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1.
Sci Adv ; 5(8): eaaw0982, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31467971

RESUMO

Carboncones, a special family of all-carbon allotropes, are predicted to have unique properties that distinguish them from fullerenes, carbon nanotubes, and graphenes. Owing to the absence of methods to synthesize atomically well-defined carboncones, however, experimental insight into the nature of pure carboncones has been inaccessible. Herein, we describe a facile synthesis of an atomically well-defined carboncone[1,2] (C70H20) and its soluble penta-mesityl derivative. Identified by x-ray crystallography, the carbon skeleton is a carboncone with the largest possible apex angle. Much of the structural strain is overcome in the final step of converting the bowl-shaped precursor into the rigid carboncone under mild reaction conditions. This work provides a research opportunity for investigations of atomically precise single-layered carboncones having even higher cone walls and/or smaller apex angles.

2.
ACS Appl Mater Interfaces ; 11(27): 23982-23989, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31257863

RESUMO

In regular perovskite solar cells (PSCs), the commonly used electron transport layer (ETL) is titanium oxide (TiO2). Nevertheless, the preparation of a high-quality TiO2 ETL demands an elevated-temperature sintering procedure, unfavorable for fabrication of PSCs on flexible substrates. Besides, TiO2-based devices often suffer from notorious photocurrent hysteresis and serious light soaking instability, limiting their potential commercialization. Herein, a novel pyridine-functionalized fullerene derivative [6,6]-(4-pyridinyl)-C61-ethyl acid ethyl ester (PyCEE) was synthesized and applied as an ETL to replace TiO2 in n-i-p PSCs. PyCEE-based devices achieved a champion power conversion efficiency (PCE) of 18.27% with significantly suppressed hysteresis, superior to that of TiO2-based devices. PyCEE has suitable energy levels and high electron mobility, which facilitate electron extraction/transport. Besides, the pyridine moiety within PyCEE affords coordination interactions with the Pb2+ ion within CH3NH3PbI3, passivating the trap states of CH3NH3PbI3 and thus improving the device performance and suppressing hysteresis greatly. Moreover, PyCEE ETLs were applied in flexible PSCs, achieving a PCE of 15.25%. Our results demonstrated the applicability of PyCEE ETLs in flexible devices and provided new opportunity for the commercialization of PSCs.

3.
J Org Chem ; 84(19): 12259-12267, 2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31315398

RESUMO

A general one-step synthesis of symmetrical or unsymmetrical 1,4-di(organo)fullerenes from organo(hydro)fullerenes (RC60H) is realized by direct oxidative arylation. The new combination of catalytic trifluoromethanesulfonic acid (TfOH) and stoichiometric o-chloranil is the first to be used to directly generate an R-C60+ intermediate from common RC60H. Unexpectedly, the in situ generated R-C60+ intermediate is shown to be quite stable in whole 13C NMR spectroscopy characterization in the absence of cation quenching reagents. Because the direct oxidation of common RC60H to form the corresponding R-C60+ has never been realized, the present combination of TfOH and o-chloranil solves the challenges associated with the formation of stable RC60+ cations from common RC60H without any coordination of an R group.

4.
J Am Chem Soc ; 141(16): 6651-6657, 2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-30879294

RESUMO

The combustion has long been applied for industrial synthesis of carbon materials such as fullerenes as well as carbon particles (known as carbon black), but the components and structures of the carbon soot are far from being clarified. Herein, we retrieve an unprecedented hydrofullerene C66H4 from a soot of a low-pressure combustion of benzene-acetylene-oxygen. Unambiguously characterized by single-crystal X-ray diffraction, the C66H4 renders a nonclassical geometry incorporating two heptagons and two pairs of fused pentagons in a C2 v symmetry. The common vertexes of the fused pentagons are bonded with four hydrogen atoms to convert the hydrogen-linking carbon atoms from sp2 to sp3 hybridization, which together with the adjacent heptagons essentially releases the sp2-bond strains on the abutting-pentagon sites of the diheptagonal fused pentagon C66 (dihept-C66). DFT computations suggest the possibility for an in situ hydrogenation process leading to stabilization of the dihept-C66. In addition, the experiments have been carried out to study heptagon-dependent properties of dihept-C66H4, indicating the key responsibility of the heptagon for changing hydrocarbon activity and electronic properties. The present work with the unprecedented double-heptagon-containing hydrofullerene successfully isolated and identified as one of the low-pressure combustion products shows that the heptagon is a new building block for constructing fullerene products in addition to pentagons and hexagons in low-pressure combustion systems.

