Three novel Co(II)/Ni(II)-based coordination polymers as efficient heterogeneous catalysts for dye degradation

Three novel networks, namely, {[Co(HL)(2)]}(n) (1), {[Co(L)H2O)] center dot [Co-3/2(L).OH-Hbdc).H2O) 2] center dot H2O}n (2), and [Ni.L).H2O) 5] center dot DMF center dot 4H2O (3), where H2L = 4'-pyridin-4-yl-biphenyl-3,-dicarboxylic acid and OH-H2bdc = -hydroxyisophthalic acid, have been hydrothermally synthesized and characterized. Compound 1 is a two-dimensional (2D) layered structure of Co2+ ions coordinated with incompletely deprotonated HL -ligands. Compound 2 is a crystal in the triclinic space group P (1) over bar and shows a very rare 2D + 2D heterogeneous framework built from 3-connected {63} hcb layers and 4-connected {44 center dot 62} sql layers. Compound 3 is a 0-D molecular complex crystallized in the chiral space group P212121, which suggests that symmetry breaking can be driven by the solvent-assisted homochiral helix without any chiral building blocks. In addition, their heterogeneous catalytic oxidation activities toward methyl orange (MO), methyl blue (MB), neutral red (NR), methylene blue (MEB), and safranine T (ST) and the mechanisms in the presence of H2O2 have been investigated in detail in aqueous solutions. The results show that the photocatalytic efficiency of NR is the highest for compounds 1-3.