Studies On Df Heterometallic And Transition Metal Coordination Polymers Constructed With Pyridyl Polycarboxylic Acid Ligands And Their Fluorescent Probes

In this paper,pyridine-containing polycarboxylic acid ligands:2,2’-bipyridine-4,4’-dicarboxylicacid（H₂LZ）and2,2’-biquinoline-4,4’-dicarboxylic acid（H₂bqdc）are selected to coordinate with transition/lanthanide metal ions.Six coordination polymers are successfully designed and synthesized self-assembly by adjusting the ratio of metal salts,reaction time and temperature,and the composition of the solvent under solvothermal conditions.Through Infrared spectroscopy,Ultraviolet-visible spectroscopy,Elemental analysis,Thermogravimetric analysis,X-ray single crystal diffraction,X-ray powder diffraction,fluorescence spectroscopy have carried out on structural analysis and characterization of their properties respectively.Specially,their sensing performance as inorganic ions,antibiotic molecules,food additives,nitro explosives,and biomolecules are investigated.In addition,the fluorescence responsive mechanisms were explored in detail.The main research contents of this paper are as follows:1.Five novel isostructural and heterogeneous metal coordination polymers were synthesized using H₂LZ as the ligand,[EuZn（LZ）₂（HCOO）（H₂O）₃]_n（Ln=Eu（1）,Tb（2）,Sm（3）,Gd（4）,Dy（5））,the crystal structure shows that the complexes 1-5 are composed of two kinds of metal ions connected by LZ^2-and HCOO^-to form a three-dimensional structure.At the same time,the complexes 1-5 have favorable thermal and chemical stability.The fluorescence experiments show that:the fluorescence quenching phenomenon of complex 1 can be used to detect 2,4,6-trinitrophenol（TNP）,sulfaquinoxaline and folic acid,and complex 2 can achieve fluorescence probe detection of TNP and carmine in aqueous solution.The experimental results demonstrates that both complexes 1 and 2 can perform high sensitivity,selectivity and recyclability of the above substances.Infrared spectroscopy,Ultraviolet-visible absorption spectroscopy,X-ray powder diffraction and X-ray photoelectron spectroscopy were used to study the fluorescence detection mechanism of complexes 1 and 2 in detail.The above results of research indicate that both complexes 1 and 2 can be used as multifunctional fluorescent sensors with potential practical value in aqueous solutions.2.Based on ligand 2,2’-biquinoline-4,4’-dicarboxylic acid（H₂bqdc）and4-（2,2’;6’,2’’-tripyridine）-4’-benzoic acid（Htpba）have synthesized a novel transition metal complex[Zn（tpba）（bqdc）_0.5]_n（6）.The crystal structure of complex 6 is composed by a series of one-dimensional chains.The two-dimensional supramolecular structure is connected through theπ···πinteraction between the benzene rings in tpba^-ligand.The experiments show that complex 6 has excellent thermal and chemical stability.The luminescent properties of complex 6 exhibit that it can be used for qualitative and quantitative detection of Fe³⁺ions,V₂O₇^4-ions and p-nitrotoluene（p-NT）through fluorescence quenching.The detection of the above analytes have anti-interference and recyclability.Meanwhile,this paper elaborates on the fluorescence quenching mechanism of 6 in detail.