Son Young Ji, Kang Hungu, Seong Sicheon, Han Seulki, Lee Nam-Suk, Noh Jaegeun
Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea.
Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea.
Molecules. 2022 Aug 23;27(17):5377. doi: 10.3390/molecules27175377.
To probe the effects of deposition temperature on the formation and structural order of self-assembled monolayers (SAMs) on Au(111) prepared by vapor deposition of 2-(2-methoxyethoxy)ethanethiol (CHO(CH)O(CH)SH, EG2) for 24 h, we examined the surface structure and electrochemical behavior of the resulting EG2 SAMs using scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM observations clearly revealed that EG2 SAMs vapor-deposited on Au(111) at 298 K were composed of a disordered phase on the entire Au surface, whereas those formed at 323 K showed improved structural order, showing a mixed phase of ordered and disordered phases. Moreover, at 348 K, uniform and highly ordered EG2 SAMs on Au(111) were formed with a (2 × 3√3) packing structure. CV measurements showed sharp reductive desorption (RD) peaks at -0.818, -0.861, and -0.880 V for EG2 SAM-modified Au electrodes formed at 298, 323, and 348 K, respectively. More negative potential shifts of RD peaks with increasing deposition temperature are attributed to an increase in van der Waals interactions between EG2 molecular backbones resulting from the improved structural quality of EG2 SAMs. Our results obtained herein provide new insights into the formation and thermally driven structural order of oligo(ethylene glycol)-terminated SAMs vapor-deposited on Au(111).
为了探究沉积温度对通过气相沉积2-(2-甲氧基乙氧基)乙硫醇（CHO(CH)O(CH)SH，EG2）24小时在Au(111)上制备的自组装单分子层（SAMs）的形成和结构有序性的影响，我们使用扫描隧道显微镜（STM）和循环伏安法（CV）研究了所得EG2 SAMs的表面结构和电化学行为。STM观察清楚地表明，在298 K下气相沉积在Au(111)上的EG2 SAMs在整个Au表面由无序相组成，而在323 K形成的SAMs显示出改善的结构有序性，呈现出有序相和无序相的混合相。此外，在348 K时，在Au(111)上形成了具有(2×3√3)堆积结构的均匀且高度有序的EG2 SAMs。CV测量显示，对于分别在298、323和348 K形成的EG2 SAM修饰的Au电极，在-0.818、-0.861和-0.880 V处有尖锐的还原脱附（RD）峰。随着沉积温度升高，RD峰的负电位偏移更大，这归因于EG2 SAMs结构质量提高导致EG2分子主链之间范德华相互作用增加。我们在此获得的结果为气相沉积在Au(111)上的寡聚（乙二醇）封端的SAMs的形成和热驱动的结构有序性提供了新的见解。
