| In recent years,the application of metal complexes has been gradually extended to the field of bioinorganic chemistry,and as the research on metalloenzymes has intensified,the artificial synthesis of functional metal complexes has received a lot of attention.The artificial synthesis of these metal complexes can help to understand the mechanism of natural metalloenzymes involved in chemical reaction processes,such as artificially simulated manganese peroxidase,manganese calcium clusters involved in photosynthesis,mononuclear non-heme ferrous enzymes and the active centers of other copper-containing and nickel-containing enzymes.Among them,mononuclear non-heme ferrous enzymes contain a metalloenzyme-?-Diketone dioxygenase(Dke1),which has the ability to catalyze the oxidative cleavage of C-C bond of?-diketone substrate to?-carboxylic acid and aldehydes and ketones,and it has become a hot research topic in the field of bioinorganic chemistry,and a large number of complexes that mimic the structure and function of Dke1 active center have been reported.The synthesis of functional complexes is mainly regulated in two directions,namely the selection of metal ion center and the design of ligand.Dke1 takes divalent iron ion as the metal center,and the surrounding ligand environment is three histidine residues,and there are also carboxyl groups in the secondary microstructure,and the role played by carboxyl groups in it is still unclear,and the influence of these factors is worth exploring in depth.Although natural enzymes are highly specific as well as highly active,there are still some problems,for example,they are not easy to isolate and preserve,so synthetic metal complexes are necessary.There are fixed patterns in different natural enzymes for the type and number of metal ion centers,which catalyze or participate in the reaction process by the synergistic action of metal centers and ligands and substrates to complete the whole process together.Therefore,Ligands with suitable substituents can be selected to introduce new functions through these substituents,and suitable reaction conditions can be selected to synthesize metal complexes that function as natural enzyme active centers.In the First Chapter,a brief introduction lists some important metalloenzymes in living organisms,focusing on Dke1 in the section on dioxygenases,and gives a brief overview of the research history of its functional compounds.The factors influencing the synthesis of model compounds and the significance of the selected topics are introduced.In the Second Chapter,the trisubstituted methanolic ligand H3L1:2-(hydroxy(biphenol-2-yl)methyl)pyridine)was successfully synthesized and[Mn3?(L1)2(HL1)(acac)(CH3CN)2(H2O)](1)was prepared by coordination experiments.The ability of complex 1 to promote the oxidative cleavage of acetylacetone was demonstrated by derivatization and isotopic labeling in the same manner as the oxidative cleavage by the action of the natural metalloenzyme Dke1.The Third Chapter focuses on the synthesis of three trisubstituted methanol-like ligands H2L2:2-(hydroxy(bipyridin-2-yl)methyl)phenol?H1L3:tris(2-pyridyl)methanol and H4L4:tris(2-phenol)methanol,in A trinuclear manganese complex[Mn?Mn2?(L2)2(acac)2(OAC)](2)was prepared under the H2L2 ligand system.The oxidative cleavage of four ligands,H3L1,H2L2,H1L3 and H4L4,after coordination with metallic manganese was compared,and the effects of different coordination environments of the metal ion center on the activity and pathway of the oxidative cleavage reaction were investigated through the modulation of the ligands.In Chapter Four,we continued the synthesis of the new trisubstituted methanolic ligand H2L5:2-(hydroxy(bipyridine-2-yl)methyl)-4,6-dimethylphenol,which has a flexible and versatile coordination pattern and can form dinuclear,or multinuclear metal complexes.We synthesized four metal complexes in the ligand H2L5 system.{[Ni2?(HL5)2(acac)2]Ni?(acac)2(CH3OH)2·H2O}(3){[Fe3?(L5)2(HL5)2](ClO4)3·(H2O)2}(4){[Mn?Mn2?(L5)2(HL5)(OAC)(CH3OH)](ClO4)}(5){[Mn2? Mn2?(L5)4]Mn?(NO3)4(CH3CN)}(6)which approximate the structures of several natural enzyme active centers,respectively,and the specific biological activities remain to be explored. |
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