摘要
在气相环境中,使用密度泛函理论（DFT）优化由n个苷脲单元组成的瓜环[n]（CB[n]）（n=5-10）,并使用密度泛函（DFT）概念指数和Multiwfn软件包计算和分析CB[n]的结构参数、前线轨道能量和化学稳定性.结果表明：α-N结构最稳定,α=O、γ-γ、γ-H和β-H（2）结构的化学稳定性较差;以CB[6]为界,主要二面角的变化呈现中心对称的形式;随着苷脲单元n的增加,CB[n]的端口直径、空腔直径和圆外径线性增大;前线轨道E_（HOMO）、E_（LUMO）值及E_（LUMO）-E_（HOMO）值逐渐降低,化学活性逐渐增强、稳定性逐渐减弱;端口O原子是最大的亲电活性位点,LUMO的电子云分布主要与H原子有关,且次甲基H原子对LUMO电子云的贡献最大;次甲基C原子、亚甲基C原子和指向CB[n]端口方向的亚甲基H原子对LUMO的电子云分布具有抑制作用,抑制能力的大小为指向CB[n]端口方向的亚甲基H原子〉亚甲基C原子〉次甲基C原子.为研究瓜环的超分子组装提供理论依据.
In gas phase,structure of cucurbituril（CB[n],n = 5-10） composed of n glycoluril units was optimized by density functional theory（DFT）. Structural parameters,frontier orbital energy levels and chemical stability of CB[n]（n = 5-10） were calculated and analyzed with conceptual DFT reactivity index and Multiwfn wave function analyzer. It showed that structure of C-N bond is most stable,chemical stability of α = O,γ-γ,γ-H and β-H（2） is poor. Change of part bond angle is bounded by CB[6],and change of main dihedral angle exhibits symmetrical. Port diameter,cavity diameter and outer diameter of CB[n]（n = 5-10） tend to increase linearly with increase of number of glycoluril units. E_（HOMO）,E_（LUMO） and E_（LUMO）-E_（HOMO） of CB[n]（n = 5-10） reduced,their chemical activity increased and stability decreased with increase of number of glycoluril units. The largest electrophilic active sites are located at port O atoms. Electron cloud distribution of LUMO is mainly related to H atoms,and contribution of methine H atom to LUMO electron cloud is the largest. Methine C atom,methylene C atom,and methylene atom H in direction of CB[n] port have an inhibitory effect on electron cloud distribution of LUMO. Inhibitory capacity is methylene H atom in direction of CB[n] 〉methylene C atom 〉methine C atom. It provides theoretical basis for study of supramolecular assembly of cucurbituril.
作者
林艳
刘芸
彭清维
魏晓楠
唐延林
LIN Yan;LIU Yun;PENG Qingwei;WEI Xiaonan;TANG Yanlin(College of Physics, Guizhou University, Guizhou Guiyang 550025, Chin)
出处
《计算物理》
EI
CSCD
北大核心
2018年第2期221-229,共9页
Chinese Journal of Computational Physics
基金
国家自然科学基金(11164004)资助项目
