Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics

• Published in: Nature communications Vol. 14; no. 1; pp. 1554 - 9
• Main Authors: Dreher, Maximilian, Dombrowski, Pierre Martin, Tripp, Matthias Wolfgang, Münster, Niels, Koert, Ulrich, Witte, Gregor
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.03.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/146; 147/138; 639/925/357/1018; 639/925/357/341; Anisotropy; Chemical bonds; Covalent bonds; Desorption; Elongation; Fabrication; Fluorination; Humanities and Social Sciences; Inorganic materials; Kinetics; Molybdenum disulfide; Monte Carlo simulation; multidisciplinary; Nanosheets; Nanostructure; Organic chemistry; Radiation effects; Science; Science (multidisciplinary); Shape control; Substrates
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-37203-7

Since molecular materials often decompose upon exposure to radiation, lithographic patterning techniques established for inorganic materials are usually not applicable for the fabrication of organic nanostructures. Instead, molecular self-organisation must be utilised to achieve bottom-up growth of desired structures. Here, we demonstrate control over the mesoscopic shape of 2D molecular nanosheets without affecting their nanoscopic molecular packing motif, using molecules that do not form lateral covalent bonds. We show that anisotropic attractive Coulomb forces between partially fluorinated pentacenes lead to the growth of distinctly elongated nanosheets and that the direction of elongation differs between nanosheets that were grown and ones that were fabricated by partial desorption of a complete molecular monolayer. Using kinetic Monte Carlo simulations, we show that lateral intermolecular interactions alone are sufficient to rationalise the different kinetics of structure formation during nanosheet growth and desorption, without inclusion of interactions between the molecules and the supporting MoS 2 substrate. By comparison of the behaviour of differently fluorinated molecules, experimentally and computationally, we can identify properties of molecules with regard to interactions and molecular packing motifs that are required for an effective utilisation of the observed effect. Structuring organic films is of scientific and technological interest. Here, the authors use partially fluorinated organic molecules exhibiting strong intermolecular interactions to form extended 2D molecular nanosheets and control their shape through growth and desorption kinetics.