| In this thesis,a series of metal organic frameworks(MOFs)have been successfully synthesized based on four aminocarboxylic acid compounds ligands with different transition metal ions using hydrothermal synthesis by changing different factors.And their structures,fluorescence properties,Hirshfeld surface analysis and density functional theory(DFT)quantitative calculation have further researched.1.[Cd(HL1)(dib)0.5(H2O)]n(1),[Zn(HL1)(dib)0.5(H2O)]n(2)and[Zn(HL1)(bipy)(H2O)]n(3)were synthesized via using 4-[(3,5-bis(methyl carboxylic)phenyl)amino]benzoic acid(H3L1)as the main ligand,1,4-bis(1H-imidazole-1-yl)benzene(dib)and 4,4'-bipyridine(bipy)as auxiliary ligand.1 exhibits a(3,4)connected three-dimensional supramolecular structure,2presents a(2,3)connected two-dimensional layered structure and 3 displays a one-dimensional chain structure.By comparison of the structures of 1 and 2,the effect of metal ions on the structure of MOFs was discussed.The regulatory effects of auxiliary on the structure of MOFs can be investigated via comparing the structures of 2 and 3.The main ligand H3L1presents different coordination modes in the MOFs structure:?3-?1:?1:?1:?1:?0:?0,?3-?1:?1:?1:?0:?0:?0,?3-?1:?0:?1:?1:?0:?0.After studying the fluorescence properties of 1-3,there is a result showed that the fluorescence intensity of 1 and 2 is significantly higher than that of ligand H3L1,and occurrs blue shifts of 185 nm and 88 nm,respectively.Compared with ligand H3L1,3 occurrs 54 nm red shift.The metal ion recognition experiment of 2 shows that Fe3+has a very obvious quenching effect on its fluorescence.When the concentration of Fe3+reaches 0.1 mol/L,it can be completely quenched.2.The semi-rigid amino carboxylic acid ligand 3-[(3,5-bis(methylcarboxy)phenyl)amino]benzoic acid(H3L2)as the main ligand,and the dib nitrogen ligand as the auxiliary ligand,combining them with Cd(?)resulted in the successful synthesis of a(3,5)connected three-dimensional supramolecular network structure{[Cd(L2)(dib)]n·(H2O)}(4).Compared with 1,the structure of 4 is significantly different,indicating that the ligand functional group site has a more obvious influence on the structure of MOFs.The fluorescence properties of 4were studied at room temperature,and it was found that compared with the ligand H3L2,the emission spectrum intensity of 4 is enhanced and occurrs a 42 nm blue shift.This is because the formation of the Zn-O coordination bond in 4 leads to the transition of the metal charge,and the coordination bond increases the"rigidity"of the ligand and reduces the energy loss through the non-radiation pathway.3.Using semi-rigid amino carboxylic acid ligand 3,5-[(3?,5?-carboxyphenyl)amino]benzoic acid(H4L3)as the main ligand and dib nitrogen-containing compound as the auxiliary ligand with metal Co(?),a(3,4,2)connected two-dimensional layered structure[Co2(L3)(dib)2.5(H2O)1.5]n(5)was synthesized.Hirshfeld surface analysis was performed on 5to study the type and distribution of the interaction force between different atoms and molecules in the crystal.And it is found that there are many strong hydrogen bonds and weak interaction forces in the structure of 5,which will make the framework of 5 more stable.In addition,DFT quantitative calculation was used to study the electronic structure and properties of ligands H4L3 and 5 frontline.The result shows that the HOMO and LUMO values of 5 were both negative,indicating that it has a good chemical stability.4.The flexible aminocarboxylic acid ligand 5-(4-(methylcarboxy)benzylamino)isophthalic acid(H3L4)as the main ligand and 1,4-bis-(1H-imidazole-1-yl)methyl benzene(btx)as the auxiliary ligand was combined with Cd(?)via hydrothermal synthesis,resulting in the formation of two(3,4)connected isomorphic three-dimensional supramolecular network structure[Cd(HL4)2(btx)(H2O)2]n(6)and[Zn(HL4)2(btx)(H2O)2]n(7).The emission spectrum of the suspension for 6 and 7 was measured at room temperature to study its fluorescence properties.The results showed that compared with the ligand H3L4,both 6 and 7 exhibited different degrees of blue shift,and the fluorescence intensity of 7 was significantly enhanced much stronger than that of 6.The metal ion recognition experiment of 7 shows that Fe3+has a very obvious quenching effect on it.When the concentration of Fe3+reaches 0.01 mol/L,it can be completely quenched. |
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