bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Strong‐Acid‐Resistant [Th6] Cluster‐Based Framework for Effectively and Size‐Selectively Catalyzing Reductive Amination of Aldehydes with N,N‐Dimethylformamide
Authors: Tian Xue‐Rui , Jiang Zhi‐Yu , Hou Sheng‐Li , Hu Han‐Shi , Li Jun , Zhao Bin 
Published: April 2023

AbstractUtilization of N,N‐dimethylformamide (DMF) as an amine source and reductant for synthesizing tertiary amines is a promising way to replace the substrates formaldehyde and dimethylamine, and it is desirable to seek porous acid‐resistant catalysts for heterogeneous catalysis of this reaction. Herein, a robust metal–organic framework (MOF) {[Th6O4(OH)4(H2O)6(BCP)3]⋅10 DMF}n (1) containing stacked nanocages with a diameter of 1.55 nm was constructed. Compound 1 can maintain its single‐crystal structure even kept in air at 400 °C for 3 h, and in DMF or water at 200 °C for 7 days. Density functional theory (DFT) calculations suggested that the high interaction energy between the [Th6O4(OH)4(H2O)6]12+ clusters and ligands was responsible for the excellent stability of 1. Catalytic investigations revealed that 1 can effectively and size‐selectively catalyze the reductive amination of aldehydes with DMF, and it can be reused at least five times without obvious loss in catalytic activity.
Inducing Covalent Atomic Interaction in Intermetallic Pt Alloy Nanocatalysts for High‐Performance Fuel Cells
Authors: Liu Xuan , Zhao Zhonglong , Liang Jiashun , Li Shenzhou , Lu Gang , Priest Cameron , Wang Tanyuan , Han Jiantao , Wu Gang , Wang Xiaoming , Huang Yunhui , Li Qing 
Published: April 2023

AbstractThe harsh working environments of proton exchange membrane fuel cells (PEMFCs) pose huge challenges to the stability of Pt‐based alloy catalysts. The widespread presence of metallic bonds with significantly delocalized electron distribution often lead to component segregation and rapid performance decay. Here we report L10−Pt2CuGa intermetallic nanoparticles with a unique covalent atomic interaction between Pt−Ga as high‐performance PEMFC cathode catalysts. The L10−Pt2CuGa/C catalyst shows superb oxygen reduction reaction (ORR) activity and stability in fuel cell cathode (mass activity=0.57 A mgPt−1 at 0.9 V, peak power density=2.60/1.24 W cm−2 in H2‐O2/air, 28 mV voltage loss at 0.8 A cm−2 after 30 000 cycles). Theoretical calculations reveal the optimized adsorption of oxygen intermediates via the formed biaxial strain on L10−Pt2CuGa surface, and the durability enhancement stems from the stronger Pt−M bonds than those in L11−PtCu resulted from Pt−Ga covalent interactions.
Co0−Coδ+ Interface Double‐Site‐Mediated C−C Coupling for the Photothermal Conversion of CO2 into Light Olefins
Authors: Ning Shangbo , Ou Honghui , Li Yaguang , Lv Cuncai , Wang Shufang , Wang Dingsheng , Ye Jinhua 
Published: April 2023

AbstractSolar‐driven CO2 hydrogenation into multi‐carbon products is a highly desirable, but challenging reaction. The bottleneck of this reaction lies in the C−C coupling of C1 intermediates. Herein, we construct the C−C coupling centre for C1 intermediates via the in situ formation of Co0−Coδ+ interface double sites on MgAl2O4 (Co−CoOx/MAO). Our experimental and theoretical prediction results confirmed the effective adsorption and activation of CO2 by the Co0 site to produce C1 intermediates, while the introduction of the electron‐deficient state of Coδ+ can effectively reduce the energy barrier of the key CHCH* intermediates. Consequently, Co−CoOx/MAO exhibited a high C2–4 hydrocarbons production rate of 1303 μmol g−1 h−1; the total organic carbon selectivity of C2–4 hydrocarbons is 62.5 % under light irradiation with a high ratio (≈11) of olefin to paraffin. This study provides a new approach toward the design of photocatalysts used for CO2 conversion into C2+ products.
Chemo‐, Stereo‐ and Regioselective Fluoroallylation/Annulation of Hydrazones with gem‐Difluorocyclopropanes via Tunable Palladium/NHC Catalysis
Authors: Qian Huijun , Nguyen Hieu D. , Lv Leiyang , Chen Shuming , Li Zhiping 
Published: April 2023

