Synthesis,crystal Structures And Recognition Properties Of Metal Phosphonates Functional Materials

In this work,by selecting N–morpholinomethylphosphonic acid(H₂L₁=O(CH₂CH₂)₂NCH₂PO₃H₂)and2,4,6–trimethylbenzene–1,3,5–tris(methylene)phosphonic acid(H₆L₂=C₆(CH₃)₃(CH₂PO₃H₂)₃)as ligand,five new unreported metal phosphonates have been successfully synthesized under hydrothermal conditions.There are two approaches that have been employed to obtain such materials.One is the direct assembly of phosphonic acid ligand with metal ions in the synthesis of metal phosphonate materials;the second approach is by introducing a second organic ligand into the structures of metal phosphonate materials.The crystal structures,thermal stabilities and luminescence properties of compounds 1–5 have been investigated by X–ray single–crystal diffraction,X–ray powder diffraction,infrared spectroscopy,thermogravimetric analysis and luminescence spectroscopy.The recognition properties of compound 1 for the sensing of amino acids,purines,pyrimidines,cations and anions were systematically studied.Based on the synthesis of compound 6 in our group,the recognition properties of this compound for amino acids have been studied in detail.The chemical formulas are listed as follow:(1)Pb₃[(L₁)₂(O₃SC₆H₃(COO)OH)(H₂O)₂](2)[Pb₃(L₁)₂(OOCC₄H₆COO)]·3H₂O(3)[Pb(H₄L₂)(H₂O)]·2H₂O(4)[Cu(H₄L₂)(H₂biim)(H₂O)](5)[Co₃(H₃L₂)₂(4,4'–bipy)₂]·H₂O(6)Zn[(L₃)(H₂biim)]Compounds 1 and 2 have been synthesized by using N–morpholinomethylphosphonic acid(H₂L₁=O(CH₂CH₂)₂NCH₂PO₃H₂)as ligand and the H₂bdc and H₃ssc as the second metal linkers.The compound 1 shows the 2D layer structure and compound 2 can be describedasa3Dframeworkstructure.Byemploying2,4,6–trimethylbenzene–1,3,5–tris(methylenephosphonic acid)(H₆L₂=C₆(CH₃)₃(CH₂PO₃H₂)₃)as ligand,compound 3 has been synthesized by direct reaction.The structure of compound 3was exhibited 1D chain,two kinds of chains are interconnected to form a 3D supramolecular structure by?-?stacking interactions and hydrogen bonding.Compounds 4 and 5 were synthesized by introducting the second ligands of H₂biim and 4,4?–bipy(bipy=bipyridine).Compound 4 shows a 1D chain structure,and two kinds of chains were interconnected to form a 3D supramolecular structure by?-?stacking interactions and hydrogen bonding.However,compound 5 was described as a 3D framework structure.The thermogravimetric curves of compounds 1–5 show that compounds 1,2 and 5 have well thermal stabilities.The compounds 1–4 and 6 exhibit good luminescence properties by the luminescent method.The luminescence recognition properties of compounds 1,4 and 6 for the sensing of biological small molecules and ions were systematically investigated.The results show that compound 1has very high quenching effects with Lys,Arg,Cu²⁺,Fe³⁺,Cr³⁺and VO^3-,and compounds 4and 6 exhibit obvious recognition responses for Trp.