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Preparation And Optical Properties Of Silver And Copper Clusters Protected By Sulfur-containing Ligands

Posted on:2021-02-22Degree:MasterType:Thesis
Country:ChinaCandidate:Q Q SunFull Text:PDF
GTID:2381330602472635Subject:Inorganic Chemistry
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In recent years,monetary metal clusters as a new class of functional materials have attracted extensive attention due to their precise molecular structure and independent size distribution,interesting physicochemical properties,and potential applications in biomedicine,chemical sensing,catalysis,and nanotechnology.The introduction of X?ray single crystal diffraction method has realized the structure-activity relationship of metal clusters at the atomic level,which has also greatly encouraged researchers to make directional synthesis of functional currency metal clusters by tailoring and designing its size and structure.To date,a large number of metal clusters have been synthesized,most of which are mercaptan or phosphine ligand protected Au clusters.Compared with Au nanoclusters,the coordination structure of Cu clusters is more complex,which increases the possibility of synthesizing a large number of new copper clusters.Although the structure of Cu clusters are very attractive,they are quite unstable in air due to the easy oxidation of Cu(I),thus hindering their practical applications.For silver clusters,their clusters stability is also very poor and the current research about them mainly focuses on the low oxidation state of silver clusters and the performance of silver clusters at low temperature.Based on the above content,this paper mainly focused on the following two parts:1.Taking advantage of the ligand p-fluorinated phenylthiol(L1)and adding the bisphosphonate ligand dppp(1,3-bis(diphenylphosphino)propane)and silver benzoate in the solution system of DMI and CHCl3,we synthesized a novel silver cluster co-protected by mercaptan and phosphine ligands via a mild solvent method:[Ag50S7(L136(dppp)6]·4·DMI(Ag50?solvents),and named Ag50?solvents that completely lost its DMI solvent molecules a s 1.Interestingly,when the temperature changes from 113-413 K or the pressure changes from 1 atm to 7.5 GPa,the optical band gaps of 1 showed a decreasing trend,accompanying by reversible thermochromic and piezochromic phenomena.We tracked the change process of the color of compound1 with the temperature.As the temperature rose,the crystals gradually changed from the original yellow to red and finally to black red.Moreover,the corresponding UV?vis solid absorption spectra of compound 1 with variable temperature showed the trend of redshift.The powder X?ray diffraction and thermogravimetric analysis showed that the structure of compound 1 did not collapse during the process of heating and cooling.Then,the color of compound 1 was traced with the change of pressure.With the increase of pressure,the crystals color gradually changed from the original orange to red and finally to an opaque dark red.The corresponding pressure dependent UV?vis solid absorption spectra of 1 showed a red-shift trend.In addition,the pressure dependent Raman spectra of compound 1 were tested.By comparing the Raman spectra before and after pressure,the Raman peak remained almost unchanged,indicating that there was no phase change during pressure.2.Taking advantage of the ligands tert-butyl mercaptan,the corresponding auxiliary ligand 2,6-bis-diphenylphosphanyl-pyridine(L2)and three dithiocarbamate ligand:carbazole-9-carbodithioate(L3),R-2-(diphenylhydroxymethyl)pyrrolidine?1-carbodithioate(L4)and S-2-(diphenylhydroxymethyl)pyrrolidine-1-carbodithioate(L5),we successfully obtained four silver,copper nanoclusters with accurate atomic size via one?pot method.They are Ag10(CF3COO)4tBu S)6(L22(2),Cu8(L34tBu S)4(3),R-Cu8(L46(PF62(4)and S-Cu8(L56(PF62(5)respectively.The compounds 4 and5 are enantiomers.Moreover,the compound 2 has the property of photoluminescence both solid and solution at room temperature,which emits yellow-green fluorescence.The corresponding fluorescence spectra have been tested.The compound 3,4 and 5 are all eight-core copper clusters.
Keywords/Search Tags:Silver cluster, Copper cluster, Thermochromism, Piezochromatism, Enantiomers
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