Self-assembly of metal-organic frameworks based on N-donor ligand and flexible tricarboxylic acids with different angular characters

Five metal-organic frameworks (MOFs), namely, [Zn-2(L-1)(BIMB)(mu(2)-OH)] (1), [Zn-3(L-1)(2)(BIMB)(3)]center dot 4H(2)O (2), [Zn(HL2)(BIMB)(0.5)]center dot H2O (3), [Zn-3(L-2)(2)(BIMB)(3)]center dot 8H(2)O (4) and [Zn-3(L-2)(2)(BIMB)(3)]center dot 4H(2)O (5) (H3L1 = 5-(3-carboxybenzyloxy) isophthalic acid, H3L2 = 5-(4-carboxybenzyloxy) isophthalic acid and BIMB = 1,4-di(1H-imidazol-1-yl) benzene), have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Complex 1 is a (3,4)-connected 3D interlocking polycatenated framework with the (6(3))(6(6)) topology by 2D parallel interpenetration. Complex 2 adopts a self-penetrating 3D (3,4)-connected network with (6.8(2))(4.6.8)(6.8(4).9)(4.6(2).8(2).10) topology, which contains rotaxane- and catenane-like motifs together. Complex 3 is a 3D supramolecular structure formed by hydrogen bonds between adjacent 2D (4,4) sheets. For complex 4, it shows a three-folded 3D framework by a (3,4)-connected net with (6(2).8)(4.6.8)(6(3).7.8.9)(4.6(2).7(2).8)(6(2).7(2).9(2)) topology. Complex 5 is a (3,4)-connected 3D framework. We have discussed the influence of synthetic conditions and different carboxylate ligands on the final structures. In addition, powder X-ray diffraction and photoluminescent properties for 1-5 have been studied in detail at room temperature.