The Rational Chemical Synthesis of a C60H12 Carbon Nanotube End-cap and Novel Geodisc Polyarenes

Abstract

The distinctive molecular structure of carbon nanotubes makes them desirable for electronic and chemical materials; however, current production methods are limited with respect to purity and chirality. Geodesic polyarenes serve as superb templates for the bottom up synthesis of carbon nanotube end-caps, setting the chirality and dimensions of the carbon nanotubes. The work herein describes the synthetic efforts towards the rational synthesis of a [6,6] carbon nanotube end-cap. Chapter 1 describes the efforts towards the synthesis of a C60H12 end-cap, in which the synthesis of an advanced intermediate, peri-bis(dibenzo[a,g]corannulene) is complete; however, the insolubility of this material proved to be problematic in a subsequent cycloaddition reaction. This reaction is examined computationally in order to understand the failure of the addition of dienophile, maleic anhydride, to peri-bis(dibenzo[a,g]corannulene). In Chapters 2 and 3, the development of solubility-enhancing methods is described. The development of a solubility-enhancing dienophile is successfully employed to induce the solubility of a formerly insoluble diene, peri-bis(dibenzo[a,g]corannulene), through Diels-Alder addition. Another method, employs the incorporation of tert-butyl groups onto peri-bis(dibenzo[a,g]corannulene) to successfully induce solubility. The enhanced-solubility enables the successful Diels-Alder addition of simple maleimide dienophiles, installing all necessary carbon atoms for the desired end-cap. Pyrolysis of the bis-anhydride derived from the aromatized bis-maleimide adduct afforded the C60H12 end-cap, which is the second carbon nanotube end-cap ever synthesized and the first of these dimensions. Chapter 3 also explores a palladium catalyzed intramolecular arylation reaction to form a pivotal intermediate in the synthesis of the end-cap, dibenzo[a,g]corannulene. The mechanism for the formation of a problematic byproduct resulting from reductive dehalogenation is discussed. Utilizing a deuterium labeled solvent, it is found that deuterium is incorporated onto the hydrocarbon, indicating that the solvent (N,N-dimethylformamide-d7) is the source of hydrogen for the reductive dehalogenation. These conditions are further exploited in Chapter 4 for the convenient perdeuteration of a variety of polycyclic aromatic hydrocarbons. Chapter 5 describes the first synthesis of a nitrogen containing geodesic polyarene, dibenzo[g,m]azacorannulene. This synthesis is completed in seven steps from a commercially available source in a 28% overall yield.