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β-Fluoromethyl (CH2F, CHF2, and CF3)-substituted chiral ketones are essential moieties and are vital building blocks in pharmaceutical and agrochemistry. However, general and convenient methods for enantio-diverse access to diverse β-fluoromethylated ketones are lacking, hindering the further development of these functional moieties. In this study, we developed an ene-reductase-based photobiocatalytic platform for efficient synthesis of enantio-divergent β-fluoromethylated chiral ketones. Our method highlights substrate-type diversity, excellent enantioselectivity, enzymatic enantio-divergent synthesis, as well as a dicyanopyrazine (DPZ)-type photosensitizer for biocompatible olefin E/Zisomerization in enzymatic stereoconvergent olefin asymmetric reduction, thereby providing a general photobiocatalytic solution to diverse β-fluoromethylated chiral ketones.

While photochemical deracemization significantly enhances atom economy by eliminating the necessity for additional oxidants or reductants, the laborious presynthesis of substrates from feedstock chemicals is often required, thereby compromising the practicality of this method. In this study, we propose a novel approach known as de novo deracemization synthesis, which involves direct utilization of simple substrates undergoing both photochemical transformation and reversible photochemical transformation. The efficient enantiocontrol of chiral catalysts in the latter process establishes an effective platform for deracemization. This alternative and practical approach to address the challenges of asymmetric photocatalysis has been successfully demonstrated in the photosensitized de novo deracemization synthesis of azaarene-functionalized cyclobutanes featuring three stereocenters, including an all-carbon quaternary center. By exclusively employing a suitable chiral catalyst to enable kinetically controlled [2 + 2] photocycloreversion, we pave a creative path toward achieving more cost-effective photochemical deracemization.

Visible-light-driven photoredox catalysis is known to be a powerful tool for organic synthesis. Its occurrence critically depends on the twice exothermic single-electron transfer processes of photosensitizers, which are governed by the redox properties of the species involved. Hence, the inherently narrow range of redox potentials of photosensitizers inevitably constrains their further availability. Sensitization-initiated electron transfer has recently been found to effectively overcome this substantial challenge. However, feasible and practical strategies for designing such complicated catalytic systems are rather scarce. Herein we report an elaborate dual-catalyst platform, with dicyanopyrazine as a visible light photosensitizer and a pyrenyl-incorporated chiral phosphoric acid as a co-sensitizer, and we demonstrate the applicability of this sensitization-initiated electron transfer strategy in an asymmetric formal de Mayo-type reaction. The catalysis platform enables otherwise thermodynamically unfavourable electron transfer processes to close the redox cycle and allows for precise access to valuable enantioenriched 1,5-diketones with a wide substrate range.

In the present work, the surface of glassy carbon electrode (GCE) was modified with graphitic carbon nitride (g-C3N4) prepared from the freeze-dried dicyandiamide. The physiochemical properties and electrocatalytic ability of the g-C3N4nanosheets have been well investigated. Differential pulse voltammetry (DPV) method was employed to determine bisphenol A (BPA) using the modified GCE. To obtain the conditions for maximum DPV response, the effects of experimental parameters, such as the solution pH and nano-sized modifier concentration, were investigated and optimized. The proposed BPA sensing assay indicated a linear range of 0.01 to 75.0 µM under optimal conditions, with a detection limit of 9.0 nM. The anti-interference investigations revealed that the presence of various organic and inorganic species did not hinder the accurate measuring of BPA. In addition, the presented modified electrode exhibited satisfactory results in terms of stability and reproducibility. The obtained results also confirm the efficacy of the g-C3N4nanocatalyst for determination of BPA in different real samples (drinking water, milk and orange juice) with satisfactory recovery values (95.6–104.0%). The suggested assay provides a powerful sensing platform for the fast and sensitive analysis of BPA in food samples.

Direct enantioselective reduction of the C=C bond of β-polyfluoro-alkylated enones is an important but long-pending subject in asymmetric catalysis. Here, we report on the viability of visible light-driven cooperative photoredox and chiral hydrogen-bonding catalysis to effectively address this challenge, as a variety of products are obtained in high yields (up to 85%) with good to excellent enantioselectivities (up to 98% ee). The formation of thermodynamically favorable enol intermediates after double single-electron reduction represents the center of the success. Additionally, the utility of the current method is validated by the convenient regio-specific and -diverse synthesis of various deuterated derivatives for these products using inexpensive D2O as the deuterium source.

Chemodivergent synthesis has been achieved in asymmetric photocatalysis. Under a dual catalyst system consisting of a chiral phosphoric acid and DPZ as a photosensitizer, different inorganic bases enabled the formation of two sets of valuable products from the three-component radical tandem transformations of 2-bromo-1-arylenthan-1-ones, styrenes, and quinoxalin-2(1H)-ones. The key to success was the distinct pKaenvironment, in which the radicals that formed on the quinoxalin-2(1H)-one rings after two radical addition processes underwent either single-electron oxidation or single-electron reduction. In addition, this work represents the first use of quinoxalin-2(1H)-ones in asymmetric photoredox catalysis.

