Synthesis, structures and luminescent properties of new heterobimetallic Zn-4f Schiff base complexes

A series of new 3d–4f heterobimetallic Schiff base complexes of the general formula [Zn(μ-L2)Ln(NO3)3(H2O)n] (Ln = La 1, Nd 2, Gd 3, Er 4 and Yb 5; n = 1 or 2; H2L2 = N,N′-bis(3-methoxy-5-p-tolylsalicylidene)ethylene-1,2-diamine) are synthesized and characterized. Complexes 1, 2, 4 and 5 are structurally characterized by X-ray crystallography. The photophysical properties of these complexes are also investigated. At room temperature, complexes 1–5 exhibit similar solution absorption and emission spectra in the UV–Vis region. Furthermore, compounds 2, 4 and 5 exhibit solution emission corresponding to the lanthanide(III) ion in the near-infrared region at room temperature. The triplet state emission of the 3d–4f bimetallic complexes without energy transfer is also determined through the photophysical study of complex 3.