AbstractDefluorinative manipulation of polyfluorinated molecules has shown great promise due to its granting of synthetic versatility to inert C−F bonds. The development of chemo‐, stereo‐ and regioselective strategies to realize highly efficient formation of either the linear/branched or E/Z products from gem‐difluorocyclopropanes (gem‐F2CPs) is a challenging task. Herein, we have realized palladium/NHC‐catalyzed fluoroallylation/annulation of hydrazones with gem‐F2CPs that incorporate the hydrazone N2 moiety into the products. The thermodynamically unstable fluorinated E‐allylation products with aryl ketone hydrazones were obtained for the first time, while the di‐alkyl ketone hydrazones yielded the monofluorinated products with branched selectivity under similar reaction conditions. With aldehyde hydrazones, two kinds of pyrazoles were obtained via a defluorinative allylation/annulation cascade, in which different carbon atoms of gem‐F2CPs could be incorporated into the pyrazole rings regiospecifically. DFT calculations revealed that the divergent selectivity was kinetically controlled and the final C−C bond formation proceeded through a 7‐membered TS.
Discovery of the Lanthipeptide Curvocidin and Structural Insights into its Trifunctional Synthetase CuvL
Authors: Sigurdsson Arnar , Martins Berta M. , Düttmann Simon A. , Jasyk Martin , Dimos‐Röhl Benjamin , Schöpf Felix , Gemander Manuel , Knittel Caroline H. , Schnegotzki Romina , Schmid Bianca , Kosol Simone , Pommerening Lea , Gonzáles‐Viegaz María , Seidel Maria , Hügelland Manuela , Leimkühler Silke , Dobbek Holger , Mainz Andi , Süssmuth Roderich D. 
Published: April 2023

AbstractLanthipeptides are ribosomally‐synthesized natural products from bacteria featuring stable thioether‐crosslinks and various bioactivities. Herein, we report on a new clade of tricyclic class‐IV lanthipeptides with curvocidin from Thermomonospora curvata as its first representative. We obtained crystal structures of the corresponding lanthipeptide synthetase CuvL that showed a circular arrangement of its kinase, lyase and cyclase domains, forming a central reaction chamber for the iterative substrate processing involving nine catalytic steps. The combination of experimental data and artificial intelligence‐based structural models identified the N‐terminal subdomain of the kinase domain as the primary site of substrate recruitment. The ribosomal precursor peptide of curvocidin employs an amphipathic α‐helix in its leader region as an anchor to CuvL, while its substrate core shuttles within the central reaction chamber. Our study thus reveals general principles of domain organization and substrate recruitment of class‐IV and class‐III lanthipeptide synthetases.
meta‐Selective C−H Functionalization of Pyridines
Authors: Cao Hui , Cheng Qiang , Studer Armido 
Published: April 2023

AbstractThe pyridine moiety is an important core structure for a variety of drugs, agrochemicals, catalysts, and functional materials. Direct functionalization of C−H bonds in pyridines is a straightforward approach to access valuable substituted pyridines. Compared to the direct ortho‐ and para‐functionalization, meta‐selective pyridine C−H functionalization is far more challenging due to the inherent electronic properties of the pyridine entity. This review summarizes currently available methods for pyridine meta‐C−H functionalization using a directing group, non‐directed metalation, and temporary dearomatization strategies. Recent advances in ligand control and temporary dearomatization are highlighted. We analyze the advantages as well as limitations of current techniques and hope to inspire further developments in this important area.
Rapid chemical characterization of Danggui Buxue decoction using processed Astragali Radix and Angelicae Sinensis Radix based on diagnostic ion and molecular network
Authors: Cui Xiaojing , Qin Xuemei , Du Guanhua , Liu Yuetao 
Published: April 2023

AbstractDanggui Buxue decoction (DBD), a classic prescription of traditional Chinese medicine (TCM) for invigorating qi and generating blood, contains honey‐processed Astragali Radix (HAR) and wine‐processed Angelicae Sinensis Radix (WDG) in its original prescription. In this study, the compositions of DBD, WDG, and HAR were characterized using ultra‐high‐performance liquid chromatography coupled with the quadrupole‐time‐of‐flight tandem mass spectrometry technique in combination with molecular network and diagnostic ion strategies. Finally, 200 compounds were identified in DBD, 114 compounds were identified in WDG, and 180 compounds were identified in HAR; there were 48 common compounds in total. The results demonstrated that compatibility led to changes in the chemical composition of TCM, and the qualitative method used in this study provided an effective data processing strategy for the characterization of components and the database for the study of the compounding mechanism of TCM.
Four New Polyhydroxy Cyclohexanes from the Stems of Fissistigma tientangense
Authors: Wu Mei‐Zhu , Chen Ming‐Chang , Zhang Xiao‐Zheng , Sun Chen , Chen Guang‐Ying , Yang Zi‐Han , Zheng Cai‐Juan , Luo You‐Ping , Zhou Xue‐Ming 
Published: April 2023

