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Functional Supramolecular Networks on Surfaces

Final Report Summary - FUNSURF (Functional Supramolecular Networks on Surfaces)

Introduction and summary of project objectives:
Functional Supramolecular Networks on Surfaces (FUNSURF) is a multidisciplinary project which aims to use two-dimensional (2D) supramolecular self-assembly to produce functional molecular networks. These networks were studied using scanning probe microscopy (SPM) a technique which allows visualisation of structures with molecular resolution. The molecular building blocks used in this study were designed to have the ability to respond to external stimuli such as light irradiation or voltage pulses applied using an SPM tip.
These responses include light induced structural changes or controlled covalent reactions. The final objective was to implement an analysis method that combines the high spatial resolution of SPM with chemical sensitivity, tipenhanced Raman spectroscopy (TERS).
The self-assembly of simple molecules into complex structures is a ubiquitous process in nature. The self-assembly of molecules at surfaces into 2D molecular networks is promising areas of research. These structures can quickly and easily organise chemical groups across a surface with nanometre precision. Areas of particular interest are self-assembly at the liquid-solid interface and the formation of nanoporous networks. The molecular systems studied in FUNSURF are based on a previously studied system that is known to self-assemble at the liquid solid interface between graphite and organic solvents, alkoxylated dehydrobenzo[12] annulenes (DBA). DBA molecules consist of a triangular annulene core decorated with six alkoxy chains. The DBA molecules interact with each other through the chain interdigitation. DBAs form two distinct network structures, a close packed linear phase and a hexagonal porous network. Which structure is formed depends on the length of the alkoxy chains, the solvent used and the concentration. DBA is an ideal system for functional networks as the alkoxy chains can be altered at the synthesis stage to include specific chemical groups.