Development of Ordered Monolayer Based on the Self Assembly of Molecular Tripods

1)分子三脚架-二茂铁及其单层膜的合成合成了分子三脚架与二茂铁通过不同长度的低聚(苯乙炔)连接物连接而成的三脚架-二茂铁双分子膜。该三脚架有一个坚硬的金刚烷核，其上连接着三个CH_2sh支腿，以便能够在金表面进行化学吸附。在Au(111)表面制备了自组装单分子膜，并对其进行了电化学分析。单分子膜的表面密度与连接物的长度无关，表明由于金刚烷和线性连接物的刚性骨架，相邻的二茂铁单元以均匀的分子间距离固定。结果还表明，相邻的二茂铁单元之间的相互作用可以忽略不计。2)扩展分子三脚架及其单层的合成合成了一个新的金刚烷三脚架，用C(CH3)2sh取代CH2sh基团合成了一个新的金刚烷三脚架。由于两个甲基的体积较大，预计每个三脚架分子都会占据更大的面积，从而导致更大的分子距离。该三硫醇在Au(111)面上自组装单分子膜的还原脱附实验表明，其分子间距明显大于未加甲基的分子间距(10.9A)。未来这种新的三脚架和功能分子单元的二元体的合成将使大尺寸功能分子的单分子层的形成成为可能

1) Synthesis of Molecular Tripod-Ferrocene Dyads and Their MonolayersDyads consisting of a molecular tripod and ferrocene, connected through oligo (phenyleneethynylene) linkers of different lengths, were synthesized. The tripod has a rigid adamantane core to which three CH_2SH legs are attached in order to enable chemisorption on gold surface. The self-assembled monolayers of these dyads were prepared on Au (111) surface and analyzed by means of electrochemical measurements. The surface densities of the monolayers were shown to be constant irrespective of the length of the linker, demonstrating that the adjacent ferrocene units are fixed with a uniform intermolecular distance due to the rigid framework of adamantane and linear linker. It was also shown that there is negligible interaction among neighboring ferrocene units. This indicates that each ferrocene unit is kept independent from adjacent molecules, suggesting that these dyads are of potential use as molecular memories.2) Synthesis of an Extended Molecular Tripod and Its MonolayerA new adamantane tripod, having C(CH_3)2SH groups in place of the CH_2SH groups, was synthesized. Owing to the bulkiness of the two methyl groups, each tripod molecule is expected to occupy an increased area, resulting in greater molecular distance. Reductive desorption experiments for the self-assembled monolayer on Au(111) surface of this new trithiol showed that the molecular distance is significantly wider(10.9 A) than without the methyl groups. Future synthesis of dyads of this new tripod and functional molecular units would enable formation of monolayers of large-sized functional molecules