Modular construction of an autonomous and programmable multi‐function heterogeneous biochemical circuit that can identify, transform, translate and amplify biological signals into physicochemical signals based on logic design principle can be a powerful capability for the development of diverse biotechnologies. To explore this conceptual validity, we design a CRISPR array mediated primer exchange reaction based biochemical circuit cascades, which probe a specific biomolecular input, transform the...
Mon Aug 24, 2020 21:38
A structure–activity relationship study was performed for a set of rigidified platinum–acridine anticancer agents containing linkers derived from chiral pyrrolidine and piperidine scaffolds. Screening of a small modular library of microscale reactions and selected resynthesized compounds in non‐small‐cell lung cancer (NSCLC) cells showed that cytotoxicities varied by more than three orders of magnitude. A potent hit compound was discovered containing a (R)‐N‐(piperidin‐3‐yl) linker ( P2‐6R ),...
Mon Aug 24, 2020 20:03
Organic co‐crystal engineering has emerged as a promising method to make multifunctional materials. Here, we report that the marriage of macrocyclic chemistry and co‐crystal engineering provides a smart strategy to build vapochromic materials. The macrocycle co‐crystals (MCCs) have been constructed by π‐electron rich pillar[5]arene (P5) and an electron‐deficient pyromellitic diimide derivative (PDI) on a ten‐gram scale. MCCs of P5‐PDI are in red color due to the formation of charge‐transfer (CT)...
Mon Aug 24, 2020 19:45
Chemical looping provides an energy and cost effective route for alkane utilization. However, there is considerable CO 2 co‐production caused by kinetically mismatched O 2‐ bulk diffusion in current chemical looping oxidative dehydrogenation systems, rendering a decreased olefin productivity. This paper describes the successful construction of sub‐monolayer or monolayer vanadia nanostructures to suppress CO 2 production in oxidative dehydrogenation of propane by evading the interference of...
Mon Aug 24, 2020 18:41
Nature adopts complex chemical networks to finely tune biochemical processes. Indeed, small biomolecules play a key role in regulating the flux of metabolic pathways. Chemistry, which was traditionally focused on reactions in simple mixtures, is dedicating an increasing attention to the network reactivity of highly complex synthetic systems, able to display new kinetic phenomena. Here we show that the addition of monophosphate nucleosides to a mixture of amphiphiles and reagents leads to the selective...
Mon Aug 24, 2020 18:20
Kopsinitarines A‐E are complex octacyclic caged kopsia alkaloids, whose strained cage skeleton and the unique cyclic hemiaminal bridge make them challenging for the total synthesis. Herein, we disclose the first total synthesis of kopsinitarine E. The key synthetic features include a SmI 2 ‐mediated radical cascade cyclization and a subsequent semi‐pinacol rearrangement to install its key carbocyclic skeleton, a chemoselective hydrosilyl amide reduction to build up its hemiaminal ether bridge,...
Mon Aug 24, 2020 18:19
Lead halide perovskite quantum dots (QDs) are promising materials for the next generation optoelectronic devices. Importantly, the bonding nature of QD capping ligands plays a crucial role in the resultant device performance. To fine‐tuning the surface ligand towards high‐performance devices, we first developed an in‐situ passivation process for all‐inorganic cesium lead iodide (CsPbI 3 ) perovskite QDs by using a bi‐ functional ligand, namely L‐phenylalanine (L‐PHE). Through the addition of...
Mon Aug 24, 2020 17:23
<p class="Abstract" style="margin: 0in 0in 30pt; text‐align: justify; line‐height: 11.25pt; font‐size: 8pt; font‐family: Arial, sans‐serif; caret‐color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><span lang="EN‐GB">Reactive sulfur species, such as hydrogen sulfide, persulfides, and polysulfides, have recently emerged as key signaling molecules and important physiological mediators within mammalian systems. To better assess the therapeutic potential of their exogenous administration, we report...
Mon Aug 24, 2020 17:22
We have developed a highly regio‐ and diastereoselective rhodium‐catalyzed allylic substitution of challenging alkyl‐substituted branched allylic carbonates with benzylzinc reagents, which are prepared from widely available benzyl halides. This process utilizes rhodium(III) chloride as a commercially available, high‐oxidation state and bench‐stable pre‐catalyst to provide a rare example of regio‐ and diastereoselective allylic substitution in the absence of an exogenous ligand. This reaction...
