Chain, pillar, layer, and different pores:: A N-[(3-carboxyphenyl)-sulfonyllglycine ligand as a versatile building block for the construction of coordination polymers

Five novel coordination polymers containing N-[(3-carboxyphenyl)-sulfonyl]glycine (H3L), namely [Co3L2(mu(2-)bipy)(2)(H2O)(6)](n)center dot 2nCH(3)OH center dot 8nH(2)O (1), [Mn(HL)(mu(2)-bipy)(H2O)(2)](n) center dot nH(2)O (2), [Mn(HL)(mu(2)-bipy)(H2O)](n)center dot 3nH(2)O (3), [Mn(HL)(bipy)(mu(2)- bipy)(0.5)(H2O)](n)center dot 4nH(2)O (4) [Ca(H2O)(4)Cu-2(mu(2)-bipy)(2)L-2]n center dot 4nH(2)O (5) (bipy = 4,4'-bipyridine), were prepared under control by tuning reaction conditions such as pH value, reaction temperature, and starting materials. X-ray structural analyses of 1-5 reveal their structural diversity ranging from one-dimensional (1D) (1), two-dimensional (2D) (2), and noninterpenetrating 3-D porous coordination polymers (3, 4) to a 2-fold 3D interpenetrating network (5). Compound 1 presents a 1D chain structure with alternating [CoL(H2O)](2)(2-) binuclear and [Co(4,4'-bipy)(2)(H2O)(4)](2+) mononuclear units along the a-axis. Polymer 2, which was formed at a comparatively lower temperature, has a 2D structure extended by a HL2- ligand and a monopillar of bipy, A higher temperature was used in the preparation of 3 and 4. In addition, 3 was synthesized also at a higher pH value. In 3, HL2- ligands link the metal ions to form 2D wavelike rectangle-grid layers which are held together through mu(2)-bipy molecules in a double-pillar supporting fashion to give a 3D porous framework. A decrease of the pH value led to the formation of another 3D porous framework 4, in which each Mn center binds two trans-located bipy molecules. One bipy behaves as a terminal ligand, while the other one acts as a bridging ligand extending the 2D layers into a unique 3D porous framework. When calcium hydroxide was used, it led to the construction of a 2-fold 3D interpenetrating network of 5 where the Cu atoms are joined by bipy ligands to generate a 1D zigzag chain. The thermogravimetric (TG) and powder X-ray diffraction (PXRD) measurements reveal that both 3 and 4 are stable after dehydration. All of these suggest that the ligand of H3L is a versatile building block for the construction of metal organic frameworks (MOFs).