Scanning Tunneling Microscope Tip-Induced Formation of a Supramolecular Network of Terarylene Molecules on Cu(111)

Abstract

Bottom-up approaches allow for molecularlevel control of engineering new nanostructures. For nextgeneration molecular circuits, machines, and phase-change materials, supramolecular structure formation and interactions must be investigated on a two-dimensional solid substrate. Scanning tunneling microscopy (STM) provides a method not only to address such supramolecular structures at the molecular level on a solid surface but also to locally control and manipulate such structures. In this article, we show that a terarylene molecule, a subfamily of photoswitching diarylethenes that promise a lot of applications from molecular switches to photoelectronics, assembles upon application of a bias voltage pulse from an STM tip. We show that molecules organize themselves in order to align their dipole moment to follow those of the electric field induced in the tunneling junction. The 2D assembly is stabilized by π−π stacking interactions and van der Waals interactions. This expands the repertoire of currently available bottom-up techniques for fabrication of supramolecular nanostructures.

Tip-Induced $β$-Hydrogen Dissociation in an Alkyl Group Bound on Si(001)

“…According to the number of configurations reacted at 50 K, this minority species accounts for less than 3 % of the initial configurations. Field-induced effects, which are also largely independent of the tunneling current [25], can be ruled out: also at 50 K, we observe the process to take place only with the tip very close to the adsorbate, in contrast to the nonlocal character of field-induced processes [25,39,40].…”

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

“…Islands having two ordered domains separated by a disordered domain were found but larger single‐domain islands were also imaged. (Figure d) The 3‐fold symmetry of the Cu(111) surface seemed to influence assembly formation as all domains are oriented 60° with respect to each other . The assembly formation was proposed to be due to electric‐field induced alignment of molecules.…”

“…With enough molecules aligning in the same direction, intermolecular forces take over and stabilize the self‐assembled monolayer. However, it was seen that molecules in the peripheries diffuse on the surface after several hours proving the dynamic nature of the assembly …”

“…(Figure 9d) The 3-fold symmetry of the Cu(111) surface seemed to influence assembly formation as all domains are oriented 60°with respect to each other. [88] The assembly formation was proposed to be due to electric-field induced alignment of molecules. The bias pulse induced an electric field between tip and surface which caused molecules to align in one direction according to their dipole moment.…”

“…However, it was seen that molecules in the peripheries diffuse on the surface after several hours proving the dynamic nature of the assembly. [88] Imaging at 5 K was therefore performed to lower the kinetic mobility of the molecules. However, imaging (Figure 9f) did not show similar shapes as at 80 K and did not reveal the symmetry of the compound.…”