| Monolayer-ligand-protected metal nanoclusters often have diverse atomically precise structures,smaller size,unique physical and chemical properties,and have been extensively researched and applied in the fields of biosensing,organic catalysis and quantum computing.Especially in the past two decades,significant progress has been made in the syntheses,structures and characterizations of monolayer-ligand-protected metal nanoclusters.However,there are still big challenges in achieving accurate synthesis of metal nanoclusters with high yield and high stability and clarifying the reaction mechanism.Therefore,it is of far-reaching significance to study how to realize the controllable preparation of metal nanoclusters.This thesis focuses on the synthesis and characterization of gold and silver nanoclusters protected by thiols and phosphines.In the first chapter,the research progress of metal nanoclusters protected by monolayer ligands,especially gold and silver nanoclusters protected by thiol and phosphine,is briefly introduced;In the second and third chapters,the synthesis,structure and related properties of silver nanoclusters protected by thiols and monodentate/bidentate phosphine ligands are studied in detail;Chapter 4 studies the synthesis and related properties of gold nanoclusters protected by thiols and phosphines;Chapter 5 briefly summarizes the research of gold and silver nanoclusters in this thesis,and looks forward to the future research direction and content of this topic.The main contents are as follows:(1)Silver nanoclusters protected by thiols and monodentate phosphinesFirstly,a mononuclear Ag(I)complex[Ag(PPh3)3]CF3SO3(compound 1)was synthesized,and the strategies were adjusted on this basis to obtain Ag14(4-FPh S)12(PPh3)8(compound 2)with photoluminescence properties under the co-protection of triphenylphosphine and 4-fluorothiophenol ligands.Then,while keeping the metal atoms and coordination atoms in the main skeleton unchanged,we adjusted the types of thiol and phosphine ligands,and explored the influence of the electronic effects of the substituent groups on the benzene ring of the ligands on the cluster structure and properties.A series of Ag14 nanoclusters were obtained,including Ag14S0.06(4-ClPh S)12(PPh3)8(compound 3),Ag14(4-ClPhS)12(P(4-MePh)3)8(compound 4),Ag14S(4-ClPhS)12(P(4-MePh)3)8(compound 5).At the same time,two cocrystallized silver nanoclusters,Ag14S(4-FPh S)12(PPh3)8·Ag100(4-FPh S)48(PPh3)8and(compound 6)Ag14S(4-FPh S)12(PPh3)8·Ag110(4-FPh S)48(PPh3)12(compound 7),were successfully obtained by using different silver salts as precursors,and their structure,properties and catalytic performance have been studied.Among them,FCC stacked Ag100has a three-layer core-shell structure of Ag44@Ag48@Ag8.It can be regarded as the anti-hollow-cube-shaped 33 Rubik cube,at the same time,Ag100 also contains very interesting numerical meanings.The Ag110 core in compound 7 has a four-layer core-shell structure of Ag6@Ag32@Ag60@Ag12,and the conversion rate of the oxidation reaction of dimethylphenylsilane can reach 99.69%in 8 hours.(2)Silver nanoclusters protected by thiols and bidentate phosphinesA binuclear Ag(I)complex Ag2(CF3COO)2(dppm)2(compound 8)with a bidentate phosphine participating in the coordination was synthesized,on this basis,by using different thiols and bidentate phosphines,seven silver nanoclusters co-protected by thiols and bidentate phosphines were successfully synthesized.Ag6(compound 9),Ag26(compound 10)and Ag78(compound 11)were synthesized by using dppm,dppe and dppp with increasing alkyl chain length.The effects of the alkyl chain length of the bidentate phosphine ligand on the cluster structure were preliminarily explored,and the catalytic performance nanoclusters was studied.Among them,Ag2@Ag16@Ag8 three-layer core-shell Ag26 can quickly converts dimethylphenylsilane to dimethylphenylsilanol within 20 minutes,and the conversion rate can reach 98.88%.The effects of the thiol ligand types on the core of the nanocluster were studied using different thiols and the same bidentate phosphine ligand(dpppe).Four clusters Ag14S4((CF3)2-C6H3S)8(dpppe)4(compound 12),Ag32S2(4-FPhS)24(dpppe)6(compound 13),Ag32S2(4-ClPhS)24(dpppe)6(compound 14),Ag10S2(4-ClPhS)6(dpppe)6(compound 15)with completely different structures were successfully synthesized.By using cyclohexyl mercaptan,a fully thiol-protected silver nanocluster Ag211(C6H12S)x(compound 16)was synthesized.(3)Gold nanoclusters protected by thiols and bidentate phosphinesTwo gold nanoclusters Au25(4-ClPhSH)5(P(4-MePh)3)10Cl2(compound 17)and Au11(dpph)4Cl2(compound 18),were synthesized using tris(4-methylphenyl)phosphine,1,6-bisdiphenylphosphine hexane and 4-chlorothiophenol,and their single crystal structures,spectrum,MS and stability.catalytic performance have been studied.At the same time,a preliminary study on the catalytic performance of Au25 on the catalytic reaction of silane and alcohol dehydrogenation coupling was carried out.We found that as the number of C atoms in the alcohol increases,the time required for the catalytic reaction is longer.The conversion rate of the base silane and ethanol reached 99.90%within 70 minutes.After the substrate was replaced,as the phenyl group in the silane increased,it took a long time for the complete catalysis. |
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