On-Surface Synthesis of BN-Substituted Heteroaromatic Networks

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• 作者：Carlos S谩nchez-S谩nchez ; Sebastian Br眉ller ; Hermann Sachdev ; Klaus M眉llen ; Matthias Krieg ; Holger F. Bettinger ; Adrien Nicola茂 ; Vincent Meunier ; Leopold Talirz ; Roman Fasel ; Pascal Ruffieux
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：9
• 期：9
• 页码：9228-9235
• 全文大小：581K
• ISSN：1936-086X

文摘

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.