We report an earth‐abundant metal catalyzed double and single methylation of alcohols. A manganese catalyst, which operates at low catalyst loadings and short reaction times, mediates these reactions efficiently. A broad scope of primary and secondary alcohols including purely aliphatic examples and 1,2‐aminoalcohols can be methylated. In addition, alcohol methylation for the synthesis of pharmaceuticals has been demonstrated. The catalyst system tolerates many functional groups among them hydrogenation...
Tue Nov 19, 2019 19:21
The separation of xenon/krypton (Xe/Kr) mixture is of great importance to industry, but the available porous materials allow the adsorption of both Xe and Kr with limited selectivity. Herein we report an anion‐pillared ultramicroporous material NbOFFIVE‐2‐Cu‐i (ZU‐62) with finely tuned pore aperture size and structure flexibility, which for the first time enables inverse size‐sieving effect in separation along with record Xe/Kr selectivity and ultrahigh Xe capacity. Evidenced by the single‐crystal...
Tue Nov 19, 2019 19:25
Super specific separations: Unparalleled structural specificity for isobaric, isotopic, and isomeric compounds is obtained through the first combination of high efficiency separations with high‐resolution rotational resonance spectroscopy. Even closely related species in minute amounts of complex mixtures can be rapidly and unambiguously identified and quantified. Abstract We designed and demonstrated the unique abilities of the first gas chromatography–molecular rotational resonance spectrometer...
Tue Nov 19, 2019 19:34
Nonsymmetrical ligands are usually not considered building blocks for discrete self‐assembled products. In their Communication (DOI: https://doi.org/10.1002/anie.20191109710.1002/anie.201911097), J. Yuasa and D. Ogata employ a new imidazole/pyridine‐based ditopic ligand as a building block for the construction of a dynamic Pd2L4 open cage compound that is available for turn‐on/off anion binding through stoichiometry‐driven structural transitions.
Tue Nov 19, 2019 19:37
Driven by electricity, the dehydrogenative coupling reaction of phenols carrying electron‐withdrawing groups to give 2,2′‐biphenols or the corresponding polycyclic derivatives is facilitated for the first time. 1,1,1,3,3,3‐Hexafluoroisopropanol and a small amount of base in the electrolyte make additional supporting electrolyte superfluous. The electrolysis is scalable, can be conducted with very simple equipment, and is much more concise than previous conventional syntheses. Abstract We herein...
Tue Nov 19, 2019 19:37
The CaH effect: The calcium hydride cation [CaH]+ catalyzes the regioselective hydrosilylation of ethylene, α‐olefins, and styrene derivatives. Aliphatic hydrosilanes are preferred over commonly employed silanes such as PhSiH3 as the latter undergoes scrambling reactions. Abstract Chemo‐ and regioselectivity are often difficult to control during olefin hydrosilylation catalyzed by d‐ and f‐block metal complexes. The cationic hydride of calcium [CaH]+ stabilized by an NNNN macrocycle was found...
Tue Nov 19, 2019 19:37
Three boron groups in one step: A straightforward copper‐catalyzed triboration of terminal alkynes gives access to triborylalkenes by sequential dehydroborylation and diboration. The triborylalkene products were applied in the synthesis of multisubstituted olefins with excellent regio‐ and stereoselectivity. Abstract We report herein the catalytic triboration of terminal alkynes with B2pin2 (bis(pinacolato)diboron) using readily available Cu(OAc)2 and Pn Bu3. Various 1,1,2‐triborylalkenes,...
Tue Nov 19, 2019 19:40
Going through a phase: Oligosilyl linker molecules are assembled into 2D metal–organic frameworks (MOFs) connected by copper paddlewheel nodes. Crystal structures demonstrate preferential anti‐conformations of silicon chains. Powder X‐ray diffraction reveals the crystalline phases of the MOFs are interconvertible through rearrangement of stacking motifs. Abstract We report the synthesis of a set of 2D metal–organic frameworks (MOFs) constructed with organosilicon‐based linkers. These oligosilyl...
