Multi‐Step Nucleation of a Crystalline Silicate Framework via a Structurally Precise Prenucleation Cluster
Multi‐Step Nucleation of a Crystalline Silicate Framework via a Structurally Precise Prenucleation Cluster
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通过结构精确的预成核簇对结晶硅酸盐框架进行多步成核
DOI：
10.1002/ange.202303770
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发表时间：
2023
影响因子：
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通讯作者：
De Yoreo, James J.
中科院分区：
文献类型：
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作者：
Jin, Biao;Chen, Ying;Tao, Jinhui;Lachowski, Kacper J.;Bowden, Mark E.;Zhang, Zihao;Pozzo, Lilo D.;Washton, Nancy M.;Mueller, Karl T.;De Yoreo, James J.
层状成核途径在矿物和材料的合成中普遍存在。在沸石和金属有机骨架的情况下，预先组织的多离子“二次建筑单元”(SBUs)已被提议作为基本的构建块。然而，详细描述从单体物种到稳定晶体的多步骤反应机理的进展并确定SBUS的结构仍然是一个尚未满足的挑战。结合原位核磁共振、小角X射线散射和原子力显微镜，我们证明了骨架硅酸盐的结晶是通过较小的硅酸盐单体和其他齐聚物的交联和聚合形成的立方八聚阴离子Q38多阴离子组装而成的。这些Q38通过与周围的H2O和四甲基铵离子(TMA+)的氢键稳定。当Q38水平达到≈占总硅酸盐物种的32 %的阈值时，就会发生成核。通过将[(Tma)x(Q38)⋅nH2O](x−8)包络络合物引入晶体的台阶边缘，进一步生长。
Hierarchical nucleation pathways are ubiquitous in the synthesis of minerals and materials. In the case of zeolites and metal–organic frameworks, pre‐organized multi‐ion “secondary building units” (SBUs) have been proposed as fundamental building blocks. However, detailing the progress of multi‐step reaction mechanisms from monomeric species to stable crystals and defining the structures of the SBUs remains an unmet challenge. Combining in situ nuclear magnetic resonance, small‐angle X‐ray scattering, and atomic force microscopy, we show that crystallization of the framework silicate, cyclosilicate hydrate, occurs through an assembly of cubic octameric Q38polyanions formed through cross‐linking and polymerization of smaller silicate monomers and other oligomers. These Q38are stabilized by hydrogen bonds with surrounding H2O and tetramethylammonium ions (TMA+). When Q38levels reach a threshold of ≈32 % of the total silicate species, nucleation occurs. Further growth proceeds through the incorporation of [(TMA)x(Q38)⋅nH2O](x−8)clathrate complexes into step edges on the crystals.