Evaluation of structural transformation in 2D metal-organic frameworks based on a 4,4 '-sulfonyldibenzoate linker: microwave-assisted solvothermal synthesis, characterization and applications

Six 2D metal-organic frameworks containing V-shaped 4,4'-sulfonyldibenzoate (SBA) linkers, [Zn-3(SBA)(2)(OH)(2)]center dot EtOH (1 or CYCU-5 center dot EtOH), [M-3(OH)(2)(SBA)(2)(EtOH)(H2O)(3)]center dot 3.5H(2)O (2-4, M = Mg, Ni, and Co), [Mn(SBA)(EtOH)] (5) and [Mn(SBA)(H2O)] (6), have been synthesized rapidly under microwave-assisted solvothermal conditions. The structural analysis revealed that all compounds display two-dimensional structures containing inorganic motifs with one-dimensional chains (1-5) or dimers of trigonal prisms (6) connected through SBA linkers and forming 2D neutral and porous channels. Compounds 1-4 were further characterized by elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) measurements and IR spectroscopy. The desolvated phases of compounds 1-2/3-4 have thermal stabilities up to about 400/350 degrees C. The desolvated frameworks of 1-4 above 200 degrees C have similar CYCU-5-like conformations and exhibit gas adsorption properties with N-2, CO2 and H-2 gases. Interestingly, CYCU-5 displays selective adsorption of CO2 over N-2 and CH4 gases at 273 K. In addition, the catalytic ability of CYCU-5 as an initiator for ring-opening polymerization of L-lactide has also been demonstrated.