We compile a complete collection of reliable Hubble parameter H(z) data to redshift z ≤ 2.36 and use them with the Gaussian Process method to determine continuous H(z) functions for various data ...subsets. From these continuous H(z)'s, summarizing across the data subsets considered, we find H0 ∼ 67 4 km s−1 Mpc−1, more consistent with the recent lower values determined using a variety of techniques. In most data subsets, we see a cosmological deceleration-acceleration transition at 2 significance, with the data subsets transition redshifts varying over at 1 significance. We find that the flat-ΛCDM model is consistent with the H(z) data to a z of 1.5 to 2.0, depending on data subset considered, with 2 deviations from flat-ΛCDM above this redshift range. Using the continuous H(z) with baryon acoustic oscillation distance-redshift observations, we constrain the current spatial curvature density parameter to be , consistent with a flat universe, but the large error bar does not rule out small values of spatial curvature that are now under debate.
The use of a chiral, emitting skeleton for axially chiral enantiomers showing activity in thermally activated delayed fluorescence (TADF) with circularly polarized electroluminescence (CPEL) is ...proposed. A pair of chiral stable enantiomers, (−)‐(S)‐Cz‐Ax‐CN and (+)‐(R)‐Cz‐Ax‐CN, was designed and synthesized. The enantiomers, both exhibiting intramolecular π‐conjugated charge transfer (CT) and spatial CT, show TADF activities with a small singlet–triplet energy difference (ΔEST) of 0.029 eV and mirror‐image circularly polarized luminescence (CPL) activities with large glum values. Notably, CP‐OLEDs based on the enantiomers feature blue electroluminescence centered at 468 nm with external quantum efficiencies (EQEs) of 12.5 and 12.7 %, and also show intense CPEL with gEL values of −1.2×10−2 and +1.4×10−2, respectively. These are the first CP‐OLEDs based on TADF‐active enantiomers with efficient blue CPEL.
Let's twist again: Axially chiral molecules with thermally activated delayed fluorescence and circularly polarized electroluminescence (CPEL) are presented. CP‐OLEDs based on these molecules display high efficiencies and blue CPEL with large gEL values.
A couple of fluorescent enantiomers, which are suitable for the emitters of high‐efficiency TADF‐sensitized CP‐OLEDs, have been developed. The enantiomers show configurational stability, high PLQY of ...98 %, large kr of 7.8×107 s−1, and intense CPL activities with |glum| values of about 2.5×10−3. Notably, by using matchable TADF sensitizer, the enantiomers were then exploited as emitter to fabricate CP‐OLEDs. The TADF‐sensitized CP‐OLEDs not only show mirror‐image CPEL activities with gEL values of +1.8×10−3 and −1.4×10−3, but also display fast start‐up featuring with low VT of 3.0 V as well as driving voltage of 4.8 V at 10 000 cd m−2. Meaningfully, the TADF‐sensitized fluorescent devices show high EQEmax of 21.5 % and extremely low efficiency roll‐off, whose EQEs are 21.2 % and 15.3 % at 1000 and 10 000 cd m−2, respectively. The obtained EQEs are comparable to those of CP‐TADF emitters, which provides a promising perspective to break through the EL efficiency limit of CP‐FL emitters.
A couple of fluorescent enantiomers with high PLQY of 98 % and mirror‐imaged CPL activities have been developed to fabricate TADF‐sensitized CP‐OLEDs. The resulting devices not only display intense CPEL with |gEL| of about 1.8×10−3, but also show high EQEmax of 21.5 % with remarkably low efficiency roll‐off, whose EQE is 15.3 % even at 10 000 cd m−2.
Purely organic TADF emitters have been rapidly developed in recent years and their TADF has become one of the most promising achievement towards highly efficient OLEDs. Apart from the advantages such ...as stable structure, low-cost and high internal quantum efficiency of these emitters that have been found, the demand for high colour purity has become a new challenge. There have been many reports that show possibilities of designing narrowband TADF emitters using totally different methods. Recently, TADF emitters have exhibited a narrow emission with a FWHM of below 20 nm. Therefore, broad emission spectra and bad colour purity shall not always be considered as fatal defects of TADF emitters. Herein, a review of narrowband TADF emitters is presented with a focus on the molecular design, photophysical properties and performance of the corresponding OLED devices. Besides, this review will exhibit the common characteristics of emitters for the purpose of further designs.
Advances in narrowband TADF emitters with a focus on the molecular design, photophysical properties and performance of the corresponding OLED devices are presented.
