Alkali/alkaline earth metal and solvents-regulated construction of novel heterometallic coordination polymers based on a semirigid ligand and tetranuclear metal clusters

•Five novel coordination polymers based on a new semirigid multicarboxylate ligand.•These compounds display five different heterometallic tetranuclear Zn2M2 units.•It exhibits strong yellow luminescence at room temperature.

Five novel three-dimensional (3D) heterometallic coordination polymers, [ZnCa(dcppa)(DMF)2]n (1), [ZnCa(dcppa)(DMA)2]n (2), [ZnBa(dcppa)(DMF)2]n (3), [ZnBa(dcppa)(DMA)2]n (4), and [ZnNa(dcppa)(DMF)]n·n(Me2NH2)·n(H2O)2 (5) (Me2NH2+ = dimethylammonium cation; DMA = N,N-dimethylacetamide; DMF = N,N-dimethylformamide; H4dcppa = 3-(3′,5′-dicarboxylphenoxy) phthalic acid), have been hydrothermally synthesized and structurally characterized with the aid of single-crystal X-ray diffraction. Complexes 1–5 are heterometallic Zn/M (M = Ca, Ba, Na) coordination polymers constructed from a semirigid H4dcppa ligand and tetranuclear metal clusters. Topological analyses show that 1/3/4 and 2/5 exhibit complicated 3D framework that could be simplified into binodal (3,6)-connected rtl nets and binodal (3,6)-connected flu nets, respectively. Unlike 1–4, 5 features a unique 3D anionic framework with Me2NH2+ cations occupying the voids. From the viewpoint of crystal structure diversity and comparison, our results further prove that the coordination modes of metal ions and ligands play indispensable roles in the construction of the final crystal structure. Moreover, the thermal stability and solid-state luminescence properties of 1–5 have also been investigated at room temperature.

Graphical abstractPresented here are a series of bimetallic Zn/M (Ca, Ba, Na) MOFs based on a semirigid multicarboxylate ligand and tetranuclear metal clusters. Of particular interest is that the five compounds are 3D frameworks with (3,6)-connected rtl/flu topologies.Figure optionsDownload full-size imageDownload as PowerPoint slide