Asymmetric olefin isomerization can be appreciated as an ideal synthetic approach to access valuable enantioenriched C═C-containing molecules due to the excellent atom economy. Nonetheless, its occurrence usually requires a thermodynamic advantage, namely, a higher stability of the product to the substrate. It has thus led to rather limited examples of success. Herein, we report a photoredox catalytic hydrogen atom transfer (HAT) and enantioselective protonation strategy for the challenging asymmetric olefin isomerization. As a paradigm, by establishing a dual catalyst system involving a visible light photosensitizer DPZ and a chiral phosphoric acid, with the assistance of N-hydroxyimide to perform HAT, a wide array of allylic azaarene derivatives, featuring α-tertiary carbon stereocenters and β-C═C bonds, was synthesized with high yields, ees, and E/Zratios starting from the conjugated α-substituted alkenylazaarene E/Z-mixtures. The good compatibility of assembling deuterium on stereocenters by using inexpensive D2O as a deuterium source further underscores the broad applicability and promising utility of this strategy. Moreover, mechanistic studies have provided clear insights into its challenges in terms of reactivity and enantioselectivity. The exploration will robustly inspire the development of thermodynamically unfavorable asymmetric olefin isomerizations.

An intramolecular amination of allylic alcohols is developed as an efficient and general access to biologically important multisubstituted indolizines and their variants. Two metal-free synthetic platforms including using aqueous hydrochloric acid solution as the solvent and p-toluenesulfonic acid as the catalyst have been established, enabling the divergent synthesis of these valuable compounds in high yields.

An enantioselective intermolecular [3 + 2] cycloaddition of N-arylcyclopropylamines with 2-aryl acrylates/ketones and cyclic ketone-derived terminal olefins via asymmetric photoredox catalysis is reported. A dual catalyst system involving DPZ and a chiral phosphoric acid is effective for the transformations, leading to a wide array of valuable cyclopentylamines with high yields, ee’s, and drs. Among them, elaborate modulation of the ester group of 2-aryl acrylates was shown to be effective in improving reactivity, thereby enabling the success of the transformations.

Alternations in the brain nitric oxide (NO) homeostasis are associated with a variety of neurodegeneration diseases; therefore, high-resolution imaging of NO in the brain is essential for understanding pathophysiological processes. However, currently available NO probes are unsuitable for this purpose due to their poor ability to cross the blood–brain barrier (BBB) or to image in deep tissues with spatial resolution. Herein, we developed a photoacoustic (PA) probe with BBB crossing ability to overcome this obstacle. The probe shows a highly selective ratiometric response toward NO, which enables the probe to image NO with micron resolution in the whole brain of living mice. Using three-dimensional PA imaging, we demonstrated that the probe could be used to visualize the detailed NO distribution in varying depth cross-sections (0–8 mm) of the living Parkinson’s disease (PD) mouse brain. We also investigated the therapeutic properties of natural polyphenols in the PD mouse brain using the probe as an imaging agent and suggested the potential of the probe for screening therapeutic agents. This study provides a promising imaging agent for imaging of NO in the mouse brain with high resolution. We anticipate that these findings may open up new possibilities for understanding the biological functions of NO in the brain and the development of new imaging agents for the diagnosis and treatment of brain diseases.

Herein, we report a class of 1,4-bisvinylbenzene-bridged BODIPY dimers with fluorescence emission in the second near-infrared window (NIR-II, 1000–1700 nm). These dyes show excellent NIR-II fluorescence properties and can be easily functionalized to achieve good water-solubility or tumor-targeting ability. In vivo imaging results demonstrate that these dyes have high resolution and deep-penetration NIR-II imaging ability, which enable them to be used as promising NIR-II imaging agents.

The microscopic structure and tensile statistical fracture behavior of microinjection molded polyethylene samples with and without a weldline were investigated as a function of mold temperature using small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and stress–strain measurements. Probability density functions were adopted to describe the statistical nature of bulk mechanical parameters. The distributions of the elongation at break and fracture toughness follow a Gaussian function for the samples molded at 27 and 50 °C, whereas the fracture feature distributions deviate evidently from Gaussian statistics in the case of the samples molded at 75 °C. This discrepancy is due to the different extent of structural heterogeneity along the shear flow direction as evidenced by the distributions of crystallinity and degree of molecular orientation. Being composed of a more uniform structural distribution on both the lamellar and molecular length scales across the length, a fraction of the samples molded at 75 °C can surpass the barrier of localized homogeneous deformation as observed in the ones produced at low mold temperatures upon tensile stretching and thus are globally elongated to a large strain before ultimate failure, resulting finally in a broad non-Gaussian distribution of the fracture parameters. The fracture toughness–yield stress relationships revealed that the degree of orientation of the polymeric chains is of more importance than the crystallinity with regard to the fracture toughness.

