Nanoscale assemblies of gigantic molecular {Mo154}-rings: (dimethyldioctadecylammonium)20[Mo154O462H8(H2O)70].
Nanoscale assemblies of gigantic molecular {Mo154}-rings: (dimethyldioctadecylammonium)20[Mo154O462H8(H2O)70].
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DOI：
10.1021/la701364k
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
T. Akutagawa;Reina Jin;Ryo Tunashima;S. Noro;L. Cronin;Takayoshi Nakamura
中科院分区：
文献类型：
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作者：
T. Akutagawa;Reina Jin;Ryo Tunashima;S. Noro;L. Cronin;Takayoshi Nakamura
基于混合价无机巨环[Mo 154 O 462 H14（H2O）70]14-（{Mo 154}-环）和二甲基双十八烷基铵（多达）的簇合物被组装成新型的无机-有机杂化分子体系LB和流延膜。采用阳离子交换法合成了（多达）20[Mo 154 O 462 H8（H2O）70]（2），并通过热重分析、IR、UV-vis-NIR、1HNMR和XRD对其进行了表征。结果表明，多达阳离子表面活性剂包封的{Mo 154}环在CHCl 3中的化学稳定性高于{Mo 154}环钠盐在H2O中的化学稳定性。在稀THF溶液中观察到了（多达）20[Mo 154 O 462 H8（H2O）70]的均匀球形囊泡状分子组装体，其平均直径为95 nm，归一化方差为5.7%。2作为流延膜的沉积显示出典型直径约为100 nm的圆形域，表明溶液和表面沉积结构之间可能存在相似性。将盐2的所得LB膜从pH = 1.5的酸性缓冲亚相转移到云母上，得到具有单位转移比的二维膜表面。此外，LB多层膜的电子吸收光谱与钼蓝{Mo 154}-环系统熟知的经典II型混合价MoV/MoVI电子态一致，并且似乎在表面上，{Mo 154}-环的平面近似平行于衬底表面，如偏振电子光谱所示，而多达的烷基链相对垂直于基底表面。因此，{Mo 154}-环和多达阳离子之间的层沿膜传播方向沿着交替堆叠。最后，发现铸膜和LB膜的表面形貌分别由（多达）20[Mo 154 O 462 H8（H2O）70]在溶液和空气-水界面中的分子组装决定。
Clusters based on the mixed-valence gigantic inorganic ring [Mo154O462H14(H2O)70]14- ({Mo154}-ring) and dimethyldioctadecylammonium (DODA) were combined to form novel molecular assemblies of an inorganic-organic hybrid molecular system as Langmuir-Blodgett (LB) and cast films. (DODA)20[Mo154O462H8(H2O)70] (2) was prepared by cation exchange and was characterized by a combination of thermogravimetry, IR, UV-vis-NIR, 1H NMR, and XRD measurements. The salt 2 was soluble in common organic solvents, and the chemical stability of {Mo154}-ring encapsulated by DODA cationic surfactants in CHCl3 was found to be higher than that of the "native" sodium salt of the {Mo154}-ring in H2O. Uniform spherical vesicle-like molecular assemblies of (DODA)20[Mo154O462H8(H2O)70] were observed in dilute THF, whose average diameter of 95 nm and a normalized variance of 5.7% were confirmed by a X-ray small-angle scattering. Deposition of 2 as a cast film showed circular domains with a typical diameter of approximately 100 nm, indicating possible similarities between solution and surface-deposited structures. The resulting LB films of salt 2 were transferred from an acidic buffer subphase with pH = 1.5 onto mica, giving a two-dimensional film surface with a unity transfer ratio. Further, the electronic absorption spectra of the LB multilayer were consistent with the classic type II mixed-valence MoV/MoVI electronic state well know for molybdenum blue {Mo154}-ring systems, and it appears that on the surface the plane of the {Mo154}-ring is approximately parallel to the substrate surface, as indicated by polarized electronic spectra, while the alkyl chains of DODA were relatively normal to the substrate surface. Therefore, the layer between the {Mo154}-rings and DODA cations was alternately stacked along the direction of film propagation. Finally, it was found that the surface morphology of the cast and LB films was determined by the molecular assembly of (DODA)20[Mo154O462H8(H2O)70] in solution and the air-water interface, respectively.