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1.
ACS Nano ; 15(9): 13901-13923, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34516074

RESUMO

The increasing demand for wearable electronic devices necessitates flexible batteries with high stability and desirable energy density. Flexible lithium-sulfur batteries (FLSBs) have been increasingly studied due to their high theoretical energy density through the multielectron chemistry of low-cost sulfur. However, the implementation of FLSBs is challenged by several obstacles, including their low practical energy density, short life, and poor flexibility. Various graphene-based materials have been applied to address these issues. Graphene, with good conductivity and flexibility, exhibits synergistic effects with other active/catalytic/flexible materials to form multifunctional graphene-based materials, which play a pivotal role in FLSBs. This review summarizes the recent progress of graphene-based materials that have been used as various FLSB components, including cathodes, interlayers, and anodes. Particular attention is focused on the precise nanostructures, graphene efficacy, interfacial effects, and battery layout for realizing FLSBs with good flexibility, energy density, and cycling stability.

2.
Molecules ; 26(12)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207751

RESUMO

In this review, we present an assessment of recent advances in alkyne functionalization reactions, classified according to different classes of recyclable catalysts. In this work, we have incorporated and reviewed the activity and selectivity of recyclable catalytic systems such as polysiloxane-encapsulated novel metal nanoparticle-based catalysts, silica-copper-supported nanocatalysts, graphitic carbon-supported nanocatalysts, metal organic framework (MOF) catalysts, porous organic framework (POP) catalysts, bio-material-supported catalysts, and metal/solvent free recyclable catalysts. In addition, several alkyne functionalization reactions have been elucidated to demonstrate the success and efficiency of recyclable catalysts. In addition, this review also provides the fundamental knowledge required for utilization of green catalysts, which can combine the advantageous features of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis.

3.
ACS Appl Mater Interfaces ; 13(16): 18627-18637, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33826284

RESUMO

Flexible lithium-air batteries (FLABs) with ultrahigh theoretical energy density are considered as the most promising energy storage devices for next-generation flexible and wearable electronics. However, their practical application is seriously hindered by various obstacles, including bulky and rigid electrodes, instability/low conductivity of electrolytes, and especially, the inherent semi-open structure. When operated in ambient air, moisture penetrated from an air cathode inevitably corrodes a Li metal anode, and most of the reported FLABs can only work under a pure oxygen or specific air (relative humidity: <40%) atmosphere, which cannot be regarded as a real "lithium-air battery". Herein, the author designed an innovative battery configuration by the synergy of a 3D open-structured Co3O4@MnO2 cathode and an integrated structure: a composite lithium anode encased in a gel electrolyte. A composite lithium anode fabricated through a simple, low-cost, and effective rolling method significantly relieves the fatigue fracture of the lithium electrode. Subsequently, an in situ-formed gel electrolyte encloses the composite lithium electrode, which not only reduces the electrode/electrolyte interfacial resistance but also acts as a protective layer, effectively preventing the lithium anode from corrosion. Consequentially, the battery can achieve more than 100 stable cycles in ambient air with a high relative humidity of 50%. To our surprise, the FLAB remains operational under extreme conditions, such as bending, twisting, clipping, and even soaking in water, demonstrating widespread applications in flexible electronics.

4.
J Org Chem ; 85(9): 6181-6187, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32242417

RESUMO

A highly efficient benzylic hydroperoxidation has been realized through a visible-light-induced Csp3-H activation. We believe that this reaction undergoes a direct HAT mechanism catalyzed by eosin Y. This approach features the use of a metal-free catalyst (eosin Y), an energy-economical light source (blue LED), and a sustainable oxidant (molecular oxygen). Primary, secondary, and tertiary hydroperoxides as well as silyl, benzyl, and acyl peroxides were successfully prepared with good yields and excellent functional group compatibility.

5.
Org Lett ; 21(18): 7450-7454, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31508970

RESUMO

Rare-earth catalysis has become a hot topic in the field of catalytic organic reaction. Chain ethers mostly have lower reactivity and lower boiling points which limited their reaction scope. Herein, we found a rare-earth Y(OTf)3 can catalyze the coupling reaction of ethers especially chain ethers and thioethers with azaarenes. This protocol features simple operations, a broad substrate scope (31 examples), moderate to good yields (up to 85%), and atom economy.

