A strategy of chiral donor–acceptor copolymerization is proposed to develop chiral nonconjugated polymers with thermally activated delayed fluorescence (TADF). Based on this strategy, two pairs of ...chiral polymers (R,R)‐/(S,S)‐pTpAcDPS and (R,R)‐/(S,S)‐pTpAcBP were synthesized. The alternating copolymerization of the chiral donors and acceptors could effectively separate the frontier molecular orbitals, which made the polymers show small ΔEST of 0.01–0.03 eV and efficient TADF properties. Moreover, the polymers also showed the quantum yield of up to 92 % and the circularly polarized luminescence. The solution‐processed circularly polarized organic light‐emitting diodes showed circularly polarized electroluminescence signals with high external quantum efficiencies of up to 22.1 % and maximum luminance of up to 34350 cd m−2. This is the first report of CP‐OLEDs based on chiral TADF polymer, which provides a useful and valuable guidance for the development of high‐efficiency CPEL polymers.
Based on a chiral donor–acceptor copolymerization strategy, two pairs of chiral nonconjugated TADF polymers with low ΔEST values and high PLQYs were constructed. The corresponding solution‐processed CP‐OLEDs exhibited intense CPEL signals and high device efficiencies with an EQEmax of up to 22.1 %.
Recently, circularly polarized organic light‐emitting diodes (CP‐OLEDs) fabricated with thermally activated delayed fluorescence (TADF) emitters are developed rapidly. However, most devices are ...fabricated by vacuum deposition technology, and developing efficient solution‐processed CP‐OLEDs, especially nondoped devices, is still a challenge. Herein, a pair of triptycene‐based enantiomers, (S,S)‐/(R,R)‐TpAc‐TRZ, are synthesized. The novel chiral triptycene scaffold of enantiomers avoids their intermolecular π–π stacking, which is conducive to their aggregation‐induced emission characteristics and high photoluminescence quantum yield of 85% in the solid state. Moreover, the triptycene‐based enantiomers exhibit efficient TADF activities with a small singlet‐triplet energy gap (ΔEST) of 0.03 eV and delayed fluorescence lifetime of 1.1 µs, as well as intense circularly polarized luminescence with dissymmetry factors (|gPL|) of about 1.9 × 10−3. The solution‐processed nondoped CP‐OLEDs based on (S,S)‐/(R,R)‐TpAc‐TRZ not only display obvious circularly polarized electroluminescence signals with gEL values of +1.5 × 10−3 and −2.0 × 10−3, respectively, but also achieve high efficiencies with external quantum, current, and power efficiency up to 25.5%, 88.6 cd A−1, and 95.9 lm W−1, respectively.
A pair of thermally activated delayed fluorescence enantiomers with aggregation‐induced emission properties are developed by introducing the chiral donor based on a triptycene scaffold. Highly efficient solution‐processed nondoped circularly polarized organic light‐emitting diodes (CP‐OLEDs) with external quantum efficiency up to 25.5% is realized based on the emitter. In addition, the CP‐OLEDs exhibit intense circularly polarized electroluminescence activities with opposing gEL signals.
With sunlight or blue LEDs irradiation, regioselective decarboxylative alkylation of various non‐aromatic heterocycles has been realized via C(sp3)‐centered radical C(sp2)−C(sp3) bond formation under ...oxidant‐free conditions at room temperature. This reaction readily incorporates various functional alkyl groups into heterocyclic compounds without observation of any alkyl radical rearrangement and represents a mild and general tool for the preparation of valuable alkyl group‐functionalized heterocyclic compounds.
The introduction of oxygen vacancies (Ov) has been regarded as an effective method to enhance the catalytic performance of photoanodes in oxygen evolution reaction (OER). However, their stability ...under highly oxidizing environment is questionable but was rarely studied. Herein, NiFe‐metal–organic framework (NiFe‐MOFs) was conformally coated on oxygen‐vacancy‐rich BiVO4 (Ov‐BiVO4) as the protective layer and cocatalyst, forming a core–shell structure with caffeic acid as bridging agent. The as‐synthesized Ov‐BiVO4@NiFe‐MOFs exhibits enhanced stability and a remarkable photocurrent density of 5.3±0.15 mA cm−2 at 1.23 V (vs. RHE). The reduced coordination number of Ni(Fe)‐O and elevated valence state of Ni(Fe) in NiFe‐MOFs layer greatly bolster OER, and the shifting of oxygen evolution sites from Ov‐BiVO4 to NiFe‐MOFs promotes Ov stabilization. Ovs can be effectively preserved by the coating of a thin NiFe‐MOFs layer, leading to a photoanode of enhanced photocurrent and stability.
A core–shell Ov‐BiVO4@NiFe‐MOFs photoanode was constructed via a coordination‐assisted self‐assembly method. A NiFe‐MOFs thin layer acts as protective layer and cocatalyst to shift active sites from oxygen vacancies to NiFe‐MOFs, leading to improved stability and activity for OER. This molecular‐based approach tailors the coordination and electronic structure of active sites and provides mechanistic insights for rational design of photocatalysts.
