Asymmetric reactions merging organocatalysis and metal catalysis significantly broaden the scope of organic synthesis. Nevertheless, the accomplishment of stereoselective annulations combining two ...types of dipole species, independently generated from the activations of organocatalysts and metal complexes, still remains as a challenging task. Now, Morita–Baylis–Hillman carbonates from isatins and carbamate‐functionalized allyl carbonates could be chemoselectively activated by achiral Lewis basic tertiary amines and chiral iridium complexes. The zwitterionic allylic ylides and 1,4‐π‐allyliridium dipoles formed in situ are assembled in a highly stereoselective 4+3 annulation pattern. Similar cooperative catalytic strategy could be applied for the reactions of Morita–Baylis–Hillman carbonates and vinyl aziridines, furnishing an asymmetric 3+3 annulation reaction also with excellent stereocontrol.
Morita–Baylis–Hillman carbonates from isatins and carbamate‐functionalized allylic carbonates were activated by a Lewis basic tertiary amine and chiral iridium complex. The resulting zwitterionic allylic ylides and π‐allyliridium complex‐contained 1,4‐dipoles underwent regio‐ and stereoselective 4+3 annulations. Similar π‐allyliridium complex‐containing 1,3‐dipoles from vinyl aziridines were utilized in asymmetric 3+3 annulations.
Spatiotemporal organization of distinct biological processes in cytomimetic compartments is a crucial step towards engineering functional artificial cells. Mimicking controlled bi‐directional ...molecular communication inside artificial cells remains a considerable challenge. Here we present photoswitchable molecular transport between programmable membraneless organelle‐like DNA coacervates in a synthetic microcompartment. We use droplet microfluidics to fabricate membraneless non‐fusing DNA coacervates by liquid‐liquid phase separation in a water‐in‐oil droplet, and employ the interior DNA coacervates as artificial organelles to imitate intracellular communication via photo‐regulated uni‐ and bi‐directional transfer of biomolecules. Our results highlight a promising new route to assembly of multicompartment artificial cells with functional networks.
Photoswitchable bi‐directional trafficking of biomolecules between programmable DNA‐based artificial membraneless organelles in a cell‐like microcompartment has been achieved to imitate intracellular communication towards construction of advanced functional artificial cells.
Sub-micrometer particles (0.10-1.0 μm) are of great significance to study, e.g., microvesicles and protein aggregates are targets for therapeutic intervention, and sub-micrometer fluorescent ...polystyrene (PS) particles are used as probes for diagnostic imaging. Focusing of sub-micrometer particles - precisely control over the position of sub-micrometer particles in a tightly focused stream - has a wide range of applications in the field of biology, chemistry and environment, by acting as a prerequisite step for downstream detection, manipulation and quantification. Microfluidic devices have been attracting great attention as desirable tools for sub-micrometer particle focusing, due to their small size, low reagent consumption, fast analysis and low cost. Recent advancements in fundamental knowledge and fabrication technologies have enabled microfluidic focusing of particles at sub-micrometer scale in a continuous, label-free and high-throughput manner. Microfluidic methods for the focusing of sub-micrometer particles can be classified into two main groups depending on whether an external field is applied: 1) passive methods, which utilize intrinsic fluidic properties without the need of external actuation, such as inertial, deterministic lateral displacement (DLD), viscoelastic and hydrophoretic focusing; and 2) active methods, where external fields are used, such as dielectrophoretic, thermophoretic, acoustophoretic and optical focusing. This article mainly reviews the studies on the focusing of sub-micrometer particles in microfluidic devices over the past 10 years. It aims to bridge the gap between the focusing of micrometer and nanometer scale (1.0-100 nm) particles and to improve the understanding of development progress, current advances and future prospects in microfluidic focusing techniques.
