CRISPR/Cas12a-Powered Amplification-Free RNA Diagnostics by Integrating T7 Exonuclease-Assisted Target Recycling and Split G-Quadruplex Catalytic Signal Output.

Rapid and sensitive RNA detection is of great value in diverse areas, ranging from biomedical research to clinical diagnostics. Existing methods for RNA detection often rely on reverse transcription (RT) and DNA amplification or involve a time-consuming procedure and poor sensitivity. Herein, we proposed a CRISPR/Cas12a-enabled amplification-free assay for rapid, specific, and sensitive RNA diagnostics. This assay, which we termed T7/G4-CRISPR, involved the use of a T7-powered nucleic acid circuit to convert a single RNA target into numerous DNA activators via toehold-mediated strand displacement reaction and T7 exonuclease-mediated target recycling amplification, followed by activating Cas12a trans-cleavage of the linker strands inhibiting split G-Quadruplex (G4) assembly, thereby inducing fluorescence attenuation proportion to the input RNA target. We first performed step-by-step validation of the entire assay process and optimized the reaction parameters. Using the optimal conditions, T7/G4-CRISPR was capable of detecting as low as 3.6 pM target RNA, obtaining ∼100-fold improvement in sensitivity compared with the most direct Cas12a assays. Meanwhile, its excellent specificity could discriminate single nucleotide variants adjacent to the toehold region and allow species-specific pathogen identification. Furthermore, we applied it for analyzing bacterial 16S rRNA in 40 clinical urine samples, exhibiting a sensitivity of 90% and a specificity of 100% when validated by RT-quantitative PCR. Therefore, we envision that T7/G4-CRISPR will serve as a promising RNA sensing approach to expand the toolbox of CRISPR-based diagnostics.

Heterostructured MoO3 Anchored Defect-Rich NiFe-LDH/NF as a Robust Self-Supporting Electrocatalyst for Overall Water Splitting.

The rational design of inexpensive metal electrocatalysts with exciting catalytic activity for overall water splitting (OWS) remains a significant challenge. Heterostructures of NiFe layered double hydroxides (NiFe-LDHs) with abundant oxygen defects and tunable electronic properties have garnered considerable attention. Here, a self-supporting heterostructured catalyst (named MoO3/NiFe-NF) is synthesized via a hydrothermal method to grow NiFe-LDH with oxygen vacancies (OV) in situ on inexpensive nickel foam (NF). Subsequently, MoO3 is anchored and grown on the surface of NiFe-LDH by electrodeposition. The obtained catalysts achieved outstanding oxygen/hydrogen evolution reaction (OER/HER, 212 mV/85 mV@10 mA cm-2) performance in 1 m KOH. Additionally, when MoO3/NiFe-NF is utilized as the cathode and anode in OWS, a current density of 10 mA cm-2 can be obtained as an ultralow battery voltage of 1.43 V, a significantly lower value compared to the commercial electrolyzer incorporating Pt/C and IrO2 electrode materials. Finally, density functional theory (DFT) calculations and advanced spectroscopy technology are conducted to reveal the effects of heterojunctions and OV on the internal electronic structure of the electrical catalysts. Mainly, the present study provides a novel tactic for the rational design of remarkable, low-cost NiFe-LDH electrocatalysts with heterostructures for OWS.

Strong Oxidizing Molten Salts for Strengthening Structural Restoration Enabling Direct Regeneration of Spent Layered Cathode.

