1 Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven Celestijnenlaan 200F B-3001 Leuven Belgium steven.defeyter@kuleuven.be.
2 Department of Chemistry and Applied Biosciences, ETH Zurich Zurich CH-8093 Switzerland.
3 imec Kapeldreef 75 3001 Leuven Belgium.
4 Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University Suzhou 215123 PR China.
5 Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University Suzhou 215123 Jiangsu PR China.
6 Department of Chemistry and Biochemistry, Concordia University 7141 Sherbrooke St. W. Montreal Québec Canada.
7 Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University Suzhou 215123 Jiangsu PR China ivasenko@suda.edu.cn.

Herein we report the impact of covalent modification (grafting), inducing lateral nanoconfinement conditions, on the self-assembly of a quinonoid zwitterion derivative into self-assembled molecular networks at the liquid/solid interface. At low concentrations where the compound does not show self-assembly behaviour on bare highly oriented pyrolytic graphite (HOPG), close-packed self-assembled structures are visualized by scanning tunneling microscopy on covalently modified HOPG. The size of the self-assembled domains decreases with increasing the density of grafted molecules, i.e. the molecules covalently bound to the surface. The dynamics of domains are captured with molecular resolution, revealing not only time-dependent growth and shrinkage processes but also the orientation conversion of assembled domains. Grafted pins play a key role in initiating the formation of on-surface molecular self-assembly and their stabilization, providing an elegant route to study various aspects of nucleation and growth processes of self-assembled molecular networks.