Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Small. 2019 Sep;15(38):e1902936. doi: 10.1002/smll.201902936. Epub 2019 Aug 5.
The widely employed crystallization of organic molecules in solution is not well understood and is difficult to control. Employing polymers as crystallization media may allow enhanced control via temperature-induced regulation of polymer dynamics. Crystallization of a small organic molecule (perylene diimide) is investigated in polymer matrices (polystyrene) that enable the mechanistic study and control over order evolution. The crystallization is induced by heating above the glass transition temperature of the polymer, and quenched by cooling, leading to stabilization of crystallization intermediates. The mechanistic studies include direct imaging by electron microscopy, revealing a complex self-assembly process starting from amorphous aggregates that densify and transform into an unstable crystalline phase of N ,N'-bis(2,6-dimethylphenyl)perylene-3,4,9,10-tetracarboxylic diimide (DMP-PDI), followed by a conversion into a more stable crystalline form. Stabilization of crystallization intermediates at room temperature provides diverse structures based on a single molecular component. These findings have implications for the rational design of organic crystalline materials.
溶液中有机分子的广泛应用结晶过程还没有被很好地理解，也难以控制。采用聚合物作为结晶介质可以通过温度诱导的聚合物动力学调节来增强控制。在能够进行机理研究和控制有序演变的聚合物基质（聚苯乙烯）中，对小分子有机分子（苝二酰亚胺）的结晶进行了研究。结晶是通过加热到聚合物玻璃化转变温度以上来诱导的，然后通过冷却淬火来稳定结晶中间体。机理研究包括通过电子显微镜直接成像，揭示了一个复杂的自组装过程，从无定形聚集体开始，这些聚集体致密化并转化为不稳定的 N，N'-双（2,6-二甲基苯基）-3,4,9,10-苝四羧酸二酰亚胺（DMP-PDI）的晶相，然后转化为更稳定的晶相。在室温下稳定结晶中间体可以提供基于单个分子组件的多种结构。这些发现对有机晶体材料的合理设计具有重要意义。
