Syntheses, structures and photoluminescent properties of lanthanide coordination polymers based on pyridyl functionalized imidazole dicarboxylic acid

Abstract

A series of lanthanide coordination polymers formulated as {[Ln₂(HPIDC)₂(H₂O)₈]·2(H₂PIDC)·18H₂O}_n [Ln = Sm (1), Eu (2)], {[Dy₂(HPIDC)₂(H₂O)₉]·2(H₂PIDC)·17H₂O}_n (3), {[Dy₃(HPIDC)₄(H₂O)₈]·(NO₃)·6H₂O}_n (4), {[Dy₂(HPIDC)₂(bdc)(H₂O)₄]·8H₂O}_n (5), {[Ln(HPIDC)(bdc)]·H₃O⁺·H₂O}_n [Ln = Er (6), Tm (7), Yb (8)] (H₃PIDC = 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid, H₂bdc = 1,4-benzenedicarboxylic acid) based on pyridyl functionalized imidazole dicarboxylic acid ligand have been synthesized by hydrothermal methods and characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis and thermogravimetric analysis. Compounds 1–3 are one-dimensional (1D) cationic chains linked by the H₃PIDC ligands, and the free H₂PIDC⁻ act as counter ions in the crystal lattice. Compound 4 displays a 2D layer built up from 3-connected HPIDC²⁻ ligands and 4-connected Dy(III) ions. While compounds 5–8 possess 2D network constructed from HPIDC²⁻ and bdc²⁻ ligands. The solid-state photoluminescent measurements show the photoluminescence of 1–5 are typical narrow emission bands of their lanthanide cations.