Setting the hook for specific single walled carbon nanotubes (SWCNT)

The electronic properties of SWCNTs depend strongly on well-defined characteristics such as their diameter, n,m-indices and chirality.[1–4] Traditional purification methods do not allow to selectively obtain samples of SWCNTs with precisely defined characteristics and high purity. The separation and purification of SWCNTs is an ongoing challenge as the selectivity towards traditional means of purification remains low at best.
Here, we propose a new strategy to achieve a controlled and selective debundling and separation of SWCNTs depending on their size and chirality. The focus of this thesis is the design and synthesis of a molecular hook for specific SWCNTs. Conceptually, the hook consists of a chiral building block with a concave π-system, which can be accessed using stereospecific Diels-Alder reactions as key steps. Polymerization with interlinking building blocks then leads to chiral ribbons, which are envisaged to selectively coat a specific SWCNT and disperse it. The driving force for the coating process is mainly the interaction of the SWCNT with the concave π-moiety while the size exclusion is defined by the resulting secondary structure of the polymer, the polymer backbone and the interlinking molecules. Variation of the interlinking building blocks allows altering of the properties of the polymer at a late stage in the synthesis and ultimately defines the dispersion capability of the polymer. Each of the three successfully synthesized copolymers contains an enantiomerically pure ethenoanthracene derivative as the concave π-moiety. As a reliable release of the coated SWCNT is highly desirable, we further present a diamine monomer unit designed for Schiff base linked copolymerization that will allow for acid-labile depolymerization resulting in uncoating of the dispersed SWCNTs. Each of the polymer was characterized and the dispersion capability assessed subsequently.