen to the Ni-site and through the oxygen to the Ln-site. The fluorescence intensity of the mononuclear Eu(III) complex is much greater than that of the heteronuclear Ni(II)-Eu(III) complex.