A Series of Guest-Defined Metal-Complex/Disulfonate Frameworks of Hydrogen-Bonded [Co(en)2(ox)] and 2,6-Naphtalenedisulfonate

A new series of soft-host frameworks assembled by charge-assisted hydrogen bonds between a cationic metal complex (MC) and an anionic disulfonate specifically [Co(en)2(ox)] and 2,6-naphthalenedisulfonate (NDS), is synthesized and structurally characterized. The five new compounds have a general formula (MC)2(NDS) ·n(guest) where guests are H2O, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), p-nitrophenol (pnp), and 4-dimethylaminopyridine (dmapy). All five structures are of the pillared-layer type where the layers are constructed of MC cations held together by a multitude of hydrogen bonds, both direct and indirect via sulfonate groups. The organic residues of the disulfonate serve as pillars. The structures of the layers and the orientations of the pillars adjust to the specifics of the guest molecules, and, as a result, four different patterns are observed. Compared to the recently reported analogous compounds with [Co(NH3)6], these compounds have larger interpillar galleries because of the lower charge of the complex. The same effect was observed in a similar series with [Co(en)2(ox)] complexes but linked with 4,4′biphenyldisulfonate. The factors that influence the frameworks such as the charge of the metal complex and the guest molecules are discussed.