5.
Nat Commun ; 10(1): 485, 2019 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-30700716

RESUMO

The assembly of spherical fullerenes, or buckyballs, into single crystals for crystallographic identification often suffers from disordered arrangement. Here we show a chiral configuration of decapyrrylcorannulene that has a concave 'palm' of corannulene and ten flexible electron-rich pyrryl group 'fingers' to mimic the smart molecular 'hands' for self-adaptably cradling various buckyballs in a (+)hand-ball-hand(-) mode. As exemplified by crystallographic identification of 15 buckyball structures representing pristine, exohedral, endohedral, dimeric and hetero-derivatization, the pyrryl groups twist with varying dihedral angles to adjust the interaction between decapyrrylcorannulene and fullerene. The self-adaptable electron-rich pyrryl groups, susceptible to methylation, are theoretically revealed to contribute more than the bowl-shaped palm of the corannulene in holding buckyball structures. The generality of the present decapyrrylcorannulene host with flexible pyrryl groups facilitates the visualization of numerous unknown/unsolved fullerenes by crystallography and the assembly of the otherwise close-packed spherical fullerenes into two-dimensional layered structures by intercalation.

6.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 36(2): 184-189, 2018 Apr 01.
Artigo em Chinês | MEDLINE | ID: mdl-29779281

RESUMO

OBJECTIVE: To evaluate the effects of tumor necrosis factor-α (TNF-α) on osteogenic differentiation and Notch signaling pathway of periodontal ligament stem cells (PDLSCs) and to investigate the regulatory role of Notch signaling pathway on the osteogenic differentiation of PDLSCs under the influence of TNF-α. METHODS: PDLSCs were obtained through enzyme digestion and tissue block method. The expression levels of stem cell surface markers CD105, CD90, CD146, CD45, and CD31 were detected by fluorescence activated cell sorter (FACS). PDLSCs were divided into experimental (10 ng·mL⁻¹ TNF-α) and control groups (0 ng·mL⁻¹ TNF-α). The proliferation ability of PDLSCs was detected using cell counting kit-8 (CCK-8). The effect of TNF-α on the osteogenic ability of PDLSCs were tested by measuring alkaline phosphatase (ALP) activity and conducting alizarin red staining and quantitative real-time polymerase chain reaction (PCR). We tested Notch signal pathway receptors Notch1, Notch2, ligand JAG1, JGA2, and downstream gene Hes-1. Changes in DLL1 expression were detected by quantitative real-time PCR. RESULTS: FACS profiling showed that PDLSCs were strongly positive for CD105, CD90, and CD146 but negative for CD45 and CD31. CCK-8 results showed that TNF-α could promote the proliferation of PDLSCs (P<0.05). ALP activity in the experimental group was lower than that in the control group (P<0.05). Alizarin red staining showed that the experimental group had decreased mineralized nodules as compared with the control group. Quantitative real-time PCR results showed that the mRNA expression of osteogenic marker genes cementum attachment protein (CAP), osteopontin (OPN), and Runt-related transcription factor 2 (Runx2) significantly decreased in the experimental group as compared with those in the control group (P<0.05). The expression levels of Notch1, Notch2, JAG1, JGA2 and Hes-1 were significantly decreased (P<0.05), whereas those of Notch3 and DLL1 were increased in Notch signaling pathway-related molecules (P<0.05). CONCLUSIONS: TNF-α can promote PDLSCs proliferation and inhibit bone differentiation and Notch signaling pathway expression, indicating that the Notch signaling pathway regulates PDLSCs osteogenic differentiation.


