A Potassium Diboryllithate: Synthesis, Bonding Properties, and the Deprotonation of Benzene

A potassium diboryllithate (B2LiK) was synthesized and structurally characterized. DFT calculations, including NPA and AIM analyses of B2LiK, revealed ionic interactions between the two bridging boryl anions and Li+ and K+. Upon standing in benzene, B2LiK deprotonated the solvent to form a hydroborane and a phenylborane. On the basis of DFT calculations, a detailed reaction mechanism, involving deprotonation and hydride/phenyl exchange processes, is proposed. An NBO analysis of the transition state for the deprotonation of benzene suggests that the deprotonation should be induced by the coordination of benzene to the K+.A â LiK â of work: A potassium diboryllithate, B2LiK, was synthesized and structurally characterized. The bonding situation in this compound was examined by NMR, XRD, NPA, and AIM analyses. B2LiK is able to deprotonate benzene with concomitant formation of phenylborane as the major product. A detailed reaction mechanism based on DFT calculations suggests that the deprotonation of benzene should be initiated by a transition state involving the coordination of benzene to K+.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/1/anie201605005_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/2/anie201605005-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137264/3/anie201605005.pd

Extremely low nucleotide diversity in the X-linked region of papaya caused by a strong selective sweep

Collection sites of wild Costa Rican papaya. Table S2. Summary of sequencing statistics of re-sequenced papaya genomes. Table S3 Annotation of polymorphisms. Table S4. Synonymous site diversity for genes in the X-linked region. (DOCX 37 kb

The bracteatus pineapple genome and domestication of clonally propagated crops

Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a 'one-step operation'. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars 'Smooth Cayenne' and 'Queen' exhibited ancient and recent admixture, while 'Singapore Spanish' supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops

Knowledge and attitudes of healthcare workers in Chinese intensive care units regarding 2009 H1N1 influenza pandemic

<p>Abstract</p> <p>Background</p> <p>To describe the knowledge and attitudes of critical care clinicians during the 2009 H1N1 influenza pandemic.</p> <p>Methods</p> <p>A survey conducted in 21 intensive care units in 17 provinces in China.</p> <p>Results</p> <p>Out of 733 questionnaires distributed, 695 were completed. Three hundred and fifty-six respondents (51.2%) reported their experience of caring for H1N1 patients. Despite the fact that 88.5% of all respondents ultimately finished an H1N1 training program, only 41.9% admitted that they had the knowledge of 2009 H1N1 influenza. A total of 572 respondents (82.3%) expressed willingness to care for H1N1 patients. Independent variables associated with increasing likelihood to care for patients in the logistic regression analysis were physicians or nurses rather than other professionals (odds ratio 4.056 and 3.235, p = 0.002 and 0.007, respectively), knowledge training prior to patient care (odds ratio 1.531, p = 0.044), and the confidence to know how to protect themselves and their patients (odds ratio 2.109, p = 0.001).</p> <p>Conclusion</p> <p>Critical care clinicians reported poor knowledge of H1N1 influenza, even though most finished a relevant knowledge training program. Implementation of appropriate education program might improve compliance to infection control measures, and willingness to work in a pandemic.</p

Formation of Nanopits in Si Capping Layers on SiGe Quantum Dots

In-situ annealing at a high temperature of 640°C was performed for a low temperature grown Si capping layer, which was grown at 300°C on SiGe self-assembled quantum dots with a thickness of 50 nm. Square nanopits, with a depth of about 8 nm and boundaries along 〈110〉, are formed in the Si capping layer after annealing. Cross-sectional transmission electron microscopy observation shows that each nanopit is located right over one dot with one to one correspondence. The detailed migration of Si atoms for the nanopit formation is revealed by in-situ annealing at a low temperature of 540°C. The final well-defined profiles of the nanopits indicate that both strain energy and surface energy play roles during the nanopit formation, and the nanopits are stable at 640°C. A subsequent growth of Ge on the nanopit-patterned surface results in the formation of SiGe quantum dot molecules around the nanopits

Successive modification of polydentate complexes gives access to planar carbon-and nitrogen-based ligands

