School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Phys Chem Chem Phys. 2010 Jul 28;12(28):7959-67. doi: 10.1039/c002058c. Epub 2010 Jun 2.
The effect of benzene fluorination on C-H...pi interactions is studied using a number of computational methods applied to a range of intermolecular complexes. High level wavefunction methods (CCSD(T)) predict a slightly greater interaction energy for complexes of benzene with methane or fucose, compared to corresponding complexes involving hexafluorobenzene. A number of more approximate treatments, DFT with the M06-2X functional, PM3-D* and MM methods, give interaction energies within 1 kcal mol(-1) of the high level values, and also correctly predict that the interaction energy is slightly greater for benzene compared to hexafluorobenzene. However, the DFT-D model used here predicts that the interaction energy is slightly greater for hexafluorobenzene. Molecular dynamics simulations, employing the GLYCAM-06 force field, validated here, are used to model the complexes of benzene and hexafluorobenzene with beta-cyclodextrin in aqueous solution. We predict the binding free energies of the complexes to be within 0.5 kcal mol(-1), and suggest that the different chemical shifts of the H5 protons observed in the two complexes arise from their slightly different structures, rather than from different binding energies.
使用多种计算方法研究了苯的氟化对 C-H…π 相互作用的影响，这些方法应用于一系列的分子间复合物。高精度波函数方法（CCSD(T)）预测，与涉及六氟苯的相应复合物相比，苯与甲烷或岩藻糖形成的复合物的相互作用能略高。一些更近似的处理方法，包括 M06-2X 函数、PM3-D*和 MM 方法的密度泛函理论，给出的相互作用能与高精度值相差 1 kcal/mol 以内，并且还正确地预测了苯与六氟苯相比，相互作用能略高。然而，这里使用的 DFT-D 模型预测六氟苯的相互作用能略高。分子动力学模拟，采用在此验证的 GLYCAM-06 力场，用于模拟苯和六氟苯与β-环糊精在水溶液中的复合物。我们预测复合物的结合自由能在 0.5 kcal/mol 以内，并表明在两个复合物中观察到的 H5 质子的不同化学位移源自它们略微不同的结构，而不是不同的结合能。