The spatial scale mismatch between satellite and in situ-based measurements can be reduced by deploying multiple in situ sites within the coarse pixel. However, upscaling in situ measurements from the ground-support scale to the coarse pixel scale is still necessary due to their “point” measurement characteristics. The previous upscaling methods were generally developed merely for the in situ measurements. Nevertheless, the uncertainty of in situ measurements, such as measurement errors and spatial representativeness errors, was not dealt with. Consequently, the upscaling results inevitably suffer from errors, which will finally propagate into the pixel scale ground “truth.” For the first time, this study presents an improved upscaling method with the consideration of the uncertainty of in situ measurements based on the error theory and measurement adjustment theory. The effectiveness of the corrected upscaling coefficients was evaluated by comparing the accuracy of the corrected upscaling results with those based on the upscaling coefficients without considering the uncertainty of in situ measurements. The results indicate that the accuracy of the upscaling results can be enhanced by 11.06% in the condition in which in situ measurements suffer from large uncertainty. However, if the uncertainty of in situ measurements is negligible, the corrected upscaling model is not necessary because it does not bring many benefits. Although the effectiveness of this method was only tested on a limited study area, it makes an important first step toward a higher precision pixel-scale ground “truth,” especially when the uncertainty of in situ measurements is nonnegligible.

This article is the first attempt to employ deep learning to estimate the mechanical performance of multi-phase systems. Features of the design-points are obtained with the aid of the fast-converging numerical method used to solve the governing motion equations developed according to the kinematics of shear deformable structures. The optimum values of the parameters involved in the mechanism of the fully-connected neural network are determined through the momentum-based optimizer. The strength of the method applied in this survey comes from the high accuracy besides lower epochs needed to train the multi-layered network. It should be mentioned that the mechanical characteristics of the structure are computed through a two-step micromechanical scheme including the Halpin–Tsai method. The accuracy of the employed approach is examined and verified through the comparison of the results with those published in the literature. The numerical results give the practical hint that increasing the content of the reinforcement phase not always equal to increasing the resistance of the composite structure toward static instability. Thus, designers must choose the weight content of nano or macro-scale reinforcements by considering the shape factors of these materials to boost the strength of the system appropriately.

Developing cost-effective methods for synthesizing Nitrogen-doped carbon cryogels is crucial for advancing supercapacitor technology due to their enhanced electrochemical properties. Nitrogen-doped porous carbon cryogels are synthesized through the freeze-drying method by substituting resorcinol with phenol and using urea/melamine as nitrogen sources. The effect of nitrogen sources on the structure and electrochemical performance is investigated. In the case of carbon cryogel composites samples, using melamine as the nitrogen source (PMF) is more favorable than using urea (PUF), while both nitrogen-doped samples significantly outperform the undoped samples (PF). The PMF sample displays a specific surface area of 1119.00 m2 g−1, and a nitrogen content of 2.19 wt%. In the three-electrode system, the specific capacitance of the PMF sample reaches up to 247.9 F g−1at a current density of 0.5 A g−1, and its rate performance is 85.52 %. By comparison, the PF sample exhibits specific capacitance and rate performance of 85.4 F g−1and 33.44 % under the same parameters. The assembled symmetric supercapacitor in a buckle type system also demonstrates exceptional energy density (14.41 Wh kg−1), long-term cycle stability, and a favorable capacitance retention rate (72.2 %). These excellent electrochemical performances can be attributed to the synergistic effects of the hierarchical pore structures and heteroatoms doping.

β-Amino sulfides hold significant biological importance, motivating the development of several methods for sulfenylamination of alkenes. However, these methods often involve a three-component system with limited alkene substrate range. In this study, we present a pioneering two-component approach utilizing readily accessible sulfenamides as efficient difunctionalization reagents. Key to its success is the careful selection of a suitable photosensitizer, which enables precise modulation of sulfenamides by promoting unprecedented energy transfer rather than traditional single-electron oxidation. This novel strategy leads to the concurrent formation of N- and S-radical species, ensuring high regioselectivity for both electron-neutral and electron-deficient alkenes. As a result, a wide range of valuable β-amino sulfides, including those with congested amine groups, can be readily synthesized. These findings highlight the potential of this method for the efficient synthesis of diverse functionalized β-amino sulfides.

Cooperative hydrogen atom transfer and chiral hydrogen-bonding catalysis as a new platform for the asymmetric synthesis of azaarene derivatives is reported. By using a tetrabutylammonium decatungstate as the photocatalyst and a chiral phosphoric acid as the hydrogen-bonding catalyst, transformations of a variety of commercially available hydrocarbons and silanes with diverse α-branched 2-vinylazaarenes could efficiently experience a tandem radical conjugate addition and enantioselective protonation process, providing a convenient and fully atom economical approach to access a range of valuable enantioenriched α-tertiary azaarenes in high yields with good to excellent enantioselectivities (up to 93% ee). Through the direct use of tert-butyl methylcarbamate as the feedstock, this method enables a highly practical and concise synthesis of the enantiomerically pure medicinal molecule pheniramine (Avil).