以碳和氮为键合原子的多齿螯合物是配合物家族中非常重要的一类。具有更高齿数的平面构型NC螯合物实例相对较少，代表性的例子为四齿金属碳卟啉类化合物，这类螯合物以其独特的结构和丰富的物理化学性质引起广泛关注。然而平面五齿、六齿的NC螯合物由于几何构型“拥挤”导致合成难度高，该工作从含三元环内金属卡宾结构的CCCC型碳龙配合物出发，利用经典有机反应（炔烃对金属卡宾的插入反应），成功地实现了CCCCN/NCCCN型平面五齿螯合物的合成。这一研究为高配位型螯合物的合成提供了新思路并为平面五齿螯合物家族添加新成员。特别是，这些高配位型螯合物在可见光和近红外区域均有较好的吸收，表现出良好的光声成像、光热转换及声动力学性能。 该研究工作在张弘教授指导下完成，第一作者为iChEM博士后周小茜。该工作充分体现了多学科协同研究优势：相关化合物的合成、表征及理论计算工作由周小茜博士完成；声动力学性能研究由厦门大学公共卫生学院庞鑫博士及刘刚教授完成；光声成像研究由厦门大学公共卫生学院聂立铭教授完成。iChEM fellow卓庆德博士、博士生卓凯玥、陈志昕参与了部分实验工作。夏海平教授、香港科技大学林振阳教授和南京大学朱从青教授对研究工作给予了大力支持。【Abstract】Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.This research was supported by the National Natural Science Foundation of China (Nos. 21572185, 21561162001, and 81571744), the Research Grants Council of Hong Kong (N_HKUST603/15), the Excellent Youth Foundation of Fujian Scientific Committee (2018J06024), and the Fundamental Research Funds for the Central Universities (20720170065).该工作得到国家自然科学基金委、香港研究资助局、福建省自然科学基金、厦门大学校长基金的资助

Probing the Reactivity of the Ce=O Multiple Bond in a Cerium(IV) Oxo Complex

The reactivity of the cerium­(IV) oxo complex [(L_OEt)₂Ce^IV(O)­(H₂O)]·MeC­(O)­NH₂ (<b>1</b>; L_OEt^– = [CoCp­{P­(O)­(OEt)₂}₃]⁻, where Cp = η⁵-C₅H₅) toward electrophiles and Brønsted acids has been investigated. The treatment of <b>1</b> with acetic anhydride afforded the diacetate complex [Ce^IV(L_OEt)₂(O₂CMe)₂] (<b>2</b>). The reaction of <b>1</b> with B­(C₆F₅)₃ yielded [Ce^IV(L_OEt)₂(Me₂CONH₂)₂]­[B­(C₆F₅)₃(OH)]₂ (<b>3</b>), in which the [B­(C₆F₅)₃(OH)]⁻ anions are H-bonded to the O-bound acetamide ligands. The treatment of <b>1</b> with HCl and HNO₃ afforded [Ce^IV(L_OEt)₂Cl₂] and [Ce^IV(L_OEt)₂(NO₃)₂], respectively. Protonation of <b>1</b> with triflic acid (HOTf) gave the diaqua complex [Ce^IV(L_OEt)₂(H₂O)₂]­(OTf)₂ (<b>4</b>), in which the triflate anions are H-bonded to the two aqua ligands. The treatment of <b>1</b> with phenol afforded the phenoxide complex [Ce^IV(L_OEt)₂(OPh)₂] (<b>5</b>). The oxo-bridged bimetallic complex [(L_OEt)₂(Me₂CONH₂)­Ce^IV(O)­NaL_OEt] (<b>6</b>) with the Ce–O_oxo and Na–O_oxo distances of 1.953(4) and 2.341(4) Å, respectively, was obtained from the reaction of <b>1</b> with [NaL_OEt]. Density functional theory calculations showed that the model complex [(L_OMe)₂Ce^IV(Me₂CONH₂)­(O)­NaL_OMe] (<b>6A</b>; L_OMe^– = [CoCp­{P­(O)­(OMe)₂}₃]⁻) contains a polarized CeO multiple bond. The energy for dissociation of the {NaL_OMe} fragment from <b>6A</b> in acetonitrile was calculated to be +33.7 kcal/mol, which is higher than that for dissociation of the H-bonded acetamide from [(L_OMe)₂Ce^IV(O)­(H₂O)]·MeC­(O)­NH₂ (<b>1A</b>) (calculated to be +17.4 kcal/mol). In hexanes containing trace water, complex <b>1</b> decomposed readily to a mixture of a tetranuclear cerium­(IV) oxo cluster, [Ce^IV₄(L_OEt)₄(μ₄-O)­(μ₂-O)₄(μ₂-OH)₂] (<b>7</b>), and a cerium­(III) complex, [Ce^III(L_OEt)₂(H₂O)₂]­[L_OEt] [<b>8</b>(L_OEt)], whereas the cerium/sodium oxo complex <b>6</b> is stable under the same conditions. The crystal structures of <b>3</b>, <b>4</b>·H₂O, <b>6</b>, and <b>8</b>(L_OEt) have been determined