Assuntos
Diferenciação Celular , Osteogênese , Ligamento Periodontal , Receptores Notch , Transdução de Sinais , Fator de Necrose Tumoral alfa , Fosfatase Alcalina , Proliferação de Células , Células Cultivadas , Humanos , Ligamento Periodontal/citologia , Ligamento Periodontal/metabolismo , Receptores Notch/metabolismo , Células-Tronco , Fator de Necrose Tumoral alfa/fisiologia
7.
Org Lett ; 20(8): 2328-2332, 2018 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-29634273

RESUMO

Controlled synthesis of the equatorial tetra-, hexa-, and octaorgano[70]fullerenes with mixed addends was achieved via the reaction of equatorial 7,23-Bn2C70 with MeO- and ArCH2Br. The products were structurally characterized by single crystal X-ray diffraction. The regioselectivity of the reaction was studied by in situ vis-NIR and Fukui function analysis. A surprising electrophilic triorgano[70]fullerene carbanion was shown, and an enhanced fluorescence was observed for the mixed octaadducts.

8.
J Org Chem ; 82(16): 8676-8685, 2017 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-28731698

RESUMO

C60 o-quinodimethane bisadducts [C60(QM)2] are promising electron acceptors for bulk heterojuction (BHJ) organic solar cells (OSCs). However, previous production of C60(QM)2 often resulted in excessive regioisomers, which were difficult to purify and might consequently obscure the structure-performance study of the organofullerene acceptors. Herein, the electrosynthesis of C60(QM)2 is reported. The reaction exhibits a strong regiocontrol with generation of fewer regioisomers. Pure regioisomers of cis-2, trans-3, and e C60(QM)2 are obtained, and the structures are solved with single-crystal X-ray diffraction. Interestingly, the cis-2 and trans-3 regioisomers exhibit better photovoltaic performance than the e regioisomer in the OSCs based on poly(3-hexylthiophene) (P3HT), which can be correlated with their structural difference.

9.
J Org Chem ; 82(17): 9253-9257, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28748692

RESUMO

The C70 δ-adducts with closed [5,6]-ring fusion are an important type of compound in classifying bond delocalization in the equatorial belt of C70. However, the formation of such compounds is severely restricted due to the low reactivity of the carbon atoms in the flat equatorial region. Such a restriction is lifted when reduced anionic C70 species are used, where the inert equatorial carbon atoms are activated.

10.
Chemistry ; 22(52): 18709-18713, 2016 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-27735092

RESUMO

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC71 BM (phenyl-C71 -butyric acid methyl ester) usually has a "random" composition of mixed regioisomers or stereoisomers. Here PC71 BM has been isolated into three typical isomers, α-, ß1 - and ß2 -PC71 BM, to establish the isomer-dependent photovoltaic performance on changing the ternary composition of α-, ß1 - and ß2 -PC71 BM. Mixing the isomers in a ratio of α/ß1 /ß2 =8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC71 BM as photoactive layer (PTB7=poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]). The three typical PC71 BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average-performing PCE of 1.28-7.44 % due to diverse self-aggregation of individual or mixed PC71 BM isomers in the otherwise same polymer solar cells.

11.
Phys Chem Chem Phys ; 18(28): 18683-6, 2016 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-27375165

RESUMO

Negative ion photoelectron spectroscopy shows interesting regioisomer-specific electron affinities (EAs) of 2,5- and 7,23-para-adducts of C70 [(ArCH2)2C70] (Ar = Ph, o-, m-, and p-BrC6H4). Their EA values are larger than that of C70 by 5-150 meV with the 2,5-polar adducts' EAs being higher than their corresponding 7,23-equatorial counterparts, exhibiting appreciable EA tunable ranges and regioisomeric specificity. Density functional theory (DFT) calculations reproduce both the experimental EA values and EA trends very well.

12.
Chem Commun (Camb) ; 52(33): 5710-3, 2016 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-27039948

RESUMO

C70 multiadducts with a novel 1,2,3,4,41,56,57,58-configuration were prepared via oxazolination and benzylation reactions. The structures of the adducts were determined by single crystal X-ray diffraction and spectral characterization. The compounds exhibit a high LUMO level, and result in a high open-circuit voltage in devices with P3HT.

