3,4\u27,5-Trichlorobiphenyl-4-yl 2,2,2-trichloroethyl sulfate

Crystals of the title compound, C14H8Cl6O4S, are twinned by inversion, with unequal components [0.85 (3):0.15 (3)]. The asymmetric unit contains two independent molecules that are related by a pseudo-inversion center. The Car-O [1.393 (9) and 1.397 (9) Å] and ester S-O bond lengths [1.600 (5) and 1.590 (5) Å] of both molecules are comparable to the structurally related 2,3,5,5-trichlorobiphenyl-4-yl 2,2,2-trichloroethyl sulfate. The dihedral angles between the benzene rings in the two molecules are 37.8 (2) and 35.0 (2)°

Negative thermal expansion in YbMn2Ge2 induced by the dual effect of magnetism and valence transition

AbstractNegative thermal expansion (NTE) is an intriguing property, which is generally triggered by a single NTE mechanism. In this work, an enhanced NTE (αv = −32.9 × 10−6 K−1, ΔT = 175 K) is achieved in YbMn2Ge2 intermetallic compound to be caused by a dual effect of magnetism and valence transition. In YbMn2Ge2, the Mn sublattice that forms the antiferromagnetic structure induces the magnetovolume effect, which contributes to the NTE below the Néel temperature (525 K). Concomitantly, the valence state of Yb increases from 2.40 to 2.82 in the temperature range of 300–700 K, which simultaneously causes the contraction of the unit cell volume due to smaller volume of Yb3+ than that of Yb2+. As a result, such combined effect gives rise to an enhanced NTE. The present study not only sheds light on the peculiar NTE mechanism of YbMn2Ge2, but also indicates the dual effect as a possible promising method to produce enhanced NTE materials

Aromatic organosulfates in atmospheric aerosols: Synthesis, characterization, and abundance

Aromatic organosulfates are identified and quantified in fine particulate matter (PM2.5) from Lahore, Pakistan, Godavari, Nepal, and Pasadena, California. To support detection and quantification, authentic standards of phenyl sulfate, benzyl sulfate, 3-and 4-methylphenyl sulfate and 2-, 3-, and 4-methylbenzyl sulfate were synthesized. Authentic standards and aerosol samples were analyzed by ultra-performance liquid chromatography (UPLC) coupled to negative electrospray ionization (ESI) quadrupole time-of-flight (ToF) mass spectrometry. Benzyl sulfate was present in all three locations at concentrations ranging from 4 – 90 pg m−3. Phenyl sulfate, methylphenyl sulfates and methylbenzyl sulfates were observed intermittently with abundances of 4 pg m−3, 2-31 pg m−3, 109 pg m−3, respectively. Characteristic fragment ions of aromatic organosulfates include the sulfite radical (•SO3−, m/z 80) and the sulfate radical (•SO4−,m/z 96). Instrumental response factors of phenyl and benzyl sulfates varied by a factor of 4.3, indicating that structurally-similar organosulfates may have significantly different instrumental responses and highlighting the need to develop authentic standards for absolute quantitation organosulfates. In an effort to better understand the sources of aromatic organosulfates to the atmosphere, chamber experiments with the precursor toluene were conducted under conditions that form biogenic organosulfates. Aromatic organosulfates were not detected in the chamber samples, suggesting that they form through different pathways, have different precursors (e.g. naphthalene or methylnaphthalene), or are emitted from primary sources

The Genomes of Oryza sativa: A History of Duplications

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000–40,000. Only 2%–3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family

Recent Progress in Chemical Syntheses of Sphingosines and Phytosphingosines

International audienceSphingolipids and their derivatives such as glycosphingolipids and sphingomyelins exist ubiquitously in biomembrane of all eukaryotic cells, which play pivotal roles in cell proliferation, recognition, adhesion, and signal transduction. Sphingosine is shown to be the important lipid moiety in the large majority of glycosphingolipids and sphingomyelins, while phytosphingosine is one of the major long-chain moieties of glycosphingo-lipids. Due to the significance of the two bioactive lipids, tremendous efforts have been made to synthesize sphingosine or phytosphingosine using chiral pool approaches, chiral auxiliary and asymmetric reactions to construct the continuous stereogenic centers in them. This review covers the synthetic literatures published in the year after 2000

New Organoselenium (NSAIDs-Selenourea and Isoselenocyanate) Derivatives as Potential Antiproliferative Agents: Synthesis, Biological Evaluation and in Silico Calculations

In this study, we report on the synthesis of new organoselenium derivatives, including nonsteroidal anti-inflammatory drugs (NSAIDs) scaffolds and Se functionalities (isoselenocyanate and selenourea), which were evaluated against four types of cancer cell line: SW480 (human colon adenocarcinoma cells), HeLa (human cervical cancer cells), A549 (human lung carcinoma cells), MCF-7 (human breast adenocarcinoma cells). Among these compounds, most of the investigated compounds reduced the viability of different cancer cell lines. The most promising compound 6b showed IC50 values under 10 μM against the four cancer cell lines, particularly to HeLa and MCF-7, with IC50 values of 2.3 and 2.5 μM, respectively. Furthermore, two compounds, 6b and 6f, were selected to investigate their ability to induce apoptosis in MCF-7 cells via modulation of the expression of anti-apoptotic Bcl-2 protein, pro-inflammatory cytokines (IL-2) and proapoptotic caspase-3 protein. The redox properties of the NSAIDs-Se derivatives were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), bleomycin-dependent DNA damage and glutathione peroxidase (GPx)-like assays. Finally, a molecular docking study revealed that an interaction with the active site of thioredoxin reductase 1 (TrxR1) predicted the antiproliferative activity of the synthesized candidates. Overall, these results could serve as a promising launch point for further designs of NSAIDs-Se derivatives as potential antiproliferative agents

Chiron Approaches to the Antitumor Natural Product Fuzanin D

International audienceFuzanin D, a pyridine-containing natural product, which exhibits cytotoxic activity against DLD-1 cells, is synthesized in a concise manner using l-arabinose or ethyl l-lactate as chiral pool substrates in nine steps (14.4% overall yield) and six steps (30.8% overall yield), respectively. The key steps involve Wittig olefination and olefin cross-­metathesis

3,4′,5-Trichlorobiphenyl-4-yl 2,2,2-trichloroethyl sulfate

Crystals of the title compound, C14H8Cl6O4S, are twinned by inversion, with unequal components [0.85 (3):0.15 (3)]. The asymmetric unit contains two independent molecules that are related by a pseudo-inversion center. The Car—O [1.393 (9) and 1.397 (9) Å] and ester S—O bond lengths [1.600 (5) and 1.590 (5) Å] of both molecules are comparable to the structurally related 2,3,5,5-trichlorobiphenyl-4-yl 2,2,2-trichloroethyl sulfate. The dihedral angles between the benzene rings in the two molecules are 37.8 (2) and 35.0 (2)°