Metal-Organodiphosphonate Chemistry: Hydrothermal Syntheses and Structures of Two Novel Copper(II) Coordination Polymers with o-Xylylenediphosphonic Acid and 4,4′-Bipyridine Ligands

Abstract

Abstract Two novel copper organodiphosphonates, namely [Cu4(L)2(H2O)4]n (MOF 1) and [Cu4(bpy)(HL)2(OH)2]n•2nH2O (MOF 2), (where H4L = o-xylylenediphosphonic acid and bpy = 4,4′-bipyridine), have been synthesized as a result of changing the pH values (Initial pH: 3.50 for MOF 1 and pH: 6.00 to 3.50 for MOF 2) under hydrothermal conditions. Coordination polymers were characterized by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction analysis. MOFs 1 and 2 crystalize in the orthorhombic Pna21 and triclinic P$\bar{1}$ space groups, respectively. The organophosphates acted as multidentate bridging ligands in both compounds to link copper ions into a framework. From the analysis of magnetic susceptibility measurements between 1.8 to 300 K, all the Cu valences were confirmed to be 2+, and antiferromagnetic interactions were characterized. The adsorption properties of MOFs 1 and 2 as well as known [Cu3(HL)2]n, [Cu(SO4)(bpy)(H2O)3]n•2nH2O, and [Cu(SO4)(bpy)(H2O)3]n•2nH2O have also been investigated with mono- and divalent dyes including Bromophenol Blue and Orange G as a pollutant removal model.