bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 2‐Aryl‐(3‐Organochalcogenyl)Thieno[2,3‐b]Pyridines Promoted by Oxone®
Authors: Peglow Thiago J. , Bartz Ricardo H. , Barcellos Thiago , Schumacher Ricardo F. , Cargnelutti Roberta , Perin Gelson 
Published: April 2021

AbstractWe describe herein an alternative method for the synthesis of 2‐aryl‐(3‐organochalcogenyl)thieno[2,3‐b]pyridines through the electrophilic cyclization of 3‐(arylethynyl)‐2‐(alkylthio)pyridines promoted by electrophilic species of organochalcogen compounds. These species were generated in situ by the oxidative cleavage of chalcogen‐chalcogen (Se, Te) bond of diorganyl dichalcogenides using Oxone® in ethanol as solvent in an open‐flask at 78 °C. The protocol allowed the synthesis of highly substituted thieno[2,3‐b]pyridines starting from several diorganyl dichalcogenides and 3‐(arylethynyl)‐2‐(alkylthio)pyridines, obtaining 21 new compounds in good to excellent yields (70–99%). Still, the method showed good efficiency on the gram‐scale synthesis. In addition, several synthetic transformations such as oxidation, selenylation and hydrogenation reactions were demonstrated.
Regenerable Radical‐Trapping and Preventive Selenazolonamine Antioxidants
Authors: Kumar Manish , Yadav Manisha , Chhillar Babli , Singh Vijay P. 
Published: April 2021

AbstractSelenazolonamines 10 a–d with free amine (‐NH2) group, a new series of preventive and radical‐trapping antioxidants were synthesized from their corresponding diselenides. The radical‐trapping antioxidant capacity of compounds 10 a–d was determined in a chlorobenzene/water membrane‐like model system in which azo‐initiated peroxidation of linoleic acid was carried out in the lipid phase. The regeneration occurred in the aqueous ascorbic acid as co‐antioxidant, which could regenerate the antioxidants and enhance their inhibition times. The best antioxidant 10 d substituted with para‐NMe2 a strong electron‐donating group quenched the peroxyl radicals more efficiently than α‐tocopherol almost 5.5‐fold longer inhibition time. The novel selenazolonamines 10 a–d and their derivatives exhibited good preventive i. e. glutathione peroxidase‐like activity in the coupled reductase assay. Based on 77Se NMR spectroscopy, a catalytic cycle for 10 d, involving diselenide, selenosulfide, and selenol as intermediates was proposed. The mechanism for quenching of peroxyl radicals for 10 d was also considered to be involved via proton‐coupled electron transfer reaction.
Photo‐Induced Arylation of Carbazoles With Aryldiazonium Salts
Authors: Maeda Bumpei , Mori Genki , Sakakibara Yota , Yagi Akiko , Murakami Kei , Itami Kenichiro 
Published: April 2021

AbstractArylcarbazoles have been widely used in materials science as important organic semiconductor molecules. To investigate the electronic and photophysical properties of arylcarbazole with different substitution patterns, facile and straightforward synthesis of arylcarbazole derivatives is sought after. Herein we report on photo‐induced direct arylation reactions of carbazole. Treatment of carbazoles with aryldiazonium salts afforded the arylated carbazole. Although the reaction was not regioselective, C1 and C4‐arylated carbazoles were obtained as the major isomers. When N‐pyridylcarbazole was employed as the substrate with palladium catalyst, the reaction proceeded selectively at C1 position.
Katalytische Oxygenierung von Kohlenwasserstoffen durch Mono‐μ‐oxo‐Dikupfer(II)‐Spezies erzeugt durch O‐O‐Spaltung von tetranuklearen CuI/CuII‐Peroxo‐Komplexen
Authors: Jurgeleit Ramona , Grimm‐Lebsanft Benjamin , Flöser Benedikt Maria , Teubner Melissa , Buchenau Sören , Senft Laura , Hoffmann Jonas , Naumova Maria , Näther Christian , Ivanović‐Burmazović Ivana , Rübhausen Michael , Tuczek Felix 
Published: April 2021

