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1.
Nano Lett ; 24(29): 8902-8910, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-39008627

RESUMEN

Ion transportation at the interface significantly influences the electrochemical performance of the lithium ion battery, especially at high rates and low temperatures. Here, we develop a controlled self-assembly strategy for constructing a mesoporous carbon nanolayer with a uniform pore size and varied thicknesses on the two-dimensional monolayer MXene substrate. On the basis of the excellent electron conductivity of MXene, the mesoporous carbon layer is found with a voltage-driven ion accumulation effect, acting as an "ionic pump". The thicker mesoporous layer (∼2.28 nm) has the ability to accommodate a substantial quantity of ions, demonstrating enhanced ionic conductivity, remarkable cycling stability (192.8 mAh/g after 9400 cycles at 5.0 A/g), and outstanding rate capability at ambient and sub-zero temperatures (∼601 mAh/g at 0 °C and 0.05 A/g). This work provides valuable insights and guidance for the further development of high-performance electrode materials at high rates or low temperatures.

2.
Anal Bioanal Chem ; 416(23): 5025-5035, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39028344

RESUMEN

Free iron in human serum or non-transferrin-bound iron (NTBI) can generate free radicals and lead to oxidative damage. Moreover, it is highly toxic to various tissues and a vital biomarker related to the iron-loading status of thalassemia and Alzheimer's patients. In NTBI in healthy individuals, NTBI levels are typically less than 1 µM; current NTBI analysis usually requires advanced instrumentation and many-step sample pretreatment. To address this issue, we employed our invented BODIPY derivative, BODIPY-PH, as a fluorescence probe and trapped it onto the microcentrifuge tube lid using tapioca starch. The fluorescence intensity of BODIPY-PH increased with increasing NTBI concentration (turn-on). The developed portable reaction chamber facilitates rapid analysis (∼5 min) using small sample volumes (10 µL sample in a total volume of 600 µL). Under optimum conditions, using the sample-developed portable fluorescence device and fluorescence spectrometer, we achieved impressive limits of detection (LOD) of 0.003 and 0.0015 µM, respectively. Furthermore, the developed sensors show relatively high selectivity toward Fe3+ over other metal ions and biomolecules (i.e., Fe2+, Cr3+, Cu2+, and glucose). The sensor performance in serum samples of thalassemia patients exhibited no significant difference compared to the labeled value (obtained from standard methods). Overall, the developed fluorescence sensor is suitable for determining NTBI and offers high sensitivity, high selectivity, and a short incubation time (5 min). Moreover, the method requires a limited number of reagents, is simple to use, and uses low-cost equipment to determine NTBI in human serum samples.


Asunto(s)
Compuestos de Boro , Colorantes Fluorescentes , Hierro , Límite de Detección , Espectrometría de Fluorescencia , Humanos , Hierro/sangre , Compuestos de Boro/química , Espectrometría de Fluorescencia/métodos , Colorantes Fluorescentes/química , Hidrazonas/química , Transferrina/análisis
3.
Molecules ; 29(3)2024 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-38338348

RESUMEN

Chronic inflammation plays a crucial role in the development and progression of numerous chronic diseases. To search for anti-inflammatory metabolites from endophytic fungi isolated from plants growing in Thai mangrove areas, a chemical investigation of those fungi was performed. Five new oxygenated isocoumarins, setosphamarins A-E (1-5) were isolated from the EtOAc extract of an endophytic fungus Setosphaeria rostrata, along with four known isocoumarins and one xanthone. Their structures were determined by extensive spectroscopic analysis. The absolute configurations of the undescribed compounds were established by comparative analysis between experimental and calculated circular dichroism (ECD) spectroscopy. All the compounds were evaluated for their anti-inflammatory activity by monitoring nitric oxide inhibition in lipopolysaccharide-induced macrophage J774A.1 cells. Only a xanthone, ravenelin (9), showed potent activity, with an IC50 value of 6.27 µM, and detailed mechanistic study showed that it suppressed iNOS and COX-2 expression.


