Hydrothermal syntheses, structures, and properties of four metal–organic coordination polymers assembled from V-shaped tetracarboxylate ligands and N-donor ancillary ligands

A series of four metal–organic frameworks, namely, [Cu(sdpa)0.5(2,2′-bpy)]·H2O (1), [Zn2(sdpa)(2,2′-bpy)2(H2O)2]·3H2O (2), [Zn2(sdpa)(4,4′-bpy)]·3H2O (3), [Cd2(sdpa)(4,4′-bpy)1.5(H2O)2](4), have been hydro(solvo)thermally synthesized through the reaction of 2,3,2′,3′-sulfonyldiphthalic acid (H4sdpa) with divalent copper, zinc and cadmium salts in the presence of ancillary nitrogen ligands (4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine) and structurally characterized by elemental analysis, IR and X-ray diffraction. Both complex 1 and 2 show metal–organic chain structure, and the adjacent chains are further linked by π⋯π and C–H⋯π interactions for 1 and hydrogen bonds and π⋯π interactions for 2 to form 3D supramolecular structure. In complex 3, two Zn1 and two Zn2 atoms appear alternately and are bridged by sdpa4− anion ligands to form an infinite Zn-sdpa chain. Such chains are further linked together through 4,4′-bpy ligands in four orientations to form a robust 3D metal–organic network. In compound 4, a 3D Cd-sdpa metal–organic network is accomplished through sdpa4− anion ligands, and further stabilized by 4,4′-bpy in six orientations. Their luminescence and thermal analysis have also been investigated.

Graphical abstractIn this paper, a series of four metal-organic frameworks have been hydro(solvo)thermally synthesized through the reaction of 2,3,2′,3′-sulfonyldiphthalic acid (H4sdpa) with divalent copper, zinc and cadmium salts in the presence of ancillary nitrogen ligands (4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine) and structurally characterized by elemental analysis, IR and X-ray diffraction.Figure optionsDownload full-size imageDownload as PowerPoint slide