As a mainstream technology for recycling spent lithium-ion batteries, direct regeneration is rapidly developed due to its high efficiency and green characteristics. However, efficient reuse of spent LiNixCoyMn1- x - yO2 cathode is still a significant challenge, as the rock salt/spinel phase on the surface hinders the Li replenishment and phase transformation to the layered structure. In this work, the fundamental understanding of the repair mechanism is confirmed that the oxidizing atmosphere is the crucial factor that can greatly improve the rate and degree of phase restoration. Particularly, a ternary-component molten salt system (LiOH-Li2CO3-LiNO3) is proposed for direct regeneration of LiNi0.5Co0.2Mn0.3O2 (NCM523), which can in situ generate the strong oxidizing intermediate of superoxide radicals. Additionally, it shows a liquid-like reaction environment at a lower temperature to acceclerate the transport rate of superoxide-ions. Therefore, the synergistic effect of LiOH-Li2CO3-LiNO3 system can strengthen the full restoration of rock salt/spinel phases and achieve the complete Li-supplement. As anticipated, the regenerated NCM523 delivers a high cycling stability with a retention of 91.7% after 100 cycles, which is even competitive with the commercial NCM523. This strategy provides a facile approach for the complete recovery of layer structure cathode, demonstrating a unique perspective for the direct regeneration of spent lithium-ion batteries.

A Dual-Polythiophene Blending Strategy to Reduce the Efficiency-Stability-Cost Gap of Solar Cells.

Benefiting from the photovoltaic material innovation and delicate device optimization, high-efficiency solar cells employing polymeric materials are thriving. Reducing the gap of cost, efficiency, and stability is the critical challenge faced by the emerging solar cells such as organics, quantum dots and perovskites. Poly(3-alkylthiophene) demonstrates great potential in organic solar cells and quantum dot solar cells as the active layer or the hole transport layer due to its large scalability, excellent photoelectric performance, and favorable hydrophobicity. The present low efficiency and insufficient stability, restrict its commercial application. In this work, a facile strategy of blending two simple polythiophenes is put forward to manipulate the film microstructure and enhance the device efficiency and thermal stability of solar cells. The introduction of P3PT can improve the power conversion efficiency (PCE) of a benchmark cost-effective blend P3HT:O-IDTBR to 7.41%, and the developed ternary solar cells also exhibit increased thermal stability. More strikingly, the quantum dot solar cells with the dual-polythiophene hole transport layer achieve the highest PCE of 10.51%, which is among the topmost efficiencies for quantum dots/polythiophene solar cells. Together, this work provides an effective route to simultaneously optimize the device efficiency and thermal stability of solar cells.

Chiral Brønsted Acid-Catalyzed Asymmetric Reaction via Vinylidene ortho-Quinone Methides.

Vinylidene ortho-quinone methides (VQMs) have been proven to be versatile and crucial intermediates in the catalytic asymmetric reaction in last decade, and thus have drawn considerable concentrations on account of the practical application in the construction of enantiomerically pure functional organic molecules. However, in comparison to the well established chiral Brønsted base-catalyzed asymmetric reaction via VQMs, chiral Brønsted acid-catalyzed reaction is rarely studied and there is no systematic summary to date. In this review, we summarize the recent advances in the chiral Brønsted acid-catalyzed asymmetric reaction via VQMs according to three types of reactions: a) intermolecular asymmetric nucleophilic addition to VQMs; b) intermolecular asymmetric cycloaddition of VQMs; c) intramolecular asymmetric cyclization of VQMs. Finally, we put forward the remained challenges and opportunities for potential breakthroughs in this area.

Catalytic Epoxidation of Carbonyl Compounds via Carbonyl Ylides: from Racemic to Enantioselective.

Transition metal-catalyzed epoxidation of carbonyl compounds through carbonyl ylides represents a highly effective method for synthesizing a diverse range of valuable epoxides. This review offers an in-depth overview of the latest developments in inter- and intramolecular epoxidation reactions involving metal carbenes and carbonyl compounds, encompassing both racemic to enantioselective transformations. These catalytic epoxidations are reviewed by highlighting their product selectivity, diversity and applicability, and the related mechanistic rationale is showcased where possible.

Regulating Crystallinity Mismatch Between Donor and Acceptor to Improve Exciton/Charge Transport in Efficient Organic Solar Cells.

