Chiral Copper Nanocluster-based Assemblies:Regulation Of Supermolecular Chirality And Circular Polarization Luminescence

As a bottom-up strategy,supramolecular self-assembly overcomes the design barriers associated with the preparation of traditional nanoscale molecules.Due to the dynamic nature of non-covalent interactions that bind the molecules together,assemblies can be constructed with adaptability,tuneability,and stimulus responsiveness.When self-assembly tends to the asymmetric molecular stacking pattern,the resulting structure will be supramolecular scale chirality,i.e.supramolecular chirality.Supramolecular chirality is an important field in supramolecular assembly.Chiral metal nanoclusters(NCs)have attracted more and more attention due to their fascinating chiral structures and luminous properties.Supramolecular assembly strategy is used to regulate chiral properties of chiral metal NCs,which provides a nanoscale platform for understanding chiral transfer at organic-inorganic interface.The strategy of introducing achiral compounds to bind chiral compounds to produce co-assemblies has been used to regulate supramolecular chirality.In general,there are a variety of non-covalent interactions between achiral compounds and chiral compounds.These non-covalent interactions combine multiple components into a system with an ordered structure,and on the basis of this,some interesting phenomena such as chiral amplification,transfer and inversion can occur.In this paper,we select two kinds of glutathione-modified copper NCs with different fluorescent colors,chiral copper NCs are relatively less studied.The processes of chiral transfer and structural transformation during their co-assembly with chiral molecules are studied in detail,which has important academic research significance for exploring supramolecular assemblies,especially chiral assemblies.The main content of this paper is divided into the following four parts:In Chapter 1,we introduce the development process of supramolecular chemistry,and focus on supramolecular self-assembly which is an important branch of supramolecular chemistry,emphasize the non-covalent force in supramolecular self-assembly and the regulation of external stimuli on supramolecular assembly.The concepts of chirality and supramolecular chirality are introduced,and the way of the generation of supramolecular chirality is highlighted.The research progress of chiral optical materials,that is,circularly polarized luminescence(CPL)materials,is briefly introduced.The concept,properties and applications of metal NCs are introduced,the research significance of chiral metal NCs is introduced,and the current chiral regulation of chiral metal NCs is summarized.Finally,the research content and significance of this thesis are presented.In Chapter 2,the supramolecular hydrogels based on chiral copper NCs are successfully fabricated by achiral components,and the chirality of system was controlled.We selected a chiral copper nanocluster(G-SH-Cu NCs)showing blue emission and introduced chiral polyethyleneimine(PEI)and polyoxometalates(Na9(EuW10O36)·32H2O,denoted as EuW10)into the aqueous solution of G-SH-Cu NCs to obtain supramolecular hydrogels.The chiral inversion and recovery of G-SH-Cu NCs were realized by coordinating the intensity of electrostatic interaction and hydrogen bond interaction in the multi-component system.The general application of our method was proved by changing the types of amine substances and polyoxometalates.In Chapter 3,on the basis of the previous topic,we found that although the chiral regulation of supramolecular system is achieved through the introduction of achiral components,it leads to the reduction of the asymmetric factor(glum)value.We hope to use the spatial order of liquid crystals(LCs)to achieve the amplification of CPL by ordered arrangement of G-SH-Cu NCs.The supramolecular chiral LCs system with CPL properties was constructed by the combination of polyoxyethylene tert-octylphenyl ether(TX-100)and chiral G-SH-Cu NCs.The amplification of CPL is realized through the chiral transfer and the ordered regulation of LCs.By adjusting the mass ratio of TX-100 and G-SH-Cu NCs,the strength of the non-covalent interaction is regulated to achieve the chiral inversion.In Chapter 4,We select a chiral copper nanocluster(R-GSH-Cu NCs)showing red emission but no CPL properties.R-GSH-Cu NCs are selected as the chiral donor to study the ground state and excited state chirality of the assembly in solution by adding the chiral cationic polymer poly(allylamine hydrochloride)(PAH).The water-soluble hybrid nanostructures were formed by combining R-GSH Cu NCs with PAH through the coordination of hydrogen bonding and electrostatic.The changes of CD signal and glum value of the R-GSH-Cu NCs/PAH complexes under different CPAH were systematically studied.Meanwhile,the supramolecular chirality and CPL properties of R-GSH-Cu NCs/PAH complexes are regulated by adding hydrochloric acid(HCl)to the complexes system by changing the pH of the R-GSH-Cu NCs/PAH/H+ complexes.