Benzoxazoles extensively exist in biologically active compounds, natural products, pharmaceuticals and functional materials. Thus, facile and green synthesis of such valuable compounds from easily ...available substrates will make a contribution to drug, material, and fine chemistry. A method for the synthesis of benzoxazoles from catechols, aldehydes and ammonium acetate is developed using NaIO4 as oxidant under metal‐ and additive‐free conditions. A broad range of benzoxazoles including some fluorescent whitening agents, JTP‐426467 and tafamidis analogues are synthesized in 56–95% yields with outstanding functional group tolerance. Mechanistic investigations suggest that an interesting o‐iminocyclohexa‐diene alcohol intermediate is involved in the reaction. These salient features of the protocol make it an alternative for the synthesis of benzoxazoles.
A Cu-catalyzed selective aerobic heterocoupling of terminal alkynes is disclosed, which enables the synthesis of a broad range of unsymmetrical 1,3-diynes in good to excellent yields. The results ...disprove the long-held belief that homocouplings are exclusively favored in the Glaser–Hay reaction.
Chorioamnionitis (CA) can cause multiple organ injuries in premature neonates, particularly to the lungs. Different opinions exist regarding the impact of intrauterine inflammation on neonatal ...respiratory distress syndrome (NRDS) and bronchopulmonary dysplasia (BPD). We aim to systematically review the relationship between CA or Funisitis (FV) and lung injury among preterm infants.
We electronically searched PubMed, EMbase, the Cochrane library, CNKI, and CMB for cohort studies from their inception to March 15, 2023. Two reviewers independently screened literature, gathered data, and did NOS scale of included studies. The meta-analysis was performed using RevMan 5.3.
Sixteen observational studies including 68,397 patients were collected. Meta-analysis showed CA or FV increased the lung injury risk (OR = 1.43, 95%CI: 1.06-1.92). Except for histological chorioamnionitis (HCA) (OR = 0.72, 95%CI: 0.57-0.90), neither clinical chorioamnionitis (CCA) (OR = 1.86, 95%CI: 0.93-3.72) nor FV (OR = 1.23, 95%CI: 0.48-3.15) nor HCA with FV (OR = 1.85, 95%CI: 0.15-22.63) had statistical significance in NRDS incidence. As a result of stratification by grade of HCA, HCA (II) has a significant association with decreased incidence of NRDS (OR = 0.48, 95%CI: 0.35-0.65). In terms of BPD, there is a positive correlation between BPD and CA/FV (CA: OR = 3.18, 95%CI: 1.68-6.03; FV: OR = 6.36, 95%CI: 2.45-16.52). Among CA, HCA was positively associated with BPD (OR = 2.70, 95%CI: 2.38-3.07), whereas CCA was not associated with BPD (OR = 2.77, 95%CI: 0.68-11.21). HCA and moderate to severe BPD (OR = 25.38, 95%CI: 7.13-90.32) showed a positive correlation, while mild BPD (OR = 2.29, 95%CI: 0.99-5.31) did not.
Currently, evidence suggests that CA or FV increases the lung injury incidence in premature infants. For different types of CA and FV, HCA can increase the incidence of BPD while decreasing the incidence of NRDS. And this "protective effect" only applies to infants under 32 weeks of age. Regarding lung injury severity, only moderate to severe cases of BPD were positively correlated with CA.
This paper is devoted to the investigation of the transverse vibration and dynamic stability of the axially moving viscoelastic plate with two opposite edges simply supported and other two opposite ...edges with simply supported or free. By considering the Kelvin–Voigt model of viscoelasticity, the equation of motion of the plate is derived. The normalized power series method is employed to obtain the complex eigen equations for the axially moving viscoelastic plate. The variation relationship between the first three complex frequencies of the system and the dimensionless axially moving speed with different aspect ratio and dimensionless delay time are analyzed. The results show that the dimensionless delay time, axially moving speed as well as the aspect ratio have remarkable effects on dynamic behaviors and stability of the axially moving viscoelastic plate.
•The governing equation of the axially moving viscoelastic plate is derived.•The complex eigen equations are obtained by the normalized power series method.•The factors that affect the stability of the plate are studied.
Distinct from nominal metaphors, predicate metaphors entail metaphorical abstraction from concrete verbs, which generally involve more action and stronger motor simulation than nouns. It remains ...unclear whether and how the concrete, embodied aspects of verbs are connected with abstract, disembodied thinking in the brains of L2 learners. Since English predicate metaphors are unfamiliar to Chinese L2 learners, the study of embodiment effect on English predicate metaphor processing may provide new evidence for embodied cognition and categorization models that remain controversial, and offer practical insights into L2 metaphor processing and pedagogy. Hence, we aim to investigate whether the embodiment of verbs, via the activation of sensorimotor information, influences two groups of L2 learners during their comprehension of conventional and novel predicate metaphors. The results show a significant effect of embodiment: a stronger facilitation for novel predicate metaphors in both higher-level and lower-level groups, and a weaker facilitation for conventional predicate metaphors in the lower-level group. The findings demonstrate preliminary evidence for a graded effect of embodiment on predicate metaphors processing, modulated by L2 proficiency and metaphor novelty. The study supports a hybrid view of embodied cognition and reveals that sensorimotor aspects of verbs may be the intermediate entity involved in the indirect categorization.
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