Tab-ligated Coinage Metal Clusters:Synthesis,Structural Characterization And Properties

Coinage metal thiolate clusters have attracted considerable attention for a long time due to their remarkable structural diversity and their applications in luminescence,biological medicines,catalysis,electro-optical sensing and so on.Heterometal thiolate clusters are equally important as they have demonstrated remarkable application value in the fields of luminescence and catalysis originated from their unique structure and heterometal synergistic effect.Previously,our group have already reported a zwitterionic thiolate ligand(Tab = 4-(trimethylammonium)benzenethiolate),which can coordinate towards various metal atoms to form a variety of novel complexes.Part of these complexes had been successfully used as dielectric materials,biological fluorescent probes,organic catalysts,with promising potential.In this thesis,five Au/Au-Ag/Au-Cu clusters have been successfully constructed with the assistance of a secondary phosphine-pyridyl hybird ligand(Dppy = diphenylphosphine-2-pyridine).With the further presence of a bridging ligand(Bpea)(Bpea = 1,2-(4-pyridinyl)ethane),we synthesize a 2D Au-Ag bimetallic thiolate coordination polymer.In addition,when we replace Dppy with Dppf(Dppf =1,1’-Bis(diphenylphosphino)ferrocene),we are able to isolate three more compounds.The temperature-dependent luminescent properties of some compounds in solid state are investigated.The key results are briefly described as follows:1.A mononuclear compound [Au(Dppy)(Tab)]PF6(1)is synthesized by reactions of Au(Dppy)Cl with Tab HPF6,and K2CO3 in the CH3OH/CH2Cl2 mixed solvent.Reaction of1 with equivalent [Cu(Me CN)4]PF6 in Me CN under N2 atmosphere gives an octanuclear cluster [Au6Cu2(Dppy)4(Tab)6](PF6)8·Me CN·(0.5Me CN)4(2·3Me CN).Similarly,compound 1 reacts with Ag PF6 in a 4:3 or 1:1 ratio to afford a heptanuclear cluster[Au4Ag3(Dppy)4(Tab)4(Me CN)2.5](PF6)7·0.5Me CN(3·0.5Me CN)or an octanuclear cluster[Au4Ag4(Dppy)4(Tab)4(Me CN)4](PF6)8·6Me CN·(0.5Me CN)2(4·7Me CN).Mixing Au(Dppy)Cl with Ag PF6 in the molar ratio of 1:1 first,and then adding the Me CN solutionof Au(Dppy)PF6,and adding 1 to that solution in a 1:2 or 1:1 molar ratio,respectively,forms clusters [Au4(Dppy)4(Tab)2](PF6)4(5)and [Au8(Dppy)4(Tab)6](PF6)8(6).Furthermore,in the presence of two equivalents of the bridging ligand Bpea(Bpea =1,2-bis(4-pyridinyl)ethane,the reaction of 1 with Ag PF6 in the molar ratio of 1:2 gives rise to an Au-Ag bimetallic thiolate coordination polymer{[Au2Ag3(Tab)4(Dppy)(Bpea)(Me CN)]2[(PF6)5]2}n ·2Me CN(7·2Me CN),featuring a two-dimensional network structure.Subsequently,the temperature-dependent luminescent properties of 1-7 in solid state are investigated.2.In a similar way,we replace Dppy with the Dppf ligand,and obtain three additional compounds,namely,[Au2(Tab)2(Dppf)](PF6)2(8),{[Au2(Tab)2Dppf](PF6)2}n(9)and[Au4(Tab)2(Dppf)2](PF6)4(10).3.The high-yield product 4 is employed as a precursor to successfully prepare heteroatoms(P,N,S,F)doped carbon-based Au Ag alloy nanomaterials.We found that the morphology of the Au Ag alloy nanoparticles are different under various carbonization temperatures.At 450 °C,Au Ag NPs are more uniform and well dispersed on the carbon matrix.As the carbonization temperature increases,the nanoparticles could also are better distributed on the carbon substrates and almost no difference between 500 °C and 550 °C are identified.When the temperature is increased to 600 °C,the nanoparticles start to obviously aggregate.Thus we select 450 °C as the optimum carbonization temperature and employ Au Ag/C-450 for subsequent characterization experiments.To evaluate the feasibility of Au Ag alloy carbon materials as catalysts for aerobic oxidative dehydrogenative coupling of anilines,the optimized reaction conditions are determined to be Au Ag/C-450(2 mg),KOH(base,1 mmol),DMSO(3 m L),60 °C,24 h,in air.In addition,Au Ag/C-450 catalyzes the coupling of various anilines bearing electron-withdrawing and electron-donating substituents with high activity(Yield:32%~94%).More importantly,the catalyst can be recycled and reused for several times by simple separation and abstersion,with negligible decrease in catalytic activity.