Structure-property relationships in conjugated donor/acceptor-functionalized arylacetylenes and dehydrobenzoannulenes
Spitler, Eric Lewis, 1980-
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Spitler, Eric Lewis, 1980-
Highly conjugated carbon-rich molecules have attracted interest in recent years due to unique electronic, optical and materials properties. Carbon networks based upon the phenylacetylene subunit are increasingly recognized as building blocks for a host of sensing and electronics components due to the rigidity and linearity of carbon-carbon triple bonds. Further extending this motif into a macrocycle, generating a dehydrobenzoannulene (DBA), also confers planarity, increasing the Ã -conjugation and giving rise to enhanced materials behavior. Functionalization of arylacetylenes and DBAs with electron donating and accepting groups manipulates the energetics such that finely-tuned optoetectronic properties can be devised for customized applications, including fluorescent sensor arrays, organic light-emitting diodes, and nonlinear optical materials. Fundamental structure-property relationship studies into certain physical modifications of molecular architecture effects on the photophysics, intramolecular charge transfer (ICT), or complexation properties are of importance in the rational design of the next generation of organic electronics. Chapter I provides a review of recent advances in the field of annulene chemistry. It is organized by cycle type, size, and application within each category. Chapter II describes syntheses and ion responses of an array of donor/acceptor-functionalized arylacetylenes. The independent manipulation of frontier molecular orbital (FMO) energy levels is discussed in relation to a fluorescent switching phenomenon. Chapter III expands this effect to include DBAs. The consequences of incorporating protonatable donor/acceptor groups into a macrocycle, as well as placement of the acceptor nitrogen are examined, and comparison of calculations to experimental results imply generation of transient ICT species with induced FMO localizations. Chapter IV describes the syntheses of acyclic tetrakis(phenylethynyl)benzene (TPEB) and - and DBA systems utilizing fluorinated acceptor groups. Comparisons between these inductive acceptors and earlier resonance acceptors are made, and imply greater stability and processing potential for optoelectronic applications. Chapter V describes a series of bisDBAs functionalized with dibutylamino groups as donors and nitro groups as acceptors. The effects of 2-donor/2-acceptor versus 4-donor/4-acceptor motifs are explored, and trends are identified in the systematic adjustment of the optical band gap that will have important implications for the design of two-photon absorbing materials. This dissertation includes my previously published and co-authored material.