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Lab Chip, 2017, 17,3310-3317
DOI: 10.1039/C7LC00696A, PaperChunmei Zhou, Pingan Zhu, Ye Tian, Xin Tang, Rui Shi, Liqiu Wang
We propose a microfluidic "oil-chopper" method to produce highly uniform ATPS droplets with well-controlled size and generation frequency.
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The 7-methylguanosine (m7G) cap structure is a unique feature present at the 5ʹ ends of messenger RNAs (mRNAs) that can be subjected to extensive modifications, resulting in alterations to mRNA properties (e.g. translability, susceptibility to degradation). It also can provide molecular tools to study mRNA metabolism. Here, we developed new mRNA 5ʹ cap-based tools that enable the site-specific labeling of RNA at the 5ʹ end using strain-promoted azide-alkyne cycloaddition (SPAAC), i.e. bioorthogonal, copper-free click chemistry, and support the mRNA's basic function in protein biosynthesis. Some of these azide-functionalized compounds are equipped with additional modifications to augment mRNA properties. The application of these tools was demonstrated by labeling translationally active mRNAs in living cells.

Fabrication of hybrid MOF-on-MOF heteroarchitectures can create novel and multifunctional platforms to achieve desired properties. However, only MOFs with similar crystallographic parameters can be hybridized by the classical epitaxial growth method (EGM), which largely suppressed its applications. Herein, we demonstrated a general strategy called internal extended growth method (IEGM) for the feasible assembly of MOFs with distinct crystallographic parameters in an MOF matrix. Various MOFs with diverse functions could be introduced in a modular MOF matrix to form 3D core-satellite pluralistic hybrid system. Additionally, the number of different MOF crystals interspersed could be variable on demand. More importantly, the different MOF crystals distributed in individual domains could be used to further incorporate functional units or enhance target functions.

The base-stabilized borylene [Cp(OC)2Mn=BtBu(IMe)] readily reacts with elemental chalcogens in an insertion reaction that yields borachalcone complexes [(OC)2Mn-E=BtBu(IMe)] (E = S, Se, Te). The tellurium example features the first double bond between boron and tellurium, making Te the heaviest main-group element to make multiple bonds with boron. This unprecedented interaction has been fully investigated experimentally and computationally.

The synthesis of the peptide selenoester was efficiently carried out by the 9-fluorenylmethoxycarbonyl method using the N-alkylcysteine at the C-terminus of the peptide as the N-to-S acyl shift device. The selenoester highly selectively reacted with the terminal amino group of the peptide aryl thioester in the presence of N, N-diisopropylethylamine and dipyridyldisulfide, maintaining the aryl thioester intact. Combining with the silver ion promoted and silver ion free thioester activation method, the one-pot four-segment ligation was realized. The method was successfully used to assemble the entire sequence of the superoxide dismutase (SOD) composed of 153 amino acid residues in one-pot. After the folding reaction, the fully-active SOD was obtained.

Herein, we report a novel visible-light photoredox system with Pd(PPh3)4 as the sole catalyst to realize the first direct cross-coupling of C(sp3)─H bonds in N-aryl tetrahydroisoquinolines with general unactivated alkyl bromides. Moreover, intra- and inter-molecular alkylations of hetero-arenes were also developped under mild reaction conditions. A variety of tertiary, secondary and primary alkyl bromides undergo such reactions to generate C(sp3)─C(sp3) and C(sp2)─C(sp3) bonds in moderate to excellent yields. These redox-neutral reactions feature broad substrate scope (>60 examples), good functional group tolerance and facile generation of quaternary centers. Mechanistic studies indicate that the simple Pd-complex acts as the visible-light photocatalyst and radicals are involved in the process.

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Gérard Férey, a leader in the field of solid-state chemistry and a pioneer of metal–organic frameworks (MOFs), passed away on August 19, 2017 in Paris. Férey developed both open-framework templated metal fluorophosphates (the ULM-n series) and a series of topical porous MOFs (the MIL-n series). He also created the automated assembly of secondary building units methodology to predict the structure of new porous solids.

