Study of the Luminescent and Magnetic Properties of a Series of Heterodinuclear [Zn^IILn^III] Complexes

Herein, we report the synthesis, structural investigation, and magnetic and photophysical properties of a series of 13 [Zn^IILn^III] heterodinuclear complexes, which have been obtained employing a Schiff-base compartmental ligand derived from o-vanillin [H₂valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol)]. The complexes have been synthesized starting from the [Zn(valpn)(H₂O)] mononuclear compound and the corresponding lanthanide nitrates. The crystallographic investigation indicated two structural types: the first one, [Zn(H₂O)(valpn)Ln^III(O₂NO)₃], contains 10-coordinated Ln^III ions, while in the second one, [Zn(ONO₂)(valpn)Ln^III(H₂O)(O₂NO)₂]·2H₂O, the rare earth ions are nine-coordinated. The Zn^II ions always display a square-pyramidal geometry. The first structural type encompasses the larger Ln ions (4f⁰–4f⁹), while the second is found for the smaller ions (4f⁸–4f¹¹). The dysprosium derivative crystallizes in both forms. Luminescence studies for the heterodinuclear compounds containing Nd^III, Sm^III, Tb^III, Dy^III, and Yb^III revealed that the [Zn(valpn)(H₂O)] moiety acts as an antenna. The magnetic properties for the paramagnetic [Zn^IILn^III] complexes have been investigated.