On-Surface Synthesis of BN-Substituted Heteroaromatic Networks.
We report on the bottom-up fabrication of BN-substituted heteroaromatic networks achieved by surface-assisted polymerization and subsequent cyclodehydrogenation of specifically designed BN-substituted precursor monomers based on a borazine core structural element. To get insight into the cyclodehydrogenation pathway and the influence of molecular flexibility on network quality, two closely related precursor monomers with different degrees of internal cyclodehydrogenation have been employed. Scanning tunneling microscopy shows that, for both monomers, surface-assisted cyclodehydrogenation allows for complete monomer cyclization and the formation of covalently interlinked BN-substituted polyaromatic hydrocarbon networks on the Ag(111) surface. In agreement with experimental observations, density functional theory calculations reveal a significantly lower energy barrier for the cyclodehydrogenation of the conformationally more rigid precursor monomer, which is also reflected in a higher degree of long-range order of the obtained heteroaromatic network. Our proof-of-concept study will allow for the fabrication of atomically precise substitution patterns within BNC heterostructures.
Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
Carlos
C
Sánchez-Sánchez
Max Planck Institut for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
Sebastian
S
Brüller
Max Planck Institut for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.|Mechanische Verfahrenstechnik, TU Kaiserslautern , Gottlieb Daimler Straße 44, 67663 Kaiserslautern, Germany.
Hermann
H
Sachdev
Max Planck Institut for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
Klaus
K
Müllen
Institut für Organische Chemie, Universität Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Matthias
M
Krieg
Institut für Organische Chemie, Universität Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Holger F
HF
Bettinger
Department of Physics, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Adrien
A
Nicolaï
Department of Physics, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Vincent
V
Meunier
Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
Leopold
L
Talirz
Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.|Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland.
Roman
R
Fasel
Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
Pascal
P
Ruffieux
bottom-up; covalent network; cyclodehydrogenation; density functional theory; graphene; hexagonal boron nitride; scanning tunneling microscopy