Photoliminescence And Chiral Seperation Study Of Silver And Its Alloy Nanoclusters

Metal nanoclusters（Metal Nanoclusters）are transition materials between discrete metal atoms and plasmonic metal particles,generally composed of several to hundreds of atoms with size ranges around 1-3 nm.Due to their unique physicochemical properties（such as photoluminescence,chirality,catalytic,and electrochemical properties）,nanoclusters have attracted widespread attention in recent years.Compared with traditional metal nanoparticles,metal nanoclusters have precise compositions and structures,providing an ideal platform for studying the structure-function relationship of metal nanoclusters.This article focuses on the synthesis,characterization,photoluminescence,and chiral separation of silver and its alloy nanoclusters co-protected by thiol/phosphine ligands.By controlling experimental conditions such as organic ligands,metal types,and reaction time,a series of silver and its alloy nanoclusters were prepared.The structure,photoluminescence,and chirality of metal nanoclusters were explored and discussed using characterization and analysis techniques such as single-crystal X-ray diffraction（SC-XRD）,electrospray ionization mass spectrometry（ESI-MS）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy-energy dispersive spectroscopy（SEM-EDS）,ultraviolet-visible absorption spectroscopy（UV-vis）,photoluminescence spectroscopy（PLS）,transient absorption spectroscopy（TA）,nuclear magnetic resonance spectroscopy（NMR）,thermogravimetric analysis（TGA）,and circular dichroism spectroscopy（CD）.The main research contents are as follows:1.We synthesized the Au₁₀Ag₁₇（TPP）₁₀（SR）₆Cl₅(abbreviated as Au₁₀Ag₁₇)alloy nanoclusters co-protected by triphenylphosphine（PPh₃,abbreviated as TPP）and3,5-bis（trifluoromethyl）phenylthiol ligands using metal doping.The structure was confirmed by SCXRD,XPS,and SEM-EDS.By comparing the structure with the reported luminescent Au₁₂Ag₁₃nanoclusters,we found that the former has an additional Ag（PPh₃）（SR）shell structure.Further ultrafast dynamics show that photoluminescence（PL）quenching of Au₁₀Ag₁₇is caused by the energy/charge transfer from metal core to Ag（PPh₃）（SR）shell structure,which causes the quenching of phosphorescence.This work provides theoretical guidance for revealing luminescent mechanism of clusters and high-intensity luminescent nanoclusters.2.We synthesized Ag₄₀nanoclusters co-protected by acetate（CH₃COO^-）and p-tert-butylbenzenethiol（HSCH₂Ph C₄H₉,abbreviated as TBBM）ligands using the size-focusing method.The molecular formula of Ag₄₀（TBBM）₂₀（CH₃COO）₁₂(abbreviated as Ag₄₀)was determined by SC-XRD,SEM-EDS,XPS,NMR,and TGA.The study shows that the cluster undergoes rapid chiral enantiomer structure transformation in solution.By controlling the conversion process,we successfully converted the racemic Ag₄₀crystal（triclinic system,P-1 space group）into the homochiral Ag₄₀crystal（orthorhombic system,P2₁2₁2₁space group）.The homochiral Ag₄₀crystal was successfully amplified by the seed growth method,and the chirality of the amplified crystal was consistent with that of the initially added crystal seed.In addition,Ag₄₀was used as a chiral detector to detect the content and ee values of chiral carboxylic acid molecules.This work provides new perspectives for chiral conversion,separation,origin and related applications of nanoclusters.3.We synthesized a series of M₁Ag₁₄（M=Pt/Ag）alloy nanoclusters co-protected by thiol and phosphine ligands and the structure of the series clusters were also determined by SC-XRD.The study shows that ligand effects and metal doping effects have an impact on the structure and optical properties of the clusters.The PLQY of three clusters depend on the distance between the Ag atoms in the shell and the Ag atoms in the core.Moreover,the PLQY of Pt₁Ag₁₄（SPh）₆（P（4-Me O-Ph）₃）₇nanoclusters respectively are 52 times and107 times that of Pt₁Ag₁₄(SPh^3.5-（CF₃）₂)₆（PPh）₈and Pd₁Ag₁₄(SPh^3.5-（CF₃）₂)₆（PPh）₈nanoclusters,respectively.The luminescence intensity is determined by the coordination loss of the shell Ag atom and ligand-to-metal electron transfer（LMCT）.