Syntheses,Structures And Properties Of Coordination Polymers Based On Pyridyl-Containing Polycarboxylic Acid Ligands

The reasonable design and construction of coordination polymers with novel structures and excellent properties are still the hot topic to scientists,which is contributed by their potential application in the fields heterocatalysis,the recognition of molecules or ions,fluorescence materials,molecule-magnets,and nonlinear optical materials.In the thesis,fifteen coordination polymers based on pyridyl-containing polycarboxylic acid ligands were successfully synthesized with lanthanide series or transition metals under solvothermal conditions.Meanwhile,the structures and properties of some compounds were investigated in detail.Based on the main ligand 4-(Pyridin-3-yloxy)-phthalic acid(H2ppda),fourteen novel lanthanide coordination polymers with similar structures,and named as:[Ln(ppda)(bdc)0.5(C2H4OH)(H20)]n,(Ln= Sm(1),Eu(2),Gd(3)?Tb(4)?Dy(5)):[Ln(ppba)(pbdc)0.5(C2H5OH)(H20)]n,(Ln = Eu(6),Gd(7),Tb(8),Dy(9));[Ln(ppba)(C2O4)0.5(H2O)2]n,(Ln=Sm(10),Eu(11),Gd(12),Tb(13),Dy(14))with 3D supermolecular structure constructed from 2D layers decorated by the uncoordinated activated oxygen atoms of ether bond secondary building units by the hydrogen-bond interaction,have been prepared under solvothermal conditions based on rare-earth salts,H2ppba and three kinds of auxiliary ligands:H2bdc,H2pbdc,and H2C2O4,respectively.There are three kinds of plane grids on account of the different axial length of ligands.The average bond lengths of Ln-O in isomorphic complexes decrease with the reduction of ionic radius of Ln3+ cations,consistenting with the lanthanide contraction effect.The thermal stability(TGA),IR,elemental analysis,and PXRD properties of 1-14 were investigated,respectively.In particular,the weak ferromagnetic interaction between Gd3+ ions has been found in 3,and the relevant characteristic emission peaks of rare earth elements have been discovered in the luminescent coordination compounds of 1-2,4-5,7-8,10-11,13-14.In addition,4-Tb can not only detect a trace of nitrobenzene molecules with high selectivity and sensitivity,but can also act as a promising highly selective sensing material for Fe3+ions and Cr2O72-ions;meanwhile,13-Tb is the first difunctional fluorescent probe for the detection of Al3+ ions and CO32-ions.Finaly,the mechanisms of luminescence quenching for differentiating the analytes have been speculated and clarified in detail,respectively.The mechanism of fluorescent detection was studied by X-ray photoelectron spectroscopy,Powder X-ray diffraction and UV-visible absorption spectroscopy.A detailed deduction and explanation of the mechanism of detection for nitrobenzene,some metal ions and inorganic anions have also been given,respectively.A transition metal compound[Zn(tbda)]n(15)has been synthesized by solvothermal conditions based on 4-[2,2':6',2"-Terpyridin]-4'-yl-1,2-benzenedicarboxylic acid,demonstrating a supermolecular 2D layered structure derived from 1D chains with ?…? interaction by benzene rings of tbda2-.The thermal stability,IR,elemental analysis,PXRD,and solid-state luminescent properties of 15 were investigated respectively.Compound 15 can maintain a high stable thermostability.