Tetracoordinate boron species bearing a heteroaromatic chelating substituent (e.g., 8-quinolinolate) show interesting physical and optoelectronic properties such as relatively high electron mobilities and intense photo- or electroluminescence. Therefore, these materials have been successfully applied in organic light-emitting devices (OLEDs) where they can act as electron transporters and light emitters. In the past, a broad variety of different monoanionic bidentate ligands have been investigated in this context; however, the remaining two substituents R (cf. compound A ) attached to the boron center were typically limited to phenyl, alkyl, and fluoro moieties. We present in this contribution a novel class of spiro compounds in which the two groups R are linked to each other to build up a second p-conjugated system (cf. compound 1 ). The planar dibenzoborole and 8-quinolinolate moieties in 1  can be described as two chromophores which are orthogonally aligned with respect to each other. Due to their conformational rigidity, such systems are an excellent target to study intramolecular energy transfer processes. To modify the p system of the dibenzoborole unit we synthesized the brominated derivative 2  and are examining various transition metal catalyzed methods to introduce conjugated substituents. These methods will also provide access to p-conjugated oligomers and polymers containing the spiro dibenzoborole fragment in the main chain for potential applications in OLEDs.

Two distinct orthogonal chromophores on a spiro-tetracoordinate boron center

248th National Meeting (2014)

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