Achieving a more balanced charge transport by morphological control is crucial in reducing bimolecular and trap-assisted recombination and enhancing the critical parameters for efficient organic solar cells (OSCs). Hence, a facile strategy is proposed to reduce the crystallinity difference between donor and acceptor by incorporating a novel multifunctional liquid crystal small molecule (LCSM) BDTPF4-C6 into the binary blend. BDTPF4-C6 is the first LCSM based on a tetrafluorobenzene unit and features a low liquid crystal phase transition temperature and strong self-assembly ability, conducive to regulating the active layer morphology. When BDTPF4-C6 is introduced as a guest molecule into the PM6 : Y6 binary, it exhibits better compatibility with the donor PM6 and primarily resides within the PM6 phase because of the similarity-intermiscibility principle. Moreover, systematic studies revealed that BDTPF4-C6 could be used as a seeding agent for PM6 to enhance its crystallinity, thereby forming a more balanced and favourable charge transport with suppressed charge recombination. Intriguingly, dual Förster resonance energy transfer was observed between the guest molecule and the host donor and acceptor, resulting in an improved current density. This study demonstrates a facile approach to balance the charge mobilities and offers new insights into boosting the efficiency of single-junction OSCs beyond 20 %.

Nitrene Transfer and Carbene Transfer in Gold Catalysis.

Catalytic transformations involving metal carbenes are considered one of the most important aspects of homogeneous transition metal catalysis. Recently, gold-catalyzed generation of gold carbenes from readily available alkynes represents a significant advance in metal carbene chemistry. This Review summarizes the advances in the gold-catalyzed nitrene-transfer reactions of alkynes with nitrogen-transfer reagents, such as azides, nitrogen ylides, isoxazoles, and anthranils, and gold-catalyzed carbene-transfer reactions, involving oxygen atom-transfer reactions of alkynes with nitro compounds, nitrones, sulfoxides, and pyridine N-oxides, through the presumable α-imino gold carbene and α-oxo gold carbene intermediates, respectively. Gold-catalyzed processes are reviewed by highlighting their product diversity, selectivity, and applicability, and the mechanistic rationale is presented where possible.

Copper-Catalyzed Enantioselective Doyle-Kirmse Reaction of Azide-Ynamides via α-Imino Copper Carbenes.

[2,3]-Sigmatropic rearrangement reaction involving sulfonium ylide (Doyle-Kirmse reaction) generated from metal carbenes represents one of the powerful methods for the construction of C(sp3 )-S and C-C bonds. Although significant advances have been achieved, the asymmetric versions via the generation of sulfonium ylides from metal carbenes have been rarely reported to date, and they have so far been limited to diazo compounds as metal carbene precursors. Here, we describe a copper-catalyzed enantioselective Doyle-Kirmse reaction via azide-ynamide cyclization, leading to the practical and divergent assembly of an array of chiral [1,4]thiazino[3,2-b]indoles bearing a quaternary carbon stereocenter in generally moderate to excellent yields and excellent enantioselectivities. Importantly, this protocol represents a unique catalytic asymmetric Doyle-Kirmse reaction via a non-diazo approach and an unprecedented asymmetric [2,3]-sigmatropic rearrangement via α-imino metal carbenes.

Construction of Axially Chiral Arylpyrroles via Atroposelective Diyne Cyclization.

Axially chiral biaryls widely exist in natural products and pharmaceuticals and are used as chiral ligands and catalysts in asymmetric synthesis. Compared to the well-established axially chiral 6-membered biaryl skeletons, examples of 5-membered biaryls have been quite scarce, and mono-substituted 3-arylpyrrole atropisomers have not been reported. Here, we disclose a copper-catalyzed atroposelective diyne cyclization for the construction of a range of axially chiral arylpyrrole biaryls in good to excellent yields with generally excellent enantioselectivities via oxidation and X-H insertion of vinyl cations. Importantly, this protocol not only represents the first synthesis of mono-substituted 3-arylpyrrole atropisomers, but also constitutes the first example of atroposelective diyne cyclization and the first atropisomer construction via vinyl cations. Theoretical calculations further support the mechanism of vinyl cation-involved cyclization and elucidate the origin of enantioselectivity.

