Highly Stereoselective Assembly of Polycyclic Molecules from 1,6-Enynes Triggered by Rhodium(III)-Catalyzed C–H Activation

An Rh­(III)-catalyzed C–H activation of pyrazolones with 1,6-enynes was investigated. The regioselectivity of the C–H activation/alkyne insertion is readily solved by using symmetric enyne coupling partners, and a C–H activation-triggered cascade reaction is realized, which involves alkyne insertion, tautomerization, and double cyclization to offer a class of structurally complex polycyclic architectures. This cascade reaction tolerates a broad substrate scope in high regioselectivity and stereospecificity and furnishes three new chemical bonds and four chiral centers in a single operation. Various derivatizations of the polycyclic scaffolds are conducted, providing products with ample space for further functional transformations

Enhancing the Photovoltaic Performance by Tuning the Morphology of Polymer:PC₇₁BM Blends with a Commercially Available Nucleating Agent

The use of a commercially available nucleating agent as the additive for the fabrication of polymer:PC₇₁BM-based active layers by solution-processing can greatly enhance the power conversion efficiency (PCE) of bulk heterojunction polymer solar cells (BHJ PSCs). The enhancement of device performance is mainly due to the addition of nucleating agent, which is able to regulate the drying process of the active layer and decrease the oversized domain size of conjugated polymers. Via this effective strategy to optimize the film morphology, the designed device exhibits an enhancement as great as 30.8%

Apiaceae sequences used to evaluate the five DNA barcodes.

All sequences (3,052 ITS sequences, 3,732 ITS2 sequences, 1,011 psbA-trnH sequences, 567 matK sequences, and 566 rbcL sequences) have been used to evaluate the five DNA barcodes

Venn diagram of unigenes in the roots, stems, leaves and flowers of <i>S</i>. <i>baicalensis</i>.

<p>Venn diagram of unigenes in the roots, stems, leaves and flowers of <i>S</i>. <i>baicalensis</i>.</p

Clustering of differentially expressed genes from four different organs of <i>S</i>. <i>baicalensis</i> generated by hierarchical clustering.

<p>Clustering of differentially expressed genes from four different organs of <i>S</i>. <i>baicalensis</i> generated by hierarchical clustering.</p

Volcano plots of differentially expressed genes based on pair-wise comparison analyzed by RNA-sequencing.

<p>The x-axis and y-axis show the fold changes on a log2 scale and the <i>P</i> on a –log10 scale, respectively. Genes differentially expressed with >4-fold and P<0.001 are presented in red.</p

Overview of Illumina sequencing and transcript assembling obtained from four RNA-seq libraries.

<p>^a reads that map to assembled unigene sequences</p><p>^b percentage of reads that map to assembled unigene sequences</p><p>^cRPKM: reads per kilobase of unigene model per million mapped reads</p><p>Overview of Illumina sequencing and transcript assembling obtained from four RNA-seq libraries.</p

Monomeric Octahedral Ruthenium(II) Complex Enabled <i>meta</i>-C–H Nitration of Arenes with Removable Auxiliaries

A removable oxime-assisted <i>meta</i>-C–H nitration of arenes is reported. Mechanistic investigations and DFT calculations reveal a new monomeric octahedral ruthenium­(II) complex is responsible for the meta-selective nitration. Dioxygen as a cooxidant is crucial for achieving high conversion and good yields. Moreover, the utility of the present reaction protocol is further showcased by the late-stage modification of the clinical CNS drugs Diazepam and Fluvoxamine

Dibenzopyran-Based Wide Band Gap Conjugated Copolymers: Structural Design and Application for Polymer Solar Cells

With the efficient synthesis of the crucial dibenzopyran building block, a series of <b>PDBPTBT</b> polymers containing different alkyl side chains and/or fluorine substitution were designed and synthesized via the microwave-assisted Suzuki polycondensation. Quantum chemistry calculations based on density functional theory indicated that different substitutions have significant impacts on the planarity and rigidity of the polymer backbones. Interestingly, the alkyloxy chains of <b>PDBPTBT-4</b> tend to stay in the same plane with the benzothiadiazole unit, but the others appear to be out of plane. With the S···O and F···H/F···S supramolecular interactions, the conformations of the four polymers will be locked in different ways as predicted by the quantum chemistry calculation. Such structural variation resulted in varied solid stacking and photophysical properties as well as the final photovoltaic performances. Conventional devices based on these four polymers were fabricated, and <b>PDBPTBT-5</b> displayed the best PCE of 5.32%. After optimization of the additive types, ratios, and the interlayers at the cathode, a high PCE of 7.06% (<i>V</i>_oc = 0.96 V, <i>J</i>_sc = 11.09 mA/cm², and FF = 0.67) is obtained for <b>PDBPTBT-5</b> with 2.0% DIO as the additive and PFN-OX as the electron-transporting layer. These results indicated DBP-based conjugated polymers are promising wide band gap polymer donors for high-efficiency polymer solar cells

Deep Sequencing of the <i>Scutellaria baicalensis</i> Georgi Transcriptome Reveals Flavonoid Biosynthetic Profiling and Organ-Specific Gene Expression

<div><p><i>Scutellaria baicalensis</i> Georgi has long been used in traditional medicine to treat various such widely varying diseases and has been listed in the Chinese Pharmacopeia, the Japanese Pharmacopeia, the Korean Pharmacopoeia and the European Pharmacopoeia. Flavonoids, especially wogonin, wogonoside, baicalin, and baicalein, are its main functional ingredients with various pharmacological activities. Although pharmaological studies for these flavonoid components have been well conducted, the molecular mechanism of their biosynthesis remains unclear in <i>S</i>. <i>baicalensis</i>. In this study, Illumina/Solexa deep sequencing generated more than 91 million paired-end reads and 49,507 unigenes from <i>S</i>. <i>baicalensis</i> roots, stems, leaves and flowers. More than 70% unigenes were annotated in at least one of the five public databases and 13,627 unigenes were assigned to 3,810 KEGG genes involved in 579 different pathways. 54 unigenes that encode 12 key enzymes involved in the pathway of flavonoid biosynthesis were discovered. One baicalinase and three baicalein 7-O-glucuronosyltransferases genes potentially involved in the transformation between baicalin/wogonoside and baicalein/wogonin were identified. Four candidate 6-hydroxylase genes for the formation of baicalin/baicalein and one candidate 8-O-methyltransferase gene for the biosynthesis of wogonoside/wogonin were also recognized. Our results further support the conclusion that, in <i>S</i>. <i>baicalensis</i>, 3,5,7-trihydroxyflavone was the precursor of the four above compounds. Then, the differential expression models and simple sequence repeats associated with these genes were carefully analyzed. All of these results not only enrich the gene resource but also benefit research into the molecular genetics and functional genomics in <i>S</i>. <i>baicalensis</i>.</p></div