Design, Synthesis, and Characterization of Ester-Functionalized Group 16 Conjugated Polymers and Macrocycles

Polymeric organic semiconductors derived from group 16 heterocycles are of interest to synthetic researchers, as these materials are usually inexpensive, flexible, and easy to process relative to their inorganic counterparts. Recently, we utilized a nickel-catalyzed Suzuki-Miyaura crosscoupling strategy to prepare poly(3-hexylesterfuran). Interestingly, the introduction of the electron-withdrawing ester moiety significantly improved the photostability of polyfuran and also induced the formation of a π-stacked helical structure by enforcing a syn geometry of adjacent furan units in the buildup of the chain. Focusing on the ester-functionalization, this thesis describes the design and synthesis of both linear polymers and macrocycles to tune structural and electronic features of π-conjugated materials. Poly(3-alkylester selenophene) and statistical copolymers of thiophene-3-carboxylates and selenophene-3-carboxylates were synthesized for a thorough understanding of the conformational and optoelectronic properties of ester-substituted group 16 polymers (Chapter 2). Dynamic folding and unfolding behavior of poly(3-alkylesterfuran) were investigated in variety of side-chain structures, molecular weight, solvent, and temperature (Chapter 3 and 4). The furan ester induced syn-templating strategy was expanded to include other heterocycles in tandem with furan to synthesize alternating helical copolymers (Chapter 5). Finally, furan ester induced syn-templating strategy leaded to the synthesis of a new mixed macrocycle system, cyclo[4]thiphene[4]furan (C4TE4FE) and its dication (Chapter 6). Current effort focused on the investigation of solution aggregation behavior of cyclo[6]furan and cyclo[4]thiophene[4]furan (Chapter 7), in addition to the overall outlook for this thesis research and future direction towards the expansion of macrocycle families by post-cyclization functionalization (Chapter 8).