Variable-Rung Design for a Mixed-Valence Two-Legged Ladder System Situated in a Dimensional Crossover Region
Variable-Rung Design for a Mixed-Valence Two-Legged Ladder System Situated in a Dimensional Crossover Region
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位于维度交叉区域的混合价两足梯系统的变梯级设计
DOI：
10.1021/ic402846v
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发表时间：
2014
影响因子：
4.6
通讯作者：
Hiroshi Kitagawa
中科院分区：
文献类型：
--
作者：
Kazuya Otsubo;Atsushi Kobayashi;Kunihisa Sugimoto;Akihiko Fujiwara;Hiroshi Kitagawa
由于与维数相关的物理性质强烈地依赖于组成臂的数目，因此一维与二维交叉的梯形系统一直是一个很有吸引力的研究对象。然而，基于结构组分的替代的梯内结构和电子性质的控制仍然是材料科学中具有挑战性的任务。另一方面，使用配位化学的结构设计通过金属有机构建块的取代为结构和电子变化提供了至关重要的优势。在这里，我们展示了基于新型金属配合物的具有几个有机梯级单元的两足梯形化合物的合理设计和电子性质：4，4 ′-联吡啶，反式-1，4-二氨基环己烷和4，4 ′-偶氮吡啶。单晶X射线衍射研究表明，这些两足梯形化合物是由卤素桥连的混合价一维链（MX链）作为其组成腿。根据有机梯级单元的分子形状，实现了具有腿部周期性扭曲的双腿梯形晶格的独特配置。此外，电子吸收光谱表明，两腿梯形系统的带隙随腿的扭曲程度的增加而增加。我们已经证明了第一次，两条腿的梯子系统显示出独特的IVCT能量和腿的失真参数之间的关系，不同于一个单一的MX链系统。这些系统的研究，不仅基于横档变化的配置，而且在金属有机梯形系统的电子状态，提供了广泛的和合理的调谐的金属配合物基功能材料的物理和电子性能的可能性。
Ladder systems situated in a crossover from one dimensionality to two dimensionalities have been an attractive research target, because the physical properties, which are associated with dimensionality, are strongly dependent on the number of constituent legs. However, control of the intraladder configuration and electronic properties based on the substitution of structural components remain challenging tasks in materials science. On the other hand, structural design using coordination chemistry offers crucial advantages for architectural and electronic variations through substitutions of metal–organic building blocks. Here, we show the rational design and electronic properties of novel metal complex-based two-legged ladder compounds with several organic rung units: 4,4′-bipyridine, trans-1,4-diaminocyclohexane, and 4,4′-azopyridine. Single-crystal X-ray studies show that these two-legged ladder compounds are composed of halogen-bridged mixed-valence one-dimensional chains (MX chains) as their constituent legs. Depending on the molecular shape of the organic rung units, unique configurations of two-legged ladder lattices with periodic distortion of the legs are achieved. In addition, the electronic absorption spectra show that intervalence charge-transfer (IVCT) band gap of the two-legged ladder system increases with increasing degree of distortion of the leg. We have demonstrated for the first time that a two-legged ladder system shows a unique relationship between IVCT energy and the distortion parameter of the leg, as distinct from a single MX chain system. These systematic investigations, not only of configurations based on the rung variation but also of electronic states in metal–organic ladder system, provide the possibility for wide and rational tunings of physical and electronic properties of metal complex-based functional materials.