Abstract

A synthesis of multiply arylated naphthalenes and anthracenes with eight different substituents has been accomplished. The key intermediates are tetraarylthiophene S-oxides, which are synthesized through a method involving sequential C−H arylation and cross-coupling from 3-methoxythiophene, followed by oxidation of the sulfur atom. The resulting tetraarylthiophene S-oxides can be converted into a tetraaryl benzynes or naphthalynes and then merged through [4+2] cycloaddition reaction with another tetraarylthiophene S-oxide, thereby resulting in the programmed synthesis of octaarylnaphthalenes and octaarylanthracenes.

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Straight to eight: A novel method is presented that enables the synthesis of octaarylnaphthalenes (OANs) and octaarylanthracenes (OAAs) with eight different aryl substituents through [4+2] cycloaddition of tetraarylthiophene S-oxides with multiply arylated arynes.

Abstract

Strongly luminescent iridium(III) complexes, [Ir(C,N)2(S,S)]+ (1) and [Ir(C,N)2(O,O)] (2), containing C,N (phenylquinoline), O,O (diketonate), or S,S (dithione) chelating ligands, have been characterized by X-ray crystallography and DFT calculations. Their long phosphorescence lifetimes in living cancer cells give rise to high quantum yields for the generation of 1O2, with large 2-photon absorption cross-sections. 2 is nontoxic to cells, but potently cytotoxic to cancer cells upon brief irradiation with low doses of visible light, and potent at sub-micromolar doses towards 3D multicellular tumor spheroids with 2-photon red light. Photoactivation causes oxidative damage to specific histidine residues in the key proteins in aldose reductase and heat-shock protein-70 within living cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of enzymes involved in the glycolytic pathway.

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In for a shock: A highly luminescent organoiridium complex generates 1O2 efficiently and oxidizes specific residues of heat-shock protein-70 and aldose reductase within cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of the enzymes involved in the glycolytic pathway.

Abstract

A series of heterobimetallic complexes containing three-center, two-electron Au−H−Cu bonds have been prepared from addition of a parent gold hydride to a bent d10 copper(I) fragment. These highly unusual heterobimetallic complexes represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu−H−Cu and M−H−M+ moieties (M=Cu, Ag). The well-defined heterobimetallic hydride complexes act as precatalysts for the conversion of CO2 into HCO2Bpin with HBpin as the reductant. The selectivity of the heterobimetallic complexes for the catalytic production of a formate equivalent surpasses that of the parent monomeric Group 11 complexes.

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The golden touch: A series of heterobimetallic complexes containing three-center, two-electron Au−H−Cu bonds have been prepared. These unusual molecules represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu−H−Cu and M−H−M+ moieties (M=Cu, Ag), and act as precatalysts for the selective reduction of CO2 to HCO2Bpin.

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Pd at the crossroads: The palladium-catalyzed cross-coupling of nitroarenes has eluded chemists for decades. Recently, the first palladium-catalyzed Suzuki–Miyaura and Buchwald–Hartwig cross-couplings of nitroarenes were reported. Mechanistically, this process involves the challenging oxidative addition of LPd0 into the Ar−NO2 bond. This process features a broad substrate scope with respect to both the nitroarene and the nucleophilic coupling partners.

Abstract

The observation of an unexpected oxidative rearrangement coupling reaction led to the development of a novel method for the efficient functionalization of tetrahydro-β-carbolines (THβCs). The treatment of THβCs with photogenerated singlet oxygen (1O2) afforded unstable dioxetanes, which underwent further transformation to form new bonds in the presence of trifluoroacetic acid. This operationally simple protocol exhibits broad functional-group tolerance and is suitable for the late-stage functionalization of complex druglike molecules.

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All rearrange please: The treatment of tetrahydro-β-carbolines with photogenerated singlet oxygen led to unstable dioxetanes, which underwent ring opening to give synthetic intermediates with a nine-membered ring. These products reacted with amines in the presence of an acid to form a variety of amino-substituted dihydropyrroloquinolines (see scheme). This simple method is suitable for the late-stage functionalization of complex druglike molecules.

