Sodium ion association via bridging water molecules for different charged p-phosphonated calix[4]arene bilayers

Cone conformation p-phosphonatocalix[4]arene forms bilayer and columnar arrays with sodium ions clustering above the calixarene cavity involving bridging water molecules, and a molecular 'glue' of either DMF or carbonate ion. The DMF has a methyl group directed into the cavity of the calixarene which takes on a 5-charge, whereas in the carbonate-containing structure the calixarene takes on an 8-charge, with a hydroxyl group coordinated to sodium directed into the cavity. The nature of the interactions in both structures has been probed using Hirshfeld surface analysis.