Chain, Pillar, Layer, and Different Pores: AN-[(3-Carboxyphenyl)-sulfonyl]glycine Ligand as a Versatile Building Block for the Construction of Coordination Polymers

Five novel coordination polymers containing N -[(3-carboxyphenyl)-sulfonyl]glycine (H 3 L), namely [Co 3 L 2 (μ 2 -bipy) 2 (H 2 O) 6 ] n ·2 n CH 3 OH·8 n H 2 O ( 1 ), [Mn(HL)(μ 2 -bipy)(H 2 O) 2 ] n · n H 2 O ( 2 ), [Mn(HL)(μ 2 -bipy)(H 2 O)] n ·3 n H 2 O ( 3 ), [Mn(HL)(bipy)(μ 2 -bipy) 0.5 (H 2 O)] n ·4 n H 2 O ( 4 ), [Ca(H 2 O) 4 Cu 2 (μ 2 -bipy) 2 L 2 ] n ·4 n H 2 O ( 5 ) (bipy = 4,4′-bipyridine), were prepared under control by tuning the 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(H 2 O)] 2 2− binuclear and [Co(4,4′-bipy) 2 (H 2 O) 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 HL 2− 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, HL 2− ligands link the metal ions to form 2D wavelike rectangle-grid layers which are held together through μ 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 H 3 L is a versatile building block for the construction of metal organic frameworks (MOFs).