Chemical Theory and Computation, Department of Chemistry, Lancaster University, Lancaster LA1 4YB (UK).
Department of Pharmacy, University of Malakand, KPK (Pakistan).
Angew Chem Int Ed Engl. 2015 Dec 1;54(49):14681-4. doi: 10.1002/anie.201501216. Epub 2015 Mar 25.
Secondary nucleation, wherein crystal seeds are used to induce crystallization, is widely employed in industrial crystallizations. Despite its significance, our understanding of the process, particularly at the molecular level, remains rudimentary. An outstanding question is why do a few seeds give rise to a many-fold increase in new crystals? Using molecular simulation coupled with experiments we have uncovered the molecular processes that give rise to this autocatalytic behavior. The simulations reveal formation of molecular aggregates in solution, which on coming in contact with the surface of the seed undergo nucleation to form new crystallites. These crystallites are weakly bound to the crystal surface and can be readily sheared by fluid, making the seed surfaces available again to repeat the process. Further, the new crystallites on development can in turn serve as seeds. This mechanistic insight will enable better control in engineering crystalline products to design.
二次成核，即利用晶种诱导结晶，在工业结晶中被广泛应用。尽管它很重要，但我们对这一过程的理解，特别是在分子水平上，仍然很初级。一个悬而未决的问题是，为什么少数几个晶种会导致新晶体数量呈多倍增加？我们利用分子模拟和实验相结合的方法，揭示了导致这种自催化行为的分子过程。模拟结果显示，在溶液中形成了分子聚集体，这些聚集体与晶种表面接触后发生成核，形成新的晶体。这些晶体与晶体表面的结合较弱，容易被流体剪切，从而使晶种表面再次可用，以重复该过程。此外，新形成的晶体在发育过程中也可以作为晶种。这种机械上的洞察力将使我们能够更好地控制工程晶体产品的设计。
