The Synthesis,Structural Analysis And Optical Properties Of Silver-sulfur Molecular Clusters

Silver-sulfur clusters have attacted much attention with many scientists due to their diverse geometric topology structures or special coordination mode and nonlinear optics and luminescenceproperties.However,the formation of silver-sulfur clusters generally involves a multi-component assembly process,so its synthesis is difficult.Changing different ligand types?including mixed ligands?and using anion templates have been proved that are effective ways to synthesize silver-sulfur clusters.In this paper,it attempts to use two methods to prepare multiple silver-sulfur clusters.Structures are characterizated by the following basic characterization,such as single-crystal crystallography,mass spectrometry,and element analysis.The optical properties of clusters are further determined by Solid-state UV/Vis absorption spectra and luminescent thermometer.It is mainly divided into three parts in the paper.A six-cores cluster,[Ag?dmmp?]6·CH3OH?1,dppm=4,6-dimethyl-2-mercaptopyrimidine?,is assembled by using 4,6-dimethyl-2-mercaptopyrimidine and soluble silver salt.The structure analysis shows that the skeleton structure of 1 is a malformed-octahedral configuration which formed by the coordination of six silver ions and mercapto-pyrimidine ligands.Crystal accumulation shows that there are two types of?-?interactions between molecules and between molecules,and it has a strong fluorescence at room temperature.Two silver-sulfur chalcogenide supertetrahedral clusters?SCs?are synthesized by thiol pyridine and silver salt,one as discrete zero-dimensional?0D?V3,4-typecluster[?H₂O?₂Ag₁₀?PyS?₈?HPyS?₄?Hmba?₄·2H₂O] ?2,HPyS=1H-pyridine-4-thione;H₂mba=2-mercaptobenzoic acid?and the other as one-dimensional?1D?zigzag chain extended by alternating V_3,2-type clusters[Ag₁₀?PyS?₆?HPyS?₁₁·sba·2PF₆·10H₂O]?3,H₂sba=2-sulfobenzoic acid?.The notation V_n,m?where n is the number of metal layers,and m is the number of vacant corners?is used to describe a new series of vacant-corner SCs.The semiconductor bandwidth of 2 and 3 is separately 2.32 eV and 2.26 eV compared with typical SCs.They both are significantly lower than of that previously reported d¹⁰ metal SCs.The results show that these two SCs can significantly reduce the band gap of the semiconductor,so they are more suitable for the application of visible light regions.In addition,2 and 3 also have characteristics of variable temperature fluorescence.The angular silver sulfur SCs are not only enriched the study of metal sulfur tetrahedral clusters,but also made up for the vacancy of IB metal sulfur SCs.It also provides reference value for the synthesis of group 11 metal sulfur SCs.The 78 nuclear silver-sulfur nanoparticles with multi-layer shell structure,[SO₄@Ag₇₈S₁₅?CpS?₂₇?CF₃CO₂?₁₂]?CF₃CO₂?₇ ?4,CpSH=cyclopentanethiol?,were synthesized by introducing anion template sulfate(SO₄^2-)into the precursor cyclopentyl sulfide polymer.In a similar process,we only get a cage structure 46nuclear silver cluster{(Mo₇O₂₄)^6-@[Ag₄₆?SC₅H₉?₂₈?CF₃COO?₁₀]}²⁺?5?by using a large molybdate(Mo₈O₂₆)^4-instead of SO₄^2-.78-nucleus silver-sulfur nanocluster is a globular double-layer structure and the outer diameter of the sphere is about 1.6 nm without the outer ligand.The most striking structural motif within the cationic cluster is that the inner 18 silver atoms arranged to elongated triangular orthobicupola.The Ag18 shell combined with sulfate anion is nested by the Ag60 shell.In contrast,bulky POM anions((Mo₇O₂₄)^6-)only led to the isolation of 46-nucleus silver cluster Ag₄₆with core-shell configuration.The solid energy level band gap of 4 is 1.5 eV,which can be used as a potential narrow band gap semiconductor.The energy level band gap is significantly reduced by about 1.0 eV compared to the energy level band gap of the synthetic precursor.The results indicated that multishell structure and the incorporation of sulfate anion in 4 led to a dramatic decrease of the band gap,which makes this kind of cluster more suitable for application in the visible and near infrared region.