DESIGN OF RADIAL/LINEAR HYBRID PI-CONJUGATED SYSTEMS WITH DISJOINT SUBSTITUTION PATTERN

The understanding of pi conjugation in organic electronics has largely grown from linear conjugated oligomers and polymers. Recent research enabled the synthesis of [n]cycloparaphenylenes (CPPS) which show unique electronic properties from radial pi conjugation. Previous work in this lab incorporated CPPs into linear conjugated systems to investigate fundamental properties of the curved pi surface. This dissertation details the design of disjointly-substituted CPP incorporated into linear small molecule and polymeric systems, and synthetic attempts to extend functionalized CPPs with various aryl groups and fused polycyclic aromatic hydrocarbons (PAHs). Chapter 1 describes the design and optoelectronic characterization of [8]CPP with disjointly substituted di-alkyne subunits in collaboration with Dr. Ramesh Jasti that allows for pi extension primarily through Sonogashira cross couplings to afford small molecule and polymer systems. New electronic states arise from multiple operative radial/linear conjugation pathways, as the disjoint pattern results in both ortho and meta connections to the CPP ring. Chapter 2 details oxidation studies of linearly extended CPPs and progress made on post-construction cyclization chemistry to form fused PAH/CPP hybrids. Chapter 3 discusses progress made to synthesize CPPs with directly linked aryl groups, including the design of terphenyl model compounds, and ends with proposed CPP materials targets. Chapter 4 introduces a design theory for organic diradicals through computational studies of linear conjugated diradicals with lower symmetry patterns, as well as CPP diradicals. Synthetic progress toward some of these low symmetry molecules are included alongside considerations for designing and characterizing stable and persistent organic diradicals