| As a particular scale of matter between macroscopic and microscopic,cluster with precise atomic composition and geometric configuration is an ideal model for associating microstructure with macroscopic properties of matter.As an important branch of clusters,silver clusters with abundant structural types and diverse physicochemical properties are a new family of functional materials.It is of great scientific significance to study the synthesis and assembly mechanism of silver cluster with precise structure for establishing universal synthesis methods and promoting the practical application of silver cluster-based materials.We selected iPrSH as the main ligand and obtained a series of novel silver clusters under the guidance of anion template and geometric polyhedron principles.According to mass spectrometry,we revealed the solution assembly mechanism of several typical structures,and developed a universial synthesis method of silver clusters.The main research contents and conclusions are as follows:?:Synthesis and assembly mechanism of polyhedral silver clustersThe 180-nuclei silver cage with fullerene topology was synthesized for-the first time by using geometric polyhedral strategy,[Ag180(iPrS)90(CH3SO3)44]·46CH3SO3·34CH3OH(1).Consisting of 60 trigons,90 tetragons,12 pentagons and 20 hexagons,the quantitative relationship among vertices,faces and edges in accordance with Euler Theorem,the silver polyhedron belongs to classical convex polyhedron.This is the first synthetic molecule with the characteristics of goldberg polyhedron and its "Silver-Trigon" assembly route is revealed by mass spectrometry.A series of silver clusters with Johnson polyhedron characteristics were obtained by introducing anion template(2-6),(H3O)8[S@Ag60S14(iPrS)24(CF3SO3)14(CH3OH)4(DMF)2·2CH2C12](2);[SO4@Ag20(iBuS)10(PhSO3)8(H2O)4·2H2O]n(3);?-Mo5O18@Ag36(iPrS)18(PhSO3)12(DMF)6(4);{(nBu4NH)[?-Mo5O18@Ag36(iBuS)18(PhSO3)13(CH3OH)]}n(5);[Mo2O8@Ag30(iBuS)15(PhSO3)11(CH3OH)2(H2O)·H2O]2(6).The above structural analysis revealed the key elements of the formation of polyhedral silver clusters,which lays a foundation for the establishment of the synthesis method of such silver clusters.?:Synthesis and assembly mechanism of silver clusters of encapsulating ultrasmall silver nanocrystals Four cases of 62-nuclei silver wheels with seven fold symmetry were obtained under the condition of weak reducing agent DMF,Ag6@(MoO4)9@Ag56(iPrS)28(RSO3/NO-3)14(8-11),the core of which is Ag64+octahedron,passivated by MoO42-on the surface and nested in the shell of Ag56.This is the maximum number of MoO42-ions as template trapped in one cluster.As a contrast,two silver(?)clusters with POM as the template were obtained in the system without DMF,Mo7O24@Ag41(iPrS)19(p-TOS)16(CH3OH)-4·4CH3OH(12)and(nBu4N)15[Mo5O18@Ag36(iPrS)18(p-TOS)13.5(CH3CN)·1.5CH3CN](13).The mass spectrometry revealed the overall hierarchical cluster-in-cluster growth process.CrO42-can also be used as an anionic passivation layer to passivate Ag64+(14).The carboxylic acid ligands can construct silver pentagons by inserting silver atoms into the Ag62 shell.Successfully,three 66-nuclei silver clusters were obtained,Ag6@(MoO4)-9@Ag6o(iPrS)28(RCOO)18(15-17).Mass spectrometry confirmed that carboxylate can be easily dissociated from the silver shell.Furthermore,silver clusters are endowed with certain structural flexibility,which provides a new idea for the stimulation induced transformation of silver clusters.?:Stimulation-induced transformation synthesis and mechanism of silver clusters Using the 44-nuclei silver cluster synthesized by PhCOOAg:[Mo6O22@Ag44(iPrS)20(PhCOO)16(CH3CN)2]·2CH3CN(18)as the reactant,under the stimulation of PhCOOH,the synergetic core-shell growth of the internal anion template and the external silver shell layer can be realized to generate a new 50-nuclei silver cluster:[Mo8O28@Ag50(iPrS)24(PhCOO)18(CH3CN)-2]·4CH-3CN(19).Time-resolved mass spectrometry revealed the transformation mechanism of "breakage-growth-reassembly".Similar results were obtained for differernt substituted benzoic acids,indicating the universality of this transformation(20-22).In addition,an 84-nuclei silver cluster can be synthesized using fatty acids,[Ag10@(W7O26)2@Ag74S2(iPrS)40(nPrCOO)18]·2CH3OH(23).Under the stimulation of PhCOOH,the silver cluster isomerization was achieved through the rearrangement of silver atoms on the surface of the silver shell,and another 84-nuclei silver cluster was obtained:Ag10@(W7O26)2@Ag74S2(iPrS)40(PhCOO)18(24).?:Synthesis and mechanism of "super-calix" silver cluster protected by small thiolate and big thiacalix[4]arene Two polymorphism 88-nuclei super calix silver clusters of,K2[(CrO4)9@Ag88(TC4A)8(EtS)32(OAc)8]·8CH3CN·4DMF(25-26),were successfully synthesized by using(EtSAg)n and thiacalix[4]arene(H4TC4A)under the action of anion templates.Mass spectrometry revealed a growth route for 88-nuclei silver clusters from bowl-like[(CrO4)@Ag11]SBU,a tetrameric semicircular Ag44 fragment to the final octameric circular Ag88 super calix.The local and global template effect of the anion template in this silver cluster was perfectly reflected and the shape delivery from macrocyclic ligand to super calix was successfully realized. |
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