Executive Summary : | Polycyclic aromatic hydrocarbons (PAHs) including curved aromatics, nanographene, heterodoped graphene, carbon nanotubes (CNTs), cycloparaphenylenes (CPPs), graphene nanoribbons (GNRs), nanoflakes, nanobelts etc. have attracted tremendous attention in the field of chemistry and materials science due to their fascinating electronic, optical, and magnetic properties. Among them, zigzag-edged graphene nanostructures (ZGNs) with precisely-tunable π-magnetism serve as potential candidates for applications in spintronics and quantum devices. To improve the stability, processability and to protect the reactive edges of ZGNs, substitutional groups are often introduced in organic synthesis, which renders the study of their intrinsic properties difficult. Conventional wet-chemistry methods are promising approaches in contrast to the on-surface bottom-up synthesis for the fabrication of unsubstituted as well as functionalized ZGNs with atomic precision by using diverse-catalysed transformation of rationally-designed precursors. In this proposal, we will synthesize curved polycyclic aromatics, nanographene, carbon nanoribbons and nanobelts through bottom-up solution phase synthesis. Several synthetic strategies have been developed for final step graphitization of oligoaryl intermediates including Scholl reaction, photochemical cyclodehydrohalogenation, photocyclization and Pd- and Ni-catalysed reaction but mostly used is oxidative cyclodehydrogenation reaction which was pioneered by Roland Scholl. Although Scholl reaction is a highly effective method for graphitization, still it is less explored. Recently, Durola et al. developed a new technique to prepare scalable graphitized precursors based on the Perkin reaction. For example, Perkin condensations between arylglyoxylic acids and arylacetic acids, followed by the addition of alkyl amine yielded diarylmaleimides in a one-pot procedure. This synthetic strategy would be suitable for the preparation of long and soluble edge functionalized CNRs such as phenacenes through complementary protecting techniques of functionalised glyoxylic acid. The controlled condensation through the Perkin reaction could produce more than five building blocks of which each block will consist seven naphthalene units. By applying this technique, oligo-arylenemaleates of any size and their corresponding nanoribbon-style cyclization products including macrocyclic species are now straightforwardly targetable. The inclusion of further extended π-conjugated arene fragments such as naphthalene, anthracene, pyrene, perylene could reduce the electronic bandgap to values more similar to those of inorganic semiconductors such as As, Ga or Si. As a result, the shifting of optical absorption will occur bathochromically to allow efficient absorption through the visible part of the solar spectrum, as desired for optoelectronics. |