铅离子与镉离子高选择性的大环化合物:对称四甲基六元瓜环与过渡金属及重金属离子的配合作用

摘要

利用微分脉冲伏安法研究了对称四甲基六元瓜环(TMeQ[6])与过渡金属的相互作用.结果表明该主体大环化合物对pb2+ 和Cd2+离子具有较好的选择性作用.伏安数据测定表明Pb2+及Cd2+离子与对称四甲基六元瓜环以nM2TMeQ[6]=2配位,其配合平衡常数分别为(Kpb=2.12×109 L2· mol-2,KCa2+=2.10× 109 L2· mo1-2).Pb2+离子与TMeQ[6]的晶体结构进一步证实了上述实验结果.%The complexation of α,α＇,δ,δ＇-tetramethylcucurbit[6]uril (TMeQ[6]) complexes with transition-metal ions was studied by differential pulse voltammetry (DPV).The results reveal that this water-soluble cage-type compound shows very high selectivity for Pb2+ and Cd2+,while it is a masking compound for other transition-metal ions,particularly for Fe3+,Co2+,Zn2+,and Cr3+,due to a sharp decrease in the DPV peak current of these metal ions in the presence of TMeQ[6].Binding constants were determined from voltammetric data.The Pb2+ and Cd2+ cations display a high binding affinity for TMeQ[6] (KPb2+=2.12×109 L2·mol-2,KCa2+=2.10×109 L2·mol-2) and form 2:1 nM2TMeQ[6]=2 complexes.The crystal structure of TMeQ[6]-Pb2+ indicates a 2:1 (npb2+TMeQ[6]=2) complex in the solid state,which is consistent with the results in solution.CCDC:723280.