Highly selective trifluoroacetic ester/ketone metathesis: an efficient approach to trifluoromethyl ketones and esters

A highly selective and atom efficient ‘trifluoroacetic ester/ketone metathesis’ has been sincerely witnessed. Enolizable alkyl (at least two non-hydrogen atoms) aryl ketones were found to react readily with ethyl trifluoroacetate under the promotion of NaH to afford trifluoroacetic ester/ketone exchange products, trifluoromethyl ketones (TFMKs), and aromatic acid esters, which were quite different from the general Claisen condensation products, 1,3-diketones. The outcome of the reaction between ketone and ethyl trifluoroacetate is strongly related to the structures of substrates, the steric congestion caused by alkyl group is in favor of the C–C bond cleavage. DFT investigation further disclosed that the metathesis reaction was a kinetically favored pathway. Using only a slight excess of cheap trifluoromethylation reagent, simple operation and mild conditions make it a practical method for preparation of TFMKs on large scale, as well as a new choice of converting aryl alkyl ketones to aromatic acid esters.     

Aequorin mutants with increased thermostability

Bioluminescent labels can be especially useful for in vivo and live animal studies due to the negligible bioluminescence background in cells and most animals, and the non-toxicity of bioluminescent reporter systems. Significant thermal stability of bioluminescent labels is essential, however, due to the longitudinal nature and physiological temperature conditions of many bioluminescent-based studies. To improve the thermostability of the bioluminescent protein aequorin, we employed random and rational mutagenesis strategies to create two thermostable double mutants, S32T/E156V and M36I/E146K, and a particularly thermostable quadruple mutant, S32T/E156V/Q168R/L170I. The double aequorin mutants, S32T/E156V and M36I/E146K, retained 4 and 2.75 times more of their initial bioluminescence activity than wild-type aequorin during thermostability studies at 37 °C. Moreover, the quadruple aequorin mutant, S32T/E156V/Q168R/L170I, exhibited more thermostability at a variety of temperatures than either double mutant alone, producing the most thermostable aequorin mutant identified thus far.     

Clickable SBA‐15 to Screen Functional Groups for Adsorption of Antibiotics

Pharmaceutical antibiotics, as emerging contaminants, are usually composed of several functional groups that endow them with the ability to interact with adsorbents through different interactions. This makes the preparation of adsorbents tedious and time‐consuming to screen appropriate functionalized materials. Herein, we describe the synthesis of clickable SBA‐15 and demonstrate its feasibility as a screening material for the adsorption of antibiotics based on similar adsorption trends on materials with similar functional groups obtained by a click reaction and cocondensation/grafting methods.     

Antibacterial cotton fabric prepared by a “grafting to” strategy using a QAC copolymer

Quaternary ammonium compounds (QACs) have outstanding antimicrobial effect, but covalent immobilization of plentiful QAC onto cotton fiber surface to realize a durable function remains a challenge. Herein, a quaternary ammonium monomer, [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) was co-polymerized with methyl acrylate (MA) to prepare an antibacterial copolymer, poly(DMC-co-MA). To graft the copolymer with an improved grafting efficiency, cotton fabric was treated using carboxymethyl chitosan (CMC) to establish an amino-functionalized fiber surface first. This treatment allows the amidation reactions between the amino groups and the pendant ester groups in the poly(DMC-co-MA) to take place, achieving a durable anionic polymer coating onto the fiber surfaces with remarkably antibacterial effect. Characterization results indicated that when DMC/MA monomer ratio was 100:1, the resulting copolymer endows the modified cotton fabric with antibacterial capability that inactivates all Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Even after 50 laundering cycles, more than 98.0% of the antibacterial rate could still be retained. Moreover, the wearing comfort properties such as softness, water absorption and air permeability of the finishing cotton fabrics have been insignificantly changed by comparing to the untreated cotton fabric.