AbstractEine der Herausforderungen der Katalyse ist die Transformation inerter C‐H‐Bindungen in nützliche Produkte. Kupferhaltige Monooxygenasen spielen hier eine wichtige Rolle. Wir zeigen, dass die Tieftemperatur‐Oxygenierung zweikerniger Kupfer(I)‐Komplexe zu tetranuklearen, gemischtvalenten μ4‐Peroxo‐[CuI/CuII]2‐Komplexen führt. Diese Cu4O2‐Intermediate erfahren eine irreversible, thermisch aktivierte O‐O‐Bindungsspaltung, wobei Cu2O‐Komplexe entstehen, die eine stark exotherme H‐Atom‐Abstraktion von Kohlenwasserstoffen, gekoppelt an einen O‐Transfer, katalysieren. Die Cu2O‐Spezies können auch mit N2O erzeugt werden, was ihr Potential zur Aktivierung kleiner Moleküle zeigt. Die Bindung und Spaltung von O2, die zu den primären Cu4O2‐Intermediaten bzw. ‐Komplexen führt, wird mit lösungsspektroskopischen Methoden und Massenspektrometrie aufgeklärt. Die Reaktivitäten dieser Spezies etablieren ein neues, zu 100 % atomökonomisches Szenario für die katalytische, kupfervermittelte Monooxygenierung organischer Substrate, bei dem beide O‐Atome von O2 eingebaut werden.
pH‐Amplified CRET Nanoparticles for In Vivo Imaging of Tumor Metastatic Lymph Nodes
Authors: Wang Zenghui , Xia Heming , Chen Binlong , Wang Yaoqi , Yin Qingqing , Yan Yue , Yang Ye , Tang Mingmei , Liu Jianxiong , Zhao Ruiyang , Li Wenzhe , Zhang Qiang , Wang Yiguang 
Published: April 2021

AbstractNoninvasive imaging strategies have been extensively investigated for in vivo mapping of sentinel lymph nodes (SLNs). However, the current imaging strategies fail to accurately assess tumor metastatic status in SLNs with high sensitivity. Here we report pH‐amplified self‐illuminating near‐infrared nanoparticles, which integrate chemiluminescence resonance energy transfer (CRET) and signal amplification strategy, enabling accurate identification of metastatic SLNs. After draining into lymph nodes, the nanoparticles were phagocytosed and dissociated in acidic phagosomes of inflammatory macrophages to emit near‐infrared luminescent light. Using these nanoparticles, we successfully differentiated tumor metastatic lymph nodes from benign ones. These nanoparticles also exhibited excellent imaging capability for early detection of metastatic SLNs in diverse animal tumor models with small tumor volume (100–200 mm3).
ZW800‐PEG: A Renal Clearable Zwitterionic Near‐Infrared Fluorophore for Potential Clinical Translation
Authors: Yang Chengeng , Wang Haoran , Yokomizo Shinya , Hickey Morgan , Chang Hyejin , Kang Homan , Fukuda Takeshi , Song Mi Young , Lee Sang Yeul , Park Jin Woo , Bao Kai , Choi Hak Soo 
Published: April 2021

AbstractNear‐infrared (NIR) fluorescence imaging has advanced medical imaging and image‐guided interventions during the past three decades. Despite tremendous advances in imaging devices, surprisingly only a few dyes are currently available in the clinic. Previous fluorophores, ZW800‐1A and ZW800‐1C, significantly improved the poor performance of the FDA‐approved indocyanine green. However, ZW800‐1A is not stable in serum and ZW800‐1C induces severe stacking in aqueous media. To solve such dilemmas, ZW800‐PEG was designed by introducing a flexible yet stable thiol PEG linker. ZW800‐PEG shows high solubility in both aqueous and organic solvents, thus improving renal clearance with minimal binding to serum proteins during systemic circulation. The sulfide group on the meso position of the heptamethine core improves serum stability and physicochemical properties including the maximum emission wavelength shift to 800 nm, enabling the use of ZW800‐PEG for image‐guided interventions and augmenting photothermal therapy.
Iron‐Catalyzed Wacker‐type Oxidation of Olefins at Room Temperature with 1,3‐Diketones or Neocuproine as Ligands**
Authors: Puls Florian , Linke Philipp , Kataeva Olga , Knölker Hans‐Joachim 
Published: April 2021

