Six uranyl-organic frameworks with naphthalene-dicarboxylic acid and bipyridyl-based spacers: syntheses, structures, and properties.

A new series of uranium coordination polymers have been hydrothermally synthesized by using 1,4-naphthalene dicarboxylic acid (HNDC), namely, (HO)[(UO)(NDC)]·HO (1), (H-bpp)[(UO)(NDC)]·EtOH·5HO (2), (H-bpe)[(UO)(NDC)]·EtOH (3), (H-bpp)[(UO)(NDC)]·5HO (4), (H-bpp)[(UO)(HNDC)(NDC)]·2HO (5), and (H-bpy)[(UO)(NDC)] (6) [bpp = 1,3-di(4-pyridyl) propane, bpe = 4,4'-vinylenedipyridine, bpy = 4,4'-bipyridine]. Single-crystal X-ray diffraction demonstrates that complex 1 represents the uranyl-organic polycatenated framework derived from a simple two-dimensional honeycomb grid network structure via a HNDC linker. Complexes 2-4 contain the dinuclear motifs of the two UO pentagonal and one UO hexagonal bipyramids which are linked by NDC anions creating a (UO)(NDC) unit, and further extend to a 2D layer through NDC anions.