About the event
Shammi Rana (Hipps Group)
Title: Exploring Aluminum (Oxy)hydroxide/Aqueous Interfaces: Role of Organic and Inorganic Adsorbed Ions Self-Assembly of Y[C6S-Pc]2 and Y[C4O-Pc]2 complexes at the Solution−Solid Interface
Abstract: Substituents present on a molecule are known to significantly control the self-assembly, adsorption, and orientation behavior on solid surfaces. Using STM, self-assembly of the Y[C6S-Pc]2 and Y[C4O-Pc]2 complexes was investigated at solution−solid interface. The Y[C6S-Pc]2 complex forms a well-defined monolayers with molecular vacancy defect on HOPG while dense groups of small islands with some isolated molecules on Au(111) surface.
At low concentrations (1 μM), stable isolated single molecules of Y[C6S-Pc]2 were observed on Au(111) but not on HOPG. On both HOPG and Au(111), isolated molecules of Y[C4O-Pc]2 are never observed. We suggest that core moieties with peripheral S-linked alkanes may generally be particularly strong adsorbates on gold. DFT calculations suggest that the S-linked alkane substituent system may be as much as 1 eV more stable on Au than a similar O-linked system.
We observe defects in the form of molecular vacancies in monolayer whose number can be controlled by bias voltage. Consecutive STM scanning shows the diffusion, disappearance, and appearance of new vacancies which are induced both thermally and by the STM tip. This work demonstrates the important role of molecule−substrate interactions, bias voltage, tunneling current, and the STM tip in controlling and stabilizing molecular assembly.
Meeting ID: 938 0915 3065