Three two-dimensional coordination polymers constructed from transition metals and 2,3-norbornanedicarboxylic acid: Hydrothermal synthesis, crystal structures and photocatalytic properties

Abstract

Three novel coordination polymers based on transition metals like Co(II), Cu(II) and Mn(II), namely [Co2(bpy)2(nbda)2(H2O)2]·2H2O (denoted as BUC-1), [Cu2(bpy)2(nbda)2(H2O)2]·2H2O (BUC-2), [Mn2(bpy)2(nbda)2(H2O)2]·2H2O (BUC-3), (where bpy = 4,4′-bipyridine, H2nbda = 2,3-norbornanedicarboxylic acid, BUC = Beijing University of Civil Engineering and Architecture), were synthesized under hydrothermal conditions, and characterized by CNH elemental analyses (EA), Fourier Transform infrared spectroscopy (FTIR), and single crystal X-ray diffraction (SCXRD). BUC 1–3 were isostructural and crystallized in the monoclinic space group C2/c, in which the corresponding metal atoms were linked by typical bidentate bpy ligands into two adjacent 1D [M1(bpy)]n2n+ and [M2(bpy)]n2n+ (M = Co(II), Cu(II), Mn(II)), further joined by versatile nbda2− ligands into 2D [M2(bpy)2(nbda)2]n sheets. Finally, three-dimensional supramolecular frameworks were constructed with the aid of the intermolecular hydrogen bonding interactions. BUC 1–3 exhibited different photocatalytic degradation ability to decompose methylene blue (MB) and methyl orange (MO) under UV light irradiation. Additionally, a possible photocatalytic mechanism HOMO-LUMO was proposed and discussed, which was further confirmed by radicals trapping experiments using isopropanol as radical scavenger.