Asunto(s)
Ascomicetos , Xantonas , Isocumarinas/química , Tailandia , Ascomicetos/química , Antiinflamatorios/farmacología , Xantonas/farmacología , Estructura Molecular
4.
Angew Chem Int Ed Engl ; : e202413774, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39136239

RESUMEN

Developing sustainable energy solutions is critical for addressing the dual challenges of energy demand and environmental impact. In this study, a zinc-nitrate (Zn-NO3 -) battery system was designed for the simultaneous production of ammonia (NH3) via the electrocatalytic NO3 - reduction reaction (NO3RR) and electricity generation. Continuous wave CO2 laser irradiation yielded precisely controlled CoFe2O4@nitrogen-doped carbon (CoFe2O4@NC) hollow nanocubes from CoFe Prussian blue analogs (CoFe-PBA) as the integral electrocatalyst for NO3RR in 1.0 M KOH, achieving a remarkable NH4 + production rate of 10.9 mg h-1 cm-2 at -0.47 V versus Reversible Hydrogen Electrode with exceptional stability. In situ and ex situ methods revealed that the CoFe2O4@NC surface transformed into high-valent Fe/CoOOH active species, optimizing the adsorption energy of NO3RR (*NO2 and *NO species) intermediates. Furthermore, density functional theory calculations validated the possible NO3RR pathway on CoFe2O4@NC starting with NO3 - conversion to *NO2 intermediates, followed by reduction to *NO. Subsequent protonation forms the *NH and *NH2 species, leading to NH3 formation via final protonation. The Zn-NO3 - battery utilizing the CoFe2O4@NC cathode exhibits dual functionality by generating electricity with a stable open-circuit voltage of 1.38 V versus Zn/Zn2+ and producing NH3. This study highlights the innovative use of CO2 laser irradiation to transform Prussian blue analogs into cost-effective catalysts with hierarchical structures for NO3RR-to-NH3 conversion, positioning the Zn-NO3 - battery as a promising technology for industrial applications.

5.
Anal Chem ; 93(18): 6989-6999, 2021 05 11.
Artículo en Inglés | MEDLINE | ID: mdl-33909416

RESUMEN

This work presents a simple hydrothermal synthesis of nitrogen-doped carbon dots (N-CDs), fabrication of microfluidic paper-based analytical device (µPAD), and their joint application for colorimetric determination of total cholesterol (TC) in human blood. The N-CDs were characterized by various techniques including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD), and the optical and electronic properties of computational models were studied using the time-dependent density functional theory (TD-DFT). The characterization results confirmed the successful doping of nitrogen on the surface of carbon dots. The N-CDs exhibited high affinity toward 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-diammonium salt (ABTS) with the Michaelis-Menten constant (KM) of 0.018 mM in a test for their peroxidase-like activity. Particularly, since hydrogen peroxide (H2O2) is the oxidative product of cholesterol in the presence of cholesterol oxidase, a sensitive and selective method of cholesterol detection was developed. Overall, the obtained results from TD-DFT confirm the strong adsorption of H2O2 on the graphitic N positions of the N-CDs. The laminated three-dimensional (3D)-µPAD featuring a 6 mm circular detection zone was fabricated using a simple wax screen printing technique. Classification of TC according to the clinically relevant criteria (healthy, <5.2 mM; borderline, 5.2-6.2 mM; and high risk, >6.2 mM) could be determined by the naked eye within 10 min by simple comparison using a color chart. Overall, the proposed colorimetric device serves as a low-cost, rapid, simple, sensitive, and selective alternative for TC detection in whole blood samples that is friendly to unskilled end users.