Mon Aug 24, 2020 17:22
The potency of spiro‐conjugation has been proposed to dictate the efficiency of charge transfer, which could directly affect spin‐orbit charge transfer intersystem crossing (SOCT‐ISC) process, as predicted by the El‐Sayed rule. However, this process has yet to be exemplified. Herein, we judiciously prepared three novel spirobis[anthracene]diones, in which two benzophenone moieties are locked in close proximity and differentially functionalized to fine‐tune the charge transfer state. Its feasibility...
Mon Aug 24, 2020 17:10
Operando nuclear resonant inelastic X‐ray scattering (NRIXS) and X‐ray absorption fine‐structure spectroscopy (XAFS) measurements have been used to gain insight into the structure and surface composition of FeCu and FeAg nanoparticles (NPs) during the CO 2 electrochemical reduction (CO 2 RR) and to extract correlations with their catalytic activity and selectivity. The formation of a core‐shell structure during CO 2 RR for FeAg NPs was inferred from the analysis of the operando NRIXS data...
Mon Aug 24, 2020 16:14
Nowadays, fossil‐based platform molecules such as ethylene and ethylene oxide serve as primary feedstock for the C 2 ‐based chemical industry. However, in search for a more sustainable chemical industry, fossil‐based resources may preferentially be replaced by renewable alternatives, provided realistic economic feasibility. This review compares and critically discusses several production routes toward bio‐based structural analogs of ethylene oxide and the required adaptations for their implementation...
Mon Aug 24, 2020 16:00
Since carbon–carbon (C–C) covalent bonds are rigid and robust, the bond length is, in general, nearly constant and depends only on the bond order and hybrid orbitals. We report here direct visualization of the reversible expansion and contraction of a Csp3–Csp3 single bond by light and heat. This flexibility of a C–C bond was demonstrated by X‐ray analyses and Raman spectroscopy of hexaphenylethane (HPE)‐type hydrocarbons with two spiro‐dibenzocycloheptatriene units, where intramolecular [2+2] photocyclization...
Mon Aug 24, 2020 13:26
Supramolecular wires are created in a confined nanoscale junction by using metalloporphyrin coordination chemistry in a similar fashion to that found in bacteria nanowires. Slight chemical changes in the axial ligands and in the porphyrin ring determine the exact final supramolecular scaffold, which defines the electron pathway along the supramolecular wire. Abstract Nature has developed supramolecular constructs to deliver outstanding charge‐transport capabilities using metalloporphyrin‐based...
Mon Aug 24, 2020 13:15
An unprecedented [4+1] spiroannulation of halophenols with α,β‐unsaturated imines has been developed for the rapid assembly of highly valuable azaspirocycles. This intermolecular domino reaction was realized through a sequence of electrophile‐triggered dearomatization of phenol derivatives at their halogenated sites and followed by halogen‐displacement with N‐nucleophiles via a radical‐based SRN1 mechanism. Abstract A novel [4+1] spiroannulation of o‐ & p‐bromophenols with α,β‐unsaturated...
Mon Aug 24, 2020 13:14
Two lanthanide EuII complexes, Eu‐1 and Eu‐2, are presented. The blue‐emitting Eu‐1 showed excellent air stability while the orange‐emitting Eu‐2 showed promising performance in organic light emitting diodes (OLEDs). This work deepens the understanding of structure–property relationship in molecular EuII complexes and could inspire further research on their application in OLEDs. Abstract Luminescent EuII complexes with a characteristic 5d–4f transition have potential applications in many...
Mon Aug 24, 2020 13:13
A nickel‐catalyzed dicarbofunctionalization of endocyclic enecarbamates and enamides has been developed. This reaction provides straightforward and efficient access to an array of pyrrolidine‐ and azetidine‐containing fluorinated amino acids and oligopeptides, which may have applications in the life sciences. Specifically, this protocol delivers functionalized azetidines that are of great interest in pharmacological studies. Abstract Efficient methods for the dicarbofuntionalization of...
Mon Aug 24, 2020 13:13
AI‐aided models were trained to assist the development of nonprecious metal electrocatalysts designed for proton‐exchange membrane fuel cells. Among the tested algorithms, XGBoost analyzed the 26 features involved and found that operating conditions are more important than chemical properties. ANN showed a strong ability to predict the maximum power density (R2=0.9621) and superior reproducibility (R2>0.99) on entire polarization curves. Abstract Traditionally, a larger number of experiments...
