Construction of three lanthanide organic frameworks with (3,5)-connected topology based on 2-methyl-4,5-imidazoledicarboxylate and oxalate

Three novel 3D lanthanide organic frameworks [Ln2(H2O)3(HMImDC)2(OX)]·4H2O (Ln = Sm(1), Eu(2) and Gd(3), H3MImDC = 2-methyl-4,5-imidazoledicarboxylic acid, OX = oxalic acid) have been solvothermally synthesized and structurally characterized by elemental analyses, Infrared spectra (IR), thermogravimetric analyses (TGA), powder X-ray diffractions (PXRD), and single-crystal X-ray diffractions. Compounds 1–3 are isostructural and exhibit novel 3D architectures with open channels viewed along the a axis, which constructed from [Ln(HMImDC)(OX)] layers and Ln2(HMImDC)2 dimers. The framework of 1–3 can be rationalized as a (3, 5)-connected net with a unique (4.5.7)2(5.6.7)(52.63.7.83.10) topology. The luminescence and magnetic properties are also investigated.

Graphical abstractStructural views of the three three-dimensional coordination polymers [Ln2(H2O)3(HMImDC)2(OX)]·4H2O (Ln = Sm(1), Eu(2) and Gd(3)). In the structure, the lanthanide ions coordinate with 2-methyl-4,5-imidazoledicarboxylate and oxalic acid mixed ligands to give a 2D layer, which is further connected by the Ln2(HMImDC)2 dimers to construct 3D frameworks with (3,5)-connected network.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Lanthanide organic frameworks based on 2-methyl-4,5-imidazoledicarboxylate and oxalic acid mixed ligands. ► Compounds 1–3 have (3, 5)-connected networks. ► Compound 2 exhibits strong red luminescence emission. ► Compound 3 shows weak antiferromagnetic interactions.