Controllable Synthesis,Structure And Properties Of A Series Of FCC-packed Ag Nanoclusters

Sub-nanometer metal nanoscale has unique physical and chemical properties and has potential applications in chemical sensing,biomarkers,catalysis and other fields.At the same time,the clear structural composition of metal clusters can be used as an ideal platform to study the structure-property correlation.In the past few decades,nano-chemists have been developing synthetic strategies to regulate the composition,structure,and properties of metal nanoclusters at the atomic level,providing a basis for elucidating the correlations between new levels of material structure and the nucleation evolution process.By systematically studying the structure and properties of a series of atomically precise metal nanoclusters,new insights can be gained into the correlation of structural properties,as well as the size evolution and morphology.Therefore,this paper focuses on the regulation,synthesis,characterization and properties of face-centered cubic silver nanoclusters.We selected mercaptans and triphenylphosphine ligands as capping agents to regulate the synthesis.A series of Ag₁₄,Ag₂₃ and Ag₁₀₀ nanoclusters with different nucleuses were successfully prepared and their properties were studied.The main work and innovation of this paper are as follows:In the first part,we successfully obtained two kinds of face-centered cubic（FCC）configuration silver nanoclusters with different sizes through the classic"one-pot direct synthesis method"--single FCC configuration Ag₁₄（PET）₁₂（PPh₃）₈ and two FCC assembly configuration Ag₂₃(SC₆H₄^4-OCH₃)₁₈（PPh₃）₈ nanoclusters.These two silver nanoclusters form a group of comparable systems with Ag₁₄(SC₆H₃^3,4F₂)₁₂（PPh₃）₈ and Ag₁₄(SC₆H₃^3,4F₂)₁₂（PPh₃）₈ nanoclusters reported by others.In combination with experimental and theoretical analysis,we found that the geometric structure of Ag₁₄ and Ag₂₃nanoclusters protected by alkyl mercaptan PET has larger nuclear size and stronger Ag-S interaction than that of the equivalent silver nanoclusters protected by aryl mercaptan.In terms of electronic structure,there is no significant difference in HOMO-LUMO gap between the two groups of face-centered cubic silver nanoclusters,and the difference in spectral absorption intensity is mainly due to the contribution of aromatic ringπorbitals to the frontier orbitals.This work provides an insight into the structure and optical properties of ligand-regulated face-centered cubic silver nanoclusters.In the second part,we through the screening experiment condition and the continuous improvement of synthesis,was synthesized successfully by far the greatest face-centered cubic silver clusters-[Ag₁₀₀(SC₆H₃^3,4F₂)₄₈（PPh₃）₈]（PPh₄）,by X-ray single crystal diffraction（SC-XRD）,electrospray ionization mass spectrometry（ESI-MS）,electron paramagnetic resonance（NMR）spectroscopy,nuclear magnetic resonance spectrum（EPR）,so on the many kinds of test and analysis methods of the composition of the product and its phase mono-dispersity were characterized,The electronic structure of the cluster was verified by density functional theory（DFT）.It is worth noting that the geometry of[Ag₁₀₀(SC₆H₃^3,4F₂)₄₈（PPh₃）₈]（PPh₄）with face-centered cubic configuration does not conform to the previous structure prediction model based on the existing FCC configuration Ag nanoclusters.The structure of the clusters is helpful to extend the Ag nanocluster family of FCC configuration and provide new insights on the nucleation growth and evolution of Ag clusters.