The growth of spontaneously twisted crystals is a common but poorly understood phenomenon. An analysis of the formation of twisted crystals of a metastable benzamide polymorph (form II ) crystallizing from highly supersaturated aqueous and ethanol solutions is given here. Benzamide, the first polymorphic molecular crystal reported (1832), would have been the first helicoidal crystal observed had the original authors undertaken an analysis by light microscopy. Polymorphism and twisting frequently concur as they are both associated with high thermodynamic driving forces for crystallization. Optical and electron microscopies as well as electron and powder X‐ray diffraction reveal a complex lamellar structure of benzamide form II needle‐like crystals. The internal stress produced by the overgrowth of lamellae is shown to be able to create a twist moment that is responsible for the observed non‐classical morphologies.

中文翻译：

---

苯甲酰胺（第一个多态分子化合物）的晶体为螺旋形。

自发扭曲晶体的生长是一种常见的现象，但鲜为人知。本文给出了从高度过饱和的水溶液和乙醇溶液中结晶出的亚稳态苯甲酰胺多晶型物（II型）的扭曲晶体形成的分析。苯甲酰胺是第一个报道的多晶型分子晶体（1832年），如果原始作者通过光学显微镜进行分析，它将是观察到的第一个螺旋晶体。多态性和扭曲经常并存，因为它们都与高热力学驱动力有关。光学和电子显微镜以及电子和粉末X射线衍射揭示了II型苯甲酰胺的复杂层状结构针状晶体。薄片过度生长产生的内部应力被证明能够产生扭曲力矩，该扭曲力矩是观察到的非经典形态的原因。