Langevin模方法研究溶剂粘度对18-冠醚-6性质的影响

本文在各种溶剂粘度下对18-冠醚-6的两种稳定构象C_i和D_3d进行了Langevin模分析。结果表明,溶剂的粘度对18-冠醚-6的性质,特别是对振动频率分布和键偶极矢量的摇摆角度有较大的影响。同时表明,Langevin模方法是解释溶液中分子运动情况的一种简捷有力的模型。

Langevin Mode Study of Solvent Viscidity Influence on the Properties of 18-Crown-6

Both conformers(C_i,D_3d) of 18-crown-6 have been studied by Langevin mode method under four viscidities of solvent:0.0,3.0×10^-4,6.0×10^-4 Pa·s(about the viscidity of methol at room temperature),9.0×10^-4 Pa·s(about the viscidity of water at room temperature).For viscidity of 9.0×10^-4 Pa·s,both Oseen method and Rotne-Prage method were used in the calculation.The results showed that the viscidities of solvent greatly influenced on the properties of 18-crown-6,especially the distribution of the vibrational frequency and the librational angle of the bond vector.The effects of nondiagonal elements of the frictional matrix must be considered by using Oseen or Rotne-Prage method when the viscidity of solvent is large.At the same time,the results also show that Langevin mode method is a very effectivce model for interpreting molecular motion in solution.