Zhang Xiao-Jie, Liu Zhi-Pan
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Key Laboratory of Computational Physical Science (Ministry of Education), Fudan University, Shanghai 200433, China.
Phys Chem Chem Phys. 2015 Jan 28;17(4):2757-69. doi: 10.1039/c4cp04456h. Epub 2014 Dec 15.
The prediction of chemical reactivity and thus the design of new reaction systems are the key challenges in chemistry. Here, we develop an unbiased general-purpose reaction sampling method, the stochastic surface walking based reaction sampling (SSW-RS) method, and show that the new method is a promising solution for reactivity prediction of complex reaction systems. The SSW-RS method is capable of sampling both the configuration space of the reactant and the reaction space of pathways, owing to the combination of two recently developed theoretical methods, namely, the stochastic surface walking (SSW) method for potential energy surface (PES) exploration and the double-ended surface walking (DESW) method for building pathways. By integrating with first principles calculations, we show that the SSW-RS method can be applied to investigate the kinetics of complex organic reactions featuring many possible reaction channels and complex hydrogen-bonding networks, as demonstrated here using two examples, epoxypropane hydrolysis in aqueous solution and β-d-glucopyranose decomposition. Our results show that simultaneous sampling of the soft hydrogen-bonding conformations and the chemical reactions involving hard bond making/breaking can be achieved in the SSW-RS simulation, and the mechanism and kinetics can be predicted without a priori information on the system. Unexpected new chemistry for these reactions is revealed and discussed. In particular, despite many possible pathways for β-d-glucopyranose decomposition, the SSW-RS shows that only β-d-glucose and levoglucosan are kinetically preferred direct products and the 5- or 7-member ring products should be secondary products derived from β-d-glucose or levoglucosan. As a general tool for reactivity prediction, the SSW-RS opens a new route for the design of rational reactions.
化学反应性的预测以及新反应体系的设计是化学领域的关键挑战。在此，我们开发了一种无偏通用反应采样方法，即基于随机表面行走的反应采样（SSW - RS）方法，并表明该新方法是预测复杂反应体系反应性的一种有前景的解决方案。由于结合了两种最近开发的理论方法，即用于势能面（PES）探索的随机表面行走（SSW）方法和用于构建反应路径的双端表面行走（DESW）方法，SSW - RS方法能够对反应物的构型空间和反应路径空间进行采样。通过与第一性原理计算相结合，我们表明SSW - RS方法可用于研究具有许多可能反应通道和复杂氢键网络的复杂有机反应的动力学，本文以水溶液中环氧化丙烷水解和β - D - 吡喃葡萄糖分解两个例子进行了说明。我们的结果表明，在SSW - RS模拟中可以同时对软氢键构象和涉及硬键形成/断裂的化学反应进行采样，并且无需关于该体系的先验信息即可预测反应机理和动力学。揭示并讨论了这些反应中意外的新化学现象。特别是，尽管β - D - 吡喃葡萄糖分解有许多可能的路径，但SSW - RS表明只有β - D - 葡萄糖和左旋葡聚糖是动力学上优先的直接产物，而5元或7元环产物应是源自β - D - 葡萄糖或左旋葡聚糖的次级产物。作为一种用于反应性预测的通用工具，SSW - RS为合理反应的设计开辟了一条新途径。
