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.
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.
New phosphorescent tellurophenes were derived from a di(isopropoxy)boryl tellurophene precursor and the Suzuki–Miyaura cross-coupling of borylated tellurophenes with 2-bromothiophene was investigated.
The hydrothermal aging of a commercial polyimide film, (poly[pyromellitic dianhydride‐co‐4,4′‐oxydianiline]) is investigated, providing further insight into the well‐known loss of properties that can occur for these materials in the presence of moisture. The study involved measuring ATR‐FTIR, ultimate tensile strength, and percent elongation at break, under accelerated hydrothermal aging conditions at three different temperatures (70, 80, and 90°C). ATR‐FTIR data was analyzed using chemometrics in order to identify significant trends that develop upon the accelerated aging conditions. The most dramatic changes were observed for the aging at 90°C. Changes in the ATR‐FTIR spectra for aging at all three temperatures can be attributed to hydrolysis of the imide groups. Ultimate tensile strength was also used to monitor the hydrothermal aging process. This data was used to construct an Arrhenius plot from which an activation energy of 71.8 KJ/mol was determined for the hydrothermal aging process. This value is comparable to that of textiles used in fire protective clothing, suggesting that polyimide is a viable candidate for modeling the degradation of these textiles. This paper also shows the large potential of chemometrics for polymer aging studies as it allows identifying degradation mechanisms from subtle chemical changes in the materials.
A series of planar π-extended Te-containing heteroacenes, termed tellura(benzo)bithiophenes, were synthesized. This new structural class of heterocycle features a tellurophene ring fused to a benzobithiophene unit with aromatic side groups (either −C 6 H 4 i Pr or −C 6 H 4 OCH 3 ) positioned at the 2-and 5-positions of the tellurophene moiety. Although attempts to enhance molecular rigidity and extend ring-framework πdelocalization in a cumenyl (−C 6 H 4 i Pr)-capped tellura(benzo)bithiophene led to oxidation (and Te−C bond scission) to form a diene−one, the formation of an oligomeric tellura(benzo)bithiophene was possible via Kumada catalyst-transfer polycondensation (KCTP). Furthermore, one tellura(benzo)bithiophene derivative exhibits orange-red phosphorescence at room temperature in air when incorporated into a poly(methyl methacrylate) host; accompanying TD-DFT computations provided insight into a potential mechanism for the observed phosphorescence.
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