     

The Varied Frustrated Lewis Pair Reactivity of the Germylene Phosphaketene (CH{(CMe)(2,6-iPr2C6H3N)}2)GePCO

The germylene species (CH{(CMe)(2,6-iPr₂C₆H₃N)}₂)GePCO 1 is shown to react with the Lewis acids (E(C₆F₅)₃ E=B, Al). Nonetheless, 1 participates in FLP chemistry with electron deficient alkynes or olefins, acting as an intramolecular FLP. In contrast, in the presence of B(C₆F₅)₃ and an electron rich alkyne, 1 behaves as Ge-based nucleophile to effect intermolecular FLP addition to the alkyne. This reactivity demonstrates that the reaction pathway is controlled by the nature of the electrophile and nucleophile generated in solution, as revealed by extensive DFT calculations.     

Parameter optimization and performance study of Ni–P coatings prepared by pulse-assisted jet electrochemical deposition

Journal of Solid State Electrochemistry - Jet electrochemical deposition is a relatively new technology for selective electrochemical deposition. Its advantages include high deposition accuracy and...     

Polymer Electrolytes – New Opportunities for the Development of Multivalent Ion Batteries

Batteries, as highly concerned energy conversion system, have a great development prospect in various fields, especially in the field of energy powered vehicles. Multivalent ion batteries are getting more attention due to their low cost, high abundance in earth crust, high capacity and safety compared with Lithium batteries. Despite above advantages, several problems still need to be solved before multivalent ion batteries achieve large-scale application, such as interfacial parasitic reaction, anode passivation, and dendrites. The replacement of liquid electrolytes with gel polymer electrolytes (GPEs) which pose high safety, high mechanical strength and simplified battery system, is an effective strategy to inhibit dendrite growth and improve electrochemical performance. This review mainly discusses the advantages and challenges of multivalent ion batteries including zinc, magnesium, calcium and aluminum batteries. Meanwhile, the major targets of this review are introducing the recent developments and making a summary of the future trends of GPEs in the multivalent ion batteries.     

PtRu bimetallic nanoparticles embedded in MOF-derived porous carbons for efficiently electrochemical sensing of uranium

Journal of Solid State Electrochemistry - PtRu bimetallic nanoparticles embedded in MOF-derived porous carbons (PtRu-PCs) were synthesized by first loading PtRu bimetallic nanoparticles into a...     

Topological nature of in‐gap bound states in disordered large‐gap monolayer transition metal dichalcogenides

We propose a physical model based on disordered (a hole punched inside a material) monolayer transition metal dichalcogenides (TMDs) to demonstrate a large‐gap quantum valley Hall insulator. We find an emergence of bound states lying inside the bulk gap of the TMDs. They are strongly affected by spin–valley coupling, rest‐ and kinetic‐mass terms and the hole size. In addition, in the whole range of the hole size, at least two in‐gap bound states with opposite angular momentum, circulating around the edge of the hole, exist.Their topological insulator (TI) feature is analyzed by the Chern number, characterized by spacial distribution of their probabilities and confirmed by energy dispersion curves (energy vs. angular momentum). It not only sheds light on overcoming low‐temperature operating limitation of existing narrow‐gap TIs, but also opens an opportunity to realize valley‐ and spin‐qubits. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

An 18 Multi-InDels panel for analysis of highly degraded forensic biological samples

DNA genotyping from trace and highly degraded biological samples is one of the most significant challenges of forensic DNA identification. There is a lack of simple and effective methods for genotyping highly degraded samples. In this study, a multiple loci insertion/deletion polymorphisms (Multi-InDels) panel was designed for detecting 18 autosomal Multi-InDels through capillary electrophoresis (CE) with amplicon sizes no longer than 125 bp. Studies of sensitivity, degradation, and species specificity were performed and a population study was carried out using 192 samples from Han populations in Hunan province in the south of China. The combined random match probability (CMP) of these 18 Multi-InDels was 3.23 × 10^–12 and the cumulative probability of exclusion (CPE) was 0.9989, suggesting this panel could be used independently for human identification and could provide efficient supporting information for parentage testing. Complete profiles were obtained from as low as 62.5 pg of total input DNA after increasing the number of PCR cycles. Moreover, all alleles were detected from artificially highly degraded DNA after 80 min of boiling water bath treatment. This 18 Multi-InDels panel is simple, fast, and effective for the forensic analysis of highly degraded DNA.