Hierarchical Self-Assembly And Chiral Transfer Of Anion Coordination Helicate

Self-assembly is one of the most essential contents in bioscience.Non-covalent interactions are used precisely to form highly ordered and functional assemblies in living organs.Two pairs of complementary nucleobases constitute DNA double helix structure for the storage and transmission of genetic information,coiled and self-assembled into proteins with a certain spatial structure through multiple levels of self-assembly,playing a specific function in life.Drawing inspiration from the nature and learning to simulate these helical structures and multistage assembly methods,discrete supramolecular assemblies,including double helicate and triple helicate,formed by self-assembly of molecules driven by non-covalent forces are a research hotspot in supramolecular science in recent years.These self-assembled discrete systems are not only aesthetically significant in structure,but also can be used to prepare functional supramolecular systems or materials.The anion coordination driven assembly strategy is an emerging way to build supramolecular architectures without metal ions developed in recent years.For example,based on the directionality and saturation between o-phenylene diurea(or polyurea)ligands and oxygen-containing acid(phosphate,sulfate,etc.),a series of well-defined discrete assemblies have been constructed.The previous work of our research group shows that the helicate structure constructed by anion coordination can have different properties by changing the intermediate linker(methylene,4,4'-diphenyl methyl,etc.).In this thesis,based on the A₂L₃type("A"for anion and"L"for ligand)triple helicates constructed by ligands with 4,4'-diphenyl methyl linker,a series of different terminal groups were designed to investigate the influence of terminal groups on structural stability and functionalization;to study the chiral transcription from chiral guests to the triple helicate through host-guest interaction and to the hierarchical assemblies by a hierarchical assembly.This research further summarized the influence of different factors on the construction of well-defined discrete structure by anion coordination and paves a way for the further construction of functional system by using hierarchical assembly.This paper is mainly divided into three chapters:The first chapter is an introduction,which mainly introduces the self-assembly and chiral assembly of supramolecular system.The main driving forces for the construction of the helical system and the research developments and applications of the chiral helical structure based on metal coordination are reviewed.Typical examples of hierarchical assembly of discrete structures are briefly introduced.Development of anion coordination driven helical structure is reviewed.Finally,all these lead to the topic selection and research significance.The second chapter depicts the further exploration of the anion coordination basedtriple helicate established by our group and the preliminary exploration on the supramolecular chiral self-assembly.This part mainly involves the synthesis and basic characterization of C₂-symmetric di-(diurea)ligands with 4,4'-diphenyl methyl as linker,and the characterization and chiral induction of the triple helicate structures formed by the coordination between ligands and phosphate.The third chapter is the hierarchical chiral self-assembly,which mainly introduces the synthesis,basic characterization,triple helicate construction,chiral induction and hierarchical self-assembly of C₂-di-(diurea)ligands with 4,4'-diphenyl methyl as the linker and three long carbon chains as the terminal group.Nuclear magnetic resonance spectroscopy(NMR)was used to prove that a series of ligands formed triple helicate,and circular dichroism(CD)was used to characterize the induction of chiral guests to supramolecular chiral helices.The long alkyl chain ligand L was successfully applied to form a nanoscale helix structure by hierarchical chiral self-assembly.