Single-Crystal-to-Single-Crystal Transformation of a Novel 2-Fold Interpenetrated Cadmium-Organic Framework with Trimesate and 1,2-Bis(4-pyridyl)ethane into the Thermally Desolvated Form Which Exhibits Liquid and Gas Sorption Properties

A novel 2-fold interpenetrated, pillared, cadmium metal–organic framework, namely, [Cd(HBTC)BPE] n · n DMF, has been synthesized using 1,3,5-benzenetricarboxylic acid and 1,2-bis(4-pyridyl)ethane (BPE). This compound has been desolvated and subjected to various liquids and gases for sorption studies. Structures of the as-synthesized ( 1 ), desolvated ( 2 ), and resolvated in benzene ( 3 ) have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric/differential scanning calorimetry analysis. Single crystal X-ray analysis revealed a 2-fold interpenetrated, three-dimensional (3D) framework which exhibits a 3,5-connected network with the Schläfli symbol of [(6 3 )(6 9 .8) and hms topology. Compound 1 exhibits a temperature-induced single-crystal-to-single-crystal (SC–SC) transformation upon the release of N, N ′-dimethylformamide molecules forming compound 2 (stable up to 300 °C). SC–SC transformation is also observed when it is immersed in benzene, chloroform, 1,4-dioxane, and tetrahydrofuran. The uptake of different solvent molecules was analyzed, and desolvated samples selectively adsorb benzene, chloroform, 1,4-dioxane, and THF molecules over other selected polar solvents. Gas (N 2, CO 2, and N 2 O) sorption experiments were also performed and the structure showed 2.5% N 2, 4.5% CO 2, and 3.4% N 2 O absorption by mass at room temperature and moderate gas pressures (∼10 bar).