Effect of Nanoscale Confinement on the Crystallization of Potassium Ferrocyanide
Effect of Nanoscale Confinement on the Crystallization of Potassium Ferrocyanide
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DOI：
10.1021/acs.cgd.6b00894
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发表时间：
2016-09-01
影响因子：
3.8
通讯作者：
Christenson, Hugo K.
中科院分区：
文献类型：
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作者：
Anduix-Canto, Clara;Kim, Yi-Yeoun;Christenson, Hugo K.
许多在自然界和技术上具有重要意义的结晶过程都是以小体积进行的，而不是以大体积溶液进行的。本文研究了纳米尺度限制对无机化合物亚铁氰化钾K4Fe(CN)(6)(KFC)结晶的影响。由于K4Fe(CN)(6)的高溶解度、丰富的多晶性和有趣的物理性质而被选中进行研究，它被析出在孔径分别为8、48和362 nm的受控孔玻璃(CPG)中。结果表明，尽管无水亚铁氰化钾在大体积水溶液中的沉淀过程中从未观察到，但它是第一个在CPGs中结晶的相，并且在所有三种孔径中都存在至少1天。然后发生缓慢转变为三水K4Fe(CN)(6)中心点3H(2)O(KFCT)的亚稳四方晶型，该晶型在8 nm孔中稳定了一个月。最后，观察到了热力学稳定的KFCT单斜晶型的转变，在本体溶液中几分钟后就能发现这一相。据我们所知，在8 nm孔中的这些S数量级的延迟效应比以往在无机体系中所见的都要大得多，为限制对结晶的普遍影响提供了强有力的证据。
Many crystallization processes of great significance in nature and technology occur in small volumes rather than in bulk solution. This article describes an investigation into the effects of nanoscale confinement on the crystallization of the inorganic compound potassium ferrocyanide, K4Fe(CN)(6) (KFC). Selected for study due to its high solubility, rich polymorphism, and interesting physical properties,K4Fe(CN)(6) was precipitated within controlled pore glasses (CPG) with pore diameters of 8, 48, and 362 nm. Remarkable effects were seen, such that although anhydrous potassium ferrocyanide was never observed on precipitation in bulk aqueous solution, it was the first phase to crystallize within the CPGs and was present for at least 1 day in all three pore sizes. Slow transformation to the metastable tetragonal polymorph of the trihydrate K4Fe(CN)(6)center dot 3H(2)O (KFCT) then occurred, where this polymorph was stable for a month in 8 nm pores. Finally, conversion to the thermodynamically stable monoclinic polymorph of KFCT was observed, where this phase was always found after a few minutes in bulk solution. As far as we are aware these retardation effects by up to S orders of magnitude in the 8 nm pores are far greater than any seen previously in inorganic systems and provide strong evidence for the universal effects of confinement on crystallization.