Syntheses, topologies, and luminescence of four Ln-organic polymers constructed from aromatic tetracarboxylic acids

Four new coordination polymers (CPs), {[H2N(CH3)(2)](2)[Ln(2)(BPT)(ox)(2)]}(n) (Ln = Er for 1, Yb for 2, and Sm for 3; H(2)ox = oxalic acid) and {[Gd(HDCP)(H2O)]center dot H2O}(n) (4), have been constructed from Ln ions and two aromatic tetracarboxylate acids (H4BPT = 3,3',5,5'-biphenyltetracarboxylic acid, H4DPT = 4,5-di(4'-carboxylphenyl)phthalic acid) under solvothermal reactions through the linker extension strategy. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Complexes 1-3 are isomorphous and exhibit an unprecedented (6,8)-connected 3D architecture with a point symbol of (3(3).4(10).5(7).6(2).7(6))(3(3).4(6).5(6))(2), which is built up from right- and left-handed [Ln(ox)](n) helixes. Complex 4 shows a 3D (4,8)-connected flu net with (4(12).6(12).8(4))(4(6))(2) topology based on 1D [Gd(COO)(2)](n) ladder chains. Moreover, their luminescence properties have been investigated.