Identifying novel drug-target interactions (DTIs) plays an important role in drug discovery. Most of the computational methods developed for predicting DTIs use binary classification, whose goal is ...to determine whether or not a drug-target (DT) pair interacts. However, it is more meaningful but also more challenging to predict the binding affinity that describes the strength of the interaction between a DT pair. If the binding affinity is not sufficiently large, such drug may not be useful. Therefore, the methods for predicting DT binding affinities are very valuable. The increase in novel public affinity data available in the DT-related databases enables advanced deep learning techniques to be used to predict binding affinities. In this paper, we propose a similarity-based model that applies 2-dimensional (2D) convolutional neural network (CNN) to the outer products between column vectors of two similarity matrices for the drugs and targets to predict DT binding affinities. To our best knowledge, this is the first application of 2D CNN in similarity-based DT binding affinity prediction. The validation results on multiple public datasets show that the proposed model is an effective approach for DT binding affinity prediction and can be quite helpful in drug development process.
•Lipophilicity measurement by reversed-phase high-performance liquid chromatography.•We evaluate the theoretical basis of lipophilicity.•We pay special attention to lipophilicity determination of ...dissociable compounds.•We introduce novel mobile and stationary phases for lipophilicity measurement.
Lipophilicity, quantified by the logarithm of the n-octanol/water partition coefficient (logP) or the distribution coefficient (logD), is a crucial parameter for modelling biological partition or distribution. As a maintream experimental method for lipophilicity measurement, reversed-phase high performance liquid chromatography (RP-HPLC) has attracted great interest and the attention of researchers throughout the world for its advantages including speed, reproducibility, insensitivity to impurities and degradation products, broad dynamic range, on-line detection, and reduced handling and sizes of samples. This review focuses on recent developments in lipophilicity measurement by RP-HPLC, both theoretical and experimental (mainly mobile and stationary phases).
Organic electrical gas sensors have been developed for many decades because of their high sensitivity and selectivity. However, their industrialization is severely hindered by their intrinsic ...humidity susceptibility and poor recovery. Conventional organic sensory materials can only operate at room temperature owing to their weak intermolecular interactions. Herein, we demonstrate using a croconate polymer (poly‐4,4′‐biphenylcroconate) that the “ion‐in‐conjugation” concept enables organic gas sensors to operate at 100 °C and 70 % relative humidity with almost complete recovery. The fabricated sensor had a parts‐per‐billion (ppb) detection limit for NO2 and showed the highest sensitivity (2526 ppm−1 at 40 ppb) of all reported NO2 chemiresistive sensors. Furthermore, charge transfer increased with temperature. Theoretical calculations and in situ FTIR spectra confirmed the ion‐in‐conjugation‐inspired hydrogen bond as key for excellent sensitivity. A NO2 alarm system was assembled to demonstrate the feasibility of this sensor.
A robust NO2 sensor device based on an ion‐in‐conjugation structure maintained its performance at high temperature, which counteracted the effects of humidity (see picture; NO2 blue/red, H2O green/yellow). Charge transfer between NO2 and the chemiresistor was more efficient at 100 °C than at room temperature. The fabricated sensor had a parts‐per‐billion (ppb) NO2 detection limit and showed the highest sensitivity of all reported NO2 chemiresistive sensors.
Here we report that the chemoselective activation of Tsuji's 2‐(cyanomethyl)allyl carbonates to generate the palladium–trimethylenemethane 1,3‐dipoles via a deprotonation strategy can be realized in ...the presence of Morita–Baylis–Hillman carbonates from substantial activated ketones. The following SN2′‐addition enables the formation of new 1,3‐dipole species having an activated alkene moiety through a second deprotonation process, which then undergo cascade 1+2/3+2 annulations to furnish complex bicyclic 3.1.0hexane frameworks having three contiguous quaternary stereogenic centers with good to excellent enantioselectivity. Moreover, by using benzoyl aldehyde‐derived substrates, a 1+4/3+2 annulation sequence is similarly developed to produce fused cyclopentabfuran architectures.
The palladium–trimethylenemethane 1,3‐dipoles can be chemoseletively generated from 2‐(cyanomethyl)allyl carbonates via a deprotonation strategy, which allows the SN2′‐addition to Morita–Baylis–Hillman carbonates from activated ketones. Cascade 1+2/3+2 annulations are followed to construct enantioenriched bicyclo3.1.0hexane frameworks with three contiguous quaternary stereogenic centers.
