Self-assembly of 1D, 2D, and 3D lanthanide-metal coordination polymers based on a 2-(pyridin-4-yl)-4,5-imidazoledicarboxylate linker: Synthesis, structures, and luminescence

摘要

Three series of novel lanthanide-based 1D, 2D, and 3D metallic coordination frameworks involving the 2-pyridin-4-yl-4,5-imidazoledicarboxylic acid (H _3PIDC) ligand have been characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. The compound [Tb(PIDC)(H _2O) _4]·H _3PIDC·4H _2O (1) upon slow evaporation at room temperature gave a 1D coordination chain framework constructed of [Tb _2O _2] dimers bridged through the carboxylate groups of PIDC _3- ligands; a 3D supramolecular structure is generated through hydrogen bonding and π-π interactions. The second kind of lanthanide-based coordination framework, namely [Ln(H _2PIDC)(ox)H _2O] ·3H _2O [Ln = Sm (2), Gd (3), Dy (4), and Ho (5), ox = oxalic acid], synthesized under hydrothermal conditions, self-assemble through Ln _2[H _2PIDC] _2 building blocks and bridging oxalate ligands to give a 2D coordination layer structure. The adjacent layers stack to form a 3D supramolecular framework through weak interactions such as hydrogen bonding and π-π interactions. The third series of lanthanide-based coordination compounds with chemical formula [Ln(HPIDC)(ox) 1/2H _2O]·3H _2O [Ln = Gd (6), Dy (7), Tb (8) and Ho (9)] were also synthesized by hydrothermal reaction. These isostructural compounds contain an infinite -Ln-O-C-O-Ln- zigzag chain, which connect to each other through the oxygen atoms of the HPIDC ~(2-) ligands to form a wave-like layer. The layers are bridged by oxalate ligands to generate a 3D coordination framework.