6.
Molecules ; 23(8)2018 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-30060483

RESUMO

Amino-bridged gel polymer P1 was discovered to catalyze alkyne halo-functionalization in excellent yields, regioselectivity, functional group compatibility, and recyclability. We have observed that both aromatic and aliphatic alkynes can be converted to α,α-dihalogenated ketones in the presence of polymer P1 under metal-free conditions at room temperature within a short reaction time.


Assuntos
Alcinos/química , Cetonas/síntese química , Polímeros/química , Catálise , Halogenação , Cetonas/química , Estrutura Molecular , Reciclagem , Estereoisomerismo
7.
J Org Chem ; 83(15): 7559-7565, 2018 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-29986581

RESUMO

Since carboxylic acid derivatives are commercially available, nontoxic, cheap, and normally stable to air and moisture, carboxylic acid derivatives are ideal reactants for synthetic strategy. In recent years, decarboxylative oxidative coupling reactions, which normally involve direct C-H bond activation, have attracted more and more interest from the synthetic community. Compared with conventional methods, this strategy is more environmentally friendly and step-economic. This review mainly focuses on recent advances of the decarboxylative oxidative coupling reaction.

8.
Proc Natl Acad Sci U S A ; 114(38): 10125-10130, 2017 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-28864533

RESUMO

The polycomb repressive complex 2 (PRC2) histone methyltransferase plays a central role in epigenetic regulation in development and in cancer, and hence to interrogate its role in a specific developmental transition, methods are needed for disrupting function of the complex with high temporal and spatial precision. The catalytic and substrate recognition functions of PRC2 are coupled by binding of the N-terminal helix of the Ezh2 methylase to an extended groove on the EED trimethyl lysine binding subunit. Disrupting PRC2 function can in principle be achieved by blocking this single interaction, but there are few approaches for blocking specific protein-protein interactions in living cells and organisms. Here, we describe the computational design of proteins that bind to the EZH2 interaction site on EED with subnanomolar affinity in vitro and form tight and specific complexes with EED in living cells. Induction of the EED binding proteins abolishes H3K27 methylation in human embryonic stem cells (hESCs) and at all but the earliest stage blocks self-renewal, pinpointing the first critical repressive H3K27me3 marks in development.


Assuntos
Simulação por Computador , Histonas/metabolismo , Células-Tronco Embrionárias Humanas/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Histonas/química , Células-Tronco Embrionárias Humanas/citologia , Humanos , Metilação , Complexo Repressor Polycomb 2/química
9.
Org Lett ; 18(23): 5986-5989, 2016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27934364

RESUMO

The first example of a metal-free unactivated C(sp3)-H bond functionalization of alkyl nitriles with terminal vinylarenes to provide γ-ketonitrile derivatives is described. This protocol features simple operations, a broad substrate scope, and atom and step economy. In addition, Cu-catalyzed C(sp3)-H bond functionalization of azodiisobutyronitrile (AIBN) and analogues with terminal vinylarenes to generate γ-ketonitriles was also studied. A preliminary free-radical pathway was confirmed by capturing an alkyl radical, and a conjugate system was found that can stabilize radical intermediates and be in favor of this transformation. Density functional theory (DFT) calculations also provide important evidence of the free-radical pathway.

10.
Org Lett ; 18(19): 4970-4973, 2016 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-27635983

RESUMO

A de novo asymmetric total synthesis of the macrolide natural product (S)-phoracantholide J has been achieved in 10 steps from the commodity chemicals (1-pentyne, ethyl acrylate, acetaldehyde, and hydrogen). The asymmetry of the route was introduced by a Noyori reduction of a 3-yn-2-one, which makes the route equally amenable to the synthesis of either enantiomer. In addition, this route relies upon an alkyne zipper, a hydroalkynylation, and a macrolactonization to complete the synthesis.


