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1.
Sensors (Basel) ; 24(13)2024 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-39000854

RESUMO

In the shipbuilding industry, welding automation using welding robots often relies on arc-sensing techniques due to spatial limitations. However, the reliability of the feedback current value, core sensing data, is reduced when welding target workpieces have significant curvature or gaps between curved workpieces due to the control of short-circuit transition, leading to seam tracking failure and subsequent damage to the workpieces. To address these problems, this study proposes a new algorithm, MBSC (median-based spatial clustering), based on the DBSCAN (density-based spatial clustering of applications with noise) clustering algorithm. By performing clustering based on the median value of data in each weaving area and considering the characteristics of the feedback current data, the proposed technique utilizes detected outliers to enhance seam tracking accuracy and responsiveness in unstructured and challenging welding environments. The effectiveness of the proposed technique was verified through actual welding experiments in a yard environment.

2.
J Org Chem ; 88(2): 1200-1214, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36598492

RESUMO

The continuous flow synthesis of N-sulfonyl-1,2,3-triazoles, which are convenient reactive azavinyl carbene precursors, for tandem relay Cu/Rh dual catalysis has been developed. Most reactions readily proceeded at 75 °C in a short residence time of 13.09 min in the presence of 2.5 mol % of CuTC. The scope of the reactions was explored by synthesizing diversely functionalized N-sulfonyl and sulfamoyl triazoles in yields ranging from 92 to 98%. To demonstrate the scalability of the process, the reaction was conducted on a 5.4 mmol scale with residence and collection times of 13.09 and 60 min, respectively. Furthermore, a series of controlled experiments were performed to investigate the compatibility of Cu and Rh in a batch or a continuous flow system. Finally, the first integrated flow system using the azavinyl carbene intermediate under the tandem relay Cu/Rh dual catalysis was developed for the synthesis of various cis-diamino enones from alkynes and sulfonyl azides.

3.
Vet Radiol Ultrasound ; 64(3): 402-410, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36727204

RESUMO

Ruptures of pulmonary blebs and bullae are the most common cause of spontaneous pneumothorax in dogs. Incidental bullae/blebs have been documented in otherwise healthy people, however information for veterinary patients is currently lacking. Objectives of this retrospective, observer agreement, analytical study were to characterize incidental bullae in thoracic CT studies of dogs, assess interobserver variability for characterizing the bullae, and assess anesthesia risks. Inclusion criteria were dogs presenting for non-pneumothorax related reasons that had a thoracic CT at a single specialty and emergency hospital from 2012 to 2021 and had a bulla listed in the CT report. Medical records for dogs meeting inclusion criteria were reviewed to collect data on signalment, weight, total number of general anesthesia procedures 2 years prior and 2 years following the CT scan, and adverse anesthesia events. In addition, the CT images were reviewed by three American College of Veterinary Radiology-certified veterinary radiologists to collect data on the location, size, number of bullae and thickness of the bulla wall. A total of 1119 dogs met initial inclusion criteria and 74 dogs were included in analyses. There was no sex predilection for incidental pulmonary bullae. Bullae were more commonly found in older (median age 11.3 years), large breed dogs (median weight 20.7 kg). A solitary bulla of less than 1 cm was the most common finding with no apparent predilection for a particular lung lobe. There was strong correlation among the three radiologists for bulla location, size, and number, but weak correlations for bulla wall thickness. No adverse anesthesia events were found following CT anesthesia or following repetitive anesthesia procedures.


Assuntos
Vesícula , Doenças do Cão , Cães , Animais , Vesícula/diagnóstico por imagem , Vesícula/etiologia , Vesícula/veterinária , Estudos Retrospectivos , Variações Dependentes do Observador , Tomografia Computadorizada por Raios X/efeitos adversos , Tomografia Computadorizada por Raios X/veterinária , Anestesia Geral/efeitos adversos , Anestesia Geral/veterinária , Doenças do Cão/diagnóstico por imagem , Doenças do Cão/epidemiologia , Doenças do Cão/etiologia
4.
Mar Drugs ; 20(12)2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36547902