AbstractHerein, we describe a convenient and general method for the oxidation of olefins to ketones using either tris(dibenzoylmethanato)iron(III) [Fe(dbm)3] or a combination of iron(II) chloride and neocuproine (2,9‐dimethyl‐1,10‐phenanthroline) as catalysts and phenylsilane (PhSiH3) as additive. All reactions proceed efficiently at room temperature using air as sole oxidant. This transformation has been applied to a variety of substrates, is operationally simple, proceeds under mild reaction conditions, and shows a high functional‐group tolerance. The ketones are formed smoothly in up to 97 % yield and with 100 % regioselectivity, while the corresponding alcohols were observed as by‐products. Labeling experiments showed that an incorporated hydrogen atom originates from the phenylsilane. The oxygen atom of the ketone as well as of the alcohol derives from the ambient atmosphere.
Oxygen‐Linked Cyclopentadienyl Rhodium(III) Complexes‐Catalyzed Asymmetric C−H Arylation of Benzo[h]quinolines with 1‐Diazonaphthoquinones
Authors: Pan Chongqing , Yin Si‐Yong , Wang Shao‐Bo , Gu Qing , You Shu‐Li 
Published: April 2021

AbstractChiral cyclopentadienyl rhodium (CpRh) complex‐catalyzed asymmetric C−H functionalization reactions have witnessed a significant progress in organic synthesis. In sharp contrast, the reported chiral Cp ligands are limited to C‐linked Cp and are often synthetically challenging. To address these issues, we have developed a novel class of tunable chiral cyclopentadienyl ligands bearing oxygen linkers, which were efficient catalysts for C−H arylation of benzo[h]quinolines with 1‐diazonaphthoquinones, affording axially chiral heterobiaryls in excellent yields and enantioselectivity (up to 99 % yield, 98.5:1.5 er). Mechanistic studies suggest that the reaction is likely to proceed by electrophilic C−H activation, and followed by coupling of the cyclometalated rhodium(III) complex with 1‐diazonaphthoquinones.
Highly Stable Single Crystals of Three‐Dimensional Porous Oligomer Frameworks Synthesized under Kinetic Conditions
Authors: Hou Linxiao , Shan Chuan , Song Yanpei , Chen Sifan , Wojtas Lukasz , Ma Shengqian , Sun Qi , Zhang Lin 
Published: April 2021

AbstractVarious robust, crystalline, and porous organic frameworks based on in situ‐formed imine‐linked oligomers were investigated. These oligomers self‐assembled through collaborative intermolecular hydrogen bonding interactions via liquid–liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks. The sequential formation of robust covalent linkages and highly reversible hydrogen bonds enforced long‐range symmetry and facilitated the production of large single crystals, with structures that were unambiguously determined by single‐crystal X‐ray diffraction. The unique hierarchical arrangements increased the steric hindrance of the imine bond, which prevented attacks from water molecules, greatly improving the stability. The multiple binding sites in the frameworks enabled rapid sequestration of micropollutant in water.
Development of Continuous Flow Systems to Access Secondary Amines Through Previously Incompatible Biocatalytic Cascades**
Authors: Mattey Ashley P. , Ford Grayson J. , Citoler Joan , Baldwin Christopher , Marshall James R. , Palmer Ryan B. , Thompson Matthew , Turner Nicholas J. , Cosgrove Sebastian C. , Flitsch Sabine L. 
Published: April 2021