The development of catalytic asymmetric radical reactions is an attractive but formidable task. The high reactivity of radicals enables the use of readily accessible feedstocks and mild reaction conditions, but it leads to substantial difficulty for chiral catalysts to provide sufficient enantiocontrol. Moreover, a racemic background process is often inevitable, further deteriorating enantioselectivity. In this regard, an effective protocol has been established for enantioselective intermolecular [2 + 2] photocycloadditions to overcome the challenges, which is capitalising on the ground-state preassociations of chiral catalysts with photoactivated substrates. Here, we report the viability of substrate-differentiating synergistic catalysis for this important reaction. In this new platform, energy transfer occurs between DPZ as a photosensitizer and enones or (E)-2-substituted vinylazaarenes for producing triplet-state species, and chiral phosphoric acid interacts with ground-state 2-vinylazaarenes via hydrogen bonding for subsequent enantiofacial cycloaddition. Although all active species are dispersed in the reaction system, valuable enantioenriched mono- and di-azaarene-functionalized cyclobutanes are obtained efficiently and selectively. In addition to constructing all-carbon quaternary stereocentres, flexible modulation of azaaryl groups and other substituents on the cyclobutane ring is also operative.

A modular strategy to access the remote fluoroalkylated azaarene derivatives and the α-deuterated analogues, which are the isosteres of many pharmaceutically important compounds, is reported. Transformations under the sustainable photoredox catalysis platform could efficiently experience cascade radical addition, 1,n-hydrogen atom transfer (HAT), and single-electron reduction to offer the crucial anions α to azaarenes. Through reacting with H2O or the inexpensive D2O, two series of valuable products were obtained in high yields with substantial deuterium incorporation. The work demonstrates that the HAT of the α-sp3C–H of the electron-withdrawing azaarenes with alkyl radicals is viable.

An electrochemical hydropyridylation of thioester-activated alkenes with 4-cyanopyridines has been developed. The reactions experience a tandem electroreduction of both substrates on the cathode surface, protonation, and radical cross-coupling process, resulting in a variety of valuable pyridine variants, which contain a tertiary and even a quaternary carbon at the α-position of pyridines, in high yields. The employment of thioesters to the conjugated alkenes enables no requirement of catalyst and high temperature, representing a highly sustainable synthetic method.

The first catalytic asymmetric Mannich reaction of 5‐substituted oxazolidine‐2,4‐diones is reported. By using an L‐tert‐leucine‐derived thiourea‐tertiary amine as catalyst, a variety of valuable oxazolidine‐2,4‐ones bearing a quaternary stereocenter at the 5‐position and an adjacent aza‐tertiary stereocenter at the α‐position of the heterocycles were obtained in high enantio‐ and diastereoselectivities. Meanwhile, exploiting an L‐tert‐leucine‐derived dipeptide‐based thiourea‐amide‐tertiary amine catalyst could switch diastereoselectivity, delivering the corresponding diastereomers with good to excellent enantioselectivities. The first catalytic asymmetric Mannich of 5‐substituted oxazolidine‐2,4‐dioneshas been developed. By harnessing two distinct L‐tert‐leucine‐derived bifunctional H‐bonding catalysts, respectively, a pair of diastereomers containing two adjacent stereocenters were obtained in high enantioselectivities.

The first enantioselective Beckwith-Enholm cyclization reaction is reported herein. Under cooperative photoredox and chiral hydrogen-bonding catalysis mediated by visible light, cyclization of carbonyls with azaarene-based olefins as a new reaction system offers a general and divergent synthetic pathway to furnish a variety of highly valuable enantioenriched azaarene-functionalized carbocyclic and heterocyclic alcohols, which bear adjacent 1,2- or nonadjacent 1,3-stereocentres on distinct cyclic frameworks, in high yields and enantio- and diastereoselectivities. The good compatibility of various azaarenes and carbonyls as well as the diversity of cyclic structures of the products underscores the generality of the catalysis platform. In addition to the ability to precisely introduce deuterium into molecules in an enantioselective manner, the considerable synthetic value of this method includes the excellent antioxidant stress potential of the products. In particular, molecule 29was determined to be a promising lead compound for antioxidant stress drug design.

A novel enantioselective protonation protocol that is triggered by reductive cross coupling of olefins is reported. When under cooperative photoredox and chiral hydrogen-bonding catalytic conditions and using a terminal reductant, various α-branched vinylketones with diverse vinylazaarenes could provide important enantioenriched azaarene derivatives containing tertiary stereocenters at their remote δ-position with high yields and enantioselectivities. This reaction system is also suitable for α-branched vinylazaarenes, thus successfully assembling elusive 1,4-stereocenters. The convenient late-stage modifications of products, especially the formation of remote ε-tertiary and ε-heteroquaternary carbon stereocenters, further highlight the important synthetic value of this method. Control experiments and density functional theory (DFT) calculations were conducted to elucidate the plausible reaction mechanism and origins of regioselectivity and stereoselectivity.