AbstractFour undescribed polyhydroxy cyclohexanes, fissoxhydrylenes A–D (1–4), together with two known biogenetically related polyhydroxy cyclohexanes (5 and 6) were isolated from the stems of Fissistigma tientangense Tsiang et P. T. Li. Their structures were elucidated by detailed analysis of NMR, HR‐ESI‐MS, IR, UV and Optical rotations data. The absolute configuration of 1 was confirmed by X‐ray crystallographic. The absolute configurations of 2–4 were confirmed by chemical reaction and optical rotations. Compound 4 represent the first example of a no substituent polyhydroxy cyclohexanes from natural products. All isolated compounds were evaluated for their anti‐inflammatory activities against the lipopolysaccharide‐induced nitric oxide (NO) production in mouse macrophage RAW 264.7 cells in vitro. Compounds 3 and 4 showed inhibitory activities with the IC50 values of 16.63±0.06 μM and 14.38±0.08 μM, respectively.
Factors Influencing the Chemoselectivity of Pd(OAc)2‐Catalyzed Cyclization Reactions Involving 1,6‐Enynes as a Substrate and PhI(OAc)2 as a Reagent
Authors: Shiri Farshad , Ariafard Alireza 
Published: April 2023

AbstractIt is well documented in the literature that 1,6‐enynes are cyclized using PhI(OAc)2 (PIDA) in the presence of Pd(OAc)2 as a catalyst to yield cyclopropyl ketones. In contrast, it has been reported that when 1,6‐enynes are substituted by a hydroxy group at the α‐position to the alkyne, the chemoselectivity of the cyclization reaction is altered, and polycyclic oxa‐heterocycles are formed. This suggests that the hydroxy substituent plays a crucial role in changing the mechanism of the reaction. The aim of this study is to use density functional theory (DFT) calculations at the SMD/M06‐D3/def2TZVP//SMD/M06/SDD,6‐31G(d) level of theory to shed light on the reason for this change by investigating the detailed mechanistic aspects of these transformations. This study demonstrates that the electronic nature of the Pd catalyst changes from π‐philicity to oxophilicity during the catalytic cycle, and this change plays an essential role in controlling the chemoselectivity of the cyclization reactions. In addition, it was found that (1) the hypervalent iodine reagent PIDA serves not only as an oxidant for the oxidation of Pd(II) to Pd(IV), but also as a nucleophile that drives the acetoxypalladation step of the reaction, (2) the oxidation of Pd(II) to Pd(IV) by the iodonium ion [PhIOAc]+ occurs via an interesting mechanism involving coordination of [PhIOAc]+ to the Pd(II) centre, followed by a twist in the hypervalent iodine, and (3) Pd π‐complexes are not very susceptible to oxidation. (4) A Pd(II) complex can be six coordinate if the Pd centre is partially oxidized.
Esterase Specific Fluorescent Probe: Mechanistic Understanding Using QM/MM Calculation and Cell States Discrimination
Authors: Yadav Rashmi , Munan Subrata , Kardam Vandana , Dutta Dubey Kshatresh , Samanta Animesh 
Published: April 2023

AbstractEsterases enzymes regulate the body's homeostasis by catalyzing the hydrolysis of various esters. These are also involved in protein metabolism, detoxification, and signal transmission. Most importantly, esterase plays a significant role in cell viability and cytotoxicity assays. Hence, developing an efficient chemical probe is essential for monitoring the esterase activity. Several fluorescent probes for esterase have also been reported targeting cytosol and lysosomes. However, the ability to create efficient probes is constrained due to a lack of understanding of the esterase‘s active site for hydrolyzing the substrate. In addition, the fluorescent turn‐on may limit efficient monitoring. Herein, we have developed a unique fluorescent probe, PM‐OAc, to monitor mitochondrial esterase enzyme activity ratiometrically. This probe exhibited a bathochromic wavelength shift with esterase enzyme in alkaline pH (pH∼8.0) due to an intramolecular charge transfer (ICT) process. The phenomenon is well supported by TD‐DFT calculation. Moreover, the substrate (PM‐OAc) binding at the active site of esterase and its catalytic mechanism to hydrolyze the ester bond are elucidated by molecular dynamics (MD) simulation and QM/MM (Quantum mechanics/molecular mechanics) calculations, respectively. Fluorescent image‐based analysis of the cellular environment reveals that our probe can distinguish between live and dead cells based on esterase enzyme activity.
Photoredox Synthesis of Thio‐Functionalized Cyclic Ethers Using N‐Sulfenyl Phthalimides as a Thiyl‐Radical Precursor
Authors: Lu Maojian , Liang Rong‐Bin , Zhu Can‐Ming , Tong Qing‐Xiao , Zhong Jian‐Ji 
Published: April 2023

