Multi-Component Hydrogen-Bonding Assembly of a Pharmaceutical Agent Pamoic Acid with Piperazine or 4,4′-Bipyridyl: A Channel Hydrated Salt with Multiple-Helical Motifs vs a Bimolecular Cocrystal

Assembly of pamoic acid (H2PA) with piperazine (PIPO) or 4,4′-bipyridyl (BIPY) results in two distinct supramolecular complexes [(PA)·(H2PIPO)]·3H2O (1) and [(H2PA)·(BIPY)] (2). The former displays triple-helix host arrays via charge-assisted N+−H···O− interactions with the inclusion of helical water chains, whereas the latter represents the first cocrystal of pamoic acid sustaining by the familiar carboxyl-pyridyl H-bonding synthons. Notably, the structure of 1 can be dehydrated/rehydrated with retention of crystallinity.