Gas Sorption Studies on a Microporous Coordination Polymer Assembled from 2D Grid Layers by Strong π–π Interactions

The microporous coordination polymer [Co(H 2 L)(bipy) 0.5 ] ⋅ 2 H 2 O ( 1 , bipy=4,4′‐bipyridine) was synthesized on the basis of the V‐shaped flexible diphosphonate ligand (2,4,6‐trimethyl‐1,3‐phenylene)bis(methylene)diphosphonic acid (H 4 L) and the auxiliary bipy ligand under hydrothermal conditions. The structure of this compound was characterized by single‐crystal X‐ray diffraction. By joining the diphosphonate ligands and bipy through tetrahedral [CoO 3 N] clusters, a 2D square grid layered network was formed. Further stacking of these layers on the basis of π–π interactions resulted in a pseudo‐3D microporous network with 1D channels running through the a axis. Gas sorption studies for CO 2 , H 2 , CH 4 , N 2 , and O 2 on this coordination polymer were performed, and the results revealed interesting dynamic and hysteresis sorption behavior toward H 2 at low temperature.