Surface-confined synthesis is a promising approach to build complex molecular nanostructures including macrocycles. However, despite the recent advances in on-surface macrocyclization under ultrahigh vacuum, selective synthesis of monodisperse and multicomponent macrocycles remains a challenge. Here, we report on an on-surface formation of [6 + 6] Schiff-base macrocycles via dynamic covalent chemistry. The macrocycles form two-dimensional crystalline domains on the micrometer scale, enabled by dynamic conversion of open-chain oligomers into well-defined ∼3.0 nm hexagonal macrocycles. We further show that by tailoring the length of the alkyl substituents, it is possible to control which of three possible products-oligomers, macrocycles, or polymers-will form at the surface. In situ scanning tunneling microscopy imaging combined with density functional theory calculations and molecular dynamics simulations unravel the synergistic effect of surface confinement and solvent in leading to preferential on-surface macrocyclization.

Center Lab of Longhua Branch and Department of Infectious disease Shenzhen People's Hospital second Clinical Medical College of Jinan University Shenzhen 518120 Guangdong Province China

Department of Chemistry McGill University 801 Sherbrooke Street W Montreal Quebec Canada H3A 0B8

Dipartimento di Chimica Industriale Toso Montanari Università di Bologna 40136 Bologna Italy

INRS Énergie Matériaux Télécommunications Centre 1650 boulevard Lionel Boulet Varennes Québec Canada J3X 1S2

Institut des Sciences Moléculaires UMR 5255 University of Bordeaux 33405 Talence France

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo námĕstí 542 2 166 10 Praha Czech Republic

J Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 2155 3 182 23 Praha Czech Republic

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