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1.
Chem Biol Interact ; 331: 109250, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32956706

RESUMO

Triple-negative breast cancer is the most aggressive form of breast cancer with limited intervention options. Moreover, a number of belligerent therapeutic strategies adopted to treat such aggressive forms of cancer have demonstrated detrimental side effects. This necessitates exploration of targeted chemotherapeutics. We assessed the efficacy of a novel indenone derivative (nID) [(±)-N-(2-(-5-methoxy-1-oxo-3-(2-oxo-2-phenylethyl)-2,3-dihydro-1H-inden-2-yl)ethyl)-4-methylbenzenesulfonamide], synthesized by a novel internal nucleophile-assisted palladium-catalyzed hydration-olefin insertion cascade; against triple-negative breast cancer cells (MDA-MB-231). On 24 h treatment, the nID caused decline in the viability of MDA-MB-231 and MDA-MB-468 cells, but did not significantly (P < 0.05) affect WRL-68 (epithelial-like) cells. In fact, the nID demonstrated augmentation of p53 expression, and consequent p53-dependent senescence in both MDA-MB-231 and MDA-MB-468 cells, but not in WRL-68 cells. The breast cancer cells also exhibited reduced proliferation, downregulated p65/NF-κB and survivin, along with augmented p21Cip1/WAF1 expression, on treatment with the nID. This ensued cell cycle arrest at G1 stage, which might have driven the MDA-MB-231 cells to senescence. We observed a selectivity of the nID to target MDA-MB-231 cells, whereas WRL-68 cells did not show any considerable effect. The results underscored that the nID has potential to be developed into a cancer therapeutic.


Assuntos
Antineoplásicos/síntese química , Senescência Celular , Sulfonamidas/química , Antineoplásicos/farmacologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Catálise , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Senescência Celular/efeitos dos fármacos , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Regulação para Baixo/efeitos dos fármacos , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Humanos , Paládio/química , Sulfonamidas/síntese química , Survivina/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Regulação para Cima/efeitos dos fármacos
2.
J Vis Exp ; (162)2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32894264

RESUMO

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular transformations. This opens possibilities for the use of visible or near-IR light as a sustainable input to drive and control reactions when plasmonic nanoparticles supporting LSPR excitation in these ranges are employed as catalysts. Unfortunately, this is not the case for several catalytic metals such as palladium (Pd). One strategy to overcome this limitation is to employ bimetallic NPs containing plasmonic and catalytic metals. In this case, the LSPR excitation in the plasmonic metal can contribute to accelerate and control transformations driven by the catalytic component. The method reported herein focuses on the synthesis of bimetallic silver-palladium (Ag-Pd) NPs supported on ZrO2 (Ag-Pd/ZrO2) that acts as a plasmonic-catalytic system. The NPs were prepared by co-impregnation of corresponding metal precursors on the ZrO2 support followed by simultaneous reduction leading to the formation of bimetallic NPs directly on the ZrO2 support. The Ag-Pd/ZrO2 NPs were then used as plasmonic catalysts for the reduction of nitrobenzene under 425 nm illumination by LED lamps. Using gas chromatography (GC), the conversion and selectivity of the reduction reaction under the dark and light irradiation conditions can be monitored, demonstrating the enhanced catalytic performance and control over selectivity under LSPR excitation after alloying non-plasmonic Pd with plasmonic metal Ag. This technique can be adapted to a wide range of molecular transformations and NPs compositions, making it useful for the characterization of the plasmonic catalytic activity of different types of catalysis in terms of conversion and selectivity.


Assuntos
Ligas/química , Nanopartículas Metálicas/química , Paládio/química , Prata/química , Ligas/síntese química , Catálise , Luz , Nitrobenzenos/química , Oxirredução , Ressonância de Plasmônio de Superfície , Zircônio/química
3.
Int J Nanomedicine ; 15: 5591-5602, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32848389