Assuntos
Produtos Biológicos/síntese química , Técnicas de Química Sintética/métodos , Macrolídeos/síntese química , Animais , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Catálise , Macrolídeos/química , Macrolídeos/isolamento & purificação , Compostos Organometálicos/química , Paládio/química , Rutênio/química , Estereoisomerismo
11.
Sci Rep ; 6: 20163, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26832822

RESUMO

A controlled new oxidant sulfate radical anion (SO4(·-)) was found and it can be easily prepared by mixing Na2S2O4 and TBHP with stirring. In this new metal-free oxidation system (Na2S2O4/TBHP), SO4(·-) can be used as a controllable oxidant to oxidize various aromatic alcohols to the corresponding aldehydes in good yields without any acid formation at room temperature. SO4(·-) was determined by a DMPO (5,5-dimethyl-1-pyrroline-N-oxide) spin-trapping EPR method at room temperature on a Bruker E500 spectrometer and the results suggested that SO4(·-) was generated in this transformation.

12.
Tetrahedron ; 72(18): 2280-2286, 2016 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-29445247

RESUMO

The de novo asymmetric total syntheses of daumone 1, daumone 3 along with 5 new analogs are described. The key steps of our approach are: the diastereoselective palladium catalyzed glycosylation reaction; the Noyori reduction of 2-acetylfuran and an ynone, which introduce the absolute stereochemistry of the sugar and aglycon portion of daumone; and an Achmatowicz rearrangement, an epoxidation and a ring opening installing the remaining asymmetry of daumone. The synthetic daumones 1 and 3 as well as related analogs were evaluated for dauer activity in C. elegans and for effects on hatching of the related nematode H. glycines. This data provides additional structure activity relationships (SAR) that further inform the study of nematode signaling.

13.
Mol Divers ; 20(2): 551-6, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26470864

RESUMO

Bioactive tricyclic quinazolines class of 3,4-dihydro-1H-pyrimido[2,1-b]quinazolin-6(2H)-ones I and 2,3-dihydroimidazo[2,1-b]quinazolin-5(1H)-ones II were synthesized by the formic acid-catalyzed intramolecular cyclization of 3-(2-aminoalkyl)-2-(phenylamino)quinazolin-4(3H)-ones 1 in high yields. A plausible mechanism of the cyclization step is proposed.


Assuntos
Quinazolinonas/química , Quinazolinonas/síntese química , Catálise , Técnicas de Química Sintética , Ciclização
14.
Sci Rep ; 5: 18391, 2015 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-26681470

RESUMO

A novel and convenient copper (II) bromide and 1,8-diazabicyclo[5.4.1]undec-7-ene (DBU) or 1,10-phenanthroline catalysis protocol for the construction of α-alkyl-ß-keto sulfones via C(sp(3))-H bond functionalization followed by C(sp(3))-S bond formation between aryl ketones and sodium sulfinates at room temperature has been developed. This method is applicable to a wide range of aryl ketones and sodium sulfinates. The electronic effects of aryl ketones and ligands effects of the copper salts are crucial for this transformation. Typically, substituted aryl ketones with electron-withdrawing group do not need any ligand to give a good to excellent yield, while substituted aryl ketones with electron-donating group and electron-rich heteroaromatic ketones offer a good to excellent yield only under the nitrogen-based ligands. The practical value of this transformation highlights the efficient and robust one-pot synthesis of α-alkyl-ß-keto sulfones.

15.
Sci Rep ; 5: 17458, 2015 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-26648413

RESUMO

A new type of NADH model compound has been synthesized by an efficient and convenient method. This model compound exhibits high reactivity and enantioselectivity in asymmetric reduction reactions. The results show that chiral NADH model S could be effectively combined with Mg(2+) to form ternary complexes. This novel C3 symmetrical NADH model is capable of fluorescence emission at 460 nm when excited at 377 nm.


