脲基杯[4]二(9-冠-3)对钠-卤素离子对的识别作用

The ion pair recognition of sodium-halides by urea calix[4]bis crown-3 derivative

采用Oniom方法(B3LYP/LANL2DZ∶PM3)对脲基取代的二(9-冠-3)杯[4]芳烃衍生物(H)与离子对Na+X-(X=F-,Cl-,Br-)的包合作用进行了理论研究.在上述体系中存在2种包合方式:一是阴、阳离子在包合物中是分离的,阴离子与主体分子的上沿主要以N—H…X-氢键作用;二是阴、阳离子在包合物中存在明显的离子配对作用,阴离子主要以阳离子的配对作用存在.通过对包合物Na+X-/H的结构参数、自然键轨道(NBO)以及结合能分析可知,第1种包合方式更有利.研究表明脲基取代的二(9-冠-3)杯[4]芳烃衍生物可成为有效的离子对识别受体,研究结果进一步加深了杯芳烃类受体对离子对识别机理的认识,为实验上设计合成新型离子对受体提供了理论依据.

The Oniom method（B3LYP/LANL2DZ∶PM3） was performed on the calculation of the interaction between urea calix[4]bis crown-3 derivative（H） and ion pairs Na^＋X^-（X=F-,Cl-,Br-）.Two different binding modes are found：（1） the ion pair separated by host molecule in the resulting inclusion complex;（2） the ion pair in a direct contact in complex.The stabilized energy shows that the hydrogen bonds play an important role in the formation of the result complexes Na^＋X^-/H.With the increasing of the X atomic number,hydrogen bonds become weaker and Na^＋X^-/H become less stable.The coordinations between Na^＋ and oxygen atoms in the ether segments at the lower rim of calix[4]arene are also investigated.Considered both of them,the stability order of these three complexes is Na^＋F-/H〉Na^＋Cl-/H〉Na^＋Br-/H,and all the binding energis of the first type is more negative than the second one.This study suggest that urea calix[4]bis crown-3 derivative is a potential ion-pair receptor.