Synthesis And Characterization Of Low-nuclear Simple Metal Nanoclusters

A cluster is a fluorescent,water-soluble,molecular-scale aggregate composed of several,tens,or even hundreds of atoms.Its particle diameter is generally below 2 nm,bounded between atoms and nanoparticles.The motivation for cluster research of nanoclusters was to understand how the properties of substances vary when altering their size,shape,and composition.Over the past few decades a lot of papers have been published in this field,which not only provide a good understanding of the evolution from clusters to crystals,but also reveal many unusual properties of nanocrystals deriving from their specific size effect.Nowadays nanoclusters have developed to be an interdisciplinary field,across physics,chemistry,materials science,biology and medicine.However,the current research field of nanoclusters still faces some urgent problems,such as the controllable preparation of high-yield nanoclusters and the exploration of growth mechanism.In this paper,we select gold and silver metal salts as precursors,and react with them with thiols,halogens,organophosphorus ligands and alkyne ligands.The effects of ligand steric hindrance and electron effect on the structure,core and properties of the cluster were explored.The controllable preparation of the data nanoclusters was realized,and the growth mechanism of the nanoclusters was initially explored.The main research work is as follows:1.Modulating the species of substituents in triphenylphosphine?PPh₃?and thiol ligands,the phosphine ligands with electron-withdrawing groups were investigated for the diicosahedron[Au₂₅?PPh₃?₁₀(SC_n H_2n+1)₅Cl₂]²⁺(bi-Au₂₅)the effect of cluster structures.Specifically,?F-Ph?₃P and derivatives of thiol ligands,were seected to react with Au substrates.Through a simple one-step synthesis method,we constructed three nanoclusters[Au₂₄Cl?SR?₅[?F-Ph?₃P]₁₀Cl₂],Which R is-CH₃?1?,p-CH₃Ph-?2?and p-CH₃Ph-?3?.We discovered that the structures of the three are connected by Cl atoms to two icosahedrons(Au₁₂Cl)in the form of common vertices,whrere the Cl atoms of the common apex are coordinated with the surrounding 12 Au atoms.The example that site Au is replaced by Cl in Au₂₅5 cluster was first discovered.The Au-Cl bond length is approximately 2.785?-2.840?,Which significantly increases compared to the general Au-Cl bond.Additionally,a nanocluster of Au₁₁Cl?PPh₃?₇Cl₃ was synthesized by the same method using PPh₃.Compared the common phosphine-protected Au₁₁,in which one of the Cl atoms is coordinated with four Au atoms,and the Au-Cl bond length is 2.75?-2.805?.2.Substates of phenylacetylene containing an electron-donating group and an electron-withdrawing group,OCH₃-PhC?CH and CF₃-PhC?CH were selected to react with different bidentate phosphine ligands and metal silver salts.We intended to investigate the effect of adding a substituent on the para position of phenylacetylene on the the number and structure of the cluster,and resultantly obtained two silver nanoclusters Ag₂₅?MeO-PhC?C?₂₀?dpppe?₃?CF₃SO₃?₃?5?and Ag₆?dppe?₃?CF₃-PhC?C?₅?6?,respectively.Through the analysis of the single crystal structure,we found that the electronic effect of the para-substituent of the acetylene ligand has a significant effect on the structure of the cluster?nucleus,core,etc.?.Notably the substituents on the acetylene ligand have an effect on the structure of the cluster,and the ligand containing the electron-donating group is relatively better crystallized during the synthesis than the electron-withdrawing ligand.3.In the process of cluster synthesis,duing to the influence of temperature,ligand,and crystallization,it produced some simple metal complexes,intermediates and other substances.The structure was measured by single crystal diffractometer,which were Au₄Cl₄?dppe?₂?7?,Ag₂?dppp?₂?NO₃?₂?8?,Ag₂?dpph?₂?NO₃?₂?9?,Ag?2-mna??PPh?₃?10?,Ag?dppf??NO₃?OH?11?.It laid a foundation for the follow-up mechanism inquiry process.