Synthesis And Optical Properties Of Silver And Copper Nanoclusters Protected By Thiolate Ligands

The size of nanoclusters is below 3 nm,which is a bridge between microscopic atomic or molecular and macroscopic bulk materials.Nanoclusters not only have the advantages of definite structures and molecular-like properties etc.,it is also an ideal model for studying nanomaterials at the atomic level.In this paper,we have synthesized five compounds of silver-sulfide nanoclusters(NCs)and six compounds of Cu(I)cluster-based coordination polymers(CPs)based on thiolate ligands and other phosphine or nitrogen ligands,respectively.The thesis consists of four sections:?:The research process of copper and silver clusters.? :We first obtained the racemic Ag14 nanocluster(compound 1)in acetone solvent and the enantiomers of Ag14 nanocluster(compounds 2 and 3)were successfully obtained by recrystallization in acetonitrile.Comparing the structures of compounds 1 and 4,it is found that the ?…? stacking interaction induced chirality in the compounds 2 and 3,and the non-covalent interaction between the acetonitrile molecular and the pntp-or dpph ligand promotes the homochiral crystallization of compounds 2 and 3.?:Photoswitchable arylazopyrazole-based metal clusters have become a research hotspot,but the photoisomerization behavior and photoswitchable fluorescent of silver clusters have not been exploited.Herein,the photoresponsive Ag8 clusters(compounds 5 and 6)have been synthesized with a regular Ag8 core shaped like a triangular prism with caps at both ends,which are protected by iPrPhS(or tBuPhS-),dppm(dppm=bis-(diphenylphosphino)methane)ligands and attached by 3,5-dimethyl-4-(phenyldiazenyl)-1H-pyrazole(Hazopz)-based ligands,respectively.It further demonstrated that the stability of Ag8 clusters dissolved in dichloromethane by 1H NMR and ESI-MS spectra.The trans-to-cis isomerization can be monitored easily by taking advantage of the UV-Vis absorption or 1H NMR spectra of the isomers,while the high stability of Ag8 clusters allows many switching cycles without significant decomposition.More striking,compounds 5 and 6 systems realize the effective combination of its own fluorescence and photoisomerization behavior.The trans-isomer and cis-isomer have significantly different maximum emission peaks in the solid state.?:We synthesized compounds 7-12 with Hpzt(Hpzt=pyrazine-2-thiol)ligand and the ligand-to-metal molar ratio and types of metal halides influenced the structural evolutions of 7-12.In addition,the interesting temperature-dependent photoluminescence of compound 1 and photocurrent responses of compounds 7-12 are showed.