Construction of d-f heteronuclear complexes with open-chain ether Schiff base ligand: Regulation effects of Zn(II) and Cd(II) on structures and luminescence properties

Abstract

Two series of heteronuclear Zn-Ln and Cd-Ln complexes with open-chain ether Schiff base ligand (bis(5-bromine-3-methoxysalicylidene)-3-oxapentane- 1,5-diamine (H2L) and isonicotinate (IN), with composition [Zn2LnL2(OAc)(IN)](NO3)·x(CH3OH)·y(CH2Cl2) (1 Ln = Sm, x = 1, y = 0; 2 Ln = Tb, x = 0, y = 2) and {[CdLnL(IN)(OAc)(NO3)(CH3OH)]·3(CH2Cl2)}n (3 Ln = Sm; 4 Ln = Tb), have been synthesized by interfacial diffusion methods and further performed structural characterization. The structure analysis revealed that two Zn-Ln complexes are heterotrinuclear clusters and lanthanide metal ion acts as a joint bridging of two ZnL coordination units, whereas two Cd-Ln complexes are infinite one dimensional zigzag coordination polymers formed by CdLnL secondary units through asymmetric coordination bridging isonicotinate. Luminescence properties of 1–4 in the solid state and N, N-dimethylformamide (DMF) solution at room temperature were also studied. It has been found that the Sm3+ complexes 1 and 3 exhibit corresponding Sm3+ ion characteristic emission in the solid state, but the L2− ligand can’t sensitize the Tb3+ ion in complexes 2 and 4. Finally, the structures and luminescence properties of d-f heteronuclear complexes can be adjusted by selecting different transition metals such as zinc and cadmium.