Multiple-Yolk-Shell NiO Microspheres for Selective Detection of m-Xylene.

m-Xylene is a volatile organic compound that is extensively used in various industrial processes. It is toxic, posing significant risks to human health and the environment. Therefore, developing gas sensors with high sensitivity and selectivity for m-xylene detection is critical. In this work, we demonstrated the synthesis of NiO-yolk double-shell (NiO-YDS) and NiO-yolk triple-shell (NiO-YTS) derived from NiO/Ni-BTC and NiO/Ni-PTA composites, respectively, using the microwave-assisted solvothermal method from Ni-BTC-derived NiO spheres. The NiO/Ni-BTC composite has trimesic acid (H3BTC) as an organic linker, while NiO/Ni-PTA has p-terephthalic acid (PTA). We investigated the sensing properties of these materials for 2-butanone, 2-nonanone, 3-methyl-1-butanol, acetone, benzene, ethanol, methanol, and m-xylene. These composites exhibited excellent sensitivity and selectivity for detecting m-xylene under dry conditions. Specifically, the NiO-YTS sensor showed a sensitivity of 217.5% to m-xylene, while the NiO-YDS sensor demonstrated a sensitivity of 179.8% at 350 °C in dry air. We emphasize the NiO-YTS composite due to its superior sensitivity and selectivity in detecting m-xylene compared with the NiO-YDS composite. The NiO-YTS sensor exhibited stable and reproducible sensing performance for 100 ppm of m-xylene under optimum working conditions, with a theoretical detection limit of 5.43 ppb and relatively fast response time (89 s) and recovery time (191 s). This work describes an easy method for synthesizing NiO-YDS and NiO-YTS derived from NiO/Ni-BTC and NiO/Ni-PTA composites. It demonstrates that these composites represent a new class of materials that can potentially enhance the sensitivity and selectivity of m-xylene gas sensors.

Microwave-Assisted Synthesis of Zeolite A from Metakaolinite for CO2 Adsorption.

The global demand for energy and industrial growth has generated an exponential use of fossil fuels in recent years. It is well known that carbon dioxide (CO2) is mainly produced, but not only from fuels, which has a negative impact on the environment, such as the increasing emission of greenhouse gases. Thus, thinking about reducing this problem, this study analyzes microwave irradiation as an alternative to conventional heating to optimize zeolite A synthesis conditions for CO2 capture. Synthesis reaction parameters such as different temperatures (60-150 °C) and different time durations (1-6 h) were evaluated. The CO2 adsorption capacity was evaluated by CO2 adsorption-desorption isotherms at 25 °C and atmospheric pressure. The results showed that the synthesis of zeolite A by microwave irradiation was successfully obtained from natural kaolinite (via metakaolinization), reducing both temperature and time. Adsorption isotherms show that the most promising adsorbent for CO2 capture is a zeolite synthesized at 100 °C for 4 h, which reached an adsorption capacity of 2.2 mmol/g.

Transfer Hydrogenation of Furfural to Furfuryl Alcohol Under Microwave Irradiation Using Mixed Oxides.

The reaction to obtain furan alcohols is one of the most important in the upgrading of furan derivates. An attractive route is the transfer hydrogenation of furfural using acidic-basic catalysts. In this work, mixed oxides derived from ternary hydrotalcites were employed to obtain furfuryl alcohol from furfural assisted by microwave irradiation. These materials were characterized via X-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier-transform infrared (FTIR) and the CO2 temperature-programmed desorption (CO2 -TPD) analyses. The lamellar structure of hydrotalcite-type materials collapses during the calcination process, resulting in the loss of carbonate anions and hydroxyl groups, present in the interlayer space. This leads to the formation of mixed oxides that exhibit larger surface areas. Furthermore, these changes alter the basic nature of these materials, giving rise to the formation of strong basic sites. The reaction was studied using containing Co2+ and Ni2+ in their structure and was then optimized using distinct primary and secondary alcohols as hydrogen donor sources, as well as distinct temperatures and initial concentrations of furfural. The yields to furfuryl alcohol are strongly dependent on the type of Me2+ in layered oxides mainly due to higher basicity and to the donor employed in the reaction. The mixed oxide containing Co2+ showed complete conversion of furfural and higher yields to furfuryl alcohol (>95 %) at short times of reaction (<1 h).

Fused Pyrroles in Cholestane and Norcholestane Side Chains: Acaricidal and Plant Growth-Promoting Effects.

Herein, we describe the synthesis and characterization of fused pyrroles in cholestane and norcholestane side chains derived from kryptogenin and diosgenin, respectively. Both conventional and microwave heating techniques were used to synthesize the steroidal pyrroles from primary amines, with the microwave method producing the highest yields. In particular, the norcholestane pyrroles were tested as acaricides against the two-spotted spider mite (Tetranychus urticae Koch) under laboratory conditions and as plant growth promoters on habanero pepper (Capsicum chinense Jacq) under greenhouse conditions.

Development of Radiosterilized Porcine Skin Electrosprayed with Silver Nanoparticles Prevents Infections in Deep Burns.

Extensive burns represent a significant challenge in biomedicine due to the multiple systemic and localized complications resulting from the major skin barrier loss. The functionalization of xenografts with nanostructured antibacterial agents proposes a fast and accessible application to restore barrier function and prevent localized bacterial contamination. Based on this, the objective of this work was to functionalize a xenograft by electrospray deposition with silver nanoparticles (AgNPs) and to evaluate its antibiofilm and cytotoxic effects on human fibroblasts. Initially, AgNPs were synthesized by a green microwave route with sizes of 2.1, 6.8, and 12.2 nm and concentrations of 0.055, 0.167, and 0.500 M, respectively. The AgNPs showed a size relationship directly proportional to the concentration of AgNO3, with a spherical and homogeneous distribution determined by high-resolution transmission electron microscopy. The surface functionalization of radiosterilized porcine skin (RPS) via electrospray deposition with the three AgNP concentrations (0.055, 0.167, and 0.500 M) in the epidermis and the dermis showed a uniform