Syntheses and Structures of Three Cobalt Metal-Organic Frameworks with 3-(Sulfonyl-glycine)benzoic Acid

Three new coordination networks based on a versatile and unsymmetric building block 3-(sulfonyl-glycine)benzoic acid (H3L) ligand and inorganic Co(II) salt, [Co(HL)(bipy)(2)]center dot ClO4 center dot 1.5H(2)O (1), [Co-3(L)(2)(H2O)(6)]center dot 4H(2)O (2) and [Co(HL)(bpp)(H2O)(2)]center dot 2H(2)O (3) (bipy = 2,2-bipyridine, bpp = 1,3-bi(4-pyridyl)propane), have been synthesized in aqueous media and structurally characterized by single-crystal X-ray diffraction. Reaction of Co salt with H3L afforded a neutral 1D alternating chain, which shows a 3-D supramolecular network through hydrogen bonds. When the auxiliary 2,2-bipyridine is used, a mononuclear unit is constructed; if using auxiliary ligand bpp, a neutral 1-D uniform chain is obtained and further extended into a 3-D supramolecular structure through versatile hydrogen bonds. The H3L ligand in 1 adopts a bidentate chelating coordination mode while that in 2 and 3 assumes a pentadentate bridging and a bis-monodentate bridging modes, respectively. This work and our previous work evidently demonstrate that the structures vary with altering the second ligands.