A series of 2D lanthanide (III) coordination polymers constructed from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate

Reactions of 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid (H3PyIDC) with a series of Ln(III) ions affords ten coordination polymers, namely, {[Ln(H2PyIDC)(HPyIDC)(H2O)2]·H2O}n [Ln=Nd (1), Sm (2), Eu (3) and Gd (4)], {[Ln(HPyIDC)(H2O)3]·(H2PyIDC)·H2O}n [Ln=Gd (5), Tb (6), Dy (7), Ho (8) and Er (9)], and {[Y2(HPyIDC)2(H2O)5]·(bpy)·(NO3)2·3H2O}n (10) (bpy=4,4′-bipyridine). They exhibit three types of networks: complexes 1–4 are isomorphous coordination networks containing neutral 2D metal-organic layers, while complexes 5–9 are isomorphous, which consist of cationic metal-organic layers and anionic organic layers, and complex 10 is a 2D network built up from 4-connected HPyIDC2− anion and 4-connected Y(III) ions. In addition, thermogravimetric analyses and solid-state luminescent properties of the selected complexes are investigated. They exhibit intense, characteristic emissions in the visible region at room temperature.

Structure variation of ten Ln(III) complexes is attributed to the lanthanide contraction effect and various coordination modes of H3PyIDC ligands. Moreover, photoluminescent properties and thermal behaviors of selected complexes were investigated.Figure optionsDownload as PowerPoint slideHighlights
► A series of 2D Ln(III) coordination polymers based on H3PyIDC were firstly obtained.
► The structural variation is partly attributed to the lanthanide contraction effect.
► Diverse coordination modes of H3PyIDC ligands are observed.
► The Gd(III) complexes with different structures controlled by different synthesis methods.