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This dissertation discloses the use of alkynes as a fundamental component in the design and development of new chemical reactions that pave the way for the construction of carbon-rich molecules and nanomaterials. Chapter 1 gives a short introduction into the fascinating world of graphene and other 2-dimensonal nanomaterials. A brief discussion of the chemistry that has been developed for the preparation of carbon nanostructures is also provided and the foundational series of reports for bottom-up construction of nanocarbons is presented. Then, Chapter 2 delves deep into our group’s efforts to expand the available reaction toolset for the construction of polyarenes through ‘alkyne origami’. Central to this chapter is the development and evolution of oligoalkyne radical cascades that construct carbon-rich molecules. This chapter also contains a detailed account of why alkynes are the ideal high-energy, carbon-rich functionality to apply in this endeavor, as well as the use of a ‘weak link’ approach for selective alkyne activation, and its later evolution into the traceless directing group (TDG) method. Furthermore, this chapter provides the experimental and theoretical background that lead into the development of the first ever alkyne radical peri-annulations on acene cores. Chapter 3 discloses the development of peri-annulations as a tool to modify the zigzag-edge (L-region) of polycyclic aromatic hydrocarbons through their π-extension. Depending on the choice of reaction conditions and substrates, this flexible approach can provide Bu3Sn-substituted phenalenes, benzanthrenes, and olympicenes from simple arene starting materials. Subsequent reactions with electrophiles open synthetic access to previously inaccessible functionalized polyarenes. Computational chemistry helped unveil the complex reaction mechanism that governs this transformation and provided theoretical explanations for the scarcity of similar transformations reported in the literature. Finally, a versatile synthetic route to distannyl-substituted polycyclic aromatic systems developed via double radical peri-annulations is presented in Chapter 4. The cyclization precursors were equipped with propargylic OMe traceless directing groups (TDGs) for regioselective Sn-radical attack at the triple bonds. The two peri-annulations converge at a variety of polycyclic central cores to yield expanded difunctionalized polycyclic aromatic hydrocarbons (PAHs). The product diversity derives from the identity of the polycyclic core and the choice of alkyne substitution. This approach can be extended to triple peri-annulations where annulations are coupled with a radical cascade that connects two preexisting aromatic cores via a formal C-H activation step. For example, two naphthyl moieties can be fused to form a perylene core en route to the final peropyrene product. The installed Bu3Sn groups serve as chemical handles for further functionalization of the new polyarenes via direct cross-coupling, iodination, or protodestannylation. Furthermore, these groups allow for simpler processing and purification of the reaction mixtures by increasing solubility in organic solvents. Photophysical studies reveal that the Bu3Sn-substituted PAHs are moderately fluorescent, and their protodestannylation serves as a chemical switch for ‘switching on’ high fluorescence quantum yields. DFT calculations identified the most likely possible mechanism of this complex chemical transformation involving two independent peri-cyclizations at the central core.