Syntheses, structures and sorption properties of two framework-isomeric porous copper-coordination polymers

Solvothermal and solution reactions of a V-shaped organic ligand 4,4'-oxybis( benzoic acid) (H(2)oba) and Cu(NO3)(2) yield two porous coordination polymers, namely [Cu(oba)(dmso)] (MCF-21) and [Cu-2(oba)(2)(dmf)(C2H5OH)]center dot(dmf)(2)(H2O)(MCF-22 guest) (dmso = dimethyl sulfoxide, dmf dimethylformamide), respectively. Single-crystal X-ray analyses reveal that the metal carboxylate backbones of MCF-21 and MCF-22 center dot guest are framework-isomeric as two uninodal four-connected nets, i.e. a two-dimensional ( 2-D) 4(4) layer and a 3-fold interpenetrated 1vt (4(2)8(4)) three-dimensional ( 3- D) network, respectively. After removing the solvent molecules, MCF-21 retains a rigid 2-D framework, but MCF-22 center dot guest exhibits either rigid or dynamic behavior depending on the degree of desolvation, which is confirmed by powder X-ray diffraction and sorption isotherms. Meanwhile, the different sorption behavior of the framework-isomeric materials is elucidated by the discrepancies of their pore dimensions and framework rigidities.