Topological Difference in 2D Layers Steers the Formation of Rigid and Flexible 3D Supramolecular Isomers: Impact on the Adsorption Properties

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)]·3H2O} (1) and {[Cu­(bipy)0.5(pyrdc)]·0.5bipy·3H2O} (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.