Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 5: Nanostructures at Surfaces I: Organics

O 5.1: Vortrag

Montag, 1. April 2019, 10:30–10:45, H15

Ring/Chain Competition in Organometallic Oligomers with Non-Alternant Aromatic Building Blocks — •Claudio K. Krug¹, Qitang Fan¹, Damian Nieckarz², Florian Fillsack¹, Johannes Glowatzki¹, Nicole Trebel¹, Lukas J. Heuplick¹, Tabea Koehler¹, Paweł Szabelski², and J. Michael Gottfried¹ — ¹Philipps-Universität Marburg, Fachbereich Chemie, Hans-Meerwein-Str. 4, 35032 Marburg, Germany — ²Department of Theoretical Chemistry, Maria Curie-Skłodowska University, Pl. M.C. Skłodowskiej 3, Lublin 20-031, Poland

Organometallic oligomers with C-Cu-C bonds are formed from the non-alternant aromatic compound 1,3-dibromoazulene (DBAz) after deposition on a Cu(111) surface. The oligomers appear either as macrocycles (mostly hexamers) or as chains. Depending on the DBAz coverage and the annealing temperature, the ratio between rings and chains can be tuned by kinetic and thermodynamic control. We have studied the ring/chain competition by statistical analysis of scanning tunneling microscopy (STM) images. Upon deposition at 300 K, the structure formation is kinetically controlled, resulting in the formation of mostly regio-irregular chains. Annealing theses chains to temperatures above 390 K switches the conditions to thermodynamic control, which leads to an increased yield of the thermodynamically more stable macrocycles. In the low-coverage limit, almost 80% of the deposited monomers are incorporated in cyclic hexamers. These experimental results are compared to Monte Carlo (MC) simulations, which confirm the influences of kinetic and thermodynamic control.