RESUMO

Functional ingredients for human health have recently become the focus of research. One such potentially versatile therapeutic component is fucose-containing sulfated polysaccharides (FCSPs), referred to as fucoidans. The exploitation of marine brown algae provides a rich source of FCSPs because of their role as a structural component of the cell wall. Fucoidans are characterized by a sulfated fucose backbone. However, the structural characterization of FCSPs is impeded by their structural diversity, molecular weight, and complexity. The extraction and purification conditions significantly influence the yield and structural alterations. Inflammation is the preliminary response to potentially injurious inducements, and it is of the utmost importance for modulation in the proper direction. Improper manipulation and/or continuous stimuli could have detrimental effects in the long run. The web of immune responses mediated through multiple modulatory/cell signaling components can be addressed through functional ingredients, benefiting patients with no side effects. In this review, we attempted to address the involvement of FCSPs in the stimulation/downregulation of immune response cell signaling. The structural complexity and its foremost influential factor, extraction techniques, have also attracted attention, with concise details on the structural implications of bioactivity.


Assuntos
Phaeophyceae , Alga Marinha , Humanos , Fucose/química , Polissacarídeos/farmacologia , Polissacarídeos/uso terapêutico , Polissacarídeos/química , Phaeophyceae/química , Fatores Imunológicos/farmacologia , Fatores Imunológicos/uso terapêutico , Sulfatos , Alga Marinha/química
5.
Sensors (Basel) ; 22(9)2022 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-35591120

RESUMO

A smart city is an urban area that collects data from various devices to effectively manage urban resources. The smart city IoT infrastructure connects numerous devices to an Internet-protocol-based low-power wireless network, shares massive amounts of data, and facilitates the development of new services. Message queuing telemetry transport (MQTT), a lightweight exchange protocol for the IoT environment, uses a publish and subscribe structure via a centralized broker to share data. The extent of edge computing provides distributed and closer resources to the data source while maintaining low transmission costs. However, a centralized MQTT data broker is unsuitable for distributed edge resources and could result in high latency, traffic, and bottleneck risk. Therefore, we proposed a distributed MQTT broker optimized architecture. A distributed MQTT broker for edge resources could reduce network traffic and data delivery latency by only managing consumed topics in the network. We formulate an integer non-linear program to optimize container placement and avoid wasting edge computing resources. We compared our proposed architecture to the existing distributed MQTT middleware architecture with greedy and random container placement through extensive simulation. Our methods show better performance in lowering deployment failure ratio, power consumption, network usage, and synchronization overhead.

6.
Inorg Chem ; 60(6): 4058-4067, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33645218

RESUMO

Iron(V)-oxo complexes bearing negatively charged tetraamido macrocyclic ligands (TAMLs) have provided excellent opportunities to investigate the chemical properties and the mechanisms of oxidation reactions of mononuclear nonheme iron(V)-oxo intermediates. Herein, we report the differences in chemical properties and reactivities of two iron(V)-oxo TAML complexes differing by modification on the "Head" part of the TAML framework; one has a phenyl group at the "Head" part (1), whereas the other has four methyl groups replacing the phenyl ring (2). The reactivities of 1 and 2 in both C-H bond activation reactions, such as hydrogen atom transfer (HAT) of 1,4-cyclohexadiene, and oxygen atom transfer (OAT) reactions, such as the oxidation of thioanisole and its derivatives, were compared experimentally. Under identical reaction conditions, 1 showed much greater reactivity than 2, such as a 102-fold decrease in HAT and a 105-fold decrease in OAT by replacing the phenyl group (i.e., 1) with four methyl groups (i.e., 2). Then, density functional theory calculations were performed to rationalize the reactivity differences between 1 and 2. Computations reproduced the experimental findings well and revealed that the replacement of the phenyl group in 1 with four methyl groups in 2 not only increased the steric hindrance but also enlarged the energy gap between the electron-donating orbital and the electron-accepting orbital. These two factors, steric hindrance and the orbital energy gap, resulted in differences in the reduction potentials of 1 and 2 and their reactivities in oxidation reactions.

