Synthesis And Structure On Silver-ethynide Complexes Bearing Imidazole Group

Research on metal alkynyl complexes has attracted considerable attention, owing to that silver(I)–ethynide complexes have their own unique structure, due to the diverse coordination modes of the alkynyl moiety and the tendency to form argentophilic interactions, as well as their promising application as luminescence materials, nonlinear optical materials and rigid-rod molecular wires.Silver(I)–ethynide complexes have been widely employed as structure building units(SUBs) for constructing novel metal organic coordination networks. Research shows that, the nitrogen atom on the imidazole group usually coordinate with a silver ion on silver(I)-acetylene network unit, and the negatively charged carbon on imidazole group have the possibility to form C-Ag bonds in the process of self assembly of coordination networks. Considering the above, it is reasonable to build high dimensional networks by imidazole group and alkynyl moiety,as well as using C-Ag bonds. Therefore, We designed and synthesized two new ligands: 1-(4-ethynylphenyl)-1H-imidazole(H1L1) and 1-(4-ethynylphenyl)-3-methyl-1H- imidazol(H1L2). And by using appropriate method, we obtained two new silver-ethynide complexes: [Ag3(L1)·(CF3CO2)2]n and [Ag7(L2)2·(CF3CO2)7·H2O]n.Crystallographic studies revealed that in 1, ethynide and imidazole groups are coordinate with Ag(I) respectively to form a chain. Adjacent chains are joined together through silver(I)-ligand interactions to form a 2D network, and subsequently the layers are via carboxyl stacking to generate a orderly 3D network. Crystallographic studies in 2 revealed that negatively Charged C in L2 ligand are failed to form C-Ag coordinate bond to assemble coordination network. It is ethynide group coordinates to Ag(I) with interleaving to form a chain. Adjacent chains are connected together by argentophilic interactions and trifluoroacetate groups to form a orderly 2D network. The results show that, silver-ethynide complexes bearing imidazole group can worked as structure building units for constructing metal organic coordination network, and through C-Ag coordinate bond in imidazole group to assemble coordination network remains to be seen.