I2 -Catalyzed Cycloisomerization of Ynamides: Chemoselective and Divergent Access to Indole Derivatives.

Herein, an I2 -catalyzed unprecedented cycloisomerization of ynamides is developed, furnishing various functionalized bis(indole) derivatives in generally good to excellent yields with wide substrate scope and excellent atom-economy. This protocol not only represents the first molecular-iodine-catalyzed tandem complex alkyne cycloisomerizations, but also constitutes the first chemoselective cycloisomerization of tryptamine-ynamides involving distinctively different C(sp3 )-C(sp3 ) bond cleavage and rearrangement. Moreover, chiral tetrahydropyridine frameworks containing two stereocenters are obtained with moderate to excellent diastereoselectivities and excellent enantioselectivities. Meanwhile, cycloisomerization and aromatization of ynamides produce pyrrolyl indoles with high efficiency enabled by I2 . Additionally, control experiments and theoretical calculations reveal that this reaction probably undergoes a tandem 5-exo-dig cyclization/rearrangement process.

Enantioselective Rh-Catalyzed Azide-Internal-Alkyne Cycloaddition for the Construction of Axially Chiral 1,2,3-Triazoles.

Significant advances have been achieved for the construction of chiral skeletons containing 1,2,3-triazoles via transition-metal-catalyzed asymmetric azide-alkyne cycloaddition; however, most of them have been limited to terminal alkynes in the synthesis of central chirality via desymmetrization and dynamic/dynamic kinetic resolution. Enantioselective transition-metal-catalyzed azide-internal-alkyne cycloaddition is extremely limited. Moreover, the construction of a challenging five-membered (hetero)biaryl axially chiral molecule via transition-metal-catalyzed asymmetric azide-internal-alkyne cycloaddition is still underexplored. Herein, we first report an atroposelective and atom-economical synthesis of axially chiral 1,4,5-trisubstituted 1,2,3-triazoles, directly acting as core chiral units of challenging five-membered atropisomers, via the enantioselective Rh-catalyzed azide-alkyne cycloaddition (E-RhAAC) of internal alkynes and azides. The reaction demonstrates excellent functional group tolerance, forging a variety of C-C axially chiral 1,2,3-triazoles under mild conditions with moderate to excellent yields (up to 99% yield) and generally high to excellent enantioselectivities (up to 99% ee) along with specific regiocontrol. The origin of regio- and enantioselectivity control is disclosed by density functional theory (DFT) calculations, providing new guidance for the facile construction of axially chiral compounds.

An Aggregation-Suppressed Polymer Blending Strategy Enables High-Performance Organic and Quantum Dot Hybrid Solar Cells.

Solution-processing hybrid solar cells with organics and colloidal quantum dots (CQDs) have drawn substantial attention in the past decade. Nevertheless, hybrid solar cells based on the recently developed directly synthesized CQD inks are still unexplored. Herein, a facile polymer blending strategy is put forward to enable directly synthesized CQD/polymer hybrid solar cells with a champion efficiency of 13%, taking advantage of the conjugated polymer blends with finely optimized aggregation behaviors. The spectroscopic and electrical investigations on carrier transport and recombination indicate that polymer blends can endow fast carrier transport and less recombination over the single counterparts. Moreover, the blending strategy offers a "dilution effect" for top-notch photovoltaic polymers with excessively strong aggregation tendency, resulting in moderate feature domain size and surface roughness, which afford fast hole transport and therefore high photovoltaic performance. The effectiveness of this strategy is successfully validated using two pairs of photovoltaic polymers. Accordingly, the relationships between polymer morphology, carrier transport, and photovoltaic performance are established to advance the progress of CQD/polymer hybrid solar cells. Such progress stresses that the utilization of aggregation-suppressed polymer blends is a facile approach toward the fabrication of high-efficiency organic-inorganic hybrid solar cells.