13.
Nanoscale ; 8(9): 5226-34, 2016 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-26878901

RESUMO

An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ ≥ 420 nm). It was found that the hydrogen production rate of the Ag@TiO2 NTAs prepared with ultrasonication-assisted deposition for 5 min was approximately 15 times higher than that of its pristine TiO2 NTAs counterpart. The highly efficient photocatalytic hydrogen evolution is attributed to the SPR effect of Ag for enhanced visible light absorption and boosting the photogenerated electron-hole separation/transfer. This strategy is promising for the design and construction of high efficiency TiO2 based photocatalysts for solar energy conversion.

14.
Org Lett ; 17(21): 5192-5, 2015 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-26468767

RESUMO

[60]Fullerene derivatives with novel 1,4,9,25- and 1,4,9,12-configurations were obtained by reactions of C60 with aliphatic ketones and benzyl bromide under basic conditions. The structures of the products were determined by X-ray single-crystal diffraction and spectroscopic characterization. The reactions were rationalized by a monoenolate addition experiment and in situ vis-NIR spectroscopy.

15.
J Endod ; 41(11): 1875-9, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26386948

RESUMO

INTRODUCTION: This study aims to compare the incidence of dentinal microcracks produced by the ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (Dentsply Maillefer), and ProTaper Next (Dentsply Maillefer) file systems during root canal procedures in severely curved canals using a dyeing technique. METHODS: Sixty extracted human molars with 25° to 40° root curvatures were divided into 3 groups of 20 canals each. ProTaper Universal, WaveOne, and ProTaper Next file systems were used for root canal procedures. Untreated root canals of 60 molars served as negative controls. After preparation, all roots were stained with 1% methylene blue for 24 hours. Roots were then sectioned at the most curved plane and 2 mm below and above the most curved plane with a low-speed saw under cold water. A stereomicroscope was used to inspect dentinal microcracks at 60× magnification, and differences between these 3 instrument groups were analyzed using the chi-square test. RESULTS: The ProTaper Next system induced less complete and incomplete dentinal microcracks compared with the ProTaper Universal and WaveOne systems (P < .05), and there were no significant differences between the ProTaper Universal and WaveOne systems (P > .05). The ProTaper Universal and WaveOne systems induced significantly more complete cracks in the plane 2 mm above the most curved plane compared with either of the other 2 planes (P = .004). CONCLUSIONS: The ProTaper Next system induces less dentinal microcracks during root canal procedures in severely curved root canals compared with the ProTaper Universal and WaveOne systems.


Assuntos
Instrumentos Odontológicos/efeitos adversos , Cavidade Pulpar/patologia , Dentina/patologia , Preparo de Canal Radicular/instrumentação , Preparo de Canal Radicular/métodos , Modelos Dentários , Humanos , Dente Molar/patologia , Coloração e Rotulagem , Resultado do Tratamento
16.
J Phys Chem A ; 119(36): 9534-40, 2015 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-26291551

RESUMO

Reduced fullerenes and fullerene derivatives exhibit intense absorptions in the vis-near-IR (vis-NIR) region. The absorptions are sensitive toward the addition pattern, number of addends, and oxidation state of the fullerene species and are used as an important benchmark for identifying anionic fullerene species. Similar absorptions are also shown for the reduced singly bonded C60 species, which are electronically different from reduced fullerene derivatives. However, much less work has been carried out on the vis-NIR spectroscopic study of the anionic singly bonded C60 species, likely due to the difficulty in controlled production of these species. Herein, we report the vis-NIR spectroscopic study of the mono- and dianions of the singly bonded C60 species (RC60(-), R(-)C60(-), and RC60(2-•)), which are selectively generated by controlled-potential bulk electrolysis (CPE) of the singly bonded C60 dimer and C60 oxazolino heterocycles. Time-dependent density functional theory (TD-DFT) calculations were performed to rationalize the experimental results.