The mechanism underlying burn injury-induced enhanced vascular endothelial permeability and consequent body fluid extravasation is unclear. Here, the rat aortic endothelial cells (RAECs) were treated with the serum derived from rats with burn injury to elucidate the mechanism. Sprague–Dawley (SD) rats were grouped as follows (10 rats/group): control, 2, 4, 8, 12, and 24 hours postburn groups. The heart, liver, kidney, lung, jejunum, and ileum of rats injected with 2% Evans blue (EB) through the tail vein were excised to detect the EB level in each organ. The serum levels of hypoxia-inducible factor-1α (HIF-1α) and endothelin-1 (ET-1) were examined using enzyme-linked immunosorbent assay (ELISA). The effect of serum from 12-hour postburn group on the membrane permeability of RAEC monolayer, as well as on the mRNA and protein levels of ET-1, endothelin receptor A (ETA), ETB, and zonula occludens (ZO-1), was analyzed using quantitative real-time polymerase chain reaction (qRT–PCR) and western blotting. The membrane permeability of GV230/HIF-1α-transfected or shRNA-HIF-1α-transfected RAECs, as well as the expression levels of HIF-1α, ET-1, ETA, ETB, vascular endothelial (VE)-cadherin, and claudin-5, was analyzed using qRT–PCR and western blotting, whereas the localization of VE-cadherin and claudin-5 was examined using immunofluorescence. The serum HIF-1α and ET-1 levels in the burn groups, which peaked at 12 hours postburn, were significantly upregulated (P <.01) when compared with those in the control group. Additionally, the serum HIF-1α levels were positively correlated with vascular permeability. Compared with the shRNA-negative control-transfected RAECs, the shRNA-II/HIF-1α-transfected RAECs exhibited downregulated expression of HIF-1α, ET-1, ETA, and ETB (P< .01), and upregulated expression of ZO-1, claudin-5, and VE-cadherin (P< .05). Compared with the GV230-transfected RAECs, the GV230/HIF-1α-transfected RAECs exhibited upregulated expression of HIF-1α, ET-1, ETA, and ETB (P< .01), and downregulated expression of ZO-1, claudin-5, and VE-cadherin (P< .05). The GV230/HIF-1α-transfected RAECs exhibited degradation and translocation of VE-cadherin and claudin-5. In addition to degradation of VE-cadherin and claudin-5, HIF-1α mediated enhanced endothelial cell permeability through upregulation of ET-1, ETA, and ETB, and downregulation of ZO-1 and VE-cadherin in rats with burn injury.

Circularly polarized luminescent (CPL) materials have received a lot of interest due to their potential applications in next-generation displays. However, the development of easily accessible red circularly polarized phosphorescent emitters for practical organic light-emitting diodes fabrication remains a grand challenge. In this paper, we report a new family of CPL-active platinum complexes based on the binaphthalene chiral platform. These axially chiral platinabinaphthalenes were facile synthesized by directly incorporating platinum(II) into the π-conjugated backbone of a commercially available enantiopure binaphthalene derivate. These complexes exhibit aggregation-induced circularly polarized phosphorescence enhancement with high quantum yields of up to 66% and luminescence dissymmetry factors of around 2.6 × 10–3. Moreover, solution-processable circularly polarized organic light-emitting diodes (CPOLEDs) using these complexes as emitters show good performance with the maximum luminance of up to 3500 cd m–2and dissymmetry factor values of around 1.0 × 10–3. These findings by the rational design of axially chiral platinabinaphthalenes are important for the development of high-performance CPL complexes for CPOLEDs.

A radical-based asymmetric olefin difunctionalization strategy for rapidly forging all-carbon quaternary stereocenters α to diverse azaarenes is reported. Under cooperative photoredox and chiral Brønsted acid catalysis, cyclopropylamines with α-branched 2-vinylazaarenes can undergo a sequential two-step radical process, furnishing various valuable chiral azaarene-substituted cyclopentanes. The use of the rigid and confined C2-symmetric imidodiphosphoric acid catalysts achieves high enantio- and diastereo-selectivities for these asymmetric [3 + 2] cycloadditions.

The oxygen vacancies and spinel inverse of MnFe2O4were effectively healed via a eutectic molten salt treatment, resulting in more ATdsited Mn2+active sites and higher conductivity for the improved oxygen reduction reaction (ORR) performance.

A chemodivergent reaction is an appealing way to construct molecules with enriched structure diversity in a controlled manner. A plethora of methodologies were developed based on this concept, and transition metal-catalysis plays a central role among others catalysis systems own to its longstanding history. While a chemodivergent reaction based on organo-catalysis, especially photocatalysis, is rather limited as these concepts were only prevalent in the last two decades. With the ever-increasing importance of photocatalysis, a chemodivergent reaction based on such an activation pathway would be a meaningful direction. Herein, an efficient chemodivergent strategy for visible light photocatalysis is developed. By employing commercially available Rose Bengal as a photocatalyst, naturally occurring Viridicatin and its derivatives can be transformed into three different types of products through switchable single electron transfer (SET) or energy transfer (EnT) processes. Mechanistic studies have revealed that the oxygen as a reactive center, rather than carbon, is favored, which accounts for the first example of a C-O homo-dimerization product.

An enantioselective hydroaminoalkylation of azaaryl ketones under a transition-metal-free asymmetric photoredox catalysis platform is reported. A series of valuable azaarene-functionalized 1,2-amino alcohols featuring attractive quaternary carbon stereocenters have been synthesized in high yields with good to excellent enantioselectivities. The viability of readily accessible N-aryl glycines as reaction partners facilitates the conjugate modification of these products into important derivatives, thereby enhancing the synthetic utility of the current approach.

