Alkynylated Acenothiadiazoles and N-heteroacenes: Synthesis, Functionalization, and Study of the Optical Properties for Optoelectronic and Sensory Materials

For organic electronic device applications materials are needed which display good charge carrier mobility, good processability, and stability towards oxygen and moisture. Alkynylated N-Heteroacenes fulfill many of these requirements. Substitution with alkyne groups as well as the introduction of the pyrazine subunit both inhibits oxidative degradation at sensitive position in the molecules. Additionally the trialkylsilylethynyl group aides in directing the packing motif as well as vastly increases the solubility over unsubstituted analogues.;A requisite precursor in the synthesis of alkynylated N-heteroacenes is alkynylated acenothiadiazoles. These thiadiazoles display interesting photophysical properties and can be functionalized to produce a wide range of properties in closely related materials. The acenothiadiazoles themselves have potential applications as an N-type semiconductor. Optical gaps and calculated HOMO-LUMO gaps show that these molecules, when compared to known N-type materials, should be easily injected with electrons. Additionally the crystal packing of these compounds shows favorable pi-orbital overlap which should provide excellent charge carrier mobilities.;We have also substituted benzothiadiazoles with dialkylaniline groups as well as phenol group to yield benzothiadiazole trimers. These molecules are acid/base sensitive and exhibit similar properties in their isoelectronic states. Utilizing their solvatochromic behaviors, we are able to tease out the interplay of dipole, hydrogen bond accepting, and hydrogen bond donating interactions of the chromophore with the solvent.;Additionally, we have reacted the alkyne groups on the acenothiadiazoles with triethylene glycol monomethyl ether azide to produce bis(1,2,3-triazole)benzothiadiazole and bis(1,2,3-triazole)naphthothiadiazole. These molecules are both water-soluble and exhibit strong selective binding of nickel and copper in aqueous solutions.;Chapters 3 and 4 are related and explore the photophysical interactions of hydroxy- and dibutylamino-substituted fluorophores with the solvent environment. These compounds were expected to be acid/base sensitive and display similar properties among their isoelectronic pairs. Kamlet-Taft analysis was utilized to separate the dipole, proton-accepting, and proton-donating characteristics of the solvent-fluorophore interactions. These results showed that the in the case of the protonated dibutylamino and phenol compounds hydrogen-bond interactions play a small role. In the case of the phenolate, there are strong hydrogen-bond interactions. The dibutyl compounds unexpectedly showed little hydrogen-bond interactions which is a result of the decreased basicity of the amine compared to the phenolate.;Chapter five demonstrated that dihydrodiazatetracenes are stable, antiaromatic species. These compounds were characterized utilizing x-ray crystallography as well as NICS Calculations which show that the antiaromatic destabilization of the dihydropyrazine subunit was offset by the aromatic stabilization of the adjoining rings resulting in a net aromatically stabilized material.;Finally we explored the concept of functionalizing N-heteroacenes for the purpose of reducing the bandgap of these molecules. Tetrahalogenated species were able to take advantage of an unsymmetrically distributed HOMO to furnish materials which possess significantly and somewhat unexpectedly redshifted absorption and emission profiles.