Structure-based description of a step-by-step synthesis of heterodinuclear ZnIILnIII complexes and their luminescence properties

• We present the stepwise synthesis of ZnII–LnIII heterodinuclear complexes.
• [LnIIIL(NO3)3] and [LLnIIIZnII(NO3)5(H2O)] have been structurally characterized.
• The sensitized lanthanide luminescence can be enhanced when ZnII ion is incorporated.

The stepwise course of the synthesis of ZnIILnIII complexes of a new compartmental heptadentate open amide crown ether ligand has been investigated through the determination of the intermediate and final products occurring in the process. In the first step, the ligand L is reacted with Ln(NO3)3·5H2O to give the electroneutral complex [LnIIIL(NO3)3] with the lanthanide ion being linked to the N3O2 coordination site of the ligand which are fairly stable and could be isolated. Addition of Zn(NO3)3·6H2O to the [LnIIIL(NO3)3] complexes yield the desired heterodinuclear [ZnIILnIIIL(NO3)5(H2O)] complexes. In all [ZnIILnIIIL(NO3)5(H2O)] complexes, the ZnII ions invariably occupy the N3O2 site whereas the LnIII ions show preference for the carbonyl O site. Additionally, the solid-state photophysical properties of these complexes show that the sensitized EuIII- and TbIII-based luminescence can be enhanced after ZnII ion is incorporated.

Stepwise course of the synthesis of ZnII–LnIII complexes with a new amide open crown ether ligand has been investigated through the determination of the intermediate and final products occurring in the process. The photoluminescent analyses show that the ligand to lanthanide energy transfer process is more effective in TbIII than that of EuIII, and the sensitized EuIII- and TbIII-based luminescence can be enhanced when ZnII ion is incorporated.Figure optionsDownload as PowerPoint slide