Tue Nov 19, 2019 19:41
Sweet! The enzyme ethylenediamine‐N,N′‐disuccinic acid lyase was optimized by structure‐guided mutagenesis for the enantioselective synthesis of challenging N‐substituted aspartic acids, which are important chiral precursors to artificial dipeptide sweeteners such as neotame and advantame. This redesigned C–N lyase displayed a remarkable 1140‐fold increase in activity for selective hydroamination of fumarate. Abstract Aspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents...
Tue Nov 19, 2019 19:41
Inversion symmetry increases the excited‐state lifetime of a molecular ruby at room temperature in fluid solution to 4.5 ms while the photoluminescence quantum yield remains as high as 8.2 %, as shown by K. Heinze and co‐workers in their Research Article (DOI: https://doi.org/10.1002/anie.20190932510.1002/anie.201909325). The chromium(III) complex [Cr(tpe)2]3+ is furthermore competent in light‐induced electron‐ and energy‐transfer processes, and thus resembles classical noble‐metal complexes. ...
Tue Nov 19, 2019 19:43
A novel Pd0‐catalyzed asymmetric [4+3] annulation reaction of two readily accessible starting materials has been developed for building seven‐membered heterocyclic architectures. The potential [3+2] side pathway could be suppressed though fine tuning of the conditions. A broad scope of cycloaddition donors and acceptors participated in the transformation with excellent chemo‐, regio‐, diastereo‐, and enantioselectivities, leading to valuable tetrahydroazepines and benzo[b]oxepines. Abstract...
Tue Nov 19, 2019 19:44
Electrochemiluminescence (ECL) with surface sensitivity was demonstrated to reveal cell‐matrix adhesions of single cells cultured on nanoporous electrode surfaces, as well as their dynamic variation and strength. This approach was further used for imaging cell‐matrix adhesions of an advancing cell sheet to study the moving tendency of cells in collective migration. Abstract Cell‐matrix adhesions play essential roles in a variety of biological processes. Herein, we report a label‐free method...
Tue Nov 19, 2019 19:46
Packed in: A high‐performance p‐type organic thermoelectric material based on a selenium‐substituted diketopyrrolopyrrole (DPP) polymer was developed. With strong intermolecular interactions and ordered molecular packing, PDPPSe‐12 exhibits high Hall mobilities of 1.0–2.3 cm2 V−1 s−1 in doped states, yielding a maximum PF and ZT value of 364 μW m−1 K−2 and 0.25, respectively. Abstract Development of high‐performance organic thermoelectric (TE) materials is of vital importance for flexible power...
Tue Nov 19, 2019 19:49
Fluoropolymers come alive: A photo‐mediated reversible‐deactivation radical polymerization has been developed based on a novel chain‐transfer‐agent (CTA) differentiation mechanism, enabling the precise preparation of fluoropolymers with ultra‐high molecular weights, narrow molecular weight distributions, and excellent chain‐end fidelity at complete conversions. Abstract Ultra‐high‐molecular‐weight (UHMW) polymers display outstanding properties and hold potential for wide applications. However,...
Tue Nov 19, 2019 19:50
Color, conduction, magnetism: Two new 2D hybrid perovskites exhibit both thermochromism and ferromagnetism. The (BED)2CuCl6 crystal shows high thermochromic working temperature up to 443 K, with dramatic temperature‐dependent conductivity change spans six orders of magnitude. Abstract Two‐dimensional (2D) hybrid perovskites have shown many attractive properties associated with their soft lattices and multiple quantum well structure. Herein, we report the synthesis and characterization of two...
Tue Nov 19, 2019 19:51
Return to the fold: Aromatic foldamer helical channels were synthesized by a one‐pot polymerization strategy using various amide‐coupling agents. Channels up to 2.7 nm in length were created. The 3 Å wide and electron‐rich cavity of the channels exhibit highly active and exceptionally selective transport of K+ ions, with a K+/Na+ selectivity of as much as 16.3 achieved by channels with an average length of 2.3 nm. Abstract Protein channels are characterized by high transport selectivity, which...
