Abstract Governing polymorph selection is a crucial issue in the pharmaceutical, food, and fine chemical industry. However, the multiple stages during the formation of the polymorphic crystals from solution and the concurrent processes selecting the final polymorph are still unclear. In this study, we demonstrate the existence of hydrated amorphous intermediates in the early stages of separation of organic crystal L-glutamic acid where the nucleation of crystalline metastable α-form spontaneously occurred within these intermediates, leading to the formation of odd-shaped and intergrown crystal aggregates. Further, we found that these amorphous intermediates severed not only as a transient intermediate in a nucleation process, but they also co-determined the size distribution, mean particle size, and phase transformation rates of polymorphic L-glutamic acid.

中文翻译：

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L-谷氨酸晶体形成的多个阶段

摘要 控制多晶型选择是制药、食品和精细化工行业的关键问题。然而，从溶液形成多晶型晶体的多个阶段以及选择最终多晶型的并发过程仍不清楚。在这项研究中，我们证明了在有机晶体 L-谷氨酸分离的早期阶段存在水合无定形中间体，其中在这些中间体中自发地发生晶体亚稳 α 型的成核，导致形成奇形和共生晶体聚集体。此外，我们发现这些无定形中间体不仅在成核过程中作为瞬态中间体被切断，而且它们还共同决定了尺寸分布、平均粒径、