Study Of Syntheses,Structures And Properties As Fluorescence Sensors Of Lanthanide Coordination Polymers Based On Nitrogen-containing Polycarboxylic Acid Ligands

In this paper,based on reaction of pyridine-containing polycarboxylic acid liangds 4-(Pyridin-3-yloxy)-phthalic acid(H2ppda),2,2’-bipyridyl-5,5’-dicarboxylic acid(H2bpdc)with rare earth metal salts,ten rare earth coordination polymers were synthesized under solvothermal conditions.The structure and properties of the ten compounds were analyzed and characterized by IR Spectum,thermogravimetric analysis,UV-Vis absorption spectroscopy,X-ray single crystal diffraction,X-ray powder diffraction,X-ray photoelectron spectroscopy and Energy dispersive X-ray spectroscopy.The above complexes were used as fluorescent probes for some inorganic ions,organic molecules,and biomolecules.The fluorescence responsive mechanisms for different analytes were also discussed and illustrated in detail.The main research contents of this thesis are as follows:1.Five novel lanthanide coordination polymers 1-5 possessing novel structure were synthesized based on the ligands of H2 ppda and naphthalene-1,4-dicarboxylic acid(H2npdc),namely,[Eu2(ppda)2(npdc)(H2O)2]n(1),[Ln(ppda)2(npdc)(H2O)2]n(Ln= Tb(2),Sm(3),Gd(4),Dy(5)).A 3D supramolecular structure of 1 is formed through 1D dinuclear chains of [Eu(ppda)]2 under the connection of carboxylate groups from npdc2-ligands and hydrogen bonds,and complexes 2-5 exhibit similar 2D layered structures of 1.Complexes 1-5 showed favorable thermal stability and water stability.Furthermore,it was found that the complex 1 can be utilized as a highly sensitive,recyclable multifunctional luminescent sensor to detect some trivalent cations(Fe3+,Cr3+,Al3+ ions),PO43-anions,nitrobenzene molecule,and 1,3,5-trinitrophenol.2 can qualitatively and quantitatively identify for Pb2+ ions,Cr2O72-ions and PO43-ions in aqueous solutions.And more surprisingly,2 can specifically recognize N,N-diethylformamide(DEF),tryptophan and tyrosine.The detection mechanisms for above compounds were systematically studied by X-ray powder diffraction,IR spectrum,UV-visible absorption spectroscopy,fluorescence lifetime,and X-ray photoelectron spectroscopy.In view of high sensitivity,high selectivity,and reversibility,both 1 and 2 will be utilized as potential multifunctional fluorescent probes with practical application in aqueous solutions.2.Five 3D isostructual lanthanide coordination polymers 6-10 were synthesized based on the reaction of H2 bpdc ligands with rare earth salts,namely,[Ln(bpdc)1.5(H2O)2]n(Ln= Eu(6),Tb(7),Sm(8),Gd(9),Dy(10)).Both the carboxylate groups are involved in coordination with Ln3+ ions through losing the protons of of H2 bpdc ligands,and the pyridine nitrogen atoms are acted as the active sites and may further interact with some analytes.The fluorescence properties of complex 6 and 7 were investigated in detail,and the results show that 6 can detect Fe3+ ions,Cu2+ ions,PO43-ions,OH-ions,and dichloromethane molecules by response of fluorescence quenching.7 can identify C2O42-ions by the effect of fluorescence enhancement among other anions,and exhibits the strongest efficiency of fluorescent quenching by 1,4-DNB.The mechanism of 6 detecting for above analytes were exhaustively explored and elucidated,and the excellent results of anti-interference and recycle tests confirmed that 6 and 7 can be used as potential fluorescent probes of above analytes with practical application.