Organophosphine Ligand-modified Multinuclear Silver Clusters And Property Studies

Noble metal clusters are a large family with an overall beautiful structure and elegant symmetry,and silver clusters are an important member of this family.Silver clusters with multiple coordination modes not only yield diverse structures,but also attract much attention for their potential properties in many fields such as luminescence,electrochemistry,and magnetism.Although there have been some advances in the syntheses of ligand protected silver clusters,the precise control over the number of metal atoms in kernel,the packing fashion of metal atoms and the surface coordination structures remains a long-sought issue and some detaile ligand effects are still fuzzy.Therefore,it is important to design and synthesize silver clusters with good structural features and interesting properties as well as stability.In this paper,six examples of multinuclear silver clusters were synthesized by changing the conditions of soluble silver salts as well as solvents,mainly using p-tert-butylbenzenethiol silver,p-tert-butylacetylenesilver,p-tert-butylthiol silver and methoxybenzenethiol silver as precursors and reacting with soluble silver salts,phosphine-containing ligands.The structure and composition of the complexes were characterized by a series of techniques such as single-crystal X-ray diffraction（SCXRD）,fourier transform infrared spectrometry（FI-IR）,powder X-ray diffraction（PXRD）,thermogravimetric analysis（TGA）,and ultraviolet-visible absorption spectra（UV-Vis）.The fluorescent properties,photocurrent responses and electrochemical properties of the clusters have been investigated.The main research work of this thesis is as follows:In part 1,synthesis of trinuclear silver clusters modulated by bisphosphine ligands and CF₃SO₃^-anions:[Ag₃（dppm）₃（^tBu C≡C）]（CF₃SO₃）₂（1）,[Ag₃（dppm）₃（CO₃）]CH₃OH（CF₃SO₃）·H₂O·（2）and[Ag₃（dppm）₃（Cl）₂]（CF₃SO₃）·3DMF（3）.The above three compounds were obtained by reacting different precursors with soluble silver salts as well as diphosphine ligands,in which their main backbones are composed of similar silver triangles.In the three compounds,their main body skeletons are made up by the similar Ag₃ cores shaped in a silver triangle.All the three compounds consist of three silver atoms,three bisphosphine ligands,and by the CF₃SO₃^-as an anti-counteracting anion.While the other auxiliary ligands,^tBu C≡C^-,CO₃^2-and Cl^-separately attached to the similar Ag₃ cores make them structurally different.In part 2,synthesis of octanuclear and heptadecanuclear cationic silver clusters modulated by bisphosphine ligands and CF₃SO₃^-anions:Ag₈（dppe）₄（^tBu C₆H₅S）₆（SO₃CF₃）₂（4）and Ag₁₇（dppe）₄（S）（^tBu C₆H₅S）₁₃（CF₃SO₃）₂（5）.Self-assembly of polyhedral and frog-shaped silver-sulfur clusters obtained by the reaction of silver p-tert-butylbenzenethiol as precursor with bisphosphine ligands using CF₃SO₃^-as the counterbalancing anion.The two compounds were shown to have good thermal stability.Moreover,their fluorescent and electrochemical properties were further investigated.In part 3,synthesis of decanuclear silver clusters constructed with bisphosphineligandsandsilvertrifluoroacetate:Ag₁₀（dppm）₄（S^tBu C₆H₅）₆（CF₃COO）₄·3DMAC（6）.We have obtained jellyfish-shaped silver-sulfur clusters by self-assembly in isopropanol,N,N-dimethylacetamide solution using a solvent-heated method,also using a p-tert-butylbenzenethiol silver precursor,and soluble silver salts reacting with phosphine-containing ligand.In this cluster,the internal skeleton is connected by alternating silver-sulfur bonds,and the periphery is supported by trifluoroacetate and p-tert-butylbenzenethiol as well as bisphosphine ligands.The fluorescent and electrochemical properties of the compound were also investigated.In summary,a series of multinuclear silver clusters based on biphosphine ligands have been designed and synthesized in this thesis,and their fluorescent properties,photocurrent response and electrochemical properties have been investigated to provide positive guidance for further design and synthesis of functional silver cluster materials.