Tue Nov 19, 2019 19:55
Spooky chirality: Long‐range chirality recognition is presented between neighboring 3‐bromo‐naphthalen‐2‐ol (BNOL) stripes on an inert Au(111) surface across the herringbone reconstruction as investigated by STM and DFT calculations. The key to achieving such long‐range chirality recognition is the herringbone reconstruction‐induced local dipole accumulation at the edges of the BNOL stripes. Abstract Chiral molecular self‐assemblies were usually achieved using short‐range intermolecular interactions,...
Tue Nov 19, 2019 19:57
TBI TBD: A targeted activatable NIR‐II nanoprobe (V&A@Ag2S) that specifically lights up the traumatic brain injury (TBI) regions is presented. The nanoprobe response is based on the prodromal biomarker peroxynitrite (ONOO−)‐triggered fluorescence recovery, providing a favorable approach for in vivo early real‐time assessment of TBI. Abstract Traumatic brain injury (TBI) is one of the most dangerous acute diseases resulting in high morbidity and mortality. Current methods remain limited...
Tue Nov 19, 2019 19:58
Chiral couplings made easy: Chiral secondary alkylzinc reagents undergo stereoselective palladium‐catalyzed cross‐coupling reactions with alkenyl and aryl halides. These chiral mixed dialkylzincs are configurationally stable at room temperature for several hours. DFT calculations were performed to rationalize the overall retention in the catalytic cycle. This method was applied in the total synthesis of the sesquiterpenes (S)‐ and (R)‐curcumene. Abstract We report palladium‐catalyzed cross‐coupling...
Tue Nov 19, 2019 19:59
Polyphosphate (PolyP) is one of the most compacted inorganic polyanionic biopolymers that participate in various indispensable physiological processes. However, the mechanism of the interaction between polyP and proteins remain poorly understood. Here, we report that polyP can interact with positively charged green fluorescent protein, +36GFP, to perform liquid‐liquid phase separation (LLPS) within minutes by intermolecular electrostatic interactions in vivo. Upon nutrient downshift induction, genetically...
Tue Nov 19, 2019 20:00
A FeP nanoarray on Ti mesh (FeP NA/TM) performs efficiently to electrocatalyze CO2 reduction to alcohols with a high Faradaic efficiency (FE) up to 80.2 % and a total FE of 94.3 % at −0.20 V vs. RHE. Calculations reveal that the FeP(211) surface significantly promotes the adsorption and reduction of CO2 toward CH3OH by the synergistic effect of two adjacent Fe atoms; the potential‐determining step is the hydrogenation process of *CO. Abstract Electrochemical reduction of CO2 into various chemicals...
Tue Nov 19, 2019 20:00
Controlled partial substitution of Zn and amine incorporation into Znx Cd1−x S‐Amine inorganic–organic hybrids resulted in highly efficient electrocatalysts for synthesizing syngas with tunable CO/H2 ratios (0–19.7). Syngas and dihydroisoquinoline can be simultaneously produced at a low cell voltage. Abstract Efficient electrochemical reduction of CO2 and H2O into industrial syngas with tunable CO/H2 ratios, especially integrated with anodic organic synthesis to replace the low‐value oxygen...
Tue Nov 19, 2019 20:02
Together alone: Single Rh atoms were encapsulated within MFI zeolites under in situ hydrothermal conditions and a ligand‐protected direct H2 reduction. The catalyst gave a high turnover frequency of 699 mol (molRh)−1 min−1 at 298 K for ammonia borane (AB) hydrolysis and exhibited superior catalytic efficiency in shape‐selective tandem hydrogenation of nitroarenes by coupling with the hydrolysis of AB. Abstract Single‐atom catalysts are emerging as a new frontier in heterogeneous catalysis...
