.Starting with the same precursors, pyridine-2,3-dicarboxylate (pyrdc) and 4,4'-bipyridyl (bipy), two 3D porous coordination polymers, ([Cu(bipy)(0.5)(pyrdc)]center dot 3H(2)O} (1) and ([Cu(bipy)(0.5)(pyrdc)].0.5bipy center dot 3H(2)O} (2), have been synthesized by changing the solvent system from MeOH/H2O to EtOH/H2O. Single-crystal structure analysis revealed that 1 and 2 are supramolecular isomers with 3D pillared-layer structures having 1D channel systems. Isomer 1 has a flexible structure and shows gated adsorption behavior, while framework 2 has a rigid backbone and exhibits the adsorption properties of typical microporous materials.