Construction of Cd(ii) coordination polymers used as catalysts for the photodegradation of organic dyes in polluted water

Abstract

Four Cd(II) coordination polymers formulated as {[Cd₃(tpcb)₂)(η,η-μ-SO₄)₂(H₂O)₆]SO₄·16H₂O}_n (1), {[Cd(tpcb)_0.75(OH)(H₂O)₂](NO₃)}_n (2), {[Cd₂(tpcb)(SO₄)₂(H₂O)₆]·2MeOH·3H₂O}_n (3), and {[Cd(tpcb)(NO₃)(H₂O)₂](NO₃)}_n (4) were synthesized by reactions of CdSO₄ or Cd(NO₃)₂ with tetrakis(4-pyridyl)cyclobutane (tpcb) under solvothermal conditions or at ambient temperature. Compounds 1–4 were characterized by elemental analysis, IR spectroscopy, thermal analysis, powder X-ray diffraction analysis and single crystal X-ray diffraction. Compounds 1, 2, and 4 possess three different complicated 3D frameworks with the Schläfli symbols of (4⁶)(4¹²·5⁴·6⁴·8⁸), (6³)₄(6²·8⁴)₃ and (8³)(8⁶), respectively, while 3 presents a 1D chain structure. Compounds 1–4 exhibited relatively good photocatalytic activity towards the degradation of methyl orange (MO), methyl blue (MB) and rhodamine B (RhB) in aqueous solution. These results offered a good insight into the temperature effects on the assembly of Cd(II) coordination polymers and their photocatalytic applications.