Synthesis,Crystal Structures And Fluorescence Recognition Properties Of Aromatic Metal Phosphonate Coordination Polymers

In this work,the hydrothermal synthesis method was used to synthesize eight kinds of aromatic metal phosphonates materials that were not reported in the literature by using ethyl p-carboxybenzylphosphonate(H₂L=4-HOOCC₆H₄CH₂PO(OH)(OC₂H₅))and4-nitrobenzylphosphonic acid(H₂L'=4-O₂NC₆H₄CH₂PO(OH)₂)as ligands.The crystal structures of the synthesized compounds were studied by X-ray single crystal diffraction,X-ray powder diffraction and IR spectroscopy.X-ray single crystal diffraction results show that,compound 1 is a cluster structure,which is constructed into a 3D supramolecular structure through hydrogen bonding.Compound 2 is connected into a two-dimensional layered structure by the{Mg O₆}and{CPO₃}tetrahedron,and the layer and the interlayer are bridged into a three-dimensional skeleton structure by organic phosphonic acid ligands.Compounds 3-5 are isostructural and adopt a 1D chain structure which connected by coordinating organic phosphonic acid oxygen atom.Compound 6 exhibits a 1D double-stranded structure.In the structure of the compound 7,the{Pb O₅}polyhedron and the{CPO₃}tetrahedron are connected by a common angle to form a two-dimensional layered structure.Meanwhile,the structure of compound 8 is 1D chain.And the thermal stability of the synthesized compounds was studied by thermogravimetric analysis(TG).By analyzing the thermogravimetric curves of compounds 1-8,the results show that compound 2 has relatively good thermal stability.By using fluorescence spectroscopy,the luminescence properties of compounds 1,2 and 4;and the Fluorescence lifetime of compounds 1 and 2were studied.In addition,the fluorescence spectroscopy characterization technique was used to study the selective recognition performance of compounds 1 and 2 in rare earth ions.Further research on the properties of compounds 1 and 2 for selective recognition of rare earth ions was carried out by means of fluorescence analysis,the experimental results show that compounds 1 and 2have good selective recognition for Tb³⁺ion.At the same time,this paper also conducted a preliminary study on the selective identification of ions and halogen ions in the steamer water system of compound 4.The results show that compound 4 has obviously selective recognition for NO₂^-and F^-.The chemical formulas of compounds 1-8 are listed as follow:(1)Mg_0.5[(HL)(H₂O)₂](2)Mg(L)₂(3)[La(HL')₂(OH)(H₂O)₂]·2H₂O(4)[Ce(HL')₂(OH)(H₂O)₂]·2H₂O(5)[Pr(HL')₂(OH)(H₂O)₂]·2H₂O(6)[Nd(L')(HL')(H₂L')]·H₂O(7)[Pb₄(L')₃(H₂O)](OH)₂(8)Ag(HL')...