Syntheses, crystal structures, electrochemical and photocatalytic properties of two mixed-ligand cobalt(II) coordination polymers based on flexible bis(2-methylbenzimidazole) dicarboxylic acid ligands

Two Co(II) coordination polymers (CPs), namely [Co(L)(tp)] (n) (1) and [Co(L)(0.5)(tbip)center dot H2O] (n) (2), (L = 1,6-bis(2-methylbenzimidazolyl) hexane, H(2)tp = terephthalic acid, H(2)tbip = 5-tert-butyl isophthalic acid), were hydrothermally synthesized and characterized by physicochemical and spectroscopic methods. CP 1 possesses a 2D (4,4) corrugated layer structure, which further extends into a 3D supramolecular framework by pi-pi stacking interactions, while CP 2 has a 1D ladder-like chain structure and combines into a 2D layer via O-Hai<overline>O hydrogen-bonding interactions. The thermal stabilities, luminescence and electrochemical properties of both CPs, as well as photocatalytic activities for the decomposition of methylene blue, were presented. The photocatalytic mechanism was investigated by introducing t-butyl alcohol, EDTA-2Na and benzoquinone as ai...OH, (hole)(+) and center dot O2- scavengers, respectively.