Mon Aug 24, 2020 13:11
A deep‐red TADF diode was constructed with a T‐shape donor—acceptor–donor dye. It features effective carrier transport balance, a radiative rate constant reaching 107 s−1, and a photoluminescence quantum yield of 87 %, leading to state‐of‐the‐art external quantum efficiencies of 12.3 % for maximum and 10.4 % at 1000 nits through an ultrasimple, non‐doped bilayer device structure. Abstract Device simplification is of practical significance for organic light emitting diodes (OLEDs), and remains...
Mon Aug 24, 2020 13:09
Starting from readily accessible homochiral polyepoxy alcohols with a methyl group at all endo‐cyclization sites, polyethers of up to five consecutive fused 6‐, 7‐, and/or 8‐membered rings were constructed in one step. Notably, marine ladder polyethers hemibrevetoxin B and brevenal with 7/7/6/6 and 7/7/6/7/6 polyether frameworks, respectively, could be synthesized with the corresponding 40 % and 17 % chemical yields. Abstract The rapid synthesis of marine ladder polyethers from polyepoxide...
Mon Aug 24, 2020 13:06
The choice of electrode material is critical for achieving optimal yields and selectivity in synthetic organic electrochemistry. The material imparts significant influence on the kinetics and thermodynamics of electron transfer. However, electrode processes are complex and so their optimisation is often empirical. Highlighted herein are recent instances of electrode choice where rationale is offered. Abstract The choice of electrode material is critical for achieving optimal yields and...
Mon Aug 24, 2020 13:06
Rapid remodeling of skeletal frameworks can be achieved by transition‐metal‐mediated cleavage of C−C single bonds and enable new retrosynthetic disconnections. In this Review, ten total syntheses from 2014–2019 are highlighted that illustrate how transition‐metal‐mediated cleavage of C−C single bonds can streamline synthetic efforts. Abstract Transition‐metal‐mediated cleavage of C−C single bonds can enable entirely new retrosynthetic disconnections in the total synthesis of natural products....
Mon Aug 24, 2020 13:05
Ab initio molecular dynamics shows that alkene cracking mechanisms and kinetics, as catalyzed by protonic zeolites, differ strongly as a function of the reactant and product structures. This is due to the dynamic nature of the transition structures, which either correspond to β‐scissions or to proton transfers to the zeolite. Secondary carbenium ions are not stable reaction intermediates, whereas tertiary cations and π‐complexes are. Abstract Zeolite‐catalyzed alkene cracking is key to...
Mon Aug 24, 2020 13:05
A butadienyl bridge and two antiferromagnetically coupled high‐spin FeII ions unite to form a nonplanar metalla‐aromatic molecule. A σ‐type overlap between the two Fe 3d xz orbitals and the π orbital of the butadienyl ligand makes the six‐electron‐conjugated system aromatic. Abstract A new class of nonplanar metalla‐aromatics, diiron complexes bridged by a 1,3‐butadienyl dianionic ligand, were synthesized in high yields from dilithio reagents and two equivalents of FeBr2. The complexes...
Mon Aug 24, 2020 13:04
A cyanide‐bridged coordination polymer (FePd(CN)4) consists of responsive four‐coordinate FeII centers. The FeII nodes flexibly change the distorted coordination geometry of the polymer, inducing an unusually large anisotropic thermal expansion of the PtS‐type framework. Abstract Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal–organic frameworks with desirable properties; however, FeII ions are exclusively six‐coordinated. Herein, we...
Mon Aug 24, 2020 13:04
Controlled radical polymerization of ethylene was conducted through ITP. Copolymerization with vinyl acetate provides a range of well‐defined structures, including poly(ethylene‐co‐vinyl acetate) containing VAc from 0 to 85 mol %. Abstract Controlled radical polymerization of ethylene using different commercially available, cheap, and non‐toxic iodo alkyls is performed by iodine transfer polymerization (ITP) under mild conditions (≤100 °C and ≤200 bar). The formed well‐defined iodo end‐capped...
