Yu Huanan, Qu Wentao, Liu Feng, Mehl Georg H
Department of Chemistry, University of Hull Hull HU6 7RX UK.
State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi International Research Centre for Soft Matter, Xi'an Jiaotong University Xi'an P. R. China
Chem Sci. 2020 Dec 8;12(5):1778-1782. doi: 10.1039/d0sc05100d.
Gold nanoparticles (AuNPs) have been prepared and surface-functionalized with a mixture of 1-hexanethiol co-ligands and chiral discogen ligands separated from a disulfide function a flexible spacer. Polarized optical microscopy together with differential scanning calorimetry showed that the organic corona of the nanocomposite forms a stable chiral discotic nematic phase with a wide thermal range. Synchrotron X-ray diffraction showed that gold NPs form a superlattice with 2 plane symmetry. Analysis indicated that the organic corona takes up the shape of a flexible macrodisk. Synchrotron radiation-based circular dichroism signals of thin films are significantly enhanced on the isotropic-LC transition, in line with the formation of a chiral nematic phase of the organic corona. At lower temperatures the appearance of CD signals at longer wavelengths is associated with the chiral organisation of the NPs and is indicative of the formation of a second helical structure. The decreased volume required and the chiral environment of the disc ligands drives the nanoparticles into columns that arrange helically, parallel to the shortest axis of the two dimensional lattice.
已制备出金纳米颗粒（AuNPs），并用1-己硫醇共配体和从二硫键功能分离出的手性盘状液晶配体的混合物对其进行表面功能化，该二硫键连接着一个柔性间隔基。偏光显微镜和差示扫描量热法表明，纳米复合材料的有机冠层形成了一个热稳定性良好的手性盘状向列相。同步辐射X射线衍射表明，金纳米颗粒形成了具有二维平面对称性的超晶格。分析表明，有机冠层呈柔性大圆盘形状。薄膜基于同步辐射的圆二色性信号在各向同性-液晶转变时显著增强，这与有机冠层手性向列相的形成一致。在较低温度下，较长波长处圆二色性信号的出现与纳米颗粒的手性排列有关，表明形成了第二种螺旋结构。盘状配体所需体积的减小及其手性环境促使纳米颗粒排列成螺旋状柱，平行于二维晶格的最短轴。
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