Synthesis Of Metal-Organic Frameworks (MOFs) And Their Applications In Environment

As a new kind of organic-inorganic hybrid porous crystal materials,metal organic frameworks（MOFs）has become a hot research topic in material chemistry.Because MOFs have various topological structures and functional diversity,they have been widely used in recognition,catalysis,gas adsorption and magnetism.In this paper,we synthesized three kinds of carboxylic ligands,which coordinated with different metals,such as transition metals,alkaline earth metals and rare earth metals forming 10 new MOFs,and we also studied their applications in environment.This paper includes six chapters.In the first part,we briefly introduced the concept of MOFs,synthetic methods,influence factors,and discussed the research development of MOFs which were constructed by pyridine dicarboxylic acid,pyrimidine dicarboxylic acid and conjugated thiophene dicarboxylic acid,as well as the development of dye adsorption and fluorescent MOFs.In the second part,we have synthesized three MOFs:[Mn（PIA）4（bimb）]n·nDMF（compound 1）,[Zn3（MIA）6（bimb）6]n（compound 2）and[Co（PIA）4（bimb）]n·nDMF（compoun 3）,which were constructed by 5-（pyridin-3-yl）isophthalic acid（H₂PIA）,5-（pyrimidin-5-yl）isophthalic acid（H₂MIA）and 4,4’-bis（1-imidazolyl）biphenyl（bimb）.Compound 1 and 3 formed two same 3D network structures.Compound 2 show rapid uptake and ready regeneration for the methyl orange.In the third part,we have synthesized two MOFs with 3D structure:[Zn（bdba）2（bbi）2]n·3nH₂O（compound 4）and[Cd（bdba）2（PETPE）3]n（compound 5）,which were constructed by 1,5-Dithia-S-indacene-2,6-dicarboxylic acid（H₂bdba）and neutral bridging ligands.The fluorescence spectra of compound 4 indicated that it can sensitively identify and detect three different types of analytes（Hg2+,Cr（Ⅵ）,salicylaldehyde）.And the fluorescence quenching efficiency is basically unchanged at about 80%after repeated cycle detection.In the presence of interfering ions,compound 4 can selectively recognize Hg2+ and Cr（Ⅵ）.Therefore,compound 4 can be as potential fluorescent material.Compound 5 can quantitatively detect Cu2+ and Cr（Ⅵ）by fluorescence quenching,and it detected Cr（Ⅵ）with reversibility.Moreover,compound 5 can detect Cu2+ and Cr（Ⅵ）in the presence of interfering ions.In the simulated physiological environment,compound 5 also can selectively detect Cu2+.Besides,compound 5 also show good removal effect of two pesticides,such as 2,4-dichlorophenol and trichlorine.In the forth part,we have synthesized one MOF:[Mg2（bdba）6（DMA）2]n（compound 6）,which were constructed by],5-Dithia-s-indacene-2,6-dicarboxylic acid（H₂bdba）and alkaline earth metal（Mg2+）.Compound 6 is a three-dimensional reticular structure with strong fluorescence intensity,and its emission wavelength can shift in different solvents.Compound 6 can be used as a fluorescent probe for detection of Fe3+ and Cr（VI）.In the fifth part,we have synthesized four MOFs:[Eu（bdba）5（DMF）2]n（compound 7）,[Tb（bdba）6（DMF）]n（compound 8）,[La（bdba）5（DMF）2]n（compound 9）and[Gd（bdba）5（DMF）2]n（compound 10）,which were constructed by 1,5-Dithia-s-indacene-2,6-dicarboxylic acid（H₂bdba）and four rare earth metal ions（Eu3+,Tb3+,La3+,Gd3+）.Four compounds are three-dimensional frameworks,and the compound 7,9 and 10 are isostructural.Compounds 7 and 8 are porous MOFs,and their effective free volume were calculated by PLATON analysis as 53%and 38.9%of the crystal volume respectively.Compounds 7 and 8 have fluorescent properties,and show the characteristics of Eu3+and Tb3+ emission pesk respectively.In the sixth part,we summarized the research results and put forward the innovation points of the paper,and make a prospect for the application of MOFs as a fluorescent material.