Research On Fluorescence Properties Of Coordination Polymers Based On 5-mercapto-isophthalic Acid Derivatives

In this dissertation,eight metal-organic frameworks(MOFs)1-8 were successfully constructed with 5-mercapto-isophthalic acid(H3MIPA)derivatives thioether tetracarboxylic acid ligand of 5,5’-thiodiphthalic acid(H4DMIPA)and 5,5’-dithiobis-isophthalic acid(H4DTMIPA)with greater flexibility,combining of d10 metal ions of Zn(Ⅱ)/Cd(Ⅱ),6s2 metal ion Pb(Ⅱ)containing lone electron pairs and several auxiliary ligand,including 1,2-bis(pyridine-4-methylene)hydrazine(4-BPyMHz),l,3-(imidazolyl-1-methyl)benzene(1,3-bix),2,2’-bipyridine(2,2’-bpy),etc.Eight compounds were characterized by X-ray crystallography,PXRD,EA,IR and TGA.The properties of coordination polymers as fluorescent probes for detecting metal ions,anions,nitroaromatic compounds(NACs)and nitroimidazole-based drugs were further investigated.1.Three coordination polymers {[Zn(H2DMIPA)(l,3-bix)]·0.5H2O}n(1),{[Zn(H2DMIPA)(4,4’-bpy)0.5]}n(2),{Zn2(DMIPA)(4-DiPyDz)0.5(CH3CH2OH)(H2O)3}n(3)have been synthesized via solvothermal assembly of 5,5’-thiodiphthalic acid(H4DMIPA),auxiliary ligands combining d10 metal ion of Zn(Ⅱ).Compounds 1-2 form 2D planar structure by bridging H2DMIPA2-ligand with auxiliary ligand.Compound 3 forms 3D framework with micropore by means of {Zn2(COO)2} binuclear cluster and octahedron.Coordination polymers 1-3 were obtained in different solvents at 120℃.The polarity of solvents may affect the coordination mode of ligands,and further the structure of 1-3.Coordination polymers 1-3 exhibit excellent stability.The research on fluorescence probe of coordination polymers 1-3 indicate three compounds could serve as a probe for sensing Cr2O72-,2,4,6-trinitrophenoI(TNP),4-nitroaniline(4-NA)and nitroimidazole-based drugs.2.Three coordination polymers {[Cd3(HDMIPA)2(2,2’-bpy)2]·0.25H2O}n(4),{[Cd2(DMIPA)(3-BPyMHz)(H2O)]}n(5),{Cd(H2DMIPA)(4-BPyMHz)0.5(H2O)}n(6)have been synthesized via solvothermal assembly of 5,5’-thiodiphthalic acid(H4DMIPA),auxiliary ligands combining d10 metal ion of Cd(Ⅱ).Compound 4 forms a ID chain with HDMIPA3’ ligands on both sides of {Cd3(COO)6} trinuclear metal clusters which were linked of Cd(Ⅱ)and carboxyl oxygen.The upper and lower HDMIPA3-ligands on the 1D chain through carboxyl oxygen participate in the trinuclear metal cluster coordination of adjacent twisted ID chains to form a 2D network.Compound 6 was linked into ID long chains by {Cd2(COO)4} binuclear clusters with two adjacent rows of reversed H2DMIPA2-ligands,and the adjacent ID chains are bridged by 1,2-bis(pyridine-4-methylene)hydrazine to form 2D layers.Hydrogen bonds connect adjacent layers into 3D supramolecular structure.The auxiliary ligands of compounds 5 and 6 are isomers.Different solvent ratios lead to different polarities of the reaction,thus forming distinct crystals.Similarly,all three compounds have no high selectivity and sensitivity toward metal ions,but they have good fluorescence sensing function for Cr2O72-.Relatively,compound 6 exhibits excellent sensitivity to Cr2O72-ions among three compounds.The fluorescence sensing ability of three compounds is different only for NACs and nitroimidazole-based drugs.3.Two coordination polymers {Pb2(DMIPA)}n(7),{Pb0.5(H2DTMIPA)0.5}n(8)have been synthesized via solvothermal assembly of 5,5’-thiodiphthalic acid(H4DMIPA),5,5’-dithiobis-isophthalic acid(H4DTMIPA)and Pb(Ⅱ)cations containing 6s2 lone electron pairs,respectively.7-8 are complexes with two different configurations.Compound 7 forms a microporous 3D skeleton by {Pb2(COO)2} binuclear cluster and DMIPA4-ligand,while compound 8 forms a 2D network by Pb2+ octahedron and H2DTMIPA2-ligand.The reseach on fluorescent probes properties of compounds 7-8 shows both can not effectively detect metal ions,but can effectively detect CrO72-ions,and compound 8 is more sensitive toward Cr2O72-ions(7:Ksv=5.3*103 L/mol;8:Ksv=6.3*103 L/mol).Additionally,both have excellent fluorescence sensing for five NACs and nitroimidazole-based drugs,especially TNP and 4-NA.