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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 1can be dehydrated/rehydrated with retention of crystallinity. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title complex, [Cu(bda)(bipy)2]·4H2O [H2bda = ( p-phenyl­ene­dioxy)­di­acetic acid or benzene-1,4-dioxy­acetic acid (C10H10O6) and bipy = 2,2′-bi­pyridine (C10H8N2)], the CuII centre is pentacoordinated, with a square-pyramidal geometry comprising four N atoms from two chelating bipy ligands and one carboxyl­ate O atom of the bda ligand. The other three uncoordinated carboxyl­ate O atoms of the bda ligand act as the acceptors of four O—H⋯O hydrogen bonds from the water molecules, among which another four O—H⋯O hydrogen-bonding interactions are also observed, resulting in a two-dimensional supramolecular pattern. [ABSTRACT FROM AUTHOR]

Co-crystallization of hemimellitic acid (benzene-1,2,3-tricarboxylic acid) dihydrate (H3HMA·2H2O) with 4,4′-bipyridine (4,4′-bpy) affords the 1:1 co-crystal benzene-1,2,3-tricarboxylic acid–4,4′-bipyridine (1/1), H3HMA·4,4′-bpy or C9H6O6·C10H8N2. Strong O—H⋯O hydrogen bonds connect the acid mol­ecules to form a one-dimensional zigzag chain, around which the 4,4′-bpy components are fixed as arms via O—H⋯N inter­actions, resulting in a ladder motif. Through weak C—H⋯O non-covalent forces, the resulting acid layers are extended into a three-dimensional pillar-layered architecture supported by rod-like 4,4′-bpy components. The influence on hydrogen-bonding models is also discussed, with the discovery of an unexpected inter­action motif that does not follow the routine hydrogen-bonded hierarchical rule in the construction of an acid–base co-crystal. [ABSTRACT FROM AUTHOR]