Polymorphism and Building‐Block‐Resolved STM Imaging of Self‐Assembled Monolayers of 4‐Fluorobenzenemethanethiol on Au(111)

• Published in: Chemphyschem Vol. 23; no. 19; pp. e202200347 - n/a
• Main Authors: Azzam, Waleed, Subaihi, Abdu, Rohwerder, Michael, Zharnikov, Michael, Bashir, Asif
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 06.10.2022
• Subjects: 4-fluorobenzenemethanethiol; Docking; Fluorine; Gold; Imaging; Monolayers; Polymorphism; Scanning tunneling microscopy; self-assembled monolayers; Sulfur; sulfur docking group, tunneling; Unit cell
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.202200347

Self‐assembled monolayers (SAMs) of 4‐fluorobenzenemethanethiol (p‐FBMT) on Au(111), prepared by immersion procedure (1 mM ethanolic solution; 60 °C; 18 h), were characterized by scanning tunneling microscopy (STM). The data suggest the formation of highly ordered monolayer with a commensurate structure, described by the23×13R13∘ unit cell. The STM appearance of this cell occurs, however, in two different forms, with either well‐localized individual spots or splitting of these spots in two components. These components are assigned to the tunneling through the entire molecule or sulfur docking group only. The respective spots correspond then to the terminal fluorine atom and sulfur docking group, manifesting, thus, building‐block‐resolving STM imaging. The accessibility of the docking group for direct tunneling is most likely related to a specific molecular organization for one of the two possible internal structures of the unit cell. The above results represent a showcase for potential of STM for imaging of upright‐arranged and densely packed molecular assemblies, such as SAMs. Scanning tunneling microscopy appearance of self‐assembled monolayers of 4‐fluorobenzenemethanethiol on Au(111) occurs in two different forms – with either well‐localized individual spots or splitting of these spots in two components. These components are assigned to the tunneling through the entire molecule or sulfur docking group only.