Electric Field-Triggered Monolayer Assembly or Bond Formation at Solid-Liquid Interface

• Main Authors: Kum-Yi Cheng, 鄭昆益
• Other Authors: 陳俊顯
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/6vseqd

博士 === 國立臺灣大學 === 化學研究所 === 106 === The formation of covalent bonds between elementary units transforms the dimensions of building blocks and is envisaged an important bottom-up approach for the fabrication of nanomaterials and nanodevices. To facilitate bond formation, close proximity between reactants is required. In this research presentation, we present a template-assisted method in conjunction with a concentration-enrichment skill to obtain a fullerene monolayer for the subsequent fullerene oligomerization. The template was a two-dimensional porous framework, comprised of 1,3,5-benzenetricarboxylic acid (trimesic acid, TMA), in which the void space was able to accommodate fullerenes. Fullerene monolayers were subjected to a 10-μsec pulse of 4 volts or higher via an STM (scanning tunneling microscope) tip. STM images showed that the apparent nearest neighboring spacing was reduced from 1.7 nm to 1.4 nm. STS (scanning tunneling spectroscopy) revealed an increased LUMO FWHM from 0.5 eV to 0.6 eV, suggesting that the oligomerization took place and the fullerene of molecular states overlaped with those of neighboring molecules. MS spectra exhibited signals of oligomer dimer and trimer in m/z 2000 to 4000. The mechanism is ascribed to a [2+2] cycloaddition reaction. The other part, we studied a discotic liquid crystalline (DLC) of dibenzo[a,c]phenazine at the liquid-solid interface using scanning tunneling microscopy/spectroscopy, by which we show how to tailor the DLC assemblies and in turn their electron-transfer efficiency. We presents an alternative method for phase control and electronic measurements for DLCs, especially at the microscopic level.