Mon Aug 24, 2020 13:04
A versatile strategy for modifying carbon‐based microelectrodes to achieve programmed selectivity was demonstrated. The strategy is facile, efficient, and most importantly, combines the merits of microelectrodes and aptamers, allowing the generation of a highly selective bioelectronic system for probing neurochemical dynamics in living systems. Abstract The selective sensing of neurochemicals is essential for understanding the chemical basis of brain function and pathology. Interfacing...
Mon Aug 24, 2020 13:03
Three new KBBF‐like compounds CsZn2BO3X2 (X2=F2, Cl2, and FCl) with improved SHG responses (2.8–3.5×KDP) and short UV cut‐off edges (<190 nm) have been successfully synthesized. Interestingly, CsZn2BO3FCl is the first compound in the KBBF family that contains two types of different halogen anions. The study of structure–property relationships indicates that mixing halogen anions is a feasible strategy for enhancing SHG responses for the KBBF family. Abstract Designing deep‐ultraviolet...
Mon Aug 24, 2020 13:03
A cartoonish Greek god Janus looks into the past at Erich Clar's aromatic sextet theory, which provided only a qualitative visual inspection of a single aspect of electronic structure—aromaticity. A more detailed face of Janus looks forward to a future in which the aromatic properties of molecules can be visually inspected for quantitative information using isotropic magnetic shielding contour plots. Abstract For many years, Clar's aromatic sextet theory has served as a qualitative method...
Mon Aug 24, 2020 13:02
An evanescent wave (EW) can guide the assembly of small molecules into long‐range ordered nanowire (NW) array on the interface, which is a general approach demonstrated by different small molecule precursors. While existing studies on EW often took advantages of its near‐field property for optical measurement, this work demonstrates the photochemical power of EW in the guided‐assembly of small molecules for the first time. Abstract The ordered assembly of molecules within a specific space...
Mon Aug 24, 2020 13:02
Artificially designed lasso proteins were modularly synthesized in cellulo based on assembly–reaction synergy. This enables the synthesis of protein (pseudo)rotaxanes, protein heterocatenanes, and protein‐based “slide‐ring” hydrogels via topological transformation. Abstract Entangled proteins have attracted significant research interest. Herein, we report the first rationally designed lasso proteins, or protein [1]rotaxanes, by using a p53dim‐entwined dimer for intramolecular entanglement...
Mon Aug 24, 2020 13:02
A simple aromatic dipeptide, cyclo‐ditryptophan, is reported to crystallize into supramolecular semiconductors with thermal sustainably up to 680 K. Non‐covalent interactions underlie the driving forces of the thermal sustainability, generating a high thermal‐quenching‐activity energy of up to 0.11 eV, thus resulting in a 93 % reduction of the conductive resistance from 320 K to 440 K. Abstract Bottom‐up self‐assembled bioinspired materials have attracted increasing interest in a variety...
Mon Aug 24, 2020 13:02
Cobalt nanoparticles‐catalyzed aerobic oxidative cleavage of adjacent −(C−C) n − bonds in succession in a wide range of alcohols as well as inactive long‐chain alkyl aryl alcohols to afford esters was developed. Control experiments disclose that metallic cobalt nanoparticles are responsible for the outstanding catalytic performance rather than single atom cobalt. Abstract Selective cleavage and functionalization of C−C bonds have important applications in organic synthesis and biomass...
Mon Aug 24, 2020 13:01
The rechargeable aluminum sulfur (Al‐S) battery is regarded as a potential alternative beyond‐lithium‐ion‐battery system owing to its safety, promising energy density, and the high earth abundance of the constituent electrode materials, however, sluggish kinetic response and short life‐span are the major issues that limit the battery’s development towards applications. In this article, we report Co(II, III) as an electrochemical catalyst in the sulfur cathode that renders a reduced discharge‐charge...
Mon Aug 24, 2020 11:13
We demonstrate an intermolecular reaction cascade to control the force which triggers crosslinking of a mechanochromic polymer of spirothiopyran (STP). Mechanochromism arises from rapid reversible force‐sensitive isomerization of STP to a merocyanine, which reacts rapidly with activated C=C bonds. The concentration of such bonds, and hence the crosslinking rate, is controlled by force‐dependent dissociation of a Diels‐Alder adduct of anthracene and maleimide. Because the adduct requires ~1 nN higher...
Sat Aug 22, 2020 22:00
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου