Kang Hungu, Lee Seongkeun, Ito Eisuke, Hara Masahiko, Noh Jaegeun
Department of Chemistry, Hanyang University, Seoul 133-791, Korea.
J Nanosci Nanotechnol. 2012 May;12(5):4274-8. doi: 10.1166/jnn.2012.5943.
Self-assembled monolayers (SAMs) formed by the adsorption of 4-fluorobenzenethiol (4-FBT) and 4-fluorobenzenemethanethiol (4-FBMT) on Au(111) were examined by scanning tunneling microscopy (STM) to understand the effect of a flexible methylene spacer between the sulfur head-group and phenyl group and the effect of solution temperature on the formation and structure of the SAMs. Although the adsorption of 4-FBT on Au(111) at room temperature for 24 h generated only disordered phase SAMs containing gold adatom islands, 4-FBT at 75 degrees C for 2 h formed mixed SAMs: disordered phases and ordered (2 x 12√(2))R10 degrees superlattice with a rectangular unit cell containing six adsorbed molecules. On the other hand, SAMs formed from 4-FBMT, with a methylene spacer, at room temperature for 24 h on Au(111) had irregularly ordered phases containing uniformly distributed VIs with lateral dimensions of 2-5 nm; SAMs formed from 4-FBMT at 75 degrees C for 2 h were composed of slightly improved ordered phases and larger VIs with lateral dimensions of 5-12 nm as a result of Ostwald ripening. From this study, we found that the methylene spacer plays an important role in controlling the structure of SAMs formed from p-substituted fluorinated aromatic thiols.
通过扫描隧道显微镜（STM）研究了4-氟苯硫醇（4-FBT）和4-氟苯甲硫醇（4-FBMT）吸附在Au(111)上形成的自组装单分子层（SAMs），以了解硫头基和苯基之间柔性亚甲基间隔基的作用以及溶液温度对SAMs形成和结构的影响。尽管室温下4-FBT在Au(111)上吸附24小时仅产生含有金吸附原子岛的无序相SAMs，但75℃下的4-FBT吸附2小时形成了混合SAMs：无序相和有序的(2×12√(2))R10°超晶格，其矩形晶胞包含六个吸附分子。另一方面，由具有亚甲基间隔基的4-FBMT在室温下于Au(111)上吸附24小时形成的SAMs具有不规则有序相，其中含有横向尺寸为2 - 5 nm的均匀分布的VIs；由于奥斯特瓦尔德熟化，75℃下由4-FBMT吸附2小时形成的SAMs由略有改善的有序相和横向尺寸为5 - 12 nm的更大VIs组成。通过这项研究，我们发现亚甲基间隔基在控制由对取代的氟化芳族硫醇形成的SAMs的结构中起着重要作用。
