| Metal nanoclusters are the relatively stable aggregates composed of a few to hundreds of metal atoms protected by organic ligands.Their size are generally between 1-3 nm and they have attracted considerable attention of material scientists due to their potential applications in catalysis,detection and biological medical aspects.As we know,many gold and silver nanoclusters protected by organic ligands have been synthesized and well characterized.However,it can be challenging to achieve the rational design and synthesize of atomically precise metal nanoclusters.Based on the above consideration,a series of gold silver nanoclusters were synthesized by adjusting the organic ligands and designing reasonable experimental strategies.The core structure,coordination mechanism,stability and catalytic performance of the nanoclusters were analyzed in detail.The main contents are as follows:1.Seven atomically precise alkyne-protected gold nanoclusters were synthesized by adjusting alkyne ligands,which are Au8(Ph-Ph C?C)2(dppp)4(1),Au11(4-NO2-Ph C?C)3(PPh3)7(2),Au13(4-R-Ph C?C)2(dppe)5(R=Me(3),Et(4),F(5),Ph(6))and Au20(4-Me OPh C?C)2(PPh3)8Cl4(7).The core of cluster 1 is a diedge-bridged bi-tetrahedral cluster core geometry,cluster 2 is an incomplete icosahedron,cluster 3-6 is an icosahedron,and cluster 7 could be viewed as the fusion of two Au11incomplete icosahedra.Structure analysis indicates that the structural unit of low-nuclear nanoclusters can be assembled into high-nuclear clusters.The provided a new way for the design and synthesis of high-nuclear nanoclusters.Importantly,catalytic performance was studied with these seven nanoclusters.The experimental result indicated that clusters 1-7 can selectively oxidize silane efficiently and have strong substrate adaptability.In addition,clusters 1-7 also exhibit high catalytic activities for the selective oxidation of silanes into silanols using water as an oxidant without the use of organic solvents.Unexpectedly,cluster 7 shows superior catalytic performance than clusters 1-6.The main reason is that the structure of cluster 7 contains uncoordinated gold atoms which makes the reaction substrate have full access to the gold atoms.These results point out the direction for the study of Au nanoclusters catalysis.2.In the presence of anions,two phosphine-protected gold nanoclusters[Au39(dppp)8Br5]2-(8)and Au13(dppe)5Br2(9)were synthesized by two-step reduction.Structure analysis indicates that the Au39core of cluster 8 presented the arrangement of Au1@Au17@Au21.The innermost layer and the secondary outer layer can be regarded as a"Lotus"with a core and"petal"formed by four edge-shared pentagonal pyramid.Cluster 9 is a typical structure of icosahedron and Au13 core can be regarded as a arrangement of Au1@Au12.It was reported that so far cluster 8 has the largest number of phosphine-protected Au nanocluster.Two phosphine-protected gold nanoclusters with different structures greatly revealed that organic ligands play a key role in the construction of gold nanoclusters.3.A zero dimensional silver nanocluster Ag164(SC3H7)50(10)was successfully constructed by reducing the precursor.Single crystal structural analysis indicates that cluster10 comprises a complex core-shell structure.Innermost layer is a novel and interesting "Cluster of Cluster" model composed of three point-shared Ag13 icosahedrons.The secondary layer is a sandwich structure of Ag11@Ag36@Ag11.The Outermost is a cage formed by the staggered arrangement of Ag and S atoms.In addition,catalytic experimentation of cluster 10for the selective oxidation of silanes revealed the passivation effect of thiols.Overall,this work enriched the structural diversity of high nuclear silver nanoclusters and proved that ligands can greatly affect the catalytic performance of silver nanoclusters. |
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