7.
Entropy (Basel) ; 23(5)2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33925902

RESUMO

Edge computing can deliver network services with low latency and real-time processing by providing cloud services at the network edge. Edge computing has a number of advantages such as low latency, locality, and network traffic distribution, but the associated resource management has become a significant challenge because of its inherent hierarchical, distributed, and heterogeneous nature. Various cloud-based network services such as crowd sensing, hierarchical deep learning systems, and cloud gaming each have their own traffic patterns and computing requirements. To provide a satisfactory user experience for these services, resource management that comprehensively considers service diversity, client usage patterns, and network performance indicators is required. In this study, an algorithm that simultaneously considers computing resources and network traffic load when deploying servers that provide edge services is proposed. The proposed algorithm generates candidate deployments based on factors that affect traffic load, such as the number of servers, server location, and client mapping according to service characteristics and usage. A final deployment plan is then established using a partial vector bin packing scheme that considers both the generated traffic and computing resources in the network. The proposed algorithm is evaluated using several simulations that consider actual network service and device characteristics.

8.
J Am Chem Soc ; 142(36): 15305-15319, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32786748

RESUMO

Acid effects on the chemical properties of metal-oxygen intermediates have attracted much attention recently, such as the enhanced reactivity of high-valent metal(IV)-oxo species by binding proton(s) or Lewis acidic metal ion(s) in redox reactions. Herein, we report for the first time the proton effects of an iron(V)-oxo complex bearing a negatively charged tetraamido macrocyclic ligand (TAML) in oxygen atom transfer (OAT) and electron-transfer (ET) reactions. First, we synthesized and characterized a mononuclear nonheme Fe(V)-oxo TAML complex (1) and its protonated iron(V)-oxo complexes binding two and three protons, which are denoted as 2 and 3, respectively. The protons were found to bind to the TAML ligand of the Fe(V)-oxo species based on spectroscopic characterization, such as resonance Raman, extended X-ray absorption fine structure (EXAFS), and electron paramagnetic resonance (EPR) measurements, along with density functional theory (DFT) calculations. The two-protons binding constant of 1 to produce 2 and the third protonation constant of 2 to produce 3 were determined to be 8.0(7) × 108 M-2 and 10(1) M-1, respectively. The reactivities of the proton-bound iron(V)-oxo complexes were investigated in OAT and ET reactions, showing a dramatic increase in the rate of sulfoxidation of thioanisole derivatives, such as 107 times increase in reactivity when the oxidation of p-CN-thioanisole by 1 was performed in the presence of HOTf (i.e., 200 mM). The one-electron reduction potential of 2 (Ered vs SCE = 0.97 V) was significantly shifted to the positive direction, compared to that of 1 (Ered vs SCE = 0.33 V). Upon further addition of a proton to a solution of 2, a more positive shift of the Ered value was observed with a slope of 47 mV/log([HOTf]). The sulfoxidation of thioanisole derivatives by 2 was shown to proceed via ET from thioanisoles to 2 or direct OAT from 2 to thioanisoles, depending on the ET driving force.


Assuntos
Compostos de Ferro/química , Oxigênio/química , Prótons , Teoria da Densidade Funcional , Compostos de Ferro/síntese química , Conformação Molecular , Oxirredução
9.
J Org Chem ; 85(11): 7399-7412, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32370500

RESUMO

A new and mild synthetic approach has been developed for the synthesis of pharmaceutically important unsymmetrical diarylpyridines via chemoselective Suzuki-Miyaura coupling reactions of bromo-2-sulfonyloxypyridines. Most reactions allow for facile access to aryl-2-sulfonyloxypyridines at room temperature in yields of 5-99% with excellent chemoselectivity in the presence of Pd(OAc)2 (2.0 mol %) and Ad2BnP (2.4 mol %). The second arylation of the remaining tosyl or triflyl group in the monoarylpyridine derivatives obtained was successfully accomplished for the synthesis of unsymmetrical 2,3-, 2,4-, 2,5-, and 2,6-diarylpyridine derivatives. Furthermore, a one-pot synthesis of unsymmetrical diarylpyridines starting from bromo-2-sulfonyloxypyridine was accomplished to demonstrate the practical convenience. Finally, with this method, an antibacterial agent, a topoisomerase inhibitor, and etoricoxib, a nonsteroidal anti-inflammatory drug, were successfully synthesized from the corresponding bromo-2-hydroxypyridines in overall yields of 80, 86, and 49%, respectively.

