Study On Structures And Catalytic Properties Of Polynuclear Lanthanide Complexes

Polynuclear lanthanide complexes have potential applications in many fields,such as magnetism,catalysis,recognition,and so on.Thus,the study on the relationship between the structural design and catalytic properties of polynuclear lanthanide complexes has aroused the research interest of many scientists,which is important in rare earth chemistry,structural chemistry,catalysis and other fields.This thesis focussed on the construction of polynuclear lanthanide supramolecular self-assembled materials.Two multi-dentated acylhydrazone ligands with nonsymmetric structure and a pair of chiral carboxylic acid ligands were accurately designed and synthesized.Then,three 3d-4f heteropolynuclear coordination cages(namely Zn₂Er_4,Zn₄Eu₆,and Zn₄Sm₆),one binuclear complex Nd₂,one 2s-4f heteropolynuclear complex Li₂Nd₂,and series of chiral lanthanide MOFs(namely S-La₁₆,R-La₄and S/R-Dy CMOF)were obtained.Based on the structure and characteristics of these complexes,their catalytic performance were investigated to explore the structure-activity relationship between the microenvironment in the coordination cage and the synergistic catalytic performance.The thesis consists of seven chapters:In chapter 1,the research progress of polynuclear lanthanide complexes on the structural classification,synthesis strategies,as well as their properties is briefly introduced.The application research of polynuclear lanthanide complexes in the field of catalysis was emphatically summarized.In chapter 2,a nonsymmetric acylhydrazone ligand H₅L¹was designed and synthesized.A 3d-4f hexanuclear quadruple-stranded coordination cage Zn₂Er₄was obtained through the assembly of ligand H₅L¹with Zn（II）and Er（III）ions.The structural analysis showed that Lewis acid sites in Zn₂Er₄cage are mainly located in the rare earth metal ion Er（III）.The catalytic performance of the heteropolynuclear coordination cage Zn₂Er₄catalyst for the three-component aza-Darzens reaction of substituted aniline,formaldehyde and ethyl diazoacetate was investigated,and the catalytic mechanism in the coordination cage was proposed.In chapter 3,a nonsymmetric acylhydrazone ligand H₅L²was designed and synthesized by changing the terminal group based on ligand H₅L¹.A 3d-4f decanuclear coordination cage Zn₄Eu₆was obtained by assembly the ligand H₅L²with Zn（II）and Eu（III）ions.Zn₄Eu₆cage have more Lewis acid sites and a larger cavity compared with Zn₂Er₄,which is beneficial to the entrance and reaction of the reaction substrate 4-tert-butylaniline with a larger size.The heterogeneous catalytic performance of coordination cage Zn₄Eu₆catalyst for the three-component aza-Darzens reaction of substituted aniline,formaldehyde and ethyl diazoacetate was studied in detail,and the synergistic catalytic mechanism was proposed.In chapter 4,a 3d-4f decanuclear Zn₄Sm₆coordination cage,which is similar to Zn₄Eu₆cage,was successfully synthesized based on nonsymmetric acylhydrazone ligand（H₅L²）by assembly with Zn（II）and Sm（III）ions.Its catalytic performance for the Friedel-Crafts alkylation of indole compounds and reactive aldehydes was investigated in detail,and the synergistic catalytic mechanism of the heterpolynuclear coordination cage as a microreactor was analyzed.In chapter 5,a binuclear complex Nd₂and a 2s-4f tetranuclear complex Li₂Nd₂were obtained by assembly the ligand H₅L²with Nd（III）and Nd（III）/Li（I）,respectively.Binuclear Nd₂and tetranuclear sandwich structure Li₂Nd₂as catalysts to promoted three-component Povarov reactions of aniline,benzaldehyde and vinyl ether were investigated.The selectivity and universality of the substrates were carried out,and the catalytic mechanism of three-component Povarov reactions was proposed.The results showed that Li₂Nd₂had high catalytic activity with high yield and specific selectivity,especially for the reaction of aniline,benzaldehyde and vinyl ether or dihydropyran.In chapter 6,a pair of chiral polydentate carboxylic acid ligands S-H₄L and R-H₄L were designed and synthesized by oxalyl chloride monoethyl ester combined with chiral cyclohexanediamine.A 3D chiral lanthanum-based MOF(S-La₁₆),a 2D chiral lanthanum-based MOF（R-La₄）,and a pair of chiral dysprosium-based MOFs（S-Dy CMOF and R-Dy CMOF）were obtained by self-assembly.The catalytic activities of S-La₁₆and R-La₄for the one-pot three-component Biginelli reaction were studied,and the reaction process were discussed.In chapter 7,the research of the thesis is systematically summarized and prospected.