Unraveling the Photovoltaic, Mechanical, and Microstructural Properties and Their Correlations in Simple Poly(3-pentylthiophene) Solar Cells.

The power conversion efficiency of polythiophene organic solar cells is constantly refreshed. Despite the renewed device efficiency, very few efforts have been devoted to understanding how the type of electron acceptor alters the photovoltaic and mechanical properties of these low-cost solar cells. Herein, the authors conduct a thorough investigation of photovoltaic and mechanical characteristics of a simple yet less-explored polythiophene, namely poly(3-pentylthiophene) (P3PT), in three different types of organic solar cells, where ZY-4Cl, PC71 BM, and N2200 are employed as three representative acceptors, respectively. Compared with the reference poly(3-hexylthiophene) (P3HT)-based solar cells, P3PT-based devices, all perform more efficiently. Particularly, the P3PT:ZY-4Cl blend exhibits the highest efficiency (ca. 10%) among the six combinations and outperforms the prior top-performance system P3HT:ZY-4Cl. Furthermore, the blend films based on N2200 exhibit a high crack-onset strain of ∼38% on average, which is approximately 15- and 17-times higher than those of ZY-4Cl and PC71 BM, respectively. The microstructural origins for the above difference are well elucidated by detailed grazing incidence X-ray scattering and microscopy analysis. This work not only underlines the potential of P3PT in prolific solar cell research but also demonstrates the superior tensile properties of polythiophene-based all-polymer blends for the preparation of stretchable solar cells.

Simultaneously Enhanced Efficiency and Mechanical Durability in Ternary Solar Cells Enabled by Low-Cost Incompletely Separated Fullerenes.

All-polymer solar cells (all-PSCs) are one of the most promising application-oriented organic photovoltaic technologies due to their excellent operational and mechanical stability. However, the power conversion efficiencies (PCEs) are mostly lower than 16%, restricting their core competitiveness. Furthermore, the improvement of mechanical durability is rarely paid attention to cutting-edge all-PSCs. This work deploys a low-cost "technical grade" PCBM (incompletely separated but pure mixtures containing ≥90% [70]PCBM or [60]PCBM), into the efficient PM6:PY-IT all-polymer blend, successfully yielding a high-performance ternary device with 16.16% PCE, among the highest PCE values for all-PSCs. Meanwhile, an excellent mechanical property (i.e., crack onset strain = 11.1%) promoted from 9.5% for the ternary system is also demonstrated. The "technical grade" PCBM slightly disrupts the crystallization of polymers, and disperses well into the amorphous polymer regions of the all-PSC blends, thus facilitating charge transport and improving film ductility simultaneously. All these results confirm introducing low-cost "technical grade" PCBM with high electron mobility into all-polymer blends can improve carrier mobility, reduce charge recombination, and optimize morphology of the amorphous polymer regions, thus yielding more efficient and mechanically durable all-PSCs.

A Novel MAGDM Method Based on Hesitant Picture Fuzzy Schweizer-Sklar Maclaurin Symmetric Mean Operators and Their Application.

Multiple attribute group decision making (MAGDM) issues play important roles in our daily life. In order to solve the problem that decision makers (DMs) may feel hesitant to select the appropriate evaluation values from several possible values in the process of providing evaluations, fuzzy theory and its extensions are widely applied in MAGDM problems. In this study, we first proposed hesitant picture fuzzy sets (HPFSs), which is a combination of the hesitant fuzzy set and picture fuzzy set. Subsequently, we introduced a novel Schweizer-Sklar t-norm and t-conorm operation rules of HPFSs and proposed a family of hesitant picture fuzzy Schweizer-Sklar Maclaurin symmetric mean operators. To show the application procedure of the proposed method to practical MAGDM issues, a numerical example about enterprise informatization level evaluation was employed to elaborate the calculation process with the proposed method. Finally, through the parameter analysis, validity analysis, and comparative analysis with some existing methods, we found that our method is more superior in providing DMs a greater decision-making freedom and relaxing the constraints on expressing personal preferences. This study provides a general framework of the proposed method to MAGDM problems under hesitant picture fuzzy environment, which enriches the fuzzy theory and its applications.