AbstractA key aim of biocatalysis is to mimic the ability of eukaryotic cells to carry out multistep cascades in a controlled and selective way. As biocatalytic cascades get more complex, reactions become unattainable under typical batch conditions. Here a number of continuous flow systems were used to overcome batch incompatibility, thus allowing for successful biocatalytic cascades. As proof‐of‐principle, reactive carbonyl intermediates were generated in situ using alcohol oxidases, then passed directly to a series of packed‐bed modules containing different aminating biocatalysts which accordingly produced a range of structurally distinct amines. The method was expanded to employ a batch incompatible sequential amination cascade via an oxidase/transaminase/imine reductase sequence, introducing different amine reagents at each step without cross‐reactivity. The combined approaches allowed for the biocatalytic synthesis of the natural product 4O‐methylnorbelladine.
Enantioselective Total Synthesis of Berkeleyone A and Preaustinoids
Authors: Zhang Yang , Ji Yunpeng , Franzoni Ivan , Guo Chuning , Jia Hongli , Hong Benke , Li Houhua 
Published: April 2021

AbstractHerein we report the first enantioselective total synthesis of 3,5‐dimethylorsellinic acid‐derived meroterpenoids (−)‐berkeleyone A and its five congeners ((−)‐preaustinoids A, A1, B, B1, and B2) in 12–15 steps, starting from commercially available 2,4,6‐trihydroxybenzoic acid hydrate. Based upon the recognition of latent symmetry within D‐ring, our convergent synthesis features two critical reactions: 1) a symmetry‐breaking, diastereoselective dearomative alkylation to assemble the entire carbon core, and 2) a Sc(OTf)3‐mediated sequential Krapcho dealkoxycarbonylation/carbonyl α‐tert‐alkylation to forge the intricate bicyclo[3.3.1]nonane framework. We also conducted our preliminary biomimetic investigations and uncovered a series of rearrangements (α‐ketol, α‐hydroxyl‐β‐diketone, etc.) responsible for the biomimetic diversification of (−)‐berkeleyone A into its five preaustinoid congeners.
Large‐Area Crystalline Zeolitic Imidazolate Framework Thin Films
Authors: Chen Zhi , Wang Rui , Ma Tao , Wang Jin‐Long , Duan Yu , Dai Zhi‐Zhan , Xu Jie , Wang Hui‐Juan , Yuan Jiayin , Jiang Hai‐Long , Yin Yue‐Wei , Li Xiao‐Guang , Gao Min‐Rui , Yu Shu‐Hong 
Published: April 2021

AbstractWe report that continuous MOF films with highly controlled thickness (from 44 to 5100 nm) can be deposited over length scales greater than 80 centimeters by a facile, fast, and cost‐effective spray‐coating method. Such success relies on our discovery of unprecedented perfectly dispersed colloidal solutions consisting of amorphous MOF nanoparticles, which we adopted as precursors that readily converted to the crystalline films upon low‐temperature in situ heating. The colloidal solutions allow for the fabrication of compact and uniform MOF films on a great deal of substrates such as fluorine‐doped tin oxide, glass, SiO2, Al2O3, Si, Cu, and even flexible polycarbonate, widening their technological applications where substrates are essential. Despite the present work focuses on the fabrication of uniform cobalt‐(2‐methylimidazole)2 and zinc‐(2‐methylimidazole)2 films, our findings mark a great possibility in producing other high‐quality MOF thin films on a large scale.
Polysulfates Block SARS‐CoV‐2 Uptake through Electrostatic Interactions**
Authors: Nie Chuanxiong , Pouyan Paria , Lauster Daniel , Trimpert Jakob , Kerkhoff Yannic , Szekeres Gergo Peter , Wallert Matthias , Block Stephan , Sahoo Anil Kumar , Dernedde Jens , Pagel Kevin , Kaufer Benedikt B. , Netz Roland R. , Ballauff Matthias , Haag Rainer 
Published: April 2021