Tue Nov 19, 2019 20:04
Fired up: Orange‐red‐fluorescent cinnolino[2,3‐f]phenanthridin‐9‐ium salts were synthesized with high regioselectivity from 2‐azobiaryls and alkenes by palladium(II)‐catalyzed C−H activation under mild reaction conditions (see scheme). The prepared quaternary ammonium salts showed strong fluorescence emission maxima at 575–620 nm with broad bandwidths. Abstract Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C−H bond activation on azobenzenes....
Tue Nov 19, 2019 20:09
An azide in need can be an amine indeed: An electrophlic amination of a wide range of alkyl‐, aryl‐, and heteroarylzinc halides with highly functionalized alkyl, aryl, and heterocyclic azides was developed. The reaction proceeds smoothly with FeCl3 (0.5 equiv) as an activator, providing a broad range of highly functionalized secondary amines in good yields. Abstract A wide range of alkyl‐, aryl‐ and heteroarylzinc halides were aminated with highly functionalized alkyl, aryl, and heterocyclic...
Tue Nov 19, 2019 20:09
My brave phase: A high entropy oxide (HEO) cathode, containing nine additional components, the layered O3‐phase NaNi0.12Cu0.12Mg0.12Fe0.15Co0.15Mn0.1Ti0.1Sn0.1Sb0.04O2, delivers long cycling stabilities and high rate capability. As more than 60 % of the capacity is stored in the O3‐type region, the entropy stabilization of the O3‐phase gives the cycling stability and better rate performance. Abstract Material innovation on high‐performance Na‐ion cathodes and the corresponding understanding...
Tue Nov 19, 2019 20:11
A novel palladium‐catalyzed Heck‐type reaction of thiocarbamates has been designed to construct bridged seven‐membered ring systems that are otherwise challenging to prepare. Taking advantage of this newly developed method, enantioselective syntheses of lyconadins A‐E ( 1‐5 ), lycopecurine ( 6 ) and dehydrolycopecurine ( 7 ) have been realized in a divergent fashion. Our synthetic strategy also features an intramolecular cyclization of a N‐chloroamine to forge the C6‐N bond, a transannular Mannich‐type...
Tue Nov 19, 2019 20:43
Crystals of the first quasi‐binary acetonitriletriide Sr3[C2N]2 were obtained from the solid‐state reaction of Sr metal, graphite, and Sr(N3)2. The identity of the nearly colourless crystals was proven via single‐crystal X‐ray diffraction and Raman spectroscopy. Quantum‐chemical calculations give deeper insights into bonding and charge distribution within the anion. Abstract The first quasi‐binary acetonitriletriide Sr3[C2N]2 has been synthesised and characterised. The nearly colourless crystals...
Tue Nov 19, 2019 20:58
Rechargeable aqueous zinc ion batteries are attractive for high safety, low cost and high energy density. However, the viable cathode materials, e.g., vanadium oxides, suffer from strong Coulombic ion‐lattice interactions with divalent Zn2+, leading to very limited stability when cycled at high charge/discharge depth with high capacity. Here we report a synthetic strategy to make oxygen‐deficient vanadium oxide cathode, in which the facilitated Zn2+ reaction kinetic enhances capacity and Zn2+ pathways...
Tue Nov 19, 2019 21:01
Gold nanoparticles in metallic or plasmonic state have been widely used to catalyze the homogeneous and heterogeneous reactions. However, the catalytic behaviours of gold catalysts in non‐metallic or excitonic state remain elusive. Atomically precise Aun clusters (n = number of gold atoms) bridge the gap between non‐metallic and metallic catalysts and offer new opportunities for unveiling the hidden properties of gold catalysts in the metallic, transition regime, and non‐metallic states, respectively....
Tue Nov 19, 2019 21:09
The highly oxidized and intricately fused hexacyclic structure (ABCDEF‐ring) of talatisamine with 12 contiguous stereocenters presents a formidable challenge for chemical construction. An efficient strategy, in which the entire hexacycle is assembled from a chiral AE‐ring fragment and an aromatic D‐ring, led to the total synthesis of talatisamine in 33 steps from 2‐cyclohexenone. Abstract Talatisamine (1) is a member of the C19‐diterpenoid alkaloid family, and exhibits K+ channel inhibitory...