Comprehensive SummaryA visible‐light mediated exclusively regioselective synthesis of 2,2‐disubstituted thio‐functionalized tetrahydrofurans, tetrahydro‐ pyrans and oxepanes has been described through an operationally simple and mild photoredox protocol. Thiyl radical generated from N‐phenylsulfenyl phthalimide by photoredox catalysis was proven to be the key reactive intermediate in this reaction.
Cattle preference in Paspalum atratum and its relationship with morphological and anatomical leaf characteristics
Authors: Marcón Florencia , Di Lorenzo Elio L. , Peichoto Myriam C. , Acuña Carlos A. 
Published: April 2023

AbstractNew atra paspalum (Paspalum atratum Swallen) accessions were found to be differentially grazed by cattle, without differences in herbage accumulation and nutritive value. This study aimed to evaluate cattle preference, morphological and anatomical leaf traits, and their relationships at four sampling events. Five new atra paspalum accessions and the cultivar Cambá were used. The experimental unit was a 2 m × 2 m plot. Treatments were replicated four times in a completely randomized design. Cattle preference was determined in spring (December 2016 and 2017), summer (March 2017), and autumn (May 2017) using six steers Bos spp. that grazed the plots for 4 h on two consecutive days. Plant height, leaf‐blade length, leaf‐blade width, and the proportions of five leaf tissues at three leaf regions were measured at each date. The proportion of the leaf that is curved was measured in December 2017. Cattle preference was variable among accessions and sampling events. Some accessions were shorter, with shorter and more flexible leaves than Cambá (p < 0.05). The proportion of lignified tissues was greater during the spring (2016 and 2017) and summer (7%–23%) than in the autumn. One accession had the lowest proportion of lignified tissue in the warm season (8%–12%) but the highest during the fall (around 15%). The same accession had the fewest primary vascular bundles in the warm season. Cattle preference was negatively correlated with the proportion of lignified tissues, the number of primary vascular bundles, plant height, and leaf‐blade length. Cattle preference was affected by the growing season and reduced by greater presence of leaf structural tissue.
Sustainability reporting in Africa: A systematic review and agenda for future research
Authors: Igwe Monday Nweke , Khatib Saleh F. A. , Bazhair Ayman Hassan 
Published: April 2023

AbstractThis study provides a comprehensive systematic review of the sustainability reporting research focused on Africa. Using a systematic literature review approach, we synthesized 179 high‐quality journal articles obtained from the Scopus database. The study revealed that the extent and quality of SDGs and sustainability reporting in Africa are still very low and unsatisfactory. Also, we found that the existing studies mainly concentrated on the determinants of sustainability reporting, while limited research addressed the outcomes and sustainability assurance. Furthermore, the review indicates that firms in Africa predominantly focused on reporting their economic and social impacts while paying less attention to environmental protection. The study contributes to knowledge by providing an up‐to‐date and comprehensive review of sustainability reporting studies from important research contexts such as Africa. In doing so, we offer a more nuanced understanding of sustainability research in the region. We equally identified inconsistencies, gaps, and opportunities for future research.
Organic Redox Targeting Flow Battery Utilizing a Hydrophilic Polymer and Its In‐Operando Characterization via State‐of‐Charge Monitoring of The Redox Mediator
Authors: Schröter Erik , Stolze Christian , Meyer Jakob , Hager Martin D. , Schubert Ulrich S. 
Published: April 2023

