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

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 Schlafli 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.