The dinuclear copper enzyme tyrosinase activates O2 to form a (μ‐η2:η2‐peroxido)dicopper(II) species, which hydroxylates phenols to catechols. However, the exact mechanism of phenolase reaction in the catalytic site of tyrosinase is still under debate. We herein report the near atomic resolution X‐ray crystal structures of the active tyrosinases with substrate L‐tyrosine. At their catalytic sites, CuA moved largely toward L‐tyrosine (CuA1 to CuA2), whose phenol oxygen directly coordinates to CuA2,...
Thu Apr 30, 2020 17:41
A novel strategy to prepare methanol from formic acid without external reductant is presented. The overall process described herein consists in the disproportionation of silyl formates to methoxysilanes catalyzed by ruthenium complexes and the production of methanol thereof by simple hydrolysis. Aqueous solutions of MeOH (> 1 mL, > 70 % yield) were prepared in this manner. The sustainability of the reaction has been established by the recycling of the silicon‐containing byproducts with cheap...
Thu Apr 30, 2020 15:39
We report the synthesis of anionic diniobium hydride complexes with a series of alkali metal cations (Li + , Na + , and K + ) and their counterion dependence of the reactivity with N 2 . Exposure of these complexes to N 2 initially produces the corresponding side‐on end‐on N 2 complexes, the fate of which depends on the nature of counter cations. The lithium derivative undergoes stepwise migratory insertion of the hydride ligands onto the aryloxide units, yielding the end‐on bridging...
Thu Apr 30, 2020 14:39
Redox active metalloenzymes catalyse a range of biochemical processes essential for life. However, due to their complex reaction mechanisms, and often, their poor optical signals, detailed mechanistic understandings of them are limited. Here, we develop a cryoreduction approach coupled to electron paramagnetic resonance measurements to study electron transfer between the copper centers in the copper nitrite reductase (CuNiR) family of enzymes. Unlike alternative methods used to study electron transfer...
Thu Apr 30, 2020 13:08
The first example of enantioselective S‐H insertion reactions of sulfoxonium ylides is reported. Under the influence of thiourea catalysis, excellent levels of enantiocontrol (up to 95% ee) and yields (up to 97%) are achieved for 31 examples in S‐H insertion reactions of aryl thiols and α‐carbonyl sulfoxonium ylides.
Thu Apr 30, 2020 12:41
Current bacterial RNA switches suffer from lack of versatile inputs and are difficult to engineer. Here we present versatile and modular RNA switches that are trans ‐encoded and based on tRNA mimicking structures (TMSs). These switches provide a high degree of freedom for reengineering and can thus be designed to accept a wide range of inputs including RNA, small molecules and proteins. This powerful approach allows controlling translation of protein expression from plasmid and genome DNA.
Thu Apr 30, 2020 12:39
Ligand responsiveness is one of the typical mechanisms in biological organizations to trigger the sophisticated channel switch. Here, we reported a new type of helical trimer which could undergo the transition between hollow single helix and intertwined double helix with no cavity via the complexation and decomplexation with Cu ions. In addition, the spontaneously generated 1D hollow helical tubes from single helices via π‐π interactions embedded into the lipid bilayers and displayed satisfactory...
Thu Apr 30, 2020 12:38
Open, sesame! A method for the quantitative assembly of the heterobimetallic cage, [PdPtL4]4+, is described. The cage interacts with quinone guest molecules in a 1:1 fashion. The cage can be selectively and reversibly opened then re‐closed at the PdII end by the sequential addition of base then acid. Guest molecules can be reversibly released/bound during this process. Abstract A strategy is presented that enables the quantitative assembly of a heterobimetallic [PdPtL4]4+ cage. The presence...
Thu Apr 30, 2020 10:44
The charge of the light brigade: By a sequence of absorption and photo‐induced electron‐transfer processes electron‐poor perylene bisimides (cp‐BPI) are transformed into their electron‐rich dianions which upon another photoexcitation exhibit sufficient reductive power to drive hydrogen evolution at Pt/TiO2 nanoparticles. Abstract A photocatalytic system containing a perylene bisimide (PBI) dye as a photosensitizer anchored to titanium dioxide (TiO2) nanoparticles through carboxyl groups was...
Thu Apr 30, 2020 10:44
Hematite mesocrystal superstructures with rich interfacial oxygen vacancies yield an exceedingly high carrier density of 4.1×1021 cm−3 for super bulk conductivity in the electrode and a large quantity of ultra‐narrow depletion regions (<1 nm) for high hole collection efficiency, thus boosting multihole water oxidation with a very low activation energy (E a=44 meV). Abstract Significant charge recombination that is difficult to suppress limits the practical applications of hematite (α‐Fe2O3)...
