The construction of metal-organic frameworks based on 2-(1-hydroxy-ethyl)-3H-benzoimidazole-5-carboxylic acid

Abstract

Presented here are two novel metal-organic frameworks (MOFs) synthesized by employing a trifunctional imidazolate derivative, 2-(1-hydroxy-ethyl)-3H-benzoimidazole-5-carboxylic acid (H₂ebimc) as a ligand. In compound 1, the Zn atoms and ebimc²⁻ ligands were crosslinked to build a wavelike two-dimensional (2D) layer with 3-connected (4.8²) topology, with water molecules as terminal ligands coordinated on both sides of the layers. Then, the D-(+)-camphoric acid (H₂cam) ligand was introduced into the synthesis system to obtain compound 2. In compound 2, similar topological layers were formed based on Zn₂(CO₂)₃ subunits (SBUs) and then were further pillared by cam²⁻ ligands to construct the final three-dimensional (3D) pillar-layered framework. Moreover, compound 2 exhibited high selectivity of CO₂ over N₂ and CH₄, along with a distinctive framework flexibility triggered by C₂H₆. Our results highlight the great potential of H₂ebimc as a multifunctional ligand for synthesizing MOFs.