Selective Placement of Bromide and Pinacolboronate Groups about a Tellurophene: New Building Blocks for Optoelectronic Applications

Selective protodeboronation of preformed phosphorescent di- and tetrapinacolboronate (BPin)-substituted tellurophenes controllably affords new tellurophene products that show photoluminescence or, in the case of tellurophenes lacking BPin groups at the 2,5-positions, nonemissive behavior; for comparison the protodeboronation of select thiophene and selenophenes is also reported. The resulting BPin-appended tellurophenes are promising candidates for postfunctionalization via Suzuki–Miyaura cross-coupling and can be effectively converted into their respective brominated tellurophene counterparts via treatment with excess CuBr2. It is expected from prior studies that these brominated tellurophenes will be suitable building blocks (and monomers) for the preparation of conjugated oligomers and polymers featuring narrower optical band gaps in relation to their lighter chalcogen analogues; in this regard preliminary Stille coupling chemistry is reported.