10.
Molecules ; 25(23)2020 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-33291461

RESUMO

Particulate matter (PM) is a significant participant in air pollution and is hence an inducer of serious health issues. This study aimed to evaluate the dust protective effects of alginate from Padina boryana (PBA) via inflammatory-associated pathways to develop anti-fine dust skincare products. In between the external and internal environments, the skin is considered to be more than a physical barrier. It was observed that PM stimulates inflammation in the skin via activating NF-κB and MAPK pathways. The potential of PBA to inhibit the studied pathways were evident. The metal ion content of PM was considerably reduced by PBA and thus attributed to its chelation ability. Current research demonstrated the potential of P. boryana alginates to be implemented as a protective barrier against inflammation imposed with heavy metal and bacterial-derived endotoxin bound to the surface of the PM. Concisely, the results suggest that the bioactive components derived from the brown algae Padina boryana increased the cellular resistance to PM-stimulated inflammation-driven skin damage.


Assuntos
Ácido Algínico/farmacologia , Fibroblastos/efeitos dos fármacos , Inflamação/tratamento farmacológico , Queratinócitos/efeitos dos fármacos , Material Particulado/efeitos adversos , Phaeophyceae/química , Pele/efeitos dos fármacos , Poluição do Ar/efeitos adversos , Linhagem Celular , Poeira , Fibroblastos/metabolismo , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Queratinócitos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Pele/metabolismo
11.
Angew Chem Int Ed Engl ; 58(45): 16124-16129, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31489757

RESUMO

A mononuclear nonheme manganese(IV)-oxo complex binding the Ce4+ ion, [(dpaq)MnIV (O)]+ -Ce4+ (1-Ce4+ ), was synthesized by reacting [(dpaq)MnIII (OH)]+ (2) with cerium ammonium nitrate (CAN). 1-Ce4+ was characterized using various spectroscopic techniques, such as UV/Vis, EPR, CSI-MS, resonance Raman, XANES, and EXAFS, showing an Mn-O bond distance of 1.69 Šwith a resonance Raman band at 675 cm-1 . Electron-transfer and oxygen atom transfer reactivities of 1-Ce4+ were found to be greater than those of MnIV (O) intermediates binding redox-inactive metal ions (1-Mn+ ). This study reports the first example of a redox-active Ce4+ ion-bound MnIV -oxo complex and its spectroscopic characterization and chemical properties.

12.
Inorg Chem ; 57(16): 10232-10240, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30080409

RESUMO

Mn(III)-iodosylarene porphyrin adducts, [Mn(III)(ArIO)(Porp)]+, were synthesized by reacting electron-deficient Mn(III) porphyrin complexes with iodosylarene (ArIO) at -60 °C and characterized using various spectroscopic methods. The [Mn(III)(ArIO)(Porp)]+ species were then investigated in the epoxidation of olefins under stoichiometric conditions. In the epoxidation of olefins by the Mn(III)-iodosylarene porphyrin species, epoxide was formed as the sole product with high chemoselectivities and stereoselectivities. For example, cyclohexene oxide was formed exclusively with trace amounts of allylic oxidation products; cis- and trans-stilbenes were oxidized to the corresponding cis- and trans-stilbene oxides, respectively. In the catalytic epoxidation of cyclohexene by an electron-deficient Mn(III) porphyrin complex and sPhIO at low temperature (e.g., -60 °C), the Mn(III)-iodosylarene porphyrin species was evidenced as the active oxidant that effects the olefin epoxidation to give epoxide as the product. However, at high temperature (e.g., 0 °C) or in the case of using an electron-rich manganese(III) porphyrin catalyst, allylic oxidation products, along with cyclohexene oxide, were yielded, indicating that the active oxidant(s) was not the Mn(III)-iodosylarene adduct but probably high-valent Mn-oxo species in the catalytic reactions. We also report the conversion of the Mn(III)-iodosylarene porphyrins to high-valent Mn-oxo porphyrins under various conditions, such as at high temperature, with electron-rich porphyrin ligand, and in the presence of base (OH-). The present study reports the first example of spectroscopically well-characterized Mn(III)-iodosylarene porphyrin species being an active oxidant in the stoichiometric and catalytic oxidation reactions. Other aspects, such as one oxidant versus multiple oxidants debate, also were discussed.