Abstract

Electrodeposition of Si films from a Si-containing electrolyte is a cost-effective approach for the manufacturing of solar cells. Proposals relying on fluoride-based molten salts have suffered from low product quality due to difficulties in impurity control. Here we demonstrate the successful electrodeposition of high-quality Si films from a CaCl2-based molten salt. Soluble SiIV−O anions generated from solid SiO2 are electrodeposited onto a graphite substrate to form a dense film of crystalline Si. Impurities in the deposited Si film are controlled at low concentrations (both B and P are less than 1 ppm). In the photoelectrochemical measurements, the film shows p-type semiconductor character and large photocurrent. A p–n junction fabricated from the deposited Si film exhibits clear photovoltaic effects. This study represents the first step to the ultimate goal of developing a cost-effective manufacturing process for Si solar cells based on electrodeposition.

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Creating cheaper solar cells: High-quality Si films for photovoltaic applications were fabricated by electrodeposition from molten CaCl2–CaO–SiO2. Soluble SiIV−O anions generated from solid SiO2 are electrodeposited onto a graphite substrate to form a dense and thick film of p-type Si. Impurities in the deposited Si film are controlled at low concentrations. The film exhibits good photoelectrochemical properties and clear photovoltaic effects.

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It's electrifying! Electrochemical cross-coupling of aryl compounds provides a one-step approach to unsymmetrical biaryl compounds. A boron-doped diamond electrode is used as the anode to oxidise the phenolic hydroxy group to a phenoxy radical, and 1,1,1,3,3,3-hexafluoroisopropylalcohol (HFIP) and tetraalkylammonium methylsulfate are used as the solvent and electrolyte. Since no reagents are required, no waste is formed from this source.

Abstract

Novel aqueous multiphase systems (MuPSs) formed by quaternary mixtures composed of cholinium-based ionic liquids (ILs), polymers, inorganic salts, and water are reported herein. The influence of several ILs, polymers, and salts was studied, demonstrating that a triple salting-out is a required phenomenon to prepare MuPSs. The respective phase diagrams and “tie-surfaces” were determined, followed by the evaluation of the effect of temperature. Finally, the remarkable ability of IL-based MuPSs to selectively separate mixtures of textile dyes is shown.

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Three's a crowd: A simultaneous, triple salting-out effect is required to form ionic-liquid-based three-phase aqueous systems. These novel aqueous multiphase systems (MuPSs) were used for the selective separation of textile dyes, demonstrating their great potential in environmental and industrial applications.

The use of transition metal catalysis to enable the coupling of readily available organic molecules has greatly enhanced the chemist's ability to access complex chemical structures. In this work, an intermolecular coupling reaction that unites organotriflates and aldehydes is presented. A unique catalyst system is identified to enable this reaction, featuring a Ni(0) precatalyst, a tridentate Triphos ligand, and a bulky amine base. This transformation provides access to a variety of ketone-containing products without the selectivity and reactivity-related challenges associated with more traditional Friedel-Crafts reactions. A Heck-type mechanism is postulated, wherein the pi-bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.

Lab Chip, 2017, 17,3474-3488
DOI: 10.1039/C7LC00694B, PaperThomas M. Valentin, Susan E. Leggett, Po-Yen Chen, Jaskiranjeet K. Sodhi, Lauren H. Stephens, Hayley D. McClintock, Jea Yun Sim, Ian Y. Wong
Light-based 3D printing of alginate hydrogels using ionic crosslinking enables reversible patterning with controlled degradation.
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Lab Chip, 2017, 17,3462-3473
DOI: 10.1039/C7LC00402H, PaperMikkel Schou Andersen, Emily Howard, Shulin Lu, Matthew Richard, Mark Gregory, Gordon Ogembo, Ofer Mazor, Pavel Gorelik, Nathan I. Shapiro, Anish V. Sharda, Ionita Ghiran
Magnetic levitation is a technique for measuring the density and the magnetic properties of objects suspended in a paramagnetic field.
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TOC Graphic

Organic LettersDOI: 10.1021/acs.orglett.7b03106

The shape of work to come

Nature 550, 7676 (2017). http://www.nature.com/doifinder/10.1038/550316a

Author: Emily Anthes

Three ways that the digital revolution is reshaping workforces around the world.

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