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.