13.
Adv Exp Med Biol ; 975 Pt 2: 1179-1190, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28849532

RESUMO

This study aimed to investigate the effect of doxorubicin co-treatment with taurine on B16F10 melanoma cells. Frequently, Doxorubicin is used in the treatments of many different kinds of cancers, some of which are soft tissue sarcomas, hematological malignancies and carcinomas. However, the clinical application of doxorubicin is compromised by its severe adverse effects, including cardiotoxicity. In the present study, the efficacy of doxorubicin co-treatment with taurine was investigated. B16F10 cell viability was evaluated using MTT assays, trypan blue dye exclusion assays, and fluorescent staining technique. Apoptotic cells were detected by flow cytometry and the proteins associated with apoptosis and cellular differentiations were assessed by immunoblotting. Doxorubicin inhibited cell growth and induced cell death in B16F10 cells. Interestingly, doxorubicin co-treatment with taurine inhibited apoptosis in B16F10 cells. These results indicate that doxorubicin co-treatment with taurine attenuates doxorubicin-induced cytotoxicity and reduces ROS production in B16F10 cells.


Assuntos
Antibióticos Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Doxorrubicina/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Taurina/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Melanoma Experimental , Camundongos , Espécies Reativas de Oxigênio
14.
J Org Chem ; 81(17): 7717-24, 2016 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-27484240

RESUMO

A new and mild synthetic approach for the N-arylation of 2-pyridones with diaryliodonium salts has been developed. Most reactions proceed readily at room temperature in the presence of 10 mol % of copper chloride. As a result, a wide range of N-arylpyridine-2-ones were synthesized in yields of 23% to 99%. With this method, an antifibrotic drug, Pirfenidone, was successfully synthesized in 99% yield within 30 min at room temperature.


Assuntos
Cobre/química , Oniocompostos/química , Piridonas/química , Catálise , Estrutura Molecular , Sais/química , Análise Espectral/métodos , Estereoisomerismo , Temperatura
15.
Molecules ; 21(4): 422, 2016 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-27043497

RESUMO

The fruit of Chaenomeles sinensis has been traditionally used in ethnomedicine for the treatment of various human ailments, including pneumonia, bronchitis, and so on, but the pharmacological applications of the leaf part of the plant have not been studied. In this study, we evaluated the various radical scavenging activities and anti-inflammatory effects of different Chaenomeles sinensis leaf (CSL) extracts. The water extract showed a higher antioxidant and radical scavenging activities. However the ethanolic extracts showed higher NO scavenging activity than water extract, therefore the ethanolic extract of CSL was examined for anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The 70% ethanol extract of CSL (CSLE) has higher anti-inflammatory activity and significantly inhibited the production of nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). In addition, CSLE suppressed LPS-stimulated inducible nitric oxide synthase (iNOS) and NO production, IL-1ß and phospho-STAT1 expression. In this study, we investigated the effect of CSLE on the production of inflammatory mediators through the inhibition of the TRIF-dependent pathways. Furthermore, we evaluated the role of CSLE on LPS-induced expression of pro-inflammatory cytokines, such as TNF-α, IL-1ß and IL-6. Our results suggest that CSLE attenuates the LPS-stimulated inflammatory responses in macrophages through regulating the key inflammatory mechanisms, providing scientific support for its traditional uses in treating various inflammatory diseases.


Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Inflamação/tratamento farmacológico , Extratos Vegetais/farmacologia , Rosaceae/química , Animais , Anti-Inflamatórios/química , Antioxidantes/química , Etanol/química , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Interleucina-1beta/biossíntese , Interleucina-6/biossíntese , Lipopolissacarídeos/toxicidade , Camundongos , Óxido Nítrico/biossíntese , Extratos Vegetais/química , Folhas de Planta/química , Células RAW 264.7 , Fator de Necrose Tumoral alfa/biossíntese , Água/química
16.
Angew Chem Int Ed Engl ; 55(28): 8027-31, 2016 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-27273456

