Symmetrical Electron-Deficient Materials Incorporating Azaheterocycles

To investigate the potential of di‐ and tri‐azaheterocycles as building blocks for π‐conjugated materials with high electron affinity, linear oligomers incorporating pyrazine and a C3‐symmetric discotic molecule based on triazine were synthesized. The tridodecyloxyphenyl end‐capped ethynylene pyrazinylene oligomers showed remarkable solvatochroism in absorption and emission in solution. The oligomers containing one and two pyrazine rings displayed liquid crystallinity in the solid state. The largest ethynylene pyrazinylene oligomer containing three pyrazine rings had the lowest first reduction potential at −1.08 V. The triazine‐derived discotic molecule exhibited UV/Vis and fluorescence behavior comparable to that of the linear oligomers and featured a first reduction potential at −1.49 V, somewhat lower than expected. A series of ethynylene pyrazinylene oligomers (see picture) as well as a C3‐symmetric discotic compound based on triazine were synthesized and investigated with respect to their potential as electron‐deficient materials. Furthermore, analysis of their thermotropic properties showed liquid crystallinity, while remarkable solvatochromic behavior was observed in their absorption and emission spectra.