Thu Apr 30, 2020 10:44
Two membrane proteins (one α‐helical and one β‐barrel) have been found, using solution NMR relaxation techniques, to have extraordinary side‐chain motion on the ps–ns timescale in both detergent micelles and lipid bilayers. The extensive side‐chain motion about a highly rigid backbone scaffold is consistent with a high residual conformational entropy and helps explains the stability of the folded state in the absence of the hydrophobic effect. Abstract The internal motions of integral membrane...
Thu Apr 30, 2020 10:44
A general and scalable solvent‐free self‐assembly strategy allows the synthesis of mesoporous metal oxides based on room‐temperature grinding. Compared with the traditional solvent self‐assembly process, the avoidance of solvents in the synthesis not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. Abstract Mesoporous metal oxides (MMOs) have been demonstrated great potential in...
Thu Apr 30, 2020 10:44
Concentrate (and reconcentrate): Two‐stage selective electrokinetic concentration enables one‐step purification of nucleic acids and microfluidic PCR resistant to non‐specific amplification, thereby significantly shortening the development cycle and simplifying the workflow of nucleic acid amplification tests for point‐of‐care disease diagnosis. Abstract Nucleic acid amplification tests (NAATs)integrated on a chip hold great promise for point‐of‐care diagnostics. Currently, nucleic acid (NA)...
Thu Apr 30, 2020 10:44
Perfection not required: In a study of intrinsic properties of intermetallic compounds, the synthesis of either single‐crystal or single‐phase material is the fundamental step. However, some materials cannot be prepared in single‐phase form. A new approach using a micro‐scale amount of material to study its intrinsic properties can significantly shorten this procedure and make the quest for “perfect” samples unnecessary. Abstract An efficient application of a material is only possible if we...
Thu Apr 30, 2020 10:44
Ring, ring: Conformationally restricted azabicycles are becoming increasingly important in medicinal research. Asymmetric Heck bicyclization of enynes proceeds to give medicinally useful aza[3.1.0] and aza[4.1.0] bicycles with excellent enantioselectivity. The key organopalladium species after bicyclization can be trapped by silanes and terminal alkynes. Abstract Conformationally restricted azabicycles are becoming increasingly important in medicinal research. Asymmetric Heck bicyclization...
Thu Apr 30, 2020 10:44
N,P‐co‐doped carbon aerogels (NPCA), easily prepared by the gelatinization of starch, can boost CO2 reduction to CO with a very high current density. The maximum CO faradaic efficiency was 99.1 % with a partial current density −143.6 mA cm−2 at a low overpotential. The pyridinic N is the dominant active site for CO2 reduction, and co‐doping of N and P hinder the hydrogen evolution reaction (HER) significantly. Abstract Electroreduction of CO2 to CO powered by renewable electricity is a possible...
Thu Apr 30, 2020 10:44
HER we go: An improved alkaline HER performance was achieved by modifying Pt(111) and nanostructured Pt electrocatalysts with nickel‐iron clusters. The activity was optimized by varying the Ni:Fe ratio, the coverage of the metal cluster, and the electrolyte composition. This improvement yields a more favorable balance between benefiting water dissociation and preventing *OH “poisoning”. Abstract Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of...
Thu Apr 30, 2020 10:44
What far from tangled webs we weave: By combining dynamic covalent chemistry (DCC) and coordination chemistry, divergent paths for the construction of three‐dimensional (3D) woven covalent organic frameworks (COFs) or one‐dimensional (1D) metallo‐COFs (mCOFs) are identified. The paths are distinguished by the absence or presence of ligand exchange. Abstract The marriage of dynamic covalent chemistry (DCC) and coordination chemistry is a powerful tool for assembling complex architectures from...
Thu Apr 30, 2020 10:44
Dye hard: The dye‐sensitized photo‐electrochemical cell for visible‐light‐driven H2O2 production is enhanced by simply dissolving anthraquinone redox mediators in either aqueous or non‐aqueous electrolytes. Photo‐electrochemical tests reveal high photocurrent density, H2O2 conversion efficiency, and acid stability. Therefore, the use of anthraquinone presents a universal method for O2 reductive H2O2 production in most photo‐electrochemical systems. Abstract Anthraquinone (AQ) redox mediators...