AbstractThe hydrophilic poly(2,2,6,6‐tetramethylpiperdinyloxy‐4‐yl‐methacrylamide) (PTMAm) was utilized as redox target material in an aqueous organic redox targeting flow battery (RTFB). This polymer is processed into granules, which contain a conductive agent and an alginate binder. By this, a hydrophilic, yet water‐insoluble redox target can be obtained. The target was combined with the redox mediator molecule N,N,N‐trimethyl‐2‐oxo‐2‐[(2,2,6,6‐tetramethylpiperidin‐4‐yloxyl)amino]ethan‐1‐ammonium chloride (TEMPOAmide), that has been reported earlier as flow battery active material. This target/mediator combination has been characterized electrochemically and flow battery testing has been done. Furthermore, in‐operando characterization of the redox target via electrolyte state‐of‐charge (SOC) monitoring has been performed for the first time. The approach provides estimates for the redox target's SOC changes during cycling. In addition, a figure of merit – the “redox targetivity” – is proposed, which provides insights into the efficiency of the targeting reaction and supports the future optimization of materials, cell designs, and operational parameters for RTFBs.
Continuous Flow Hydrogenation of Lignin‐model Aromatic Compounds over Carbon‐supported Noble Metals
Authors: Polidoro Daniele , Selva Maurizio , Luque Rafael 
Published: April 2023

AbstractAn efficient continuous‐flow (CF) protocol was designed for the hydrogenation of lignin‐derived aromatics to the corresponding cycloalkanes derivatives. A parametric analysis of the reaction was carried out by tuning the temperature, the H2 pressure and the flow rate, and using diphenyl ether (DPE) as a model substrate, commercial Ru/C as a catalyst, and isopropanol as a solvent: at 25 °C, 50 bar H2, and a flow rate of 0.1 mL min−1, dicyclohexyl ether was achieved in an 86 % selectivity, at quantitative conversion. By‐products from the competitive C−O bond cleavage of DPE, cyclohexanol and cyclohexane, did not exceed 14 % in total. Remarkably, prolonged experiments demonstrated an excellent stability of the catalyst whose performance was unaltered for up to 420 min of time‐of‐stream. A substrate scope evaluation proved that under the same conditions used for DPE, a variety of substrates including alkoxy‐, allyl‐, and carbonyl‐functionalized phenols, biphenyl, aryl benzyl‐ and phenethyl ethers (10 examples) yielded the ring‐hydrogenated products with selectivity up to 99 % at complete conversion.
Morphologies and potential roles of telocytes in nervous tissue
Authors: Zhang Xu , Lu Ping , Shen Xiaorong 
Published: April 2023

AbstractStructurally similar cells have been found and termed telocytes (TCs) since the first characterisation of interstitial Cajal‐like cells in 1911. TCs are a novel and peculiar interstitial cell type with a small cellular body, markedly long cell processes named telopodes and a wide distribution in numerous tissues throughout the body. Besides specific morphological characteristics and immunohistochemical profiles, TCs build three‐dimensional mixed networks through homocellular (connection to each other) and/or heterocellular contacts (connection with other cell types), interaction with extracellular matrix and their vicinity to nerve endings, and thus might play, as part of an integrated system, roles in maintaining organ/tissue function. In this mini‐review, we summarise physical properties, general characteristics and distribution of TCs in diverse organs and tissues, focusing on their potential functions in nervous tissue and current challenges in investigating TCs as a distinct cell type.
Portable smartphone‐based microfluidic electrochemical immunosensor for ultrasensitive detection of alpha‐fetoprotein in human serum
Authors: Shen Yanyun , Lu Wenhui , Fu Tengfei , Zhang Keying , Zhuo Xin , Wang Hongyan , Liu Chao , Xie Xusheng , Zhang Qing , Ma Shangshang 
Published: April 2023

AbstractRapid and accurate tracing of biomarkers is essential for early detecting and diagnosing of cancer. Therefore, a valid and convenient strategy needs to be developed for efficient monitoring of cancer biomarkers. Herein, we constructed a portable microfluidic electrochemical immunosensor based on three‐dimensional reduced graphene oxide (3D rGO) doped with gold nanoparticles (Au NPs) for ultrasensitive determination of alpha‐fetoprotein (AFP). The designed microfluidic chip, with the advantages of small injection volume, detachable structure and high integration, was fabricated by 3D printing, which only needed 9 μL of reagent to realize the high sensitivity detection. In addition, the 3D Au NPs‐rGO composites with high specific surface area and electrons transfer capacity can effectively increase electroactive sites and enhance electrochemical signals. Benefiting from these features, the 3D Au NPs‐rGO microfluidic electrochemical immunochip showed a wide detection range between 0.1 pg/mL–200 ng/mL and a best detection limit of 0.045 pg/mL with the high sensitivity of 175.008 μA (ng/mL)−1 cm−2. Meanwhile, the proposed immunosensor exhibited reliable AFP detection in human serum samples, which demonstrated that this portable smartphone‐based microfluidic electrochemical immunosensor hold great promises in clinical detection and huge potential in personalized healthcare.