Microporous La(III) Metal−Organic Framework Using a Semirigid Tricarboxylic Ligand: Synthesis, Single-Crystal to Single-Crystal Sorption Properties, and Gas Adsorption Studies

Abstract

Two La(III) coordination polymers, {[La(cpia)(2H2O)]·4H2O}n (1) and {[La(cpia)(H2O)(2DMF)}n (2) (cpiaH3 = 5-(4-carboxy-phenoxy)-isophthalic acid, DMF = N,N′-dimethylformamide), have been synthesized under hydro- and solvothermal conditions, respectively. The lattice water molecules in compound 1 could be partially replaced at RT with different solvent molecules such as ethanol, acetone, and pyridine leading to three new daughter crystals {[La(cpia)(2H2O)]·2H2O·C2H6O}n (1a), {[La(cpia)(2H2O)]·2H2O·C3H6O}n (1b), and {[La(cpia)(2H2O)]·2H2O·C5H5N}n (1c) in a single-crystal to single-crystal (SC-SC) manner. All five compounds were further characterized by IR spectroscopy, elemental analysis, X-ray powder diffraction, and thermogravimetry. Each polymer forms a carboxylate-bridged three-dimensional structure with each metal adopting LaO9 geometry. Thermogravimetric analysis (TGA) shows that compound 1 loses water molecules beginning at ∼80 °C and continues until 300 °C, and it is thermally stable up to 400 °C. A...