Asunto(s)
Carbono , Puntos Cuánticos , Humanos , Peróxido de Hidrógeno , Microfluídica , Nitrógeno , Peroxidasas
6.
J Nat Prod ; 84(5): 1498-1506, 2021 05 28.
Artículo en Inglés | MEDLINE | ID: mdl-33861594

RESUMEN

Seven new polyketides including a phenol (1), two diphenyl ethers (2 and 3), two depsidones (4 and 5), and two phthalides (6 and 7) were isolated from the fungus Aspergillus unguis PSU-MF16 along with 27 known compounds. Their structures were determined by extensive spectroscopic analysis. The absolute configurations of 1 and 4-7 were established using comparative analyses of calculated and experimental ECD spectra. Among the new metabolites, 2 exhibited the best antimicrobial activity against Staphylococcus aureus, methicillin-resistant S. aureus, and Microsporum gypseum with equal MIC values of 16 µg/mL. In addition, known emeguisin A displayed potent antimicrobial activity against S. aureus, methicillin-resistant S. aureus, and Cryptococcus neoformans with equal MIC values of 0.5 µg/mL, compared with the standard drugs, vancomycin and amphotericin B. The structure-activity relationship study of the isolated compounds for antimicrobial activity is discussed.


Asunto(s)
Antibacterianos/farmacología , Antifúngicos/farmacología , Aspergillus/química , Policétidos/farmacología , Animales , Antibacterianos/aislamiento & purificación , Antifúngicos/aislamiento & purificación , Arthrodermataceae/efectos de los fármacos , Chlorocebus aethiops , Cryptococcus neoformans/efectos de los fármacos , Dysidea/microbiología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Policétidos/aislamiento & purificación , Relación Estructura-Actividad , Tailandia , Células Vero
7.
Planta Med ; 87(8): 600-610, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33682913

RESUMEN

Three new pyrrolobenzoxazine sesquiterpenoids, talatrachyoxazines A - C (1:  - 3: ), together with fourteen known compounds (4:  - 17: ), were isolated from the fungus Talaromyces trachyspermus EU23. Their structures were identified by spectroscopic evidence and mass spectrometry. The absolute configurations of 1:  - 3: were determined by NOESY data and comparison of their calculated and experimental electronic circular dichroism (ECD) spectra. Compound 1: showed cytotoxic activity against HelaS3, KB, HT-29, MCF-7, and HepG2 cell lines with IC50 values of 7, 11, 10, 12, and 10 µM, respectively. Compounds 1: and 14: showed weak antibacterial activity against the gram-positive bacteria Bacillus cereus and Bacillus subtilis, while 1:  - 3: and 14: showed weak antibacterial activity against the gram-negative bacterium Pseudomonas aeruginosa. In addition, compound 1: showed weak antibacterial activity against Escherichia coli.


Asunto(s)
Sesquiterpenos , Talaromyces , Antibacterianos/farmacología , Células Hep G2 , Humanos , Sesquiterpenos/farmacología
8.
Angew Chem Int Ed Engl ; 60(20): 11115-11119, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33631031

RESUMEN

Multiple studies have explored using cage silsesquioxanes (SQs) as backbone elements in hybrid polymers motivated by their well-defined structures and physical and mechanical properties. As part of this general exploration, we report unexpected photophysical properties of copolymers derived from divinyl double decker (DD) SQs, [vinyl(Me)Si(O0.5 )2 ][PhSiO1.5 ]8 [(O0.5 )2 Si(Me)vinyl] (vinylDDvinyl). These copolymers exhibit strong emission red-shifts relative to model compounds, implying unconventional conjugation, despite vinyl(Me)Si(O-)2 siloxane bridges. In an effort to identify minimum SQ structures that do/do not offer extended conjugation, we explored Heck catalyzed co-polymerization of vinyl-ladder(LL)-vinyl compounds, vinyl(Me/Ph)Si(O0.5 )2 [PhSiO1.5 ]4 (O0.5 )2 Si(Me/Ph)vinyl, with Br-Ar-Br. Most surprising, the resulting oligomers show 30-60 nm emission red-shifts beyond those seen with vinylDDvinyl analogs despite lacking a true cage. Further evidence for unconventional conjugation includes apparent integer charge transfer (ICT) between LL-co-thiophene, bithiophene, and thienothiophene with 10 mol % F4 TCNQ, suggesting potential as p-type doped organic/inorganic semiconductors.

