Study On The Structure,fluorescence And Magnetic Of Lanthanide Complexes Based On In Situ Reaction

In recent years,Ln-based complexes have been intensively studied due to their great application in many fields(such as magnetism,light,electricity,catalysis and biological activity,et al).Particularly,the construction of refreshing multifunctional Ln-based complexes with excellent properties and novel topological connections has become a diligent goal of coordination chemists.In this paper,a series of different types of in-situ reactions with aldehydes and amine-derived ligands under solvothermal conditions were used to construct four types of Ln-based complexes,which with different nuclear numbers,shapes and connections.And their potential properties were explored,mainly including optical and magnetic properties.In addition,the formation process of some complexes were studied by crystallography and high-resolution electrospray mass spectrometry(HRESI),and their possible self-assembly mechanism were also proposed.The full text is divided into five chapters:The first chapter is the introduction,which expounds the significance of this thesis and the research background and progress in related fields.Among them,emphasis on the introduction of hydrogen-bonded organic frameworks and metal hydrogen-bonded organic frameworks,the application of multinuclear Ln-based complexes in the fields of optical sensing and molecular magnetism,and the research progress on the assembly mechanism of Ln-based complexes.In chapter 2,a series of Dy-HOFs([Dy(L^1-R)(L^2-R)]_n,R=H(1),Cl(2),Br(3),CH₃(4),F(5))were prepared by the reaction of salicylaldehyde,5-chloro-salicylaldehyde,5-bromosalicylaldehyde,5-methyl salicylaldehyde and5-fluoro-salicylaldehyde with 2,2-dimethyl-1,3-propylenediamine and Dy Cl₃?6H₂O respectively.This series of Dy-HOFs can remain highly stable after immersing in different p H(p H=1-13)solutions for 20 days.Furthermore,these Dy-HOF samples which immersed in an acidic solution can exhibited solid-state fluorescence"turn-on"behavior,and the fluorescence intensity increase with the increasing acidity.The anti-counterfeiting test results show that the ink made from the samples before and after acid treatment have showed double anti-counterfeiting performance under the UV light.The ion sensing experiments show that Pb(II)ions can be specifically recognized by the sample solution which has immersed in acid.And the magnetic properties show that all the Dy-HOFs display obvious frequency-dependent behavior in zero field.In chapter 3,two caged nanoclusters(Dy₁₄ and Tb₁₄)were synthesized by the reacion of o-vanillin,2,2-dimethyl-1,3-propylene diamine and Dy(NO₃)₃?6H₂O and Tb(NO₃)₃?6H₂O at 80?,respectively.The above Ln₁₄ were formed by two relatively twisted disc-shaped Ln₇ molecules and connected by strong hydrogen bonds.Combined with mass spectrometry to tracke the reaction process,we speculated that theclusteringmechanismmightbe:H₂L~1?Dy L~1?Dy₂L~1?Dy₄(L~1)₂?Dy₇(L~1)₃?Dy₁₄(L~1)₆.In addition,considering that their large cavity volume can facilitate the interaction between host and guest,we tested their selective photoresponse to various heavy metal ions by using Dy₁₄ and Tb₁₄ as probes.Interestingly,Dy₁₄ displaied a selective luminescence response to Cd(II)ions,while Tb₁₄ performed a selective luminescence response to Ag(I)ions.In chapter 4,the largest dish-shaped dysprosium nanocluster Dy₁₉ were synthesized under solvothermal conditions by using salicylaldehyde,5-chloro-salicylaldehyde and 5-methylsalicylaldehyde as ligands with1-amino-2-naphthol hydrochloride and Dy Cl₃?6H₂O respectively.Based on the structural characteristics of these Dy₁₉,we proposed two possible assembly mechanisms,which are as follows:Dy₁?Dy₇?Dy₁₃?Dy₁₉(planar epitaxial growth mechanism)and Dy₁?Dy₁₂?Dy₁₈?Dy₁₉(planar internal growth mechanism).In chapter 5,a tetraprosium cluster(11)was synthesized by the reaction of o-vanillin,1-amino-2-naphthol hydrochloride and Dy Cl₃?6H₂O under solvothermal conditions.And two other tetraprosium clusters(12 and 13)with the same structural framework as 11 were also obtained by reacting salicylaldehyde and5-methylsalicylaldehyderespectivelywithDy(NO₃)₃?6H₂Oand2,2-dimethyl-1,3-propanediamine.Among them,11 was constructed by mixed ligands,which prompted us to explore its assembly mechanism,and finally speculated that the possible mechanism might involved:L^a+L^b+L^c?L~6/L~7?Dy₁?Dy₂?Dy₃?Dy₄.However,both 12 and 13 belong to a single ligand coordination cluster.Due to the difference in topological connection mode,their molecular magnetic performance is quite different.