Institut für Physikalische Chemie, Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
J Phys Chem B. 2013 Feb 14;117(6):1862-71. doi: 10.1021/jp3115644. Epub 2013 Jan 30.
We present detailed force probe molecular dynamic simulations of mechanically interlocked dimeric calix[4]arene-catenanes, comparing the results obtained using three different commonly used force fields (GROMOS G53a5, OPLS-AA, and AMBER GAFF). The model system is well characterized as a two-state system consisting of a closed compact and an elongated structure. Both states are stabilized by a different hydrogen-bond network, and complete separation of the dimer is prevented by the mechanical lock of the entangled aliphatic loops. The system shows fully reversible rebinding meaning that after bond rupture the system rejoins when the external force is relaxed. We present a detailed study of quantities determined in simulations using a force ramp, like the rupture force and rejoin force distributions. Additionally, we analyze the dynamics of the hydrogen-bond network. We find that the results obtained from using the different force fields qualitatively agree in the sense that always the fully reversible behavior is found. The details, like the mean rupture forces, however, do depend on the particular force field. Some of the differences observed can be traced back to differences in the strength of the hydrogen-bond networks.
我们呈现了机械互锁二聚杯[4]芳烃-索烃的详细力探针分子动力学模拟，比较了使用三种常用力场（GROMOS G53a5、OPLS-AA 和 AMBER GAFF）获得的结果。该模型系统被很好地描述为一个由封闭紧凑结构和伸长结构组成的两态系统。两种状态都由不同的氢键网络稳定，并且通过纠缠的脂肪环的机械锁防止二聚体完全分离。该系统显示出完全可逆的结合，这意味着在外部力释放后，当键断裂时，系统重新结合。我们对使用力斜坡确定的模拟中的数量进行了详细研究，例如断裂力和重接力分布。此外，我们还分析了氢键网络的动力学。我们发现，使用不同力场获得的结果在完全可逆行为的意义上定性上是一致的。然而，细节，如平均断裂力，取决于特定的力场。观察到的一些差异可以追溯到氢键网络强度的差异。