9.
Phys Chem Chem Phys ; 22(35): 19877-19887, 2020 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-32852020

RESUMEN

Hydrogen sulfide (H2S) leads to corrosion in transport lines and poisoning of many catalysts. Meanwhile, H2S is an inexhaustible potential source of hydrogen, which is a very valuable chemical reagent and an environmentally friendly energy product. Therefore, removal of H2S and producing hydrogen gas using potential catalysts has been intensively studied, according to the equation: H2S(g) + CO(g) → COS(g) + H2(g). In this study, hydrogen sulfide (H2S) decomposition in the presence of CO over transition metal-doped ZSM-12 clusters (TM-ZSM-12) has been investigated based on DFT calculations at the B3LYP-D3/6-31G(d,p) level. The calculation results reveal that the proposed reaction mechanism is controlled by 4 key steps, (i) hydrogen dissociation (Ea1 = +0.04 eV for the 1st hydrogen and Ea2 = +0.22 eV for the 2nd hydrogen), (ii) COS desorption (the rate-determining step of this H2S removal process, Edes = +1.18 eV), (iii) hydrogen diffusion to the transition metal with an energy barrier (Ea3) of +0.62 eV, and (iv) the H2 formation step (Ea4 = +0.94 eV). Our results indicate that in the presence of CO, the Cu-ZSM-12 cluster has a potential application as a highly active catalyst for H2S removal together with hydrogen production.

10.
Inorg Chem ; 58(22): 15110-15117, 2019 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-31663724

RESUMEN

A coordination complex, lithium hepta(i-butyl)silsesquioxane trisilanolate (1; Li-T7), a stable intermediate in silsesquioxane (SQ) syntheses, was successfully isolated in 65% yield and found to be highly soluble in nonpolar solvents such as hexane. The structure of Li-T7 was confirmed by NMR, IR spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and computational simulation, providing detailed elucidation of the intermolecular self-association of the SQ cage with a box-shaped Li6O6 polyhedron through strong coordination bonds. After acid treatment, Li-T7 undergoes lithium-proton cationic exchange, yielding hepta(i-butyl)silsesquioxane trisilanol (2; H-T7) quantitatively. The high yield of H-T7 seems to be influenced by Li-O bonding in the Li-T7 complex that affects the selective formation of hepta(i-butyl)silsesquioxane trisilanolate and the bulky i-butyl groups which may prevent decomposition or SQ cage-rearrangement even at reflux under alkaline conditions. Single-crystal X-ray crystallography confirms the presence of the dumbbell-shaped SQ partial cages through strong intermolecular hydrogen bonds. Interestingly, lowering the polarity of the reaction solution by adding dichloromethane results in formation of the cubic octa(i-butyl)silsesquioxane (3; T8) cage in a good yield (47%), which is isolated by crystallization from the reaction solution.

11.
Phys Chem Chem Phys ; 20(32): 21194-21203, 2018 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-30083668

RESUMEN

We used density functional theory (DFT) to investigate hydrogen adsorption and diffusion on platinum-decorated carbon nanocones (Pt-CNCs). The curvature presented in the conical section of CNC materials affects the Pt binding stability. The role of Pt atoms as an active catalyst for H2 adsorption and dissociation has been investigated in perfect Pt-4CNC and defect Pt-v4CNC systems. Then, the spillover mechanism of dissociated hydrogen atoms in Pt-v4CNC is explored via two reaction steps: (i) H-migration from Pt to carbon atoms and (ii) H-diffusion via the C-C route throughout the CNC surface. Our results show that the presence of the hydrogen atom on the Pt catalyst can efficiently induce the H-diffusion process through the C-C surface, and the Pt-H bond significantly facilitates the H-migration from C-H bonds near to the active Pt catalyst to the adjacent carbon atom with an energy barrier <0.5 eV under ambient conditions. Altogether, the theoretical results support the concept of the spillover mechanism as a key process for enhancing the hydrogen storage capacity of metal-decorated CNCs. These results improve our understanding about the hydrogen spillover mechanism and the catalytic reactions which are very important for the development of highly efficient hydrogen storage materials.

