Exploring two-dimensional van der Waals supramolecular networks: a scanning tunnelling microscopy approach

Ding, Haoxuan ORCID: 0000-0003-0312-444X (2024). Exploring two-dimensional van der Waals supramolecular networks: a scanning tunnelling microscopy approach. University of Birmingham. Ph.D.

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Abstract

Supramolecular self-assembly has emerged as a strategic avenue for engineering chemically bespoke surfaces. Over the preceding three decades, research focused on a variety of key parameters, such as temperature, solute concentration, and molecular architecture, has led to the successful fabrication of self-assembled molecular networks (SAMNs). Various types of intermolecular interactions have been explored in the construction of SAMNs. The study of self-assembly on surfaces began with early investigations of hydrogen-bonded assemblies and has since expanded to include other non-covalent interactions, such as coordination bonds and weaker van der Waals (vdW) interactions.
Among the many techniques in characterising molecular assembly on surfaces, scanning tunnelling microscopy (STM) has become the most popular choice due to its ability to provide real space images with atomic resolution. One of the useful properties of the STM is that it can provide information on structures not having long range-order as well as single atom level defects.
This thesis presents a study on the role of vdW interaction in molecular assembly, exploring how this non-directional and relatively weak force influences molecular self-assembly patterns with a large number of molecules. The study examines the chemisorbed alkanethiol molecules on the Au(111) surfaces and the formation of two-dimensional (2D) vdW supramolecular structures via the self-assembled co-crystallisation of alkanethiol and fullerene molecules. The absence of specific functional groups on the molecules used in this study leads to much more complex self-assembled structures and structural diversity. The fullerene/alkanethiol co-assembly exhibits different phases on the Au(111) substrate, as investigated using high-resolution STM at room temperature. The results show how collective interactions among many molecules dictate the stable structure transition.

Type of Work:	Thesis (Doctorates > Ph.D.)
Award Type:	Doctorates > Ph.D.
Supervisor(s):	Supervisor(s) Email ORCID Guo, Quanmin UNSPECIFIED orcid.org/0000-0002-3417-8726 Theis, Wolfgang UNSPECIFIED orcid.org/0000-0002-4074-8318 Li, Ziyou UNSPECIFIED UNSPECIFIED
Licence:	All rights reserved
College/Faculty:	Colleges > College of Engineering & Physical Sciences
School or Department:	School of Physics and Astronomy
Funders:	Engineering and Physical Sciences Research Council
Subjects:	Q Science > QC Physics
URI:	http://etheses.bham.ac.uk/id/eprint/15065

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