Figure 5
Left, the idealized structure of Zn oxalate honeycomb framework; center, accessible region (in red) for a large molecular cation like piperazinium [C 4 H 12 N 2 2+ ]; right, the accessible region for potassium cation (K + ). The blue regions highlight the destabilization, mainly due to short-range repulsion when the cation center of mass is in that site.