Thu Apr 30, 2020 22:00
We report eight‐step syntheses of (–)‐ minovincine and (–)‐aspidofractinine using easily available and inexpensive reagents and catalyst. A key element of the strategy was the utilization of the chain of cascade reactions to rapidly construct the penta‐ and hexacyclic frameworks. These cascade transformations included organocatalytic Michael‐aldol condensation, a multistep anionic Michael‐S N 2 cascade reaction and Mannich reaction interrupted Fischer indolization. To streamline the synthetic routes,...
Wed Apr 29, 2020 22:00
Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to p rac tical applications is a high efficiency in conversion of light to chemical energy, a rigid structure for the trans mission of force to the environment and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines), that converts visible light with an efficiency of 18% to chemical...
Wed Apr 29, 2020 21:38
A transition‐metal‐free carbon isotope exchange procedure on phenyl acetic acids is described. Utilizing the universal precursor CO 2 , this protocol allows the carbon isotope to be inserted into the carboxylic acid position, with no need of precursor synthesis. This procedure enabled the labeling of 15 pharmaceuticals and was compatible with carbon isotopes [ 14 C] and [ 13 C]. A proof of concept with [ 11 C] was also obtained with low molar activity valuable for distribution studies.
Wed Apr 29, 2020 20:48
The reaction of zerovalent nickel compounds with white phosphorus (P4) is a barely explored route to binary nickel phosphide clusters. Here, we show that coordinatively and electronically unsaturated N‐heterocyclic carbene (NHC) nickel(0) complexes afford unusual cluster compounds with P1, P3, P5 and P8 units. Using [Ni(IMes)2] [IMes = 1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene], electron‐deficient Ni3P4 and Ni3P6 clusters have been isolated, which can be described as superhypercloso...
Wed Apr 29, 2020 20:33
Hydrophobic collapse plays crucial roles in protein functions, from accessing the complex three‐dimensional structures of native enzymes to the dynamic polymerization of non‐equilibrium microtubules. However, hydrophobic collapse can also lead to the thermodynamically downhill aggregation of the aberrant proteins which has interestingly led to the development of unique class of soft nanomaterials. There remain critical gaps in our understanding of the mechanisms of how hydrophobic collapse can regulate...
Wed Apr 29, 2020 20:11
Dynamic covalent chemistry combines in a single step the screening and synthesis of ligands for biomolecular recognition. To that, a chemical entity is used as template within a dynamic combinatorial library of interconverting species, so that the stronger binders are amplified due to the efficient interaction with the target. Here we employed whole A549 living cells as template in a dynamic mixture of imines, for which amplification reflects the efficient and selective interaction with the corresponding...
Wed Apr 29, 2020 20:10
A hybrid plladium catalyst assembled from chiral phosphoric acid (CPA) and thioamide shows a high capacity for enabling a highly efficient and enantioselective β‐C(sp 3 )‒H functionalization of thioamides (up to 99% yield, 97% e.e.). The regioselectivity is switched from the carbon adjacent to the nitrogen to the acyl side of the thioamide by introducing bulky N‐substituents. A kinetic resolution of unsymmetrical thioamides via intermolecular C(sp 3 )‒H arylation can be achieved in high‐levels...
Wed Apr 29, 2020 19:05
The light‐induced spin state switching is one of the most attractive properties of the spin‐crossover materials. In bulk, low spin (LS) to high spin (HS) conversion via the light‐induced excited spin state trapping (LIESST) effect may be achieved with a visible light while the HS‐to‐LS one (reverse‐LIESST) requires an excitation in the near infrared range. Here, we show that those phenomena are strongly modified at the interface with a metal. Indeed, we report an anomalous spin conversion from HS...
Wed Apr 29, 2020 18:34
Cyanines comprising either a benzo[e]‐ or benzo[c,d]indolium pattern facilitate initiation of radical photopolymerization combined with high power NIR‐LED prototypes emitting at 805 nm, 860 nm or 870nm while different oxime esters functioned as radical coinitiator. The conversion was studied FTIR. Sensitizers used depict different structural patterns. Radical photopolymerization followed an initiation mechanism based in the participation of excited states requesting addiitonal thermal energy to...
Wed Apr 29, 2020 17:14
Cumulene compounds are notoriously difficult to prepare and study due to dramatically increasing reactivity with increasing number of consecutive double bonds. In this respect, the emerging field of on‐surface synthesis provides exceptional opportunities because it relies on reactions on clean metal substrates under well‐controlled ultrahigh vacuum conditions. Here we report the on‐surface synthesis of a polymer linked by cumulene‐like bonds on a Au(111) surface via sequential thermally activated...
