Synthesis, Crystal Structures And Properties Of Carboxyphosphonates

In this article, eight novel metal carboxyphosphonates have been successfully synthesizedby using4–HOOCC₆H₄CH₂NHCH₂PO₃H₂, N,N’–bis（phosphonomethyl）aminoacetic acid（HOOCCH₂N–（CH₂PO₃H₂）2）, and （4–carboxypiperidyl）–N–methylenephosphonic（H₂O₃PCH₂–NC₅H₉–COOH） as carboxyphosphonate ligands under hydrothermal conditions.All compounds were structurally characterized by X ray single–crystal diffraction, X–raypowder diffraction, thermogravimetric analysis and IR spectroscopy. Furthermore, theluminescent properties of these compounds have also been studied. The chemical constitutionformulas of compounds1–8are listed as follow:（1） CdCl[O₃PCH₂NH₂CH₂C₆H₄COOH]（2） Zn[O₃PCH₂NH₂CH₂C₆H₄COO]（3） Ni[（O₃PCH₂NHCH₂C₆H₄COOH）（H₂O）2]（4） Ni₂[（4,4’-bipy）{O2CCH₂N（CH₂PO₃）（CH₂PO₃H）}（H₂O）2]·H₂O（5） Cd_1.5[（O₃PCH₂NC₅H₉COO）（H₂O）]（6） Cd_1.5Cl[（O₃PCH₂NHC₅H₉COO）（H₂O）]（7）[Pb₂Cl₃（O₃PCH₂NHC₅H₉COOH）]·H₂O（8）[Pb₂（O₃PCH₂NHC₅H₉COO）（HOOCC₆H₃（COO）2）]Compounds1–3have been synthesized by introducing4–HOOCC₆H₄CH₂NHCH₂PO₃H₂asthe phosphonate ligand. Compounds1and2show the3D framework structures. Compound3features a3D supramolecular structure via the hydrogen-bonding interactions. By usingN,N’–bis（phosphonomethyl）aminoacetic acid as the phosphonate ligand and4,4’–bipy as thesecond metal linker, compound4has been synthesized. Compound4shows a3D frameworkstructure. By employing （4–carboxypiperidyl）–N–methylenephosphonic as the phosphonateligand, compounds5–8have been synthesized. Compound8uses1,3,5–benzenetricarboxylicacid （H₃BTC） as the second metal linker at the same time. Compound7shows a2D layerstructure, and compounds5,6, and8all feature the3D framework structures.Thermal stabilities experiments reveal that compounds1，2，6，7and8have the stabilizedframework structures. The luminescence analyses indicate that compounds1–8are good candidates for luminescent materials. The dehydration/hydration experiment shows thatcompound7may be the potential reversible adsorbent material for water molecules.