Here we present a highly enantioselective [2π + 2σ] photocycloaddition of bicyclo[1.1.0]butanes (BCBs). The reaction uses a variety of vinylazaarenes as partners and is catalyzed by a polycyclic aromatic hydrocarbon (PAH)-containing chiral phosphoric acid as a bifunctional chiral photosensitizer. A wide array of pharmaceutically important bicyclo[2.1.1]hexane (BCH) derivatives have been synthesized with high yields, enantioselectivity, and diastereoselectivity. In addition to the diverse 1-ketocarbonyl-3-substituted BCBs, α/β-substituted vinylazaarenes are compatible with such an unprecedented photoredox catalytic pathway, resulting in the successful assembly of an all-carbon quaternary stereocenter or two adjacent tertiary stereocenters on the product.

An asymmetric, phase-transfer-catalyzed vinylogous conjugate addition–vinylogous cyclization cascade of olefinic azlactones with 4-nitro-5-styrylisoxazoles is reported. In the presence of an l-tert-leucine-derived urea–quaternary ammonium salt as a bifunctional phase-transfer catalyst and KF, two series of valuable optically pure cyclohexenones featuring two and three stereocenters were obtained in high yields with good to excellent enantio- and diastereoselectivities.

Pyridine, one of the most important azaarenes, is ubiquitous in functional molecules. The electronic properties of pyridine have been exploited to trigger asymmetric transformations of prochiral species as a direct approach for accessing chiral pyridine derivatives. However, the full potential of this synthetic strategy for the construction of enantioenriched γ-functionalized pyridines remains untapped. Here, we describe the first enantioselective addition of prochiral radicals to vinylpyridines under cooperative photoredox and asymmetric catalysis mediated by visible light. The enantioselective reductive couplings of vinylpyridines with aldehydes, ketones, and imines were achieved by employing a chiral Brønsted acid to activate the reaction partners and provide stereocontrol via H-bonding interactions. Valuable chiral γ-secondary/tertiary hydroxyl- and amino-substituted pyridines were obtained in high yields with good to excellent enantioselectivities.

The development of small organic molecules with intense and switchable circularly polarized luminescence (CPL) is currently attracting great interest due to their promising applications in chiroptical devices and sensors. In this paper, CPL-active BF2-bridged azaanthracene dimers (BA1and BA2) were facilely synthesized by incorporating boron difluoride unit to the binaphthalene. BA1and BA2show moderate CPL in diluted solutions, however, BA2exhibited aggregation-amplified red CPL with large dissymmetry factor up to 1.6×10−2. Moreover, acid-/base-triggered CPL switch off/on were also realized via disaggregation/aggregation of BA2in tetrahydrofuran (THF)/water binary solvents.

The electrochemical degradation of tetracycline antibiotics (TCs), such as tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC), was investigated by using SnO2-Sb2O3 and PbO2 modified Ti electrode (Ti/SnO2-Sb2O3/PbO2 anode). The modified electrode was prepared with a SnO2-Sb2O3 interlayer and a PbO2 active layer on the surface of Ti sheet, and characterized by scanning electron microscope, X-ray diffraction and cyclic voltammetry. The effects of supporting electrolyte, current density and the initial concentration of TCs on electrochemical degradation were also examined. For the degradation of 50 mg*L[?]1 TC, OTC and CTC at 5 mA [?] cm[?]2, the energy consumption were 39.9, 40.0 and 37.7 kWh[?]mol[?]1, and the removal efficiencies could reach 79.5%, 82.0% and 90.3% for 2 h, respectively. The degradation processes followed the first-order kinetic model, and the rate constants of TC, OTC and CTC were 0.78, 0.84 and 0.97 h[?]1, respectively. The possible degradation pathways were proposed through monitoring the degradation products of TCs. The results from bioluminescence inhibition assays suggested the residual biotoxicity after complete TCs degradation, and extra reaction was necessary to reduce biotoxicity. Overall, the electrochemical degradation using Ti/SnO2-Sb2O3/PbO2 anode has a great potential to remove TCs from wastewater.

With the improvement of the accuracy of experimental devices and measuring instruments, cavitation experiments such as cross-media vehicles and propellers have been carried out in small pools. However, the water quality in the laboratory and the engineering application waters differs, especially the concentration of the gas nuclei that cause cavitation, resulting in experimental results that differ from prototype experimental results, and the scale effect occurs. In order to reduce the influence of the scale effect, according to the conditions of cavitation, gas nuclei can be mixed with water before the experiment is formally implemented. Aeration behavior will affect the size and concentration of gas nuclei (gas nuclei spectrum) in water. In order to obtain better experimental results, it is necessary to clarify the variation of the gas nuclei spectrum in small-scale experimental pools before and after aeration, so as to master aeration technology. Through research, it is found that the artificial aeration method can effectively change the gas nuclei spectrum in water and increase the concentration of gas nuclei. By using the underwater acoustic measurement method, the change in the gas nuclei spectrum can be captured sensitively. The gas nuclei spectrum in water after aeration is in good agreement with the mathematical model of gas nuclei spectrum under non-artificial intervention, which shows that the distribution of gas nuclei in water under artificial aeration is similar to that under non-artificial intervention, which is conducive to the occurrence of cavitation. At the same time, it shows that the combination of experiment and numerical method can reduce the measuring state and the measurement cost and improve the measurement efficiency.