RESUMO

Introduction: The catalytic behavior of metal oxide nanomaterials for removal of organic pollutants under dark ambient conditions, without any additional stimulant, is of great interest among the scientific community. Methods: In this account, a nanomaterial of ternary metal oxides (MoO3-NiO-PdO-Pd) was synthesized via greener approach and was explored for degradation of methyl orange in water environment in dark ambient conditions in comparison with light conditions. The biochemical species of Abies pindrow were treated with aqueous solution of precursor's salt following sol gel synthesis strategy. We further attuned morphology and chemistry of MoO3-NiO-PdO-Pd by incorporating bioactive compounds of A. pindrow. Result and Discussion: The bio-fabricated MoO3-NiO-PdO-Pd revealed outstanding catalytic behavior with 92% degradation of methyl orange within 15 min in the dark at ambient temperature and pressure. Whereas, in the presence of visible light irritation, the catalyst degraded 97% of methyl orange in 15 min. According to the reaction kinetics of degradation, the catalysts illustrated good stability in light (R2=0.93) as well as in dark conditions (R2=0.98). Furthermore, the outstanding reusability and recyclability of the synthesized nanomaterial was observed for four runs of the experiment under dark and light conditions. Conclusion: Therefore, A. pindrow-synthesized MoO3-NiO-PdO-Pd nanocatalyst demonstrated significant potential for detoxification of organic pollutants for water remediation.


Assuntos
Nanoestruturas/química , Poluentes Químicos da Água/química , Abies/química , Compostos Azo/química , Catálise , Luz , Molibdênio/química , Níquel/química , Óxidos/química , Paládio/química , Pressão , Temperatura
4.
Nat Protoc ; 15(9): 2980-3008, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32839575

RESUMO

High-surface-area mesoporous materials expose abundant functional sites for improved performance in applications such as gas storage/separation, catalysis, and sensing. Recently, soft templates composed of amphiphilic surfactants and block copolymers have been used to introduce mesoporosity in various materials, including metals, metal oxides and carbonaceous compounds. In particular, mesoporous metals are attractive in electrocatalysis because their porous networks expose numerous unsaturated atoms on high-index facets that are highly active in catalysis. In this protocol, we describe how to create mesoporous metal films composed of gold, palladium, or platinum using block copolymer micelle templates. The amphiphilic block copolymer micelles are the sacrificial templates and generate uniform structures with tunable pore sizes in electrodeposited metal films. The procedure describes the electrodeposition in detail, including parameters such as micelle diameters, deposition potentials, and deposition times to ensure reproducibility. The micelle diameters can be controlled by swelling the micelles with different solvent mixtures or by using block copolymer micelles with different molecular weights. The deposition potentials and deposition times allow further control of the mesoporous structure and its thickness, respectively. Procedures for example applications are included: glucose oxidation, ethanol oxidation and methanol oxidation reactions. The synthetic methods for preparation of mesoporous metal films will take ~4 h; the subsequent electrochemical tests will take ~5 h for glucose sensing and ~3 h for alcohol oxidation reaction.


Assuntos
Ouro/química , Paládio/química , Platina/química , Álcoois/química , Catálise , Técnicas de Química Sintética , Eletroquímica , Interações Hidrofóbicas e Hidrofílicas , Micelas , Modelos Moleculares , Conformação Molecular , Oxirredução , Polímeros/química
5.
Nature ; 583(7817): 548-553, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32480398

RESUMO

Tertiary stereogenic centres containing one fluorine atom are valuable for medicinal chemistry because they mimic common tertiary stereogenic centres containing one hydrogen atom, but they possess distinct charge distribution, lipophilicity, conformation and metabolic stability1-3. Although tertiary stereogenic centres containing one hydrogen atom are often set by enantioselective desymmetrization reactions at one of the two carbon-hydrogen (C-H) bonds of a methylene group, tertiary stereocentres containing fluorine have not yet been constructed by the analogous desymmetrization reaction at one of the two carbon-fluorine (C-F) bonds of a difluoromethylene group3. Fluorine atoms are similar in size to hydrogen atoms but have distinct electronic properties, causing C-F bonds to be exceptionally strong and geminal C-F bonds to strengthen one another4. Thus, exhaustive defluorination typically dominates over the selective replacement of a single C-F bond, hindering the development of the enantioselective substitution of one fluorine atom to form a stereogenic centre5,6. Here we report the catalytic, enantioselective activation of a single C-F bond in an allylic difluoromethylene group to provide a broad range of products containing a monofluorinated tertiary stereogenic centre. By combining a tailored chiral iridium phosphoramidite catalyst, which controls regioselectivity, chemoselectivity and enantioselectivity, with a fluorophilic activator, which assists the oxidative addition of the C-F bond, these reactions occur in high yield and selectivity. The design principles proposed in this work extend to palladium-catalysed benzylic substitution, demonstrating the generality of the approach.


Assuntos
Carbono/química , Flúor/química , Alcenos/química , Catálise , Cátions , Halogenação , Hidrogênio/química , Irídio/química , Compostos Organofosforados/química , Oxirredução , Paládio/química
6.
Biofouling ; 36(3): 351-367, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32401555

RESUMO

Pseudomonas aeruginosa and Serratia marcescens are prominent members belonging to the group of ESKAPE pathogens responsible for Urinary Tract Infections (UTI) and nosocomial infections. Both the pathogens regulate several virulence factors, including biofilm formation through quorum sensing (QS), an intercellular communication mechanism. The present study describes the anti-biofilm and QS quenching effect of thiazolinyl-picolinamide based palladium(II) complexes against P. aeruginosa and S. marcescens. Palladium(II) complexes showed quorum sensing inhibitory potential in inhibiting swarming motility behaviour, pyocyanin production and other QS mediated virulence factors in both P. aeruginosa and S. marcescens. In addition, the establishment of biofilms was prevented on palladium (II) coated catheters. Overall, the present study demonstrates that thiazolinyl-picolinamide based palladium (II) complexes will be a promising strategy to combat device-mediated UTI infections.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Complexos de Coordenação/farmacologia , Paládio/farmacologia , Ácidos Picolínicos/química , Tiazóis/química , Cateteres Urinários/microbiologia , Antibacterianos/química , Antibacterianos/toxicidade , Biofilmes/crescimento & desenvolvimento , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/química , Complexos de Coordenação/toxicidade , Infecção Hospitalar/prevenção & controle , Humanos , Células MCF-7 , Paládio/química , Paládio/toxicidade , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/metabolismo , Piocianina/metabolismo , Percepção de Quorum/efeitos dos fármacos , Serratia marcescens/efeitos dos fármacos , Serratia marcescens/metabolismo , Infecções Urinárias/microbiologia , Infecções Urinárias/prevenção & controle , Virulência , Fatores de Virulência/metabolismo
7.
J Oleo Sci ; 69(5): 503-515, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32378552

RESUMO

In the present work, the palladium (Pd) modification and supporting effect of W/TiO2 catalysts on catalytic ethanol dehydration to ethylene and diethyl ether were investigated. The Pd modification with different sequence of Pd and W impregnation on the catalysts was prepared by the incipient wetness impregnation technique. The catalyst characterization and activity testing revealed that the different sequence during impregnation influenced the physicochemical properties and ethanol conversion of catalyst. The differences in structure and surface properties were investigated by XRD, BET, SEM, EDX, XPS and NH3-TPD. Upon the reaction temperature between 200 to 400°C, it was found that the conversion increased with increasing of temperature for all catalysts. The Pd incorporated into catalysts enhanced the ethanol conversion depending on the sequence of impregnation. At low temperature (ca. 200 to 300°C), diethyl ether is a major product and the Pd modification over W/TiO2 catalyst resulted in increased diethyl ether yield. This is because an increase of ethanol conversion was obtained with Pd modification, while diethyl ether selectivity did not change. This can be attributed to the higher amount of weak acids sites present after Pd modification into catalyst. Among all catalysts, the PdW/TiO2 catalyst (coimpregnation) achieved the highest diethyl ether yield of 41.4% at 300℃. At high temperature (ca. 350 to 400°C), ethylene is the major product. The W/Pd/TiO2 catalyst (with sequential impregnation of Pd on TiO2 followed by W) exhibited the highest ethylene yield of 68.1% at 400°C. It can be concluded that the modification of Pd onto W/TiO2 upon different sequence of Pd and W impregnation can improve the diethyl ether and ethylene yield in catalytic ethanol dehydration.


Assuntos
Etanol/química , Éter/química , Etilenos/química , Paládio/química , Titânio/química , Tungstênio/química , Catálise , Fenômenos Químicos , Hidrólise , Temperatura
8.
Chemistry ; 26(51): 11868-11876, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32368809

RESUMO

The first palladium organometallic compounds bearing N-trifluoromethyl N-heterocyclic carbenes have been synthesized. These η3 -allyl complexes are potent antiproliferative agents against different cancer lines (for the most part, IC50 values fall in the range 0.02-0.5 µm). By choosing 1,3,5-triaza-7-phosphaadamantane (PTA) as co-ligand, we can improve the selectivity toward tumor cells, whereas the introduction of 2-methyl substituents generally reduces the antitumor activity slightly. A series of biochemical assays, aimed at defining the cellular targets of these palladium complexes, has shown that mitochondria are damaged before DNA, thus revealing a behavior substantially different from that of cisplatin and its derivatives. We assume that the specific mechanism of action of these organometallic compounds involves nucleophilic attack on the η3 -allyl fragment. The effectiveness of a representative complex, 4 c, was verified on ovarian cancer tumoroids derived from patients. The results are promising: unlike carboplatin, our compound turned out to be very active and showed a low toxicity toward normal liver organoids.


Assuntos
Antineoplásicos/química , Cisplatino/farmacologia , Complexos de Coordenação/química , Neoplasias Ovarianas/patologia , Paládio/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cisplatino/química , Complexos de Coordenação/farmacologia , Feminino , Humanos , Ligantes
9.
Artigo em Inglês | MEDLINE | ID: mdl-32255737

RESUMO

A new and sensitive electrochemical sensor for rutin determination was developed based on cetyltrimethylammonium chloride (CTAC) functionalized graphene (Gr) and palladium nanoparticles (Pd) (CTAC-Gr-PdNPs) composite. Rutin displayed remarkably increased electrochemical activity on the CTAC-Gr-PdNPs composite modified electrode due to the synergistic effect of the large surface area and electrocatalytic activity of both Gr and Pd nanoparticles, which offers the feasibility for highly sensitive determination of rutin via electrochemistry. Under the optimal experimental conditions, the oxidation peak current of rutin was proportional to its concentration in the range of 2.0 × 10-8-1.0 × 10-6 mol L-1, and the limit of detection (LOD) was 5 nM (S/N = 3). The developed method was successfully applied to determine rutin in pharmaceuticals with satisfactory recoveries, which shows that the fabricated sensor has potential in pharmaceutical analysis.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Nanopartículas Metálicas/química , Paládio/química , Rutina/análise , Técnicas Eletroquímicas/instrumentação , Eletroquímica , Eletrodos , Desenho de Equipamento , Limite de Detecção , Oxirredução , Rutina/farmacologia
10.
Yakugaku Zasshi ; 140(4): 455-470, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32238625

RESUMO

Natural products are useful sources in the search for biochemical probes and drug leads because of their unique biological activities. However, synthetic studies or functional analyses of polycyclic complex natural products or conjugated lipids (e.g., glycolipids) are often hampered because of their synthesis and handling are challenging. On the basis of rational designs, synthetic studies, and chemical modifications, natural products need to be optimized to more potent compounds with improved activities, selectivities and/or physical properties. We have been synthesizing natural products and their derivatives for the elucidation of their biological mechanisms and discovery of drug leads. This review describes three topics for developing functional compounds derived from natural products for prospective involvement in pharmaceutical research: 1) direct construction of the ergot alkaloid scaffold by palladium catalyzed domino cyclization of amino allenes; 2) identification of novel sphingosine kinase inhibitors through a structure-activity relationship study of jaspine B; and 3) design, synthesis and biological evaluation of novel CD1d glycolipid ligands containing modified lipid moieties.


Assuntos
Produtos Biológicos/síntese química , Alcadienos/química , Antígenos CD1d , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Catálise , Fenômenos Químicos , Ciclização , Desenvolvimento de Medicamentos , Alcaloides de Claviceps/química , Glicolipídeos , Ligantes , Paládio/química , Fosfotransferases (Aceptor do Grupo Álcool)/antagonistas & inibidores , Relação Estrutura-Atividade
11.
PLoS One ; 15(4): e0231147, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32287324

RESUMO

This paper reports the synthesis, characterization, anticancer screening and quantum chemical calculation of a tetradentate Schiff base 2,2'-((1E,1'E)-((2,2-dimethylpropane-1,3-diyl)bis- (azanylylidene))bis(methanylylidene))bis(4-fluorophenol) (L2F) and its Pd (II) complex (PdL2F). The compounds were characterized via UV-Visible, NMR, IR spectroscopy and single crystal x-ray diffraction. Density Functional Theory (DFT) and time-dependent DFT calculations in gas and solvent phases were carried out using B3LYP, B3P86, CAM-B3LYP and PBE0 hybrid functionals combined with LanL2DZ basis set. Complexation of L2F to form PdL2F was observed to cause a bathochromic shift of the maximum absorption bands of n-π* from 327 to 410 nm; an upfield shift for δ (HC = N) from 8.30 to 7.96 ppm and a decreased wavenumber for ν(C = N) from 1637 to 1616 cm-1. Overall, the UV-Vis, NMR and IR spectral data are relatively well reproduced through DFT and TD-DFT methods. L2F and PdL2F showed IC50 of 90.00 and 4.10 µg/mL, respectively, against human colorectal carcinoma (HCT116) cell lines, signifying increased anticancer activity upon complexation with Pd (II).


Assuntos
Complexos de Coordenação/farmacologia , Paládio/farmacologia , Bases de Schiff/farmacologia , Técnicas de Química Sintética/métodos , Complexos de Coordenação/química , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Células HCT116 , Humanos , Concentração Inibidora 50 , Ligantes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Paládio/química , Bases de Schiff/química , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Chemosphere ; 253: 126726, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302906

RESUMO

We synthesized a novel material, namely palladized zero-valent zinc (Pd/ZVZ), and investigated its efficiency for the degradation of polybrominated diphenyl ethers (PBDEs). The plated Pd significantly enhances the degradation rate of PBDEs by ZVZ at the optimum loading of 1% by weight. In the Pd/ZVZ system, very few lower BDEs were accumulated during the degradation of 2,2',4,4'- tetrabromodiphenyl ether (BDE-47) and the final product is diphenyl ether, whereas the ZVZ system only debrominates BDE-47 to di-BDE and further debromination becomes very difficult. The degradation rates of BDEs by ZVZ greatly decreased with decreased bromination level, while in Pd/ZVZ system, the degradation rates of PBDEs did not show a significant difference. These indicate different mechanisms. This was confirmed by investigating the debromination pathways of the PBDEs in both systems. We determined that a H-transfer was the dominant mechanism in the Pd/ZVZ system. In addition, the reactivity of Pd/ZVZ to BDE-47 is pH-independent, which has a great advantage for various applications over ZVZ alone. Our study provides a new approach for the remediation of the PBDEs pollution.


Assuntos
Poluentes Ambientais/análise , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Ferro/química , Paládio/química , Bifenil Polibromatos/análise , Zinco/química , Halogenação , Cinética , Tamanho da Partícula , Éteres Fenílicos/análise , Pós
13.
Chemosphere ; 253: 126750, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302912

RESUMO

Palladium plays a pivotal role in most of the industrial heterogeneous catalysts, because of its unique properties such as well-defined structure, great intrinsic carrier, outstanding electronic, mechanical and thermal stability. The combination of palladium and various porous carbons (PCs) can widen the use of heterogeneous catalysts. This review highlights the advantages and limitations of carbon supported palladium-based heterogeneous catalyst in reduction of toxic hexavalent chromium (Cr(VI)). In addition, we address recent progress on synthesis routes for mono and bimetallic palladium nanoparticles supported by various carbon composites including graphene-based materials, carbon nanotubes, mesoporous carbons, and activated carbons. The related reaction mechanisms for the Cr(VI) reduction are also suggested. Finally, the challenge and perspective are proposed.


Assuntos
Carvão Vegetal/química , Cromo/análise , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Paládio/química , Poluentes Químicos da Água/análise , Catálise , Cromo/toxicidade , Oxirredução , Porosidade , Propriedades de Superfície , Poluentes Químicos da Água/toxicidade
14.
Chemistry ; 26(43): 9430-9444, 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32227537

RESUMO

The last decade has witnessed the rapid development of high-valent Pd-involved organic transformations. This has also led to a steadily growing number of publications concerning the preparation of isolable and characterizable palladium(III) and palladium(IV) complexes. A variety of one-electron and two-electron oxidants have been employed to give access to high-oxidation-state Pd compounds. Undoubtedly, the study of these stoichiometric reactions has great implications for relevant Pd-mediated catalysis. In this minireview, the focus is on the synthetic approaches to structurally determined PdIII/IV complexes starting from their PdII precursors, and the advances in this research area from early 2010 to late 2019 will be highlighted. Chemical oxidations exploiting various oxidizing agents including 1) hypervalent iodine reagents; 2) halogens; 3) electrophilic fluorination reagents; 4) alkyl/aryl halides; 5) ferrocenium salts; 6) peroxides/O2 ; 7) sulfonyl chlorides; and 8) others are covered. A "greener" electrooxidation manner has also been reviewed.


Assuntos
Compostos Ferrosos/química , Paládio/química , Catálise , Elétrons , Halogenação , Halogênios/química , Indicadores e Reagentes/química , Iodo/química , Oxirredução
15.
Mikrochim Acta ; 187(4): 226, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32170394

RESUMO

Heparin was employed as the stabilizing agent in the synthesis of peroxidase-mimicking Pd nanoparticles. The heparin-capped Pd nanozyme can act as both the signal amplifier and the selective binder of protamine. The most efficient nanozyme with the mean size of 3.5 nm consists of 70.8% metallic Pd0 and 29.2% Pd2+ species. Enzyme kinetic studies show that the Km values are 0.036 mM for 3,3',5,5'-tetramethylbenzidine and 78 mM for H2O2. Protamine shows strong affinity to the heparin-capped Pd nanozyme, and induces an apparent aggregation of the nanoparticles. This results in a significant inhibition of the peroxidase-mimicking activities. Hence, the oxidation of TMB by H2O2 to a blue product with a maximum absorption at 652 nm is suppressed. Based on this finding, a photometric assay is developed for the determination of protamine. The linear response is in the concentration range 0.02 ~ 0.8 µg mL-1, and the limit of detection is 0.014 µg mL-1. This assay presents high selectivity toward other biological substances. Graphical abstract Highly active and selective Pd nanozyme was synthesized through adopting heparin as the capping agent for quantitative determination of protamine.


Assuntos
Heparina/química , Nanopartículas/química , Paládio/química , Peroxidase/química , Fotometria , Protaminas/análise , Heparina/metabolismo , Nanopartículas/metabolismo , Paládio/metabolismo , Peroxidase/metabolismo , Protaminas/metabolismo
16.
Nat Chem ; 12(4): 399-404, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32123338

RESUMO

Site-selective functionalization of C-H bonds will ultimately afford chemists transformative tools for editing and constructing complex molecular architectures. Towards this goal, it is essential to develop strategies to activate C-H bonds that are distal from a functional group. In this context, distinguishing remote C-H bonds on adjacent carbon atoms is an extraordinary challenge due to the lack of electronic or steric bias between the two positions. Herein, we report the design of a catalytic system leveraging a remote directing template and a transient norbornene mediator to selectively activate a previously inaccessible remote C-H bond that is one bond further away. The generality of this approach has been demonstrated with a range of heterocycles, including a complex anti-leukaemia agent and hydrocinnamic acid substrates.


Assuntos
Carbono/química , Hidrogênio/química , Isoquinolinas/química , Quinolinas/química , Catálise , Complexos de Coordenação/química , Estrutura Molecular , Norbornanos/química , Paládio/química
17.
J Vis Exp ; (156)2020 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-32116307

RESUMO

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal catalysis, the literature on direct heteroarylation is scarce. The presence of heteroatoms such as nitrogen, sulfur and oxygen often make heteroarylation a challenging research field due to catalyst poisoning, product decomposition and the rest. This protocol details a highly efficient direct α-C(sp3) heteroarylation of ketones under microwave irradiation. Key factors for successful heteroarylation include the use of XPhos Palladacycle Gen. 4 Catalyst, excess base to suppress side reactions and the high temperature and pressure achieved in a sealed reaction vial under microwave irradiation. The heteroarylation compounds prepared by this method were fully characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR) and high-resolution mass spectrometry (HRMS). This methodology has several advantages over literature precedents including broad substrate scope, rapid reaction time, greener procedure and operational simplicity by eliminating the preparation of intermediates such as silyl enol ether. Possible applications for this protocol include, but are not limited to, diversity-oriented synthesis for the discovery of biologically active small molecules, domino synthesis for the preparation of natural products and ligand development for new transition metal catalytic systems.


Assuntos
Cetonas/síntese química , Metais/química , Micro-Ondas , Elementos de Transição/química , Compostos Inorgânicos de Carbono/química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Catálise , Cromatografia , Cetonas/química , Paládio/química , Espectroscopia de Prótons por Ressonância Magnética , Compostos de Silício/química , Temperatura
18.
Org Biomol Chem ; 18(12): 2242-2251, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32159571

RESUMO

An efficient palladium(ii) mediated C-glycosylation of glycals with diaryliodonium salts is described, providing a new strategy for the synthesis of 2,3-dideoxy C-aryl glycosides with excellent stereoselectivity. The C-glycosylation of a diverse range of glycals, including d-glucal, d-galactal, d-allal, l-rhamnal, l-fucal, l-arabinal, d-maltal, and d-lactal, occurred effectively and the corresponding C-glycosides were obtained in moderate to good yields. This protocol is commended as a significant addition to the field of carbohydrate chemistry due to the rich functional group compatibility, broad range of substrate scope and exceptional α-stereoselectivity.


Assuntos
Éteres Cíclicos/química , Glicosídeos/síntese química , Paládio/química , Catálise , Glicosídeos/química , Glicosilação , Polissacarídeos/química , Sais/química , Estereoisomerismo
19.
Chem Pharm Bull (Tokyo) ; 68(3): 288-291, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115536

RESUMO

We report a Pd-catalyzed ß-arylation of cyclic α,ß-unsaturated O-methyl oximes with aryl iodides. This reaction shows complete regioselectivity and excellent functional group tolerance. ß-Arylation of 2-cyclohexen-1-one O-methyl oxime (existing as 2 : 1 E/Z mixture) with certain aryl iodides such as 4-iodoanisole affords only ß-arylated (E)-O-methyl oximes.


Assuntos
Hidrocarbonetos Iodados/química , Oximas/química , Paládio/química , Catálise , Estrutura Molecular
20.
Chemosphere ; 249: 126518, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32213390

RESUMO

Biochar pyrolysed at 300 °C, 500 °C, 700 °C was modified by hydrochloric acid (HCl), hydrofluoric acid (HF), sodium hydroxide (NaOH), hydrogen peroxide (H2O2), nitric acid (HNO3) and potassium permanganate (KMnO4), and subsequently evaluated for removal efficiency of 1,2,4-trichlorobenzene (1,2,4-TCB) by biochar supported nanoscale zero-valent iron (nZVI) and palladium (Pd) composites. Under the initial 1,2,4-TCB concentration of 10 mg L-1 and the solid-liquid ratio of 0.16 g L-1, the synthesized composites of nZVI-Pd with BC700 modified by HF (FBC700-nZVI-Pd) and nZVI-Pd with BC300 modified by NaOH (SBC300-nZVI-Pd) demonstrated significantly enhanced removal efficiencies for 1,2,4-TCB achieving 98.8% and 94.7% after 48 h, respectively. The physicochemical properties of biochar including specific surface area, aromaticity and hydrophobicity after the modification by HF and NaOH were improved. Increased the supporting sites for Fe/Pd nanoparticles and the contact between composites and 1,2,4-TCB were mainly responsible for enhanced removal efficiency for 1,2,4-TCB. Both the adsorption by biochar and reduction by Fe/Pd nanoparticles effectively contributed to the removal of 1,2,4-TCB. It is estimated that the proportion of reduction was about twice that of adsorption in the first 12 h, which produced 1,2-DCB, benzene and other degradation products. Therefore, biochar treated with HF and NaOH and supported Fe/Pd nanoparticles could be effective functional materials for remediation of groundwater contaminated by 1,2,4-TCB.


Assuntos
Clorobenzenos/química , Ferro/química , Paládio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Carvão Vegetal , Água Subterrânea/química , Peróxido de Hidrogênio , Nanopartículas , Poluentes Químicos da Água/análise
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