Biomolecular Science & Engineering, University of California Santa Barbara, California 93106-9611.
Inorg Chem. 2009 Dec 7;48(23):11017-23. doi: 10.1021/ic901167u.
We report the synthesis and characterization of new structural variants of the isotypic compound with the generic chemical formula, Co(1-0.5x)(oct) Co(x)(tet) (OH)2 (Cl)x (H2O)n, all modifications of an alpha-Co(OH)2 lattice. We show that the occupancy of tetrahedrally coordinated cobalt sites and associated chloride ligands, x, is modulated by the rate of formation of the respective layered hydroxide salts from kinetically controlled aqueous hydrolysis at an air-water interface. This new level of structural control is uniquely enabled by the slow diffusion of a hydrolytic catalyst, a simple technique. Independent structural characterizations of the compounds separately describe various attributes of the materials on different length scales, revealing details hidden by the disordered average structures. The precise control over the population of distinct octahedrally and tetrahedrally coordinated cobalt ions in the lattice provides a gentle, generic method for modulating the coordination geometry of cobalt in the material without disturbing the lattice or using additional reagents. A mechanism is proposed to reconcile the observation of the kinetic control of the structure with competing interactions during the initial stages of hydrolysis and condensation.
我们报告了同晶型化合物的新型结构变体的合成与表征，其通用化学式为 Co(1-0.5x)(oct)Co(x)(tet)(OH)2(Cl)x(H2O)n，均为 alpha-Co(OH)2 晶格的修饰。我们表明，占据四面配位钴位和相关氯配体的 x 值可通过在气-水界面处的动力学控制的水合作用从层状氢氧化物盐的快速形成来调节。这种新的结构控制水平是通过水解催化剂的缓慢扩散来实现的，这是一种简单的技术。化合物的独立结构表征分别描述了材料在不同长度尺度上的各种属性，揭示了无序平均结构中隐藏的细节。在晶格中精确控制不同的八面配位和四面配位钴离子的数量提供了一种温和的、通用的方法来调节材料中钴的配位几何，而不会扰乱晶格或使用额外的试剂。提出了一种机制来协调结构的动力学控制与水解和缩合初始阶段的竞争相互作用的观察结果。
