The synthesis of the first examples of tellurophenes exhibiting phosphorescence in the solid state and under ambient conditions (room temperature and in air) is reported. Each of these main-group-element-based emitters feature pinacolboronates (BPin) as ring-appended side groups. The nature of the luminescence observed was also investigated using computational methods.
A versatile and general synthetic route for the synthesis of conjugated main group element-based polymers, previously inaccessible by conventional means, is reported. These polymers contain five-membered chalcogenophene rings based on S, Se, and Te, and we demonstrate that optoelectronic properties can be readily tuned via controlled atom substitution chemistry. In addition, regioregular hybrid thiophene-selenophene-tellurophene and selenophene-fluorene copolymers were synthesized to provide a further illustration of the scope of the presented metallacycle transfer/cross-coupling polymerization method.
The synthesis of the first examples of tellurophenes exhibiting phosphorescence in the solid state and under ambient conditions (room temperature and in air) is reported. Each of these main‐group‐element‐based emitters feature pinacolboronates (BPin) as ring‐appended side groups. The nature of the luminescence observed was also investigated using computational methods.
In this article our attempts to tune the color of luminescence within a new class of aggregation-induced emission (AIE) active tellurophenes is reported along with computational details that include spin-orbit coupling effects so as to better understand the nature of emission in the phosphorescent tellurophene (B-Te-6-B). Despite not meeting some of the initial synthetic targets, the emission within a borylated tellurophene can be altered with the addition of an N-heterocyclic carbene.
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.
Guest‐controlled diastereoselective self‐assembly of a diboryltellurophene and a chiral tetrol bearing an indacene backbone was achieved to give either hetero‐ or homochiral macrocyclic boronic esters, selectively. The heterochiral isomer (hetero‐[2+2]Te) exhibited a higher inclusion ability for electron‐deficient aromatic guests, leading to effective quenching of phosphorescence from the diboryltellurophene moieties. The reported macrocycles collectively represent a promising arene sensing approach based on phosphorescence.
Previous research in our group showed that tellurophenes with pinacolboronate (BPin) units at the 2- and/or 5-positions displayed efficient phosphorescence in the solid state, both in the presence of oxygen and water. In this current study, we show that luminescence from a tellurophene is possible when various aryl-based substituents are present, thus greatly expanding the family of known (and potentially accessible) Te-based phosphors. Moreover, for the green phosphorescent perborylated tellurium heterocycle, 2,3,4,5-TeCBPin (4BTe), oxygen-mediated quenching of phosphorescence is an important contributor to the lack of emission in solution (when exposed to air); thus, this system displays aggregation-enhanced emission (AEE). These discoveries should facilitate the future design of color tunable tellurium-based luminogens.
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