Hydrothermal syntheses, structures and luminescent properties of Zn(II) coordination polymers assembled with benzene-1,2,3-tricarboxylic acid involving in situ ligand reactions

Five Zn(II) coordination polymers, [Zn(1,2,3-Hbtc)(1,4-bix)]center dot 0.5(1,4-bix)center dot H2O (1), [Zn(mocip)(1,4-bix)] (2), [Zn-3(1,2,3-btc)(2)(4,4'-bpy)(2)(H2O)(2)](2)center dot 7H(2)O (3), [Zn-3(1,2,3-btc)(2)(bbi)(3)](2)center dot 3H(2)O (4) and [Zn(dmcaip)(1,3-bix)]center dot DMF (5), were prepared by hydro(solvo)thermal reactions of ZnO with 1,2,3-H(3)btc (1,2,3-H(3)btc = 1,2,3-benzenetricarboxylic acid) in the presence of different N-donor ligands (1,4-bix 1,4-bis(imidazol-1-ylmethyl)benzene, 4,4'-bpy = 4,4'-bipyridine, bbi = 1,1'-(1,4-butanediyl) bis(imidazole), 1,3-bix = 1,3-bis(imidazol-1-ylmethyl)benzene, H(2)mocip = 2-(methoxycabonyl)isophthalic acid and H(2)dmcaip = 2-(dimethylcarbamoyl)isophthalic acid). Their crystal structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses and IR spectra. Complex 1 has a one-dimensional (1D) infinite tubular structure, whereas 2 exhibits two-dimensional (2D) supramolecular networks assembled from 1D chains and 1,4-bix. The three-dimensional (3D) framework of 3 can be described as a trinodal 4-connected (4(2).6(4))(2)(6(5).8)(4(2).6(4))(2) topology, which consists of 2D [Zn-3(1,2,3-btc)(2)] layers and 4,4'-bpy pillars. Complex 4 features a 5-nodal (3,4)-connected 3D coordination net with a (6.7(4).8)(2)(6(2).7(2).8(2))(6.7(2))(2) topology. Complex 5 has a rare 1D double meso-helical supramolecular structure. Interestingly, in the complexes 2 and 5, the starting 1,2,3-H(3)btc reagents are converted into new ligands (mocip(2-) in 2 and dmcaip(2-) in 5) under solvothermal conditions via in situ ligand reactions. Moreover, thermal stabilities, X-ray powder diffraction and the fluorescent properties of complexes 1-5 have been investigated.