12.
J Comput Chem ; 38(12): 901-909, 2017 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-28192642

RESUMEN

The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrepancy in the observed photoconversion efficiency (PCE) of two closely related DSCs based on carbazole-containing D-π-A organic sensitizers. Detailed theoretical characterization of the absorption spectra, dye adsorption on TiO2 , and electronic couplings for charge separation and recombination permit a systematic determination of the origin of the difference in PCE. Although the two dyes produce similar spectral features, ground- and excited-state density functional theory (DFT) simulations reveal that the dye with the bulkier donor group adsorbs more strongly to TiO2 , experiences limited π-π aggregation, and is more resistant to loss of excitation energy via charge recombination on the dye. The effects of conformational flexibility on absorption spectra and on the electronic coupling between the bright exciton and charge-transfer states are revealed to be substantial and are characterized through density-functional tight-binding (DFTB) molecular dynamics sampling. These simulations offer a mechanistic explanation for the superior open-circuit voltage and short-circuit current of the bulky-donor dye sensitizer and provide theoretical justification of an important design feature for the pursuit of greater photocurrent efficiency in DSCs. © 2017 Wiley Periodicals, Inc.

13.
Chemphyschem ; 15(17): 3809-18, 2014 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-25270592

RESUMEN

In an attempt to shed light on how the addition of a benzothiadiazole (BTD) moiety influences the properties of dyes, a series of newly designed triphenylamine-based sensitizers incorporating a BTD unit as an additional electron-withdrawing group in a specific donor-acceptor-π-acceptor architecture has been investigated. We found that different positions of the BTD unit provided significantly different responses for light absorption. Among these, it was established that the further the BTD unit is away from the donor part, the broader the absorption spectra, which is an observation that can be applied to improve light-harvesting ability. However, when the BTD unit is connected to the anchoring group a faster, unfavorable charge recombination takes place; therefore, a thiophene unit was inserted between these two acceptors, providing redshifted absorption spectra as well as blocking unfavorable charge recombination. The results of our calculations provide valuable information and illustrate the potential benefits of using computation-aided sensitizer design prior to further experimental synthesis.

14.
RSC Adv ; 14(39): 28390-28400, 2024 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-39239286

RESUMEN

The roots of Cymbidium ensifolium yielded a total of 17 compounds, comprising two new compounds (1-2), one new natural product (3), and 14 known compounds (4-17). The structures of new compounds were determined through the analysis of their spectroscopic data, including NMR, MS, UV, FT-IR, optical rotation, and CD. The anti-inflammatory activity of the isolated pure compounds was assessed using lipopolysaccharide-activated BV2 microglial cells. Compounds 1, 3, 6, 12, 14, and 16 showed the ability to reduce LPS induced NO release in BV2 microglial cells, with IC50 values of 9.95 ± 2.13, 8.77 ± 3.78, 2.39 ± 0.91, 6.69 ± 2.94, 2.96 ± 1.38, 8.42 ± 2.99 µM, respectively and reduced the secretion of proinflammatory mediators (TNF-α, IL-6, MCP-1) in a concentration-dependent manner. Furthermore, the mechanistic role of the compound 3 was determined, which demonstrated its ability to inhibit the nuclear factor-κB (NF-κB) pathway through decreasing phosphorylation of p65 subunits.