With a dual organocatalytic system involving a chiral phosphoric acid and a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and under the irradiation with visible light, an enantioselective Minisci-type addition of α-amino acid-derived redox-active esters (RAEs) to isoquinolines has been developed. A variety of prochiral α-aminoalkyl radicals generated from RAEs were successfully introduced on isoquinolines, providing a range of valuable α-isoquinoline-substituted chiral secondary amines in high yields with good to excellent enantioselectivities.

Abstract In this paper, we consider the H ∞ hybrid dynamical output-feedback control problem for discrete-time switched linear systems under asynchronous switching. A time-varying multiple Lyapunov-like-function (MLF) approach is applied to derive sufficient conditions that guarantee the stability and weighted l 2 -gain performance of the closed-loop systems, where the established conditions explicitly depend on the upper and lower bounds of asynchronous switching delays. An alternative approach is proposed to decouple the bilinear problems of the control synthesis conditions. Convex optimization algorithms are also proposed based on the established conditions to determine the minimum l 2 -gain performance. Two numerical examples are provided to illustrate the effectiveness of the proposed method, demonstrating significant improvement over the existing results. [ABSTRACT FROM AUTHOR]

An organocatalytic asymmetric aldol reaction of 5-alkyl-4-nitroisoxazoles to paraformaldehyde has been developed. By using a chiral dipeptide-based urea–amide–guanidinium as the phase-transfer catalyst, the transformations were promoted by sodium acetate, leading to a range of enantio-enriched isoxazole derivatives in high yields with moderate to excellent enantioselectivities. This work represents the first example of constructing chiral C–C bonds at the α-position of 5-alkyl-4-nitroisoxazoles. The viability of readily accessing chiral fungicides from the obtained aldol products demonstrates the important utility of this method.

The first vinylogous dearomatization is reported. Under a photoinduced platform, various benzothiophenes functionalized by ketones at the 3-position could react with 3-methylenechroman-4-ones efficiently, leading to a variety of valuable products that contain the pharmaceutically significant chromones and 2,3-dihydrobenzo[b]thiophenes concurrently. The transformations were revealed to experience hydrogen-atom transfer, dearomatization, olefin migration, and radical cross coupling.

Some important biological species and microenvironments maintain a complex and delicate dynamic balance in life systems, participating in the regulation of various physiological processes and playing indispensable roles in maintaining the healthy development of living bodies. Disruption of their homeostasis in living organisms can cause various diseases and even death. Therefore, real time monitoring of these biological species and microenvironments during different physiological and pathological processes is of great significance. Fluorescent-probe-based techniques have been recognized as one of the most powerful tools for real time imaging in biological samples. In this Account, we introduce the representative works from our group in the field of fluorescent probes for biological imaging capable of detecting metal ions, small bioactive molecules, and the microenvironment. The design strategies of small molecule fluorescent probes and their applications in biological imaging will be discussed. By regulating the design strategy and mechanism (e.g., ICT, PeT, and FRET) of the electronic and spectral characteristics of the fluorescent platforms, these chemical probes show high selectivity and diverse functions, which can be used for imaging of various physiological and pathological processes. Through the exploration of the rational response mechanism and design strategy, combined with a variety of imaging techniques, such as super-resolution imaging, photoacoustic (PA) imaging, etc., we have realized multimode imaging of the important biological analytes from the subcellular level to the in vivo level, which provides powerful means to study the physiological and pathological functions of these species and microenvironments. This Account aims to offer insights and inspiration for the development of novel fluorescent probes for biological imaging, which could provide powerful tools for the study of chemical biology. Overall, we represent a series of turn-on/turn-off/ratiometric fluorescent/PA probes to visually and dynamically trace biological species and microenvironments in cells and even in vivo that seek higher resolution and depth molecular imaging to improve diagnostic methods and clarify new discoveries related to chemical biology. Our future efforts will be devoted to developing multiorganelle targeted fluorescent probes to study the mechanism of subcellular organelle interaction and employing various dual-mode probes of NIR II and PA imaging to investigate the development of related diseases and treat the related diseases at subcellular and in vivo levels.

Background: The commercially available dimeric cinchona alkaloids based on C-9 ether bond connecting are limited by the absence of Brønsted acid moiety and cannot meet the enantioselectivity demand. Objective: In this study, a family of novel C2-symmetric bis-cinchona alkaloid derivatives possessing a range of mono- and bidentate hydrogen bond donor groups at the C-9 is now reported. Method: These novel C2-symmetric bis-cinchona alkaloid derivatives were synthesized by a facile route. Results: These novel C2-symmetric bis-cinchona alkaloid derivatives exhibit a rare example of Brønsted acid moiety of C-9, basic tertiary amine moiety, and a rigid enzyme-like pocket, suggesting their potential, broadly useful bifunctional organic catalysts for asymmetric synthesis.

AbstractIn this paper, the combination of the Laplace loss function and support vector regression (SVR) is presented for the estimation of manoeuvring performance in multidisciplinary ship design optimization, and a new SVR algorithm was proposed, which has only one parameter to control the errors and automatically minimized with ν, and adds b2/2 to the item of confidence interval. It is shown that the proposed SVR algorithm in conjunction with the Laplace loss function can estimate the ship manoeuvring performance appropriately compared to the simulation results with Napa software and other approximation methods such as artificial neural network and classic SVR. In this article, we also gather enough ship information about the offshore support vessel; the Latin Hypercube Design is employed to explore the design space. Instead of requiring the evaluation of expensive simulation codes, we establish the metamodels of ship manoeuvring performance; all the numerical results show the effectiveness and practicability of the new approximation algorithms.

