Syntheses, crystallization and selective dye adsorption of three Co(II) coordination polymers via one-pot reaction

Abstract

Three novel Co(II) coordination polymers, namely [Co(HL)(4,4′-bibp)]n (1), [Co(HL)(4,4′-bibp)]n (2) and {[Co2(L)(4,4′-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n (3) (H3L=5-(2′′-carboxylphenoxy)isophthalic, 4,4′-bibp=4,4′-bis(imidazol-1-yl)biphenyl) were synthesized through one-pot reaction under co-crystallization conditions. These complexes were characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Complexes 1 and 2 were supramolecular isomers with different 2D configurations. Complex 1 shows a sql 2D-network with a [Co(HL2−)]n single-strand helix chain and another [Co(4,4′-bibp)]n single-strand helix chain, which are further assembled into 3D supramolecular architectures through H-bonds and C–H⋯N bonds. While complex 2 exhibits another 2D-network with two different [Co(HL2−)]n helix chains (left and right) and one [Co(4,4′-bibp)]n zigzag chain, which further constructing a 3D supramolecular structure through H-bonds. Compared with 1 and 2, 3 also shows a sql 2D-network with a bigger channel which influenced by the coordination environment of metal ions. Furthermore, the selective dye adsorption studies indicate that complex 1 can highly and selectively adsorb Methyl Orange (MO) in a short time, and complex 2 shows a highly adsorption activity for Alizarin Red S (ARS) than Methyl Orange, and complex 3 can selectively adsorb Methyl Orange.