RESUMO

Mononuclear nonheme high-spin (S=2) iron(IV)-oxo species have been identified as the key intermediates responsible for the C-H bond activation of organic substrates in nonheme iron enzymatic reactions. Herein we report that the C-H bond activation of hydrocarbons by a synthetic mononuclear nonheme high-spin (S=2) iron(IV)-oxo complex occurs through an oxygen non-rebound mechanism, as previously demonstrated in the C-H bond activation by nonheme intermediate (S=1) iron(IV)-oxo complexes. We also report that C-H bond activation is preferred over C=C epoxidation in the oxidation of cyclohexene by the nonheme high-spin (HS) and intermediate-spin (IS) iron(IV)-oxo complexes, whereas the C=C double bond epoxidation becomes a preferred pathway in the oxidation of deuterated cyclohexene by the nonheme HS and IS iron(IV)-oxo complexes. In the epoxidation of styrene derivatives, the HS and IS iron(IV) oxo complexes are found to have similar electrophilic characters.

17.
J Org Chem ; 80(3): 1856-65, 2015 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-25584697

RESUMO

A mild and efficient synthesis of N-arylcarbamates was achieved by reacting azidoformates with boronic acids in the presence of 10 mol % of copper chloride catalyst. The reaction proceeds readily in an open flask at room temperature without additional base, ligand, or additive. Rapid access to urea analogues via a two-step one-pot procedure is enabled by reacting N-arylcarbamates with aluminum-amine complexes. In addition, among several boronic acid derivatives prepared, dimethylphenyl boronate was found to react rapidly in its reaction with benzyl azidoformate, invoking in situ generation of this species in the catalytic cycle.


Assuntos
Azidas/química , Ácidos Borônicos/química , Carbamatos/síntese química , Cobre/química , Carbamatos/química , Catálise , Ligantes , Estrutura Molecular , Temperatura
18.
Proc Natl Acad Sci U S A ; 108(17): 6787-92, 2011 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-21245309

RESUMO

In conjunction with the construction of a diversity-oriented synthesis library of 10-membered ring "natural product-like" macrolides, the design, synthesis, and validation of a unique class of bifunctional linchpins, uniting benzyne reactivity initiated by type II anion relay chemistry (ARC) has been achieved, permitting access to diverse [2+2], [3+2], and [4+2] cycloadducts.


Assuntos
Derivados de Benzeno/química , Macrolídeos/química , Macrolídeos/síntese química , Estrutura Molecular
19.
Adv Sci (Weinh) ; 11(17): e2308829, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38403474

RESUMO

An unprecedented silver-mediated intramolecular oxy-argentation of 3-amidoaryne precursors that quickly generates a heteroarylsilver species is developed. AgF acts as both a stoichiometric fluoride source and a reagent for the formation of a benzoxazolylsilver intermediate via aryne generation. Pd-catalyzed coupling reactions of (hetero)aryl iodides with a silver species, generated in situ, allow for the synthesis of various C7-arylated benzoxazoles. As a result, an aryl group is selectively introduced into the meta-position of 3-amidobenzyne precursors. Mechanistic studies have indicated the presence of a benzoxazolylsilver intermediate and revealed that the reaction proceeds via an intramolecular oxy-argentation process, which is initiated by a direct fluoride attack on the silyl group.

20.
ACS Appl Mater Interfaces ; 16(17): 21915-21923, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38642042

RESUMO

In this study, we present a novel method for controlling the growth of perovskite crystals in the vacuum thermal evaporation process by utilizing a vacuum-processable additive, propylene urea (PU). By coevaporation of perovskite precursors with PU to form the perovskite layer, PU, acting as a Lewis base additive, retards the direct reaction between the perovskite precursors. This facilitates a larger domain size and reduced defect density. Following the removal of the residual additive, the perovskite layer, exhibiting improved crystallinity, demonstrates reduced charge recombination, as confirmed by a time-resolved microwave conductivity analysis. Consequently, there is a notable enhancement in open-circuit voltage and power conversion efficiency, increasing from 1.05 to 1.15 V and from 17.17 to 18.31%, respectively. The incorporation of a vacuum-processable and removable Lewis base additive into the fabrication of vacuum-processed perovskite solar cells offers new avenues for optimizing these devices.

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