AbstractHere we report that negatively charged polysulfates can bind to the spike protein of SARS‐CoV‐2 via electrostatic interactions. Using a plaque reduction assay, we compare inhibition of SARS‐CoV‐2 by heparin, pentosan sulfate, linear polyglycerol sulfate (LPGS) and hyperbranched polyglycerol sulfate (HPGS). Highly sulfated LPGS is the optimal inhibitor, with an IC50 of 67 μg mL−1 (approx. 1.6 μm). This synthetic polysulfate exhibits more than 60‐fold higher virus inhibitory activity than heparin (IC50: 4084 μg mL−1), along with much lower anticoagulant activity. Furthermore, in molecular dynamics simulations, we verified that LPGS can bind more strongly to the spike protein than heparin, and that LPGS can interact even more with the spike protein of the new N501Y and E484K variants. Our study demonstrates that the entry of SARS‐CoV‐2 into host cells can be blocked via electrostatic interactions, therefore LPGS can serve as a blueprint for the design of novel viral inhibitors of SARS‐CoV‐2.
Lewis Base–Brønsted Acid–Enzyme Catalysis in Enantioselective Multistep One‐Pot Syntheses
Authors: Mantel Marvin , Giesler Markus , Guder Marian , Rüthlein Elisabeth , Hartmann Laura , Pietruszka Jörg 
Published: April 2021

AbstractEstablishing one‐pot, multi‐step protocols combining different types of catalysts is one important goal for increasing efficiency in modern organic synthesis. In particular, the high potential of biocatalysts still needs to be harvested. Based on an in‐depth mechanistic investigation of a new organocatalytic protocol employing two catalysts {1,4‐diazabicyclo[2.2.2]octane (DABCO); benzoic acid (BzOH)}, a sequence was established providing starting materials for enzymatic refinement (ene reductase; alcohol dehydrogenase): A gram‐scale access to a variety of enantiopure key building blocks for natural product syntheses was enabled utilizing up to six catalytic steps within the same reaction vessel.
Coating the Right Polymer: Achieving Ideal Metal–Organic Framework Particle Dispersibility in Polymer Matrixes Using a Coordinative Crosslinking Surface Modification Method
Authors: Li Conger , Liu Junhong , Zhang Kexin , Zhang Songwei , Lee Yongjin , Li Tao 
Published: April 2021

AbstractThis work describes the first generalizable method to modify various metal–organic framework (MOF) surfaces with polyimide, polysulfone, polycarbonate, and polymer of intrinsic microporosity‐1 (PIM‐1). The method first utilizes electrostatic adsorption to rapidly decorate positively charged MOF surfaces with a layer of negatively charged metal‐organic nanocapsule, PgC5Cu. After mixing with the polymer, the copper open metal sites on PgC5Cu can coordinatively crosslink the polar functional groups on the surface polymer upon thermal activation thereby resulting in the immobilization of a uniform sub‐10 nm polymer coating. We quantitatively analyzed the distribution of free path spacing between MOF particles and demonstrated that when the surface polymer matches the matrix polymer, the MOF dispersion was not only visually improved but also found to align perfectly with a theoretically predicted ideal dispersion model where no aggregation driving force was present.
Impact behavior of aminosilane functionalized nanosilica based shear thickening fluid impregnated Kevlar fabrics
Authors: Katiyar Ajay , Nandi Tandra , Prasad N. Eswara 
Published: April 2021

AbstractIn the present work, two types of shear thickening fluids have been synthesized by using neat and aminosilane functionalized silica nanoparticles and their viscosity curves have been obtained by the rheometer. Based on the values of peak viscosity of synthesized shear thickening fluids, the surface functionalized nanosilica based shear thickening fluid has been chosen as a best candidate due to the high viscosity for impregnation into the neat Kevlar of different layers viz. four (04) and eight (08) layers for velocity impact study. The experimental investigations reveal high energy absorption of shear thickening fluid impregnated Kevlar as compared to the neat Kevlar. The maximum energy absorption 62 J is achieved corresponding to the initial velocity 154 m∙s−1 for 08 layers shear thickening fluid impregnated Kevlar specimen. The data have also been analytically determined and validated with the experimental data. The experimental data have good agreement with the analytical data within the accuracy of around 15 to 20%. The present findings can have significant inferences towards the fabrication of shear thickening fluids using nanomaterials for numerous applications such as soft armors, dampers, nanofinishing and so forth.
Transcriptomic analysis of diapause‐associated genes in Exorista civilis Rondani (Diptera:Tachinidae)
Authors: Zhang Bo , Han Hai‐Bin , Xu Lin‐Bo , Li Yan‐Ru , Song Mi‐Xia , Liu Ai‐Ping 
Published: April 2021