Sodium metal anodes are poor due to the reversibility of Na plating/stripping, which hinders their practical applications. A strategy to form a sodiophilic Au–Na alloy interphase on a Cu current ...collector, involving a sputtered Au thin layer, is shown to enable efficient Na plating/stripping for a certain period of time. Herein, electrochemical behaviors of Na plating on different substrates are explored, and it is revealed that the sodiophilic interphase can be achieved universally by in situ formation of M–Na (M = Au, Sn, and Sb) alloys during Na plating prior to Na bulk deposition in the initial cycle. Moreover, it is found that repetitive alloying–dealloying leads to falling‐off of thin film sodiophilic materials and thus limits the lifespan of efficient Na cycling. Therefore, an approach is further developed by employing particles of sodiophilic materials combined with the control over the cutoff potential, which significantly improves the stability of Na plating/stripping process. Especially, the low‐cost Cu@Sn‐NPs and Cu@Sb‐MPs composite current collectors allow Na plating and stripping to cycle for 2000 and 1700 times with the average efficiency of 99.9% at 2 mA cm−2.
Stable Na plating/stripping electrochemical behaviors are achieved by using the in situ formed sodiophilic sodium‐metal (metal = Au, Sn, Sb) alloy interphase. By simultaneous control over the stripping cut‐off potential and employment of anchored metal particles, Na plating/stripping cycling is extended to 2000 times at 2 mA cm−2 with an average Coulombic efficiency of 99.9% on the sodium‐metal alloy‐based interphase.
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 %.
Metal/ligand in situ assembly is crucial for tailoring the reactivity & selectivity in transition metal catalysis. Cooperative catalysis via a single metal/two ligands is still underdeveloped, since ...it is rather challenging to harness the distinct reactivity profiles of the species generated by self‐assembly of a single metal precursor with a mixture of different ligands. Herein, we report a catalytic system composed of a single metal/two ligands for a three‐component reaction of polyfluoroarene, α‐diazo ester, and allylic electrophile, leading to highly efficient construction of densely functionalized quaternary carbon centers, that are otherwise hardly accessible. Mechanistic studies suggest this reaction follows a cooperative bimetallic pathway via two catalysts with distinct reactivity profiles, which are assembled in situ from a single metal precursor and two ligands and work in concert to escort the transformation.
A cooperative bimetallic catalysis via one‐metal/two‐ligands in situ assembling is developed in geminal polyfluoroarylation‐allylation of diazo esters, delivering products bearing a 1,1′‐aryl, polyfluoroaryl quaternary carbon center. Detailed mechanistic investigation disclosed unique roles of two distinct ligands, suggesting two in situ formed Pd complexes display different reactivities and work cooperatively in two catalytic cycles.
Twofold C−H annulation of readily available formamides and alkynes without built‐in chelating groups was achieved. Ni−Al bimetallic catalysis enabled by a bulky BINOL‐derived chiral secondary ...phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40–98 % yield and 93–99 % ee.
Two for Two: A highly enantioselective annulation of two C−H bonds with alkynes without built‐in chelating groups was achieved through Ni−Al bimetallic catalysis enabled by a bulky BINOL‐derived secondary phosphine oxide (SPO) ligand. This reaction uses readily available formamides as starting materials and provides concise access to a broad range of chiral ferrocenes in 40–98 % yield and 93–99 % ee.
Drug response differs substantially in cancer patients due to inter- and intra-tumor heterogeneity. Particularly, transcriptome context, especially tumor microenvironment, has been shown playing a ...significant role in shaping the actual treatment outcome. In this study, we develop a deep variational autoencoder (VAE) model to compress thousands of genes into latent vectors in a low-dimensional space. We then demonstrate that these encoded vectors could accurately impute drug response, outperform standard signature-gene based approaches, and appropriately control the overfitting problem. We apply rigorous quality assessment and validation, including assessing the impact of cell line lineage, cross-validation, cross-panel evaluation, and application in independent clinical data sets, to warrant the accuracy of the imputed drug response in both cell lines and cancer samples. Specifically, the expression-regulated component (EReX) of the observed drug response achieves high correlation across panels. Using the well-trained models, we impute drug response of The Cancer Genome Atlas data and investigate the features and signatures associated with the imputed drug response, including cell line origins, somatic mutations and tumor mutation burdens, tumor microenvironment, and confounding factors. In summary, our deep learning method and the results are useful for the study of signatures and markers of drug response.
A metal‐free 2+2 cycloaddition and 1,4‐addition sequence induced by S‐centered radicals has been achieved by treating benzene‐linked allene‐ynes with aryldiazonium tetrafluoroborates and ...DABCO‐bis(sulfur dioxide) in a one‐pot procedure. The reaction provides a greener and more practical access to functionalized cyclobutaanaphthalen‐4‐ols with valuable applications. More than 50 examples are demonstrated with excellent diastereoselectivity and chemical yields. The reaction pathway is proposed to proceed by the following steps:2+2 cycloaddition, insertion of SO2, 1,4‐addition, diazotization, and tautomerization.
Just a DAB: A new metal‐free 2+2 cycloaddition/S‐centered radical induced 1,4‐addition sequence of benzene‐linked allene‐ynes has been established by treatment with aryldiazonium tetrafluoroborates and DABCO‐bis(sulfur dioxide) under convenient reaction conditions, thus providing practical access to functionalized cyclobutaanaphthalen‐4‐ols of chemical and biomedical importance. DABCO=1,4‐diazabicyclo2.2.2octane.
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