17.
J Org Chem ; 80(7): 3566-71, 2015 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-25748639

RESUMO

Upon reduction, singly bonded 1,2,4,15-C60 dimers with an oxazoline or imidazoline heterocycle dissociate into monoanionic 1,2,4-C60 intermediates, which surprisingly leads to the formation of 1,2,3,16-C60 rather than 1,2,4,15-C60 adducts of the original configuration by further benzylation, even though the analogue of dibenzylated C60 oxazoline with a 1,2,4,15-configuration is stable and has been obtained. These results are corroborated by computational calculations, which rationalize the reaction and clarify the structure of the 1,2,3,16-C60 adducts, providing new insights into the intrinsic reactivity of singly bonded C60 dimers.

18.
Chemistry ; 21(5): 1894-9, 2015 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-25488150

RESUMO

Reactions of 2,5-Bn2 C70 (Bn=CH2 Ph) with hydroxide and ArCN (Ar=Ph, m-ClPh) followed by quenching with I2 and BnBr afforded dibenzylated and tetrabenzylated oxazolino[70]fullerenes, respectively. The latter has a novel structural configuration, in which the addends are positioned from the polar to the transequatorial region. A key structural feature of this compound is that the oxygen atom of the oxazoline ring is bound to the equatorial belt region of C70 , giving structural change in its reduced state. This enables stabilization of the reduced state, suppressing charge recombination dynamics in organic solar cells to give a high open-circuit voltage (0.85, 0.93, and 1.11 V in devices using P3HT, PTB7, and DPP(TBFu)2 , respectively).

19.
Hepatogastroenterology ; 61(129): 120-4, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24895806

RESUMO

BACKGROUND/AIMS: To determine whether the use of narrow-band imaging (NBI) system could enhance the detection rate of esophageal squamous cell carcinoma and precancerous lesions during endoscopic examination of the esophagus. METHODOLOGY: 113 patients were randomized to undergo endoscopic examination using high definition television (HDTV) narrow band imaging (NBI) endoscopy or HDTV WL endoscopy. The primary endpoint was the difference in the neoplasm miss rate, and secondary outcome was the neoplasm detection rate. RESULTS: The number of esophageal cancer and high grade intraepithelial neoplasia lesions detected by HD-NBI and HD-WL was 45 and 21, respectively. The neoplasm miss rate per lesion and per patient with HD-NBI showed significant difference compared with that of HD-WL (P <0.05). Characteristics of lesions missed by use of HD-NBI were similar to those missed by use of HD-WL; all missed lesions were high grade intraepithelial neoplasia lesions. Significant difference was observed between NBI and WL in adenoma detection rate (70.2% vs. 35.7%, P < 0.01). CONCLUSIONS: Endoscopy with HD-NBI seems to improve the detection of esophageal cancer and precancerous lesions, high definition may be tested for its effect on detection of esophageal cancer and precancerous lesions in the future. These results indicate that endoscopy routinely using the NBI system for the surveillance of esophageal cancer and precancerous lesions may be recommended.


Assuntos
Carcinoma de Células Escamosas/diagnóstico , Erros de Diagnóstico/estatística & dados numéricos , Neoplasias Esofágicas/diagnóstico , Esofagoscopia/métodos , Lesões Pré-Cancerosas/diagnóstico , Diagnóstico Diferencial , Detecção Precoce de Câncer , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
20.
J Org Chem ; 79(1): 197-203, 2014 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-24188469

RESUMO

Oxazoline and imidazoline functionalization of a singly bonded C60 dimer is achieved via a one-pot reaction of C60HBn with OH(-) and aromatic nitriles, where the OH(-) not only functions as a Brønsted base that deprotonates C60HBn but also as a nucleophile that initiates the nucleophilic addition to the fullerene cage. The structures of the obtained oxazolinated and imidazolinated C60 dimeric compounds have been established by HRMS, UV-vis, and (1)H, (13)C, and HMBC NMR characterizations and computational calculations. The reaction mechanism is studied with the in situ vis-near-IR spectra, which shows that the use of I2 is crucial for the functionalization of the C60 dimer, indicating that it is likely the dimeric molecule rather than the fragment of the dimer that is involved in the reaction.

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