AbstractExorista civilis Rondani (Diptera:Tachinidae) is an excellent dominant parasitic enemy all over the world. But there has been a lack of research on the molecular regulation of diapause in E. civilis. To investigate the important diapause‐associated genes and metabolic pathways in E. civilis, we can provide a theoretical basis for clarifying the molecular mechanism of diapause at the transcriptome level. The Illumina HiSeq. 2000 platform was used to perform transcriptome sequencing and bioinformatics analysis of the non‐diapause and diapause pupae of E. civilis. 58,050 unigenes were successfully assembled, in which 4355 upregulated and 3158 downregulated unigenes were differentially expressed. Moreover, by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichments, 896 kinds of the differentially expressed genes were specifically analyzed and showed that diapause‐associated genes were related to be involved in the pathways of cold resistance, amino acid metabolism, and energy metabolism. Furthermore, these upregulated five genes showed the same trends of expression patterns between quantitative real‐time polymerase chain reaction and RNA‐Seq. This study provides a theoretical basis for the further study of the diapausing molecular mechanisms of E. civilis.
Induction of diapause by clock proteins period and timeless via changes in PTTH and ecdysteroid titer in the sugar beet moth, Scrobipalpa ocellatella (Lepidoptera: Gelechiidae)
Authors: Ahmadi Fatemeh , Mikani Azam , Moharramipour Saeid 
Published: April 2021

AbstractThe sugar beet moth, Scrobipalpa ocellatella (Boyd), one of the most severe sugar beet pests, causes quantitative and qualitative yield losses late in the autumn. Previously, it was shown that low temperature and short‐day photoperiod together cause diapause induction in pupae. Here, the interaction of the critical elements of the diapause induction, including the period (PER), timeless (TIM), prothoracicotropic hormone (PTTH), and ecdysteroid titer, were investigated. Immunohistochemistry results showed that the number of period immunoreactivity (PER‐ir) and TIM‐ir cells in nondiapause pupae (NDP) was lower than in the brain of the diapause pupae (DP). Moreover, the number of PER‐ir and TIM‐ir cells in the protocerebrum and optic lobe (OL) of NDP was lower than DP. Moreover, lower PTTH content in the brain and hemolymph of DP was confirmed by competitive enzyme‐linked immunosorbent assay. Enzyme immunoassay showed a lower 20‐hydroxyecdysone (20E) titer in the hemolymph of the DP compared with the NDP. Within a short‐day condition, PER and TIM titers increased in the brain leading to decreasing PTTH titers in the brain and hemolymph that caused decreasing 20E titer in the hemolymph, leading to the induction of diapause. This study suggests that PER and TIM could be one of the brain factors that play an essential role in regulating diapause in S. ocellatella.
Dynamics of heat shock protein responses to thermal stress changes after metamorphosis in a lepidopteran insect
Authors: Su Yaozong , Li Xiangrui , Zhang Wei , Zhang Bo , Ma Chun‐Sen 
Published: April 2021

AbstractIn the last decade, unexpected high temperatures have been frequent in spring and early summer. Numerous studies have shown that such thermal stress has substantial effects on life‐history traits that influence fitness of insects, but few have examined expression dynamics of heat shock proteins (Hsps) across developmental stages, especially as regards potential carry‐over effects at the transcriptional level across metamorphosis. We exposed pupae of the oriental fruit moth (“OFM,” Grapholita molesta Busck) to mild heat stress (38°C, 6 h) and then quantified expression patterns of six Hsps (Hsp90, 70, 60, 40, 21, and 11) from pupal through adult stages. Almost all Hsps showed a higher expression immediately after pupae were heat‐stressed, but later dropped to normal levels after metamorphosis. Although upregulation of Hsps is transient and the effects carry over longer to early adult stage, upregulation will nonetheless have positive effects on adult fitness. The fitness of some insects may benefit from higher expression of chaperon genes after mild stress, in the form of higher fecundity and longer lifespan, as a carry‐over effect. These results suggest that mild thermal stress can change genetic expression that later boosts adult fitness through a cascade effect.