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)(H 2 O)]·[Co 3/2 (L)(OH-Hbdc)(H 2 O) 2 ]·H 2 O} n ( 2 ), and [Ni(L)(H 2 O) 5 ]·DMF·4H 2 O ( 3 ), where H 2 L = 4′-pyridin-4-yl-biphenyl-3,5-dicarboxylic acid and OH-H 2 bdc = 5-hydroxyisophthalic acid, have been hydrothermally synthesized and characterized. Compound 1 is a two-dimensional (2D) layered structure of Co 2+ ions coordinated with incompletely deprotonated HL − ligands. Compound 2 is a crystal in the triclinic space group P 1̄ and shows a very rare 2D + 2D heterogeneous framework built from 3-connected {6 3 } hcb layers and 4-connected {4 4 ·6 2 } sql layers. Compound 3 is a 0-D molecular complex crystallized in the chiral space group P 2 1 2 1 2 1 , 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 H 2 O 2 have been investigated in detail in aqueous solutions. The results show that the photocatalytic efficiency of NR is the highest for compounds 1–3 .