The H∞synchronization problem for complex dynamical networks with coupling delays and external disturbance via distributed impulsive control is studied. Two types of time-varying coupling delays are considered: the delays without any restriction on the delay derivatives, and the delays whose derivatives are strictly less than 1. A time-varying Lyapunov function/functional approach is applied to L2-gain analysis of the synchronization error systems. H∞synchronization criteria are established to guarantee the synchronization to be robust with respect to disturbance in the sense that the L2-gain from the disturbance to the control output is satisfactorily small. For each type of coupling delays, an algorithm involving convex optimization is proposed to design distributed impulsive controllers achieving a suboptimal value of the sum of coupling strengths for a prescribed L2-gain. Two numerical examples illustrate the efficiency of the theoretical results.

Owing to the important utilities in many areas, the preparation of chiral sulfur-containing compounds has attracted special attention of chemists. As an alternative of the most popular asymmetric sulfur-Michael addition, asymmetric α-sulfenylation has been developed well in recent years. This short review would summarize the advance on asymmetric α-sulfenylation. Two asymmetric protocols, including transition-metal catalysis and organocatalysis, are discussed respectively.

The -butenolide structural motif is a prominent feature in many bioactive natural products and drugs. This short review summarizes catalytic asymmetric synthesis of -butenolides through direct vinylogous reactions by metal complexes and organocatalysts. In light of building chiral -tertiary and quaternary carbon centers of butenolides, three synthetic strategies are included: 1) the reactions with furanone derivatives as nucleophiles, 2) olefination of ,- disubstituted butenolides and 3) the reactions by using ,-disubstituted butenolides as nucleophiles.

Through the cleavage of the CC bond, the first catalytic tandem conjugate addition–elimination reaction of Morita–Baylis–Hillman C adducts has been presented. Various SN2′‐like C‐, S‐, and P‐allylic compounds could be obtained with exclusive Econfiguration in good to excellent yields. The Michael product could also be easily prepared by tuning the β‐C‐substituent group of the α‐methylene ester under the same reaction conditions. Calculated relative energies of various transition states by DFT methods strongly support the observed chemoselectivity and diastereoselectivity.

Summary:The crystalline structure and phase morphology of linear, branched polyethylenes and their blends during crystallization and subsequent melting were investigated, using a combination of differential scanning calorimetry (DSC), and synchrotron small angle X‐ray scattering (SAXS). A linear polyethylene (PE1) with weight‐average molecular weight (Mw) of 114 000 g/mol, and two branched polyethylene copolymers, containing 4.8 mol% (PE4) and 15.3 mol% (PE10) hexane, with molecular weights of 93 000 g/mol and 46 000 g/mol were used as pure samples. Two blends, PE1‐4 and PE1‐10, each with a weight ratio of 50/50, were prepared by solution blending. Our results indicate that in PE4 a phase separation within the branched component itself occurred, forming a broad distribution of lamellar thicknesses during the crystallization process. PE10 on the other hand did hardly crystallize because of the high degree of branching. Co‐crystallization of both components took place in blend PE1‐4 and liquid‐liquid phase separation occurred in the melt of PE1‐10. Morphological parameters were determined by using Bragg's law and the correlation function, respectively. The detected semicrystalline morphology can be well described by the lamellar insertion mode where thin lamellae develop between thicker primary lamellae. During subsequent heating, lamellae melted in the reversed sequence of their formation. The evolution of the structural parameters as a function of temperature revealed that surface melting began at first, and then the complete melting of stacks occurred until the final melting temperature was reached.

Conjugate addition to 1,4‐dicarbonylbut‐2‐enes will generate an α‐stereogenic center with respect to one of the carbonyl groups, which informally, can be considered as an inversion of normal reactivity patterns or umpolungprotocol. In this paper, the addition of tert‐butyl mercaptan to 1,4‐dicarbonylbut‐2‐enes including (E)‐4‐oxo‐4‐arylbutenamides and (E)‐4‐oxo‐4‐arylbutenones has been developed, to synthesize a series of chiral sulfur‐substituted α‐stereogenic amides and ketones in high regioselectivity and enantioselectivity (up to 98% ee).

As a result of the low reactivity of simple esters, the use of them as nucleophiles in direct asymmetric transformations is a long‐standing challenge in synthetic organic chemistry. Nature approaches this difficulty through a decarboxylative mechanism, which is used for polyketide synthesis. Inspired by nature, we report guanidine‐catalyzed biomimetic decarboxylative CC and CN bond‐formation reactions. These highly enantioselective decarboxylative Mannich and amination reactions utilized malonic acid half thioesters as simple ester surrogates. It is proposed that nucleophilic addition precedes decarboxylation in the mechanism, which has been investigated in detail through the identification of intermediates by using electrospray ionization (ESI) mass‐spectrometric analysis and DFT calculations.