15.
J Nat Med ; 78(3): 558-567, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38517622

RESUMEN

A total of five new mexicanolides (1-5), namely alliaxylines A-E, together with two known limonoids 6 and 7, were isolated and identified from Dysoxylum alliaceum (Blume) Blume ex. A.Juss. (Meliaceae). The structures of these compounds were elucidated based on extensive spectroscopic analyses, including HR-ESI-MS, UV, IR, 1D, and 2D NMR, as well as theoretical stimulation of NMR shifts with the DP4 + algorithm. Consequently, this study aimed to examine cytotoxic activities of these compounds against MCF-7 and A549 cell lines. The results implied that compound 2 was the most potent against the two tested cells, with IC50 values of 34.95 ± 0.21 and 44.39 ± 1.03 µM.


Asunto(s)
Limoninas , Meliaceae , Corteza de la Planta , Humanos , Meliaceae/química , Corteza de la Planta/química , Limoninas/química , Limoninas/farmacología , Limoninas/aislamiento & purificación , Estructura Molecular , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/farmacología , Células MCF-7 , Células A549 , Línea Celular Tumoral , Espectroscopía de Resonancia Magnética , Extractos Vegetales/química , Extractos Vegetales/farmacología , Tallos de la Planta/química
16.
Artículo en Inglés | MEDLINE | ID: mdl-39213518

RESUMEN

Nonaqueous zinc-ion batteries (NZIBs) featuring manganese dioxide (MnO2) cathodes position themselves as viable options for large-scale energy storage systems. Herein, we demonstrate the use of ammonium cation as a preintercalant to improve the performance of the δ-MnO2 cathode in wet dimethyl sulfoxide based electrolytes. Employing in situ X-ray absorption spectroscopy, Raman spectroscopy, and synchrotron X-ray diffraction, we reveal that the integration of ammonium cations promotes the formation of NH-O-Mn networks. These networks are crucial for manipulating the distortion of the MnO6 octahedral units during discharging, thereby mitigating charge disproportionation, which is a primary limitation to MnO2's charge-storage efficiency. The modified MnO2, through this idea, displays a notable improvement in capacity (∼247 mAh/g) and can pass charge-discharge cycles up to 500 cycles with a capacity retention of 85%. These findings underscore the potential of modified MnO2 in advancing MnO2-based hosts for Zn-MnO2 batteries, marking significant progress toward next-generation energy storage solutions.

17.
Dalton Trans ; 53(24): 10328-10337, 2024 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-38836318

RESUMEN

We previously reported that phenyl- and vinyl-silsesquioxanes (SQs), [RSiO1.5]8,10,12 (R = Ph or vinyl) functionalized with three or more conjugated moieties show red-shifted absorption- and emission features suggesting 3-D conjugation via a cage centered LUMOs. Corner missing [PhSiO1.5]7(OSiMe3)3 and edge opened, end capped [PhSiO1.5]8(OSiMe2)2 (double decker, DD) analogs also offer red shifted spectra again indicating 3-D conjugation and a cage centered LUMO. Copolymerization of DD [PhSiO1.5]8(OSiMevinyl)2 with multiple R-Ar-Br gives copolymers with emission red-shifts that change with degree of polymerization (DP), exhibit charge transfer to F4TNCQ and terpolymer averaged red-shifts suggesting through chain conjugation even with two (O-Si-O) end caps possibly via a cage centered LUMO. Surprisingly, ladder (LL) SQ, (vinylMeSiO2)[PhSiO1.5]4(O2SiMevinyl) copolymers offer emission red-shifts even greater for analogous copolymers requiring a different explanation. Here we assess the photophysical behavior of copolymers of a more extreme SQ form: the half cage [PhSiO1.5]4(OSiMe2Vinyl)4, Vy4HC SQs. We again see small red-shifted absorptions coupled with significant red-shifted emissions, even with just a half cage, thus further supporting the existence of pπ-dπ and/or σ*-π* conjugation through Si-O-Si bonds and contrary to most traditional views of Si-O-Si linked polymers. These same copolymers donate an electron to F4TCNQ generating the radical anion, F4TCNQ-. as further proof of conjugation. Column chromatographic separation of short from longer chain oligomers reveals a direct correlation between DP and emission λmax red-shifts as another indication of conjugation. Further, one- and two-photon absorption and emission spectroscopy reveals multiple excited fluorescence-emitting states in a violation of Kasha's rule wherein emission occurs only from the lowest excited state. Traditional modeling studies again find HOMO LUMO energy levels residing only on the aromatic co-monomers rather than through Si-O-Si bonds as recently found in related polymers.