Wed Apr 29, 2020 17:12
In the search for highly reactive oxidants we have identified high‐valent metal‐fluorides as a potential potent oxidant. The high‐valent Ni–F complex [NiIII(F)(L)] (2, L = N,N’‐(2,6‐dimethylphenyl)‐2,6‐pyridinedicarboxamidate) was prepared from [NiII(F)(L)]– (1) by oxidation with selectfluor. 1 and 2 were characterized using 1H/19F NMR, UV‐vis, and EPR spectroscopies, mass spectrometry, and X‐ray crystallography. 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic...
Wed Apr 29, 2020 17:05
Uniaxial magnetic anisotropy is an essential property that governs the performance of dysprosium metallocene single‐molecule magnets (SMMs). Determining this property using experimental methods is necessary and important as it provides direct information vital to the understanding of the magneto‐structural correlation and a valuable reference for theoretical analysis, but has been proved extremely challenging. Herein, we investigate a family of dinuclear dysprosium metallocene SMMs bridged by the...
Wed Apr 29, 2020 15:04
The protein corona of nanoparticles has in recent years received considerable attention, and even been postulated to be the missing link in the translation of nanomedicines from benchtop to bedside. Here, we highlight the different types of biological nanoparticles present in blood that need to be considered in the protein corona research field. We map their size, density and plasma concentrations and use this information to stress potential challenges related to the isolation of nanomedicines, with...
Wed Apr 29, 2020 14:07
The chromane nucleus is common to a plenum of bioactive small molecules where it is frequently oxidized at position 3. Motivated by the importance of this position in conferring efficacy, and the prominence of bioisosterism in drug discovery, an I(I)/I(III) catalysis strategy to access enantioenriched 3‐fluorochromanes is disclosed (up to 7:93 e.r. ). In situ generation of ArIF 2 enables the direct fluorocyclization of allyl phenyl ethers to generate novel scaffolds that manifest the stereoelectronic...
Wed Apr 29, 2020 14:05
The practical implementation of lithium‐sulfur batteries is obstructed by the poor conductivity, sluggish redox kinetics, notorious shuttle effect, large volume variation, and low areal loading of sulfur electrodes. Herein, to conquer these main bottlenecks of sulfur electrodes, we have meticulously designed amorphous N‐doped carbon/MoS 3 (NC/MoS 3 ) nanoboxes with hollow‐porous architectures as an advanced sulfur host. Benefiting from the enhanced conductivity by the N‐doped carbon, reduced...
Wed Apr 29, 2020 13:05
Metal‐catalyzed chelation‐assisted C –H olefinations have emerged as powerful tools for the construction of functionalized alkenes. Herein, we describe the rhodaelectro‐catalyzed C – H activation/alkenylation of arenes. The olefinations of challenging electron‐poor benzamides were thus accomplished in a fully dehydrogenative fashion under electrochemical conditions, avoiding stoichiometric chemical oxidants, and with H 2 as the only byproduct. This versatile alkenylation reaction also features...
Wed Apr 29, 2020 12:36
Key points Muscle infiltration with adipose tissue (IMAT) is common and associated with loss of skeletal muscle strength and physical function across a diverse set of pathologies. Whether the association between IMAT and muscle weakness is causative or simply correlative remains an open question that needs to be addressed to effectively guide muscle strengthening interventions in people with increased IMAT. In the present studies, we demonstrate that IMAT deposition causes decreased muscle...
Sat May 02, 2020 22:37
Key points A ketogenic low carbohydrate high fat (K‐LCHF) diet can achieve a substantial (∼200%) increase in maximal rates of fat oxidation during exercise in endurance‐trained athletes, up to ∼1.5 g min−1 at ∼70% of peak aerobic capacity. In high‐level athletes, considerable individual variability is observed but 3–4 wkof K‐LCHF preserves moderate‐intensity exercise capacity and performance. Performance of higher‐intensity endurance exercise (>80% VO2peak) is compromised, potentially due...
Sat May 02, 2020 22:37
Abstract Mitochondrial structures were probably observed microscopically in the 1840s, but the idea of oxidative phosphorylation (OXPHOS) within mitochondria did not appear until the 1930s. The foundation for research into energetics arose from Meyerhof's experiments on oxidation of lactate in isolated muscles recovering from electrical contractions in an O2 atmosphere. Today, we know that mitochondria are actually reticula and that the energy released from electron pairs being passed along the...
Sat May 02, 2020 22:35
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