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

Abstract

Four new coordination polymers (CPs), {[H₂N(CH₃)₂]₂[Ln₂(BPT)(ox)₂]}_n (Ln = Er for 1, Yb for 2, and Sm for 3; H₂ox = oxalic acid) and {[Gd(HDCP)(H₂O)]·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 (3³·4¹⁰·5⁷·6²·7⁶)(3³·4⁶·5⁶)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 (4¹²·6¹²·8⁴)(4⁶)₂ topology based on 1D [Gd(COO)₂]_n ladder chains. Moreover, their luminescence properties have been investigated.