18.
J Org Chem ; 78(13): 6702-13, 2013 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-23777195

RESUMEN

A series of bis(3,6-di-tert-butylcarbazol-9-ylphenyl)aniline end-capped oligoarylenes, BCPA-Ars, are synthesized by double palladium-catalyzed cross-coupling reactions. By using this bis(carbazol-9-yl)triphenylamine moiety as an end-cap, we are able to reduce the crystallization and retain the high-emission ability of these planar fluorescent oligoarylene cores in the solid state, as well as improve the amorphous stability and solubility of the materials. The results of optical and electrochemical studies show that their HOMOs, LUMOs, and energy gaps can be easily modified or fine-tuned by either varying the degree of π-conjugation or using electron affinities of the aryl cores which include fluorene, oligothiophenes, 2,1,3-benzothiadiazole, 4,7-diphenyl-4-yl-2,1,3-benzothiadiazole, and 4,7-dithien-2-yl-2,1,3-benzothiadiazole. As a result, their emission spectra measured in solution and thin films can cover the full UV-vis spectrum (426-644 nm). Remarkably, solution-processed nondoped BCPA-Ars-based OLEDs could show moderate to excellent device performance with emission colors spanning the whole visible spectrum (deep blue to red). Particularly, the RGB (red, green, blue) OLEDs exhibit good color purity close to the pure RGB colors. This report offers a practical approach for both decorating the highly efficient but planar fluorophores and tuning their emission colors to be suitable for applications in nondoped and solution-processable full-color emission OLEDs.

19.
Chempluschem ; 88(11): e202300306, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37787416

RESUMEN

In this work, we studied the reaction mechanisms for CO2 reduction reaction (CRR) on the iron-doped graphene and its coordinating sulfur (S) and nitrogen (N) variants, FeNn S4-n (n=1-4), using density functional theory calculations. Our results revealed that the electronic property and catalytic reactivity of the surfaces can be tuned by varying the N and S atoms ratio. The CRR activities of the mixed surfaces, FeN3 S1 , FeN2 S2 , and FeN1 S3 , were better than FeN4 and FeS4 , where the absolute value of the limiting potential of the mixed surface decreased by 0.3 V. Considering the stability, we suggest FeN3 S surface to be favorable for CRR. For the bare surfaces, we found a positive linear correlation between the magnetic moment and the charge of Fe metal. For these surfaces, the reduction of CO (*CO+(H+ +e- )→*CHO) was important in deciding the limiting potential. We found that the adsorption energy of CO displayed a volcano relationship with the magnetic moment of the Fe atom. The study showed that the change of local coordinating structure around the Fe atom could modify the electronic and magnetic properties of the active Fe center and improve the CRR activity performance.

20.
Nat Prod Res ; : 1-8, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36919631

RESUMEN

The soil-derived fungus Talaromyces thailandensis PSU-SPSF059 produced one new vermistatin derivative, talarostatin, and seven known compounds including two vermistatins, two chrodrimanins, two diphenyl ethers and one penicillide derivative. Extensive spectroscopic analysis was performed to identify their structures. The absolute configuration of talarostatin was determined by comparing the experimental and calculated electronic circular dichroism data. The antimicrobial and cytotoxic activities of the isolated secondary metabolites were also evaluated.

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