| With the development of industrialization,global environmental pollution is becoming more and more serious.In particular,many pollutants in the water body,such as heavy metal ions,pesticides and antibiotics,can enter the human body through the food chain,causing permanent damage to human DNA,nervous system and circulatory system,and leading to a variety of incurable diseases,such as organ exhaustion,cardiovascular diseases and cancer.Fluorescence detection method has attracted extensive attention because of its fast and convenient detection advantages.Therefore,the development of fluorescence sensors that can detect pollutants efficiently has become the focus of researches.Among the reported fluorescent sensors,metal organic coordination polymer fluorescent sensors have attracted extensive attention.Metal organic complexes are mainly composed of organic ligands and metal ions.They have the characteristics of large specific surface area and adjustable structure size.They can be used to efficiently identify pollutants in water.In this paper,a series of eight metal organic complexes with novel structure and good fluorescence properties were constructed by self-assembly of aromatic polycarboxylic acid ligands and nitrogen-containing heterocyclic ligands with different metal ions.Their structure and stability were studied by X-ray single crystal diffraction,infrared spectroscopy,and thermogravimetric analysis.Through fluorescence test experiments,their applications in the detection of antibiotics,pesticides and heavy metal ions were explored,and the recognition mechanisms were explored by means of density functional theory,powder diffraction and UV spectroscopy.The main contents are as follows:(1)Based on the mixed ligand strategy,p-terphenyl-2,2'',5'',5'''-tetracarboxylate acid(H4tptc)was selected as the main ligand,and nitrogen-containing heterocyclic ligands were used as auxiliary ligands((1-10 phenanthroline(phen),1,3-bis(imidazol-1-ylmethyl)benzene(bimb),2-(1H-pyrazol-3-yl)pyridine(bpz)and 2,2'-bipyridine(bpy)),four luminescent metal organic complexes with different structures were constructed by self-assembly with Zn2+and Cd2+by using solvothermal method([Cd(tptc)0.5(phen)]n(1){[Zn(tptc)0.5(bimb)]·H2O}n(2),{[Cd(tptc)0.5(bpz)(H2O)]·0.5H2O}n(3)[Cd(tptc)0.5(bpy)]n(4)).These complexes have good luminescent properties and stability.Their recognition performances in different anions and pesticides were detected by a series of fluorescence experiments,the results show that these four metal organic complexes can be used as bifunctional fluorescent sensors to detect Cr(VI)ion(Cr2O72-/Cr O42-)and pesticide 2,6-dichloro-4-nitroaniline(DCN).The recognition mechanism mainly involves internal filtration effect(IFE).(2)Based on the mixed ligand strategy,3,5-di(2',4'-dicarboxylphenyl)benozoic acid(H5ddb)was selected as the main ligand and nitrogen-containing heterocyclic ligand as the auxiliary ligand(2-(1H-pyrazol-3-yl)pyridine(bpz),1,3-bis(1H-imidazole-1-yl)benzene(bib)).Two luminescent metal organic frameworks with different structures({Cd10(ddb)4(bpz)8(DMA)(H2O)8.2]·2H2O}n(5),{[Zn2(Hddb)(bib)1.5]·3H2O}n(6))were constructed with self-assembly of Zn2+and Cd2+by using solvothermal method.Powder diffraction and thermogravimetric analysis showed that the two compounds had good stability.Fluorescence test experiments showed that the two complexes could be used as bifunctional fluorescence sensors to effectively detect Cr2O72-/Cr O42-,nitroimidazole antibiotics(MND,DND,OND and RND)and nitrofuran antibiotics(NFT and NFZ)in water.The recognition mechanism of Cr2O72-/Cr O42-mainly involves IFE,and the recognition mechanism of antibiotics involves IFE and photoinduced electron transfer(PET).(3)Two metal organic complexes({[Cd(tib)2](NO2)2·0.5DMA·H2O}n(7)?{[Ni(tipa)2]SO4·DMF·8H2O}n(8))were constructed by self-assembly of different tripod imidazole ligands(1,3,5-triimidazolobenzene(tib),tris[4-(imidazole-1yl)phenyl]amine(tipa))with Cd2+and Ni2+.They can be used as dual function fluorescent sensors.Complex 7 can detect Cr2O72-/Cr O42-,nitrofuran antibiotics(NFT and NFZ)and nitroimidazole antibiotics(DND and RDZ).Complex 8 can be used as a dual function fluorescence sensor to detect Cr2O72-/Cr O42-and DND.The study on the recognition mechanism shows that the recognition mechanism of these two complexes for Cr2O72-/Cr O42-involves IFE,while the recognition mechanism of antibiotics includes IFE and PET. |
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