title: On-surface Ullmann coupling: the influence of kinetic reaction parameters on the morphology and quality of covalent networks.
abstract: On-surface Ullmann coupling is a versatile and appropriate approach for the bottom-up fabrication of covalent organic nanostructures. In two-dimensional networks, however, the kinetically controlled and irreversible coupling leads to high defect densities and a lack of long-range order. To derive general guidelines for optimizing reaction parameters, the structural quality of 2D porous covalent networks was evaluated for different preparation protocols. For this purpose, polymerization of an iodine- and bromine-functionalized precursor was studied on Au(111) by scanning tunneling microscopy under ultrahigh vacuum conditions. By taking advantage of the vastly different temperature thresholds for C-Br and C-I cleavage, two different polymerization routes were compared - hierarchical and direct polymerization. The structural quality of the covalent networks was evaluated for different reaction parameters, such as surface temperatures, heating rates, and deposition rates by statistical analysis of STM data. Experimental results are compared to Monte Carlo simulations.
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Eichhorn
authors.forename: Damian
authors.initials: D
authors.lastname: Nieckarz
authors.forename: Oliver
authors.initials: O
authors.lastname: Ochs
authors.forename: Debabrata
authors.initials: D
authors.lastname: Samanta
authors.forename: Michael
authors.initials: M
authors.lastname: Schmittel
authors.forename: Pawel Jerzy
authors.initials: PJ
authors.lastname: Szabelski
authors.forename: Markus
authors.initials: M
authors.lastname: Lackinger