Designed Synthesis Of Size-tunable Ag₂S Nanoclusters By Distinguishable C-S Bond Cleavage Reaction With Alkyl- And Aryl-thiolates

Ag₂S nanocluster is a promising material with unique semi-conductor property,intriguing near-infrared photo-luminescent and low toxicities to living cells,which has the possibility of application in biological imaging.Therefore,the exploitaton of synthesis Ag₂S nano-materials with controllable size,performance adjustable has been a rigorous dare.In this paper,we have reported the synthesis of two distinct silver clusters with aryl-and alkyl-thiolates.And using azacalix-[6]pyridines（Py[6]）as a ligand,combining distinct silver clusters of aryl-and alkyl-thiolates to form corresponding silver thiolate cluster complexes which protected by macrocyclic.Further study of the structure was by FT-IR,1H NMR,19F NMR,X-Ray,MS and so on.Researches have proved that the formation of thiolate-centered polynuclear metal clusters can induce the cracker of the C-S bonds in thiolates owing to the electron withdrawal effect of metal cluster aggregates.This phenomenon provides the possibility of synthesis silver sulfide frorm silver thiolate cluster complexes.On the one hand,we found that complex 10 is unstable,for which would generate black precipitates within a day.On the other hand,adding CF3COOH into the solution of complex 9 to removing Py[6],forming a dull yellow solution,which was Ag₂S nanocluster wrapped around[’BuC61H4S-].This yellow solution can retain its homogeneity for several days.Thus,we combine two different methods of generation Ag₂S partical from silver thiolate cluster complexes.We proposed synthesis a core-shell cluster model of Ag₂S nanocluster,using complex 9 to build the Ag₂S nanocluster which was protect by[’BUC6H4S-]as the shell,getting Ag₂S particals from complex 10 as the core.We can control the size of the core-shell cluster model of Ag₂S by controlling the dimension of Ag₂S which synthesized from complex 10.We studied the particle size and the structure of the obtained Ag₂S nanoparticles by Powder-XRD,TEM,FT-IR,SAED and EDX.Interesting,we found that despite the variable sizes of the newly acquired Ag₂S nanocluster,their excitation and emission spectra were the same with λex（max）= 522 nm and λem（max）= 684 nm.This result shows that the photoluminescent properties of these Ag₂S nanocluster are unconcerned to their sizes.For they may facilitate the processing of devices in particular dimensions without triggering mazy quantum effects,this unique feature could make the possibility of the wide use of these nanoclusters in biological imaging,micro-and nano-electronics.