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•The incorporation of tungsten can reduce theoretical overpotential of NiFe LDH.•NiFeW LDH with a metal molar ratio of 4:1:1 exhibits the best intrinsic OER activity.•NiFeW-4:1:1 LDH ...deliver a low overpotential of 248 mV at 20 mA cm−2 toward OER.•NiFeW LDH present the excellent stability under harsh alkaline OER conditions.
The electrocatalytic oxygen evolution reaction (OER) requires stable, highly active, and robust earth-abundant electrocatalysts. In the present study, we combine theoretical simulations with experimental approaches to design and synthesize NiFeW layered double hydroxide (LDH) for efficient OER in alkaline electrolytes. Density functional theory with the Hubbard U (DFT + U) calculations suggests that W, a high-valence metal, can improve the catalytic activity of Fe sites and optimize adsorption energies for OER intermediates at the surface of NiFeW LDH. Electrochemical measurements of the as-synthesized NiFeW LDH with a constant mass loading reveals that the LDH with the NiFeW molar ratio of 4:1:1 presented the highest intrinsic OER activity among all bi- and trimetallic LDH catalysts in this study. Furthermore, the nanostructures with the optimal active metal molar ratio are in situ grown on hydrophilic-treated carbon paper to fabricate an integrated 3D electrode with an overpotential of 248 mV at the catalytic current density of 20 mA cm−2 and a low Tafel slope of 68 mV dec−1 in 1.0 M KOH solution. This indicates that NiFeW LDH is among the most active NiFe-based OER electrocatalysts reported to date. X-ray photoelectron spectroscopy and elemental analysis confirm that the optimized Ni Fe W LDH presents a stable chemical composition and Ni, Fe, and W are still present in the catalyst after alkaline OER measurements. These findings offer new insights and avenues for the future design and study of stable and active multi-metal-based OER electrocatalysts.
Chromium occurs mostly in tri- and hexavalent states in the environment. Hexavalent chromium Cr(VI) compounds are extensively used in diverse industries, and trivalent chromium Cr(III) salts are used ...as micronutrients and dietary supplements. In the present work, we report that they both induce genetic mutations in yeast cells. They both also cause DNA damage in both yeast and Jurkat cells and the effect of Cr(III) is greater than that of Cr(VI). We further show that Cr(III) and Cr(VI) cause DNA damage through different mechanisms. Cr(VI) intercalates DNA and Cr(III) interferes base pair stacking. Based on our results, we conclude that Cr(III) can directly cause genotoxicity in vivo.
Biofuels separation using membranes becomes one of the research focuses in the field of renewable energy. In this study, a series of mixed matrix membranes (MMMs) with defect-free active layer around ...1 µm thickness were elaborately prepared through interfacial synthesis for ethanol permselective pervaporation. Polydimethylsiloxane (PDMS) was employed as polymer matrix, which adjusted the nucleation of MOF precursors to in situ generate ZIF-8 nanoparticles. Within the active layer, the resultant ZIF-8 nanoparticles provided the preferential pathways for ethanol due to their ultrahigh adsorption capacity and super-hydrophobicity. Moderate aggregation could form the relatively continuous diffusion pathways. This approach rendered the uniform dispersion of ZIF-8 nanoparticles within PDMS matrix and their excellent compatibility. The ZIF-8 nanoparticles endowed the membranes with enhanced ethanol affinity, hydrophobic property, and thermal stability. More importantly, the ZIF-8 nanoparticles substantially reduced the permeation energy barriers of the membrane for penetrants. The membranes displayed the simultaneous increase in permeation flux and separation factor when utilized for ethanol recovery from aqueous solution, revealing the desirable anti-tradeoff effect. Particularly, the resultant membrane exhibited a superior pervaporation performance with relatively high permeation flux (1778 g·m-2·h-1) and comparable separation factor (12.1) in separating 5.0 wt% ethanol aqueous solution at 40 °C.
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•Mixed matrix active layer around 1 µm thickness prepared via interfacial synthesis.•Uniformly dispersed ZIF-8 nanoparticles were in situ formed within PDMS matrix.•ZIF-8 nanoparticles created the preferential paths for ethanol rather than for water.•Introducing ZIF-8 nanoparticles addressed facilely trade-off effect in PV membrane.•ZIF-8 nanoparticles notably reduced the permeation energy barriers for penetrants.
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