密度泛函理论研究间硝基苯基吡咯酰胺识别卤素阴离子

Density Functional Theory Study on Halide Anion Recognition of m-Nitrophenyl-1H-pyrrole-2-carboxamide

采用混合密度泛函B3LYP方法,在LANL2DZ水平上优化间硝基苯基吡咯酰胺(NPC)及其卤素阴离子复合物的几何构型,从几何结构参数、电荷布居、前线轨道、结合能以及热力学参数等角度探讨复合物形成过程中主体分子的构象变化以及主客体间的超分子作用.研究结果表明,吡咯酰胺主体分子识别卤素阴离子是一个自发过程.识别过程包括阴离子诱导下主体分子构象转变和“活性”构象与阴离子形成氢键两个步骤.计算表明主体分子复合阴离子过程中,两者的前线轨道发生作用,电子容易从卤素阴离子的HOMO向主体分子的LUMO转移.在所形成的四种复合物NPC-X-(X-=F-,Cl-,Br-,I-)中,以NPC-F-最稳定,与文献报道吡咯酰胺主体分子识别卤素阴离子能力的实验结果相一致.

The structure of m-nitrophenyl-lH-pyrrole-2-carboxamide （NPC） and its halide anion complex are optimized by density functional theory B3LYP method at the LANL2DZ level. The conformation change of the host and the supra-molecular interaction between the host and halide anion, in the formation of complex, have been investigated by analyzing the geometric parameters, charge population, frontier orbital, binding energy and thermodynamic parameters. The results show that anion recognition of NPC is spontaneous. Recognition process includes two steps： 1, conformation change of host in the inducement of anion; 2, hydrogen-bonding formation between the activated host and halide anion. The frontier orbital of the host interacts with that of the guest anion, and the electron is transferred from HOMO of halide anion to LUMO of host. Moreover, NPC-F^- is the most stable among the complex NPC-X^- （X^-=F^-, Cl^-, Br^-, I^-）. That agrees well with the experimental results of anion recognition of NPC reported in the literature.