Assuntos
Modelos Químicos , NAD/química , Modelos Moleculares , Conformação Molecular , NAD/síntese química
16.
Sci Rep ; 5: 17463, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-26626305

RESUMO

Stem cell maintenance requires expression of genes essential for stemness and repression of differentiation genes. How this is achieved remains incompletely understood. Here we investigate the requirement for central components of heterochromatin, Heterochromatin Protein 1 (HP1) and the histone H3 lys9 methyltransferase Su(var)3-9, in the Drosophila male germline stem cell (GSC) self-renewal, a paradigm for studying adult stem cell behavior. We found that mutations or RNAi knock down of HP1 or Su(var)3-9 cause loss of GSCs, accompanied by defects in cell division or survival and premature expression of the differentiation gene bag of marbles (bam). Conversely, over-expressing HP1 increases GSC number in wildtype flies and, strikingly, restores fertility to the sterile hopscotch (hop) mutant flies that lack niche signals. These results suggest that the central components of heterochromatin play roles including repressing differentiation genes in Drosophila male GSC maintenance.


Assuntos
Divisão Celular/fisiologia , Células Germinativas/metabolismo , Heterocromatina/metabolismo , Transdução de Sinais/fisiologia , Células-Tronco/metabolismo , Animais , Sobrevivência Celular/fisiologia , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Feminino , Células Germinativas/citologia , Heterocromatina/genética , Histona Metiltransferases , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Janus Quinases/genética , Janus Quinases/metabolismo , Masculino , Células-Tronco/citologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
PLoS Negl Trop Dis ; 9(11): e0004247, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26583925

RESUMO

INTRODUCTION: Mycobacterium ulcerans infection, known as Buruli ulcer, is a disease of the skin and subcutaneous tissues which is an important but neglected tropical disease with its major impact in rural parts of West and Central Africa where facilities for diagnosis and management are poorly developed. We evaluated fluorescent thin layer chromatography (f-TLC) for detection of mycolactone in the laboratory using samples from patients with Buruli ulcer and patients with similar lesions that gave a negative result on PCR for the IS2404 repeat sequence of M. ulcerans. METHODOLOGY/PRINCIPAL FINDINGS: Mycolactone and DNA extracts from fine needle aspiration (FNA), swabs and biopsy specimen were used to determine the sensitivity and specificity of f-TLC when compared with PCR for the IS2404. For 71 IS2404 PCR positive and 28 PCR negative samples the sensitivity was 73.2% and specificity of 85.7% for f-TLC. The sensitivity was similar for swabs (73%), FNAs (75%) and biopsies (70%). CONCLUSIONS: We have shown that mycolactone can be detected from M. ulcerans infected skin tissue by f-TLC technique. The technique is simple, easy to perform and read with minimal costs. In this study it was undertaken by a member of the group from each endemic country. It is a potentially implementable tool at the district level after evaluation in larger field studies.


Assuntos
Úlcera de Buruli/diagnóstico , Cromatografia em Camada Delgada/métodos , Técnicas de Laboratório Clínico/métodos , Testes Diagnósticos de Rotina/métodos , Macrolídeos/análise , Mycobacterium ulcerans/química , Adolescente , Adulto , África Central , Idoso , Biópsia , Criança , Pré-Escolar , Feminino , Fluorescência , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Mycobacterium ulcerans/genética , Reação em Cadeia da Polimerase , Sensibilidade e Especificidade , Tela Subcutânea/química , Fatores de Tempo , Adulto Jovem
18.
Sci Rep ; 5: 15250, 2015 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-26470633

RESUMO

Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed.

19.
Org Lett ; 17(18): 4460-3, 2015 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-26348870

RESUMO

A novel copper/manganese cocatalyzed direct oxidative coupling of terminal vinylarenes with ketones via C(sp(3))-H bond functionalization following C-C bond formation has been developed using tert-butyl hydroperoxide as the radical initiator. Various ketones underwent a free-radical addition of terminal vinylarenes to give the corresponding 1,4-dicarbonyl products with excellent regioselectivity and efficiency through one step. A possible reaction mechanism has been proposed.

20.
Molecules ; 20(9): 17208-20, 2015 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-26393558

RESUMO

An efficient multi-component reaction to synthesize multi-substituted 1,3-oxazolidine compounds of high optical purity was described. All the products were well-characterized and the absolute configuration of one chiral center was determined. The plausible mechanism was proposed and a kinetic resolution of epoxides process was confirmed.


Assuntos
Oxazóis/síntese química , Cinética , Estrutura Molecular , Oxazóis/química , Estereoisomerismo
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