Fabrication of a Robust Lanthanide Metal–Organic Framework as a Multifunctional Material for Fe(III) Detection, CO₂ Capture, and Utilization

By employing a tricarboxylate ligand 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid (H3L), four lanthanide metal–organic frameworks (Ln-MOFs) formulated as {[LnL(H2O)2]·H2O}n (Ln = Eu, 1; Gd, 2; Tb, 3; Dy, 4) have been prepared under hydrothermal conditions. Single-crystal X-ray analyses reveal that compounds 1–4 are isomorphous and exhibit a three-dimensional network structure featuring a one-dimensional rectangular channel with a size of ca. 7.8 Å × 12.1 Å along the b axis. The framework shows strong stabilities toward high temperature, humid air, water, as well as acid/base environments. Efficient ligand-sensitized characteristic luminescence can be observed in the visible region for Eu- and Tb-based compounds. Detailed property investigation shows that TbL is a promising multifunctional material, which can quantitatively detect Fe(III) ions in the solution mixtures of Fe(II)/Fe(III), selectively adsorb CO2 over CH4, and be applied as catalysts in cyclization reaction with epoxides and CO2.