Control of anisotropic self-assembly of gold nanoparticles coated with mesogens
Control of anisotropic self-assembly of gold nanoparticles coated with mesogens
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DOI：
10.1039/c2jm16794h
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发表时间：
2012-05
影响因子：
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通讯作者：
Xiao Mang;X. Zeng;B. Tang;Feng Liu;G. Ungar;Rui-bin Zhang;L. Cseh;G. Mehl
中科院分区：
文献类型：
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作者：
Xiao Mang;X. Zeng;B. Tang;Feng Liu;G. Ungar;Rui-bin Zhang;L. Cseh;G. Mehl
研究了一系列金纳米粒子（GNP）的自组装，这些金纳米粒子被横向连接的介晶分子（配体）和不同量的烷基硫醇（共配体）覆盖。介晶的存在诱导GNP的长程有序堆积。在这里，我们报告了三种不同的有序液晶相周围的GNP，其中两个还没有观察到以前在热致液晶。这些是球体的3D简单六边形堆积和面心立方（FCC）堆积，即在这种情况下的GNP。已经发现，在这样的系统中的共配体的体积分数对于GNP的自组装的各向异性是关键的;太小或太大的共配体体积分数导致形成上述两种几乎或完全各向同性的堆积类型之一。在这两种结构中，棒状介晶没有择优取向。在中间共配体分数得到高度各向异性串的GNP，包装在一个2D的六方晶格，与介晶周围的字符串，并位于平行于它们的轴。通过将实验的X射线衍射强度与从模型计算的那些相匹配，发现2 nm GNP与其理想晶格位置的平均偏差从没有共配体的材料的0.84 nm降低到具有十二烷基硫醇的复合物的0.44 nm;这种顺序的增加归因于软烷基使颗粒不均匀性均匀。这些结果有助于我们理解和控制有机分子影响纳米颗粒组织的方式，并促进通过自组装设计新的杂化材料。
The self-assembly was investigated of a series of gold nanoparticles (GNP) that were covered with laterally attached mesogenic molecules (ligands) and different amounts of alkylthiols (co-ligands). The presence of mesogens induces long-range ordered packing of GNPs. Here we report three different ordered liquid crystalline phases built around the GNPs, two of which have not been observed previously in thermotropic liquid crystals. These are the 3D simple hexagonal packing and the face-centred cubic (FCC) packing of spheres, i.e. GNPs in this case. It has been found that the volume fraction of co-ligands in such systems is critical for the anisotropy of the self-assembly of GNPs; either too small or too large a co-ligand volume fraction causes the formation of one of the two nearly or fully isotropic packing types mentioned above. In these two structures the rod-like mesogens have no preferred orientation. At intermediate co-ligand fractions highly anisotropic strings of GNPs are obtained, packed in a 2D hexagonal lattice, with the mesogens surrounding the strings and lying parallel to their axis. By matching the experimental X-ray diffraction intensities with those calculated from models, the mean deviation of the 2 nm GNPs from their ideal lattice position was found to decrease from 0.84 nm for the material with no co-ligands to 0.44 nm for the complex with dodecylthiol; this increase in order is attributed to the soft alkyls evening out the particle non-uniformities. The results help us to understand and control the way organic molecules affect the organization of nanoparticles, and facilitate the design of new hybrid materials through self-assembly.