Synthesis,Characterization And Recognition Properties Of Functionalized Lead And Cadmium Phosphonate Materials

In this work,we have successfully obtained three new metal phosphonate coordination polymers by using phenylphosphonic acid(C₆H₅PO₃H₂),4–phosphono–benzoic acid(H₂O₃PC₆H₄COOH)and 2-hydroxyphosphonoacetic acid(H₂O₃PCH(OH)CO₂H)as ligands under hydrothermal conditions.There are two approaches that have been employed to obtain such materials.One is the direct assembly of phosphonic acid ligands with metal ions in the synthesis of metal phosphonates;the second approach is by introducing a second organic ligand(1,10-phen)into the structures of metal phosphonates.The crystal structures and thermal stabilities of the synthesized compounds were studied by X–ray single crystal diffraction,X–ray powder diffraction,IR spectroscopy and TG analysis.Meanwhile,the nitro analytes molecular recognition and ion recognition properties of compounds 2,3 and compounds 4,5 which were synthesized by our group have been studied by fluorescence spectroscopy.The compounds 1–5 chemical formulas are listed as follow:(1)[Pb(1,10-phen)(C₆H₅PO₃H)₂](2)[Pb_0.5(HO₃PC₆H₄COOH)](3)[Cd(HO₃PCH(OH)CO₂)(H₂O)₂](4)[(en H₂)_0.5Cd_0.5(hedp H₂)]·H₂O(5)[Cd₂(HO₃PCH(OH)CO₂)₂(H₂O)₃]·4H₂OX-ray single crystal diffraction results show that compound 1 is a two-dimensional supramolecular structure formed by?–?stacking interactions.Compound 2 shows a three-dimensional supramolecular structure constructed by hydrogen bonding.Compound 3shows a two-dimensional layered structure formed by organic part of the ligand.TG curves of compounds 1–3 shows that the framework structure of compound 1 can be stabilized to240°C without obvious changes,and compound 2 and 3 can be stabilized to 280°C and183°C,respectively.Moreover,the nitro analytes molecular recognition and ion recognition studies show that compounds 2–5 have obvious and regular fluorescence recognition response to p-nitrophenol.The cation recognition studies show that compounds 2?4 and 5 have obvious fluorescence response to Fe³⁺,and compounds 3 have obvious fluorescence response to Fe³⁺and Cu²⁺.In the study of anion recognition,the Cr₂O₇^2-shows obvious and regular fluorescence quenching phenomena for compounds 2–5,which indicates that compounds 2–5may have fluorescence recognition effects on the Cr₂O₇^2-.