Synthesis of Axially Chiral N-Arylindoles via Atroposelective Cyclization of Ynamides Catalyzed by Chiral Brønsted Acids.

In recent years, asymmetric catalysis of ynamides has attracted much attention, but these reactions mostly constructed central chirality, except for a few examples on the synthesis of axially chiral compounds which exclusively relied on noble-metal catalysis. Herein, a facile access to axially chiral N-heterocycles enabled by chiral Brønsted acid-catalyzed 5-endo-dig cyclization of ynamides is disclosed, which represents the first metal-free protocol for the construction of axially chiral compounds from ynamides. This method allows the practical and atom-economical synthesis of valuable N-arylindoles in excellent yields with generally excellent enantioselectivities. Moreover, organocatalysts and ligands based on such axially chiral N-arylindole skeletons are demonstrated to be applicable to asymmetric catalysis.

Catalyst-Dependent Stereospecific [3,3]-Sigmatropic Rearrangement of Sulfoxide-Ynamides: Divergent Synthesis of Chiral Medium-Sized N,S-Heterocycles.

Medium-sized N,S-heterocycles have received tremendous interest due to their biological activities and potential medical applications. However, asymmetric synthesis of these compounds are extremely rare. Described herein is a catalyst-dependent [3,3]-sigmatropic rearrangement of sulfoxide-ynamides, enabling divergent and atom-economic synthesis of a series of valuable medium-sized N,S-heterocycles in moderate to good yields with broad substrate scope. Importantly, excellent enantioselectivities have been achieved via an unprecedented chirality-transfer. Moreover, theoretical calculations are employed to elucidate the origins of the catalyst-dependent stereospecific [3,3]-rearrangement.

Copper-Catalyzed Asymmetric Diyne Cyclization via [1,2]-Stevens-Type Rearrangement for the Synthesis of Chiral Chromeno[3,4-c]pyrroles.

Here, we report a copper-catalyzed asymmetric cascade cyclization/[1,2]-Stevens-type rearrangement via a non-diazo approach, leading to the practical and atom-economic assembly of various valuable chiral chromeno[3,4-c]pyrroles bearing a quaternary carbon stereocenter in generally moderate to good yields with wide substrate scope and excellent enantioselectivities (up to 99 % ee). Importantly, this protocol not only represents the first example of catalytic asymmetric [1,2]-Stevens-type rearrangement based on alkynes but also constitutes the first asymmetric formal carbene insertion into the Si-O bond.

Enantioselective Copper-Catalyzed Formal [2+1] and [4+1] Annulations of Diynes with Ketones via Carbonyl Ylides.

Carbonyl ylides have proven to be powerful synthons for the efficient construction of various valuable O-heterocycles, and the formation of carbonyl ylides by the reaction of metal carbenes with carbonyls has attracted increasing attention over the past decades. However, a catalyst-controlled highly enantioselective reaction of carbonyl ylides from metal carbenes is extremely challenging. Herein, we report a novel copper-catalyzed asymmetric formal [2+1] and [4+1] annulations of diynes with ketones via carbonyl ylides. Importantly, this protocol not only represents the first example of successful asymmetric epoxidation via carbonyl ylides, but also constitutes the first reaction of vinyl cations with carbonyl compounds. This method leads to the divergent, practical and atom-economical synthesis of a range of chiral oxiranes and dihydrofurans in moderate to excellent yields with generally excellent enantioselectivities and diastereoselectivities via remote-stereocontrol strategy.