Tue Nov 19, 2019 22:00
Photoactivation, known as significant photoenhancement phenomenon, has been found in CdSe/ZnS quantum dots (QDs) on exposure to UV/Vis light in the previous literature, can be used to improve photoluminescence (PL) and photostability of QDs. However, it has never been reported the photoactivation in fluorescent carbon quantum dots (CDs). Here, we discover photoactivated fluorescence enhancement in fluorine and nitrogen co‐doped carbon dots (F,N‐doped CDs) for the first time. At 1.0 atm, the fluorescence...
Tue Nov 19, 2019 22:34
Trypanosoma protozoan parasites are the causative agents of Chagas disease and sleeping sickness, two neglected tropical diseases where there is an urgent need for improved treatments and the evaluation of promising drug leads like the actinoallolides. Enabled by the highly stereocontrolled aldol reactions of three chiral ketone building blocks, an efficient first total synthesis of the potent anti‐trypanosomal macrolide (+)‐actinoallolide A has been achieved in 17 steps and 8% overall yield. Our...
Tue Nov 19, 2019 22:37
Thieme, 2018. 880 pp., softcover, € 259.99.—ISBN 9783132012417
Wed Nov 20, 2019 11:33
The Beijing Declaration on basic research was recently signed by Presidents of the Chinese Academy of Sciences (CAS) and the German National Academy of Sciences, Leopoldina. With this undertaking both academies underlined their joint efforts to “promote the scientific spirit”, strive for excellence, encourage collaborative, inclusive and responsible scientific research, and foster a favorable environment for scientific development.
Wed Nov 20, 2019 11:36
Fantastic twelve naphthochromenone photocatalysts (PCs) that absorb across the UV/Vis range and feature an extremely wide redox window (up to 3.22 eV) were synthesized on gram scale. Their excited‐state redox potentials, PC*/PC.− (up to 1.65 V) and PC.+/PC* (up to −1.77 V vs. SCE), are such that these novel PCs can engage in both oxidative and reductive quenching. Abstract Twelve naphthochromenone photocatalysts (PCs) were synthesized on gram scale. They absorb across the UV/Vis range and feature...
Wed Nov 20, 2019 11:38
Traditional crown ether is injected with fresh blood of room‐temperature phosphorescence in crystalline state. Supramolecular interactions introduced by multiple oxygen atoms and K+ were explored as a general method to tune lifetime. This work opens a new world for crown ether and its intrinsic guest responsiveness offers a new avenue for versatile smart luminescent materials. Abstract Supramolecular macrocyclic hosts have long been used in smart materials. However, their triplet emission and...
Wed Nov 20, 2019 11:38
An amine oxide surfactant was synthesized using dehydroabietic acid derived from rosin, which behaves as a highly efficient low‐molecular‐weight hydrogelator by self‐assembly into left‐handed helical fibers in aqueous solution with an extremely low critical gelation concentration (CGC). O/W gel emulsions of various oils (oil volume fraction between 2 % and 95 %) are prepared at surfactant concentrations beyond the CGC. Abstract A surfactant, R‐6‐AO, derived from dehydroabietic acid has been...
Wed Nov 20, 2019 11:39
Single Pt atoms assembled on a defective TiO2 support (Pt1/def‐TiO2) as a highly efficient photocatalyst serve as proton reduction sites and promote the neighboring TiO2 units to generate surface oxygen vacancies, leading to the formation of an atomic interface between the isolated Pt atom and Ti3+ defects. This unique structure endows Pt1/def‐TiO2 with excellent photocatalytic hydrogen production performance. Abstract It is highly desirable but challenging to optimize the structure of photocatalysts...
Wed Nov 20, 2019 11:39
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου