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1.
Chemistry ; 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31803978

RESUMO

Metal-organic rotaxane frameworks (MORFs) attracted much attention in the past years for construction of intelligent functional materials. Herein, a one-pot synthesis is reported of a three-dimensional (3D) cucurbit[7]uril (Q[7])-based MORF under hydrothermal conditions, namely Q[7]-MORF-1, formed by encapsulating the anionic benzoate moieties of the tricarboxylate ligand into the cavity of Q[7]. Furthermore, Q[7]-MORF-1 shows dual-capture capacity for iodine and K+ selectively among the alkali metal ions. The captured molecular iodine is included in the cavity of Q[7] through halogen-bonding interactions and the K+ cations are positioned at the carbonyl port of the Q[7] through K-O coordination interactions.

2.
Nature ; 575(7782): 336-340, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31723273

RESUMO

Organoboron reagents are important synthetic intermediates that have a key role in the construction of natural products, pharmaceuticals and organic materials1. The discovery of simpler, milder and more efficient approaches to organoborons can open additional routes to diverse substances2-5. Here we show a general method for the directed C-H borylation of arenes and heteroarenes without the use of metal catalysts. C7- and C4-borylated indoles are produced by a mild approach that is compatible with a broad range of functional groups. The mechanism, which is established by density functional theory calculations, involves BBr3 acting as both a reagent and a catalyst. The potential utility of this strategy is highlighted by the downstream transformation of the formed boron species into natural products and drug scaffolds.


Assuntos
Compostos de Boro/química , Compostos de Boro/síntese química , Boro/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Teoria da Densidade Funcional , Descoberta de Drogas , Indóis/química , Compostos Organometálicos/química , Preparações Farmacêuticas/síntese química , Preparações Farmacêuticas/química
3.
Nature ; 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31569198

RESUMO

Organoboron reagents are important synthetic intermediates that play a key role in the construction of natural products, pharmaceuticals, and organic materials.1 The discovery of simpler, milder and more efficient approaches to organoborons opens a route to diverse substances.2-5 Here we show a general method of directed C-H activation for site-selective C-H borylation of arenes and heteroarenes avoiding the use of metal catalysts. C7 and C4-borylated indoles are produced by a mild approach with broad functional group compatibility. The mechanism involves BBr3 as both reagent and catalyst and is established with DFT calculations. Downstream transformation of the formed boron species to natural products and drug scaffolds highlights the potential utility of this strategy.

4.
Inorg Chem ; 58(13): 8517-8524, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31184876

RESUMO

It is deemed as a desired approach to utilize solar energy for the conversion of CO2 into valuable products, and the majority of the MOFs-based photocatalytic reductions of CO2 have focused on formic acid (HCOOH) production with an organic solvent as the reaction medium. Herein, we report a solvent-free reaction route for the photoreduction of CO2 catalyzed by Fe-MOFs, namely, NH2-MIL-53(Fe) [(Fe(OH)(NH2-BDC)]•G, NH2-MIL-88B(Fe) [Fe3O(H2O)3(NH2-BDC)3]Cl•G, and NH2-MIL-101(Fe) [Fe3O(H2O)3(NH2-BDC)3]Cl•G (NH2-BDC = 2-aminoterephthalic acid; G = guest and/or solvent molecules). Compared with the orthodox reaction route, the present out-of-the-way photocatalytic reduction of CO2 with superior selectivity to CO occurs at the gas-solid interface. The reaction procedure is environmentally friendly and provides a possibility to address the CO2 emission problem. Importantly, NH2-MIL-101(Fe) shows the highest photocatalytic activity among these Fe-MOFs due to its efficient charge separation and electron transfer.

5.
Chem Asian J ; 14(20): 3620-3626, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31192524

RESUMO

Due to their striking optical properties, luminescent coordination polymers as sensors for the detection of hazardous species have drawn interest of researchers in consideration of the control of environmental pollution. In this work, the organic ligand 2-(4-((E)-2-(pyridine-2-yl)vinyl)styryl)pyridine (2-bpeb), which possesses a large π-conjugated system, was employed to react with d10 metal ions to obtain novel luminescent coordination polymers. Three complexes [Cd(2-bpeb)0.5 (CNA)(H2 O)] (CP1), [Cd(2-bpeb)0.5 (NDC)] (CP2) and [Zn(2-bpeb)(BDC)] (CP3) were synthesized successfully by introducing carboxylic acids of 4-carboxycinnamic acid (H2 CNA), 2,6-naphthalene dicarboxylic acid (H2 NDC) and 1,4-benzenedicarboxylic acid (H2 BDC) as auxiliary ligands. Because of the existence of the large π-conjugated system and d10 metal ions, all of these coordination polymers exhibit striking fluorescence properties. Impressively, all of them can function as sensors for the detection of highly oxidizing anions MnO4 - and Cr2 O7 2- , with an increased sensitivity for MnO4 - .

6.
Chem Sci ; 10(18): 4834-4838, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31160958

RESUMO

Facet-dependent catalytic activity of hard materials such as metals and metal oxides is well recognized in previous works. However, it has rarely been established for metal-organic frameworks (MOFs), possibly because the soft crystals of MOFs are conceptually different from the hard solids. In this work, the surface structure of the MOF NH2-MIL-125(Ti) has been investigated by density functional theory (DFT) calculations for the first time. These calculations predict that the {110} facet has a surface energy of 1.18 J m-2, which is superior to those of the {001}, {100} and {111} facets. This difference can be attributed to the larger percentage of exposed metal clusters, which can act as active sites in catalysis. Thus, we have devised and successfully obtained a series of nanoscaled NH2-MIL-125(Ti) MOFs with controlled facets both experimentally and theoretically. The sample containing the {110} facet exhibits the highest photocatalytic hydrogen production activity and apparent quantum yield, which are approximately three times those of the sample with a dominant {111} facet.

7.
Dalton Trans ; 48(23): 8221-8226, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31090769

RESUMO

Conversion of carbon dioxide (CO2) into useful chemicals is an important and urgent task from the energy and environment perspective. Herein, through a post-synthetic modification (PSM) approach, we synthesized three new metal-organic frameworks (MOFs) UiO-68-PSMs with different functional groups, namely, UiO-68-F, UiO-68-CH3 and UiO-68-OCH3, for the photocatalytic reduction of CO2. By introducing electron-withdrawing and electron-donating groups, UiO-68-PSMs showed different performance for the selective photocatalytic reduction of CO2 to CO because of change in charge separation and band gap of UiO caused by the presence of different functional groups.

8.
Angew Chem Int Ed Engl ; 58(27): 9099-9103, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31124280

RESUMO

A ligand-promoted RhIII -catalyzed C(sp2 )-H activation/thiolation of benzamides has been developed. Using bidentate mono-N-protected amino acid ligands led to the first example of RhIII -catalyzed aryl thiolation reactions directed by weakly coordinating directing amide groups. The reaction tolerates a broad range of amides and disulfide reagents.

9.
Biosens Bioelectron ; 134: 117-122, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30981130

RESUMO

DNA methylation is catalyzed by DNA methyltransferase (MTase) and concerned with many biological processes including pathogenesis of various human diseases. The monitoring of MTase activity is thus of great significance in disease diagnosis and drug screening. Herein, we developed a facile way to synthesize biocompatible invertase enzyme modified metal-organic framework (Invertase/MOF) materials, and explored its application in constructing a dual-response Dam MTase sensor for the first time. By using them as signal probes, in which high density of metal sites could be electrochemically detected and invertase could hydrolyze sucrose into glucose for generation of glucometer signal output, dual-response for accurate detection of Dam MTase was realized. In the presence of Dam MTase, the methylation of hairpin probe 1 (HP1) occurred and thus caused the cleavage of HP1 assisted by a restriction endonuclease (DpnI) to produce the binding sequences. The binding sequences then hybridized with the electrode-assembled HP2 to expose their sticky termini which sequentially hybridized with the Invertase/MOFs-tethered capture probes. Finally, the electrodes were incubated with a sucrose solution, followed by the separate electrochemical and glucometer detection. The present assay brought good performance which could detect Dam MTase activity as low as 0.001 U mL-1 with wide linear range and good selectivity against other cytosine MTase (M.SssI MTase). Moreover, it also owns ability to be potentially applied for the inhibitors screening by utilization of 5-fluorouracil as an inhibitor model. The results imply that our proposed method provides a convenient platform for early cancer diagnosis and therapeutic applications.


Assuntos
Técnicas Biossensoriais/métodos , Ensaios Enzimáticos/métodos , Estruturas Metalorgânicas/química , DNA Metiltransferases Sítio Específica (Adenina-Específica)/análise , Automonitorização da Glicemia/métodos , Cobre/química , Enzimas Imobilizadas/química , Glucose/análise , Ouro/química , Humanos , DNA Metiltransferases Sítio Específica (Adenina-Específica)/metabolismo , beta-Frutofuranosidase/química
10.
ACS Appl Mater Interfaces ; 11(10): 10389-10398, 2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30776891

RESUMO

We have developed a green and versatile method to prepare hierarchically porous Cu3(BTC)2@carboxymethyl chitosan (HKUST-1@CMCS) with a macroscopic shape control and designable performance via the cross-linking of Cu(II) ions with CMCS. Furthermore, atomic force microscopy, scanning electron microscopy, powder X-ray diffraction, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy analyses showed that the morphology of HKUST-1 could be controlled and changed by tailoring the surface roughness ( Rq) of polymer matrix. For the ball-like, fiberlike, and membrane-like composites, the matrix Rq values were 887, 88.4, and 18.2 nm and the average sizes of HKUST-1 crystals were about 10.2, 5.9, and 1.7 µm, respectively. It was found that the larger the Rq of the polymer matrix, the higher the drug payload. The results of drug release showed that the release percentage of dimethyl fumarate from HKUST-1@CMCS was 66% in 326 h, whereas that of Cu@CMCS was only 12 h. Obviously, the HKUST-1@CMCS had a long-acting and sustained release property compared to that of Cu@CMCS due to its complementary advantages of metal-organic frameworks (MOFs) and polymers. Therefore, this study not only provided an interesting way to make up for the shortcomings of MOFs and natural polymer but also developed a long-acting delivery system for a huge potential application prospect.


Assuntos
Preparações de Ação Retardada/química , Liberação Controlada de Fármacos , Compostos Organometálicos/química , Quitosana/análogos & derivados , Quitosana/química , Preparações de Ação Retardada/uso terapêutico , Portadores de Fármacos/química , Portadores de Fármacos/uso terapêutico , Humanos , Microscopia Eletrônica de Varredura
11.
J Am Chem Soc ; 141(1): 76-79, 2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30585063

RESUMO

Rh(III)-catalyzed meta-C-H functionalization reactions are still rare. Herein, we report the first example of Rh(III)-catalyzed meta-C-H alkenylation with disubstituted alkynes directed by a U-shaped nitrile template. Exclusive regio-selectivity has been achieved using unsymmetrical aryl and alkyl-disubstituted alkynes to afford synthetically valuable trisubstituted olefins. Propargyl alcohols are also compatible, affording complex allylic alcohols. Notably, transition metal-catalyzed meta-alkenylation with alkynes has not been successful with Pd catalysts.

12.
Dalton Trans ; 47(43): 15399-15404, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30320852

RESUMO

The stability and functionality of metal-organic frameworks (MOFs) are particularly important in considering their potential and/or practical use. Herein we report two novel aldehyde functional group-containing MOFs [Zn2(L)(BDC)2]·2DMF·MeOH·H2O (1) and [Co2(L)(BDC)2]·2DMF·2MeOH·H2O (2) (DMF = N,N-dimethylformamide, MeOH = methanol) achieved by reactions of mixed organic ligands of 2,4-bis[(pyridin-4-yl)methoxy]benzaldehyde (L) and 1,4-benzenedicarboxylic acid (H2BDC) with the corresponding metal salts under solvothermal conditions. Both 1 and 2 are 2-fold interpenetrated three-dimensional (3D) frameworks. Particularly, 1 exhibits excellent water and wide-range pH stability, and a large Qst value for carbon dioxide (CO2) adsorption. Furthermore, photoluminescence (PL) studies indicate that 1 could be considered as a potential luminescent probe for detection of nitroaromatics.

13.
Nat Commun ; 9(1): 4293, 2018 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-30327477

RESUMO

Antioxidant enzyme glutathione peroxidase (GPx) decomposes hydroperoxides by utilizing the different redox chemistry of the selenium and sulfur. Here, we report a Se-catalysed para-amination of phenols while, in contrast, the reactions with sulfur donors are stoichiometric. A catalytic amount of phenylselenyl bromide smoothly converts N-aryloxyacetamides to N-acetyl p-aminophenols. When the para position was substituted (for example, with tyrosine), the dearomatization 4,4-disubstituted cyclodienone products were obtained. A combination of experimental and computational studies was conducted and suggested the weaker Se-N bond plays a key role in the completion of the catalytic cycle. Our method extends the selenium-catalysed processes to the functionalisation of aromatic compounds. Finally, we demonstrated the mild nature of the para-amination reaction by generating an AIEgen 2-(2'-hydroxyphenyl)benzothiazole (HBT) product in a fluorogenic fashion in a PBS buffer.


Assuntos
Fenóis/química , Selênio/química , Aminação , Benzotiazóis/química , Catálise , Nitrogênio/química , Compostos de Selênio/química , Enxofre/química
14.
Angew Chem Int Ed Engl ; 57(29): 8848-8853, 2018 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-29663643

RESUMO

A straightforward method was developed for construction of aromatic compounds with a triphenylene core. The method involves Pd-catalyzed annulative dimerization of o-iodobiaryl compounds by double C-I and C-H bond cleavage steps. Simple reaction conditions are needed, requiring neither a ligand nor an oxidant, and the reaction tolerates a wide range of coupling partners without compromising efficiency or scalability. Significantly, the tetrachloro-substituted synthon, 1,6,11-trichloro-4-(4-chlorophenyl)triphenylene, can be generated and used to prepare a series of fully fused, small graphene nanoribbons by a late-stage arylation with arylboronic acids and a subsequent Scholl reaction. The synthetic strategy enables bottom-up access to extended π-systems in a controlled manner.

15.
Dalton Trans ; 47(11): 3958-3964, 2018 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-29460939

RESUMO

A novel cucurbit[6]uril-based (Q[6]) supramolecular assembly {(NH4)2·Q[6]·(HDTNB)2·2H2O} (1) with a three-dimensional (3D) framework structure was successfully constructed via outer-surface interactions between Q[6] and a flexible aromatic compound, 5,5'-dithiobis-(2-nitrobenzoic acid) (H2DTNB), as a structure-directing agent. It is interesting to find that assembly 1 can selectively capture Ba(ii) cations among the common alkaline-earth metal ions of Mg(ii), Ca(ii), Sr(ii) and Ba(ii), resulting in the formation of an isomorphic 3D assembly {Ba(H2O)2Q[6]}·(HDTNB)2 (2). Furthermore, both assemblies 1 and 2 exhibit the selective sensing of Fe(iii) ions through fluorescence quenching, which has rarely been reported for Q[n]-based supramolecular assemblies.

16.
Inorg Chem ; 57(5): 2695-2704, 2018 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-29446625

RESUMO

A combination of carbon dioxide (CO2) capture and chemical fixation in a one-step process is attractive for chemists and environmentalists. In this work, by incorporating chelating multiamine sites to enhance the binding affinity toward CO2, two novel metal-organic frameworks (MOFs) [Zn2(L)(2,6-NDC)2(H2O)]·1.5DMF·2H2O (1) and [Cd2(L)(2,6-NDC)2]·1.5DMF·2H2O (2) (L = N1-(4-(1 H-1,2,4-triazole-1-yl)benzyl)- N1-(2-aminoethyl)ethane-1,2-diamine, 2,6-H2NDC = 2,6-naphthalenedicarboxylic acid, DMF = N, N-dimethylformamide) were achieved under solvothermal conditions. Both 1 and 2 possess high selectivity for adsorption of CO2 over CH4 at room temperature under atmospheric pressure. Moreover, 1 has one-dimensional tubular channels decorated with multiactive sites including NH2 groups and coordination unsaturated Lewis acid metal sites, leading to efficient catalytic activity for chemical fixation of CO2 by reaction with epoxides to give cyclic carbonates under mild conditions.

17.
Dalton Trans ; 47(7): 2337-2343, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29369317

RESUMO

A family of novel Ln nanoclusters, namely, [Ln11(ovpho)4(µ-CH3O)2(µ-H2O)2(µ3-OH)6(CH3OH)4(H2O)2(NO3)8](OH)·xH2O·yCH3OH [Ln = Gd (1), x = 1, y = 3; Ln = Tb (2), x = 1, y = 3; Ln = Dy (3), x = 0, y = 3], was obtained via solvothermal reactions of Ln(NO3)3 with a diacylhydrazone ligand N,N'-bis(o-vanillidene)pyridine-2,6-dicarbohydrazide N-oxide (H4ovpho). Their isostructural molecular structures are composed of two crystallographically symmetric {Ln6} rings sharing a Ln3+ ion, and display an unprecedented "double boat conformation" topology that, to our knowledge, has not yet been reported. Ophenol, Oenol and Ooxynitride from ovpho4- ligands, as well as Omethanol, Owater and Ohydroxyl help to bridge the Ln3+ ions. The structural variation between these {Ln11} clusters and a previously reported {Gd18} nanowheel, both of which are assembled by H4ovpho under the same synthetic method and reaction conditions, is caused only by changing the anions of Ln salts. Magnetic investigations revealed a large magnetocaloric effect (MCE) of 1, whose maximum -ΔSm value reaches 30.1 J kg-1 K-1 for ΔH = 50 kOe at 2.0 K. Additionally, it was found that 3 shows single-molecule magnets (SMMs) behavior, with an approximated energy barrier Ueff = 6.13 K and pre-exponential factor τ0 = 1.70 × 10-6 s.

18.
J Am Chem Soc ; 139(46): 16486-16489, 2017 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-29116769

RESUMO

An efficient enantioselective protocol has been reported to build highly oxygenated and densely substituted bicyclo[m.n.1] skeletons through intramolecular asymmetric α-arylative desymmetrization of 1,3-diketones. Employing Pd catalyst and FOXAP ligand, various bicyclo[m.n.1] skeleton with different size can be accessed with high enantio- and diastereoselectivities. Utilizing the present method as a key step, formal asymmetric total synthesis of the (-)-parvifoline has been demonstrated.

19.
Inorg Chem ; 56(22): 14157-14163, 2017 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-29091416

RESUMO

The fabrication of metal-organic frameworks with controlled structure and desired properties is important but still a challenge. In this work, a zinc(II) framework, {[Zn3(L)2(DABCO)(H2O)]·9DMF} (named as Zn-1), has been synthesized based on [1,1':3',1″-terphenyl]-4,4″,5'-tricarboxylic acid (H3L) and 1,4-diazabicyclo[2.2.2]octane (DABCO), which is isostructural to the previously reported copper(II) analogue, {[Cu3(L)2(DABCO)(H2O)]·15H2O·9DMF} (named as Cu-1). Interestingly, hybrid zinc(II) and copper(II) bimetallic frameworks have been obtained via metal-ion metathesis and found to show enhanced adsorption and photoluminescence properties. Such a post-metal-ion metathesis method can be used to synthesize new and desired frameworks that could not be obtained by direct synthesis.

20.
Org Lett ; 19(21): 5940-5943, 2017 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-29048909

RESUMO

A general method for selective ortho C-H arylation of ketone, with boron reagent enabled by rhodium complexes with excellent yields, is developed. The transformation is characterized by the use of air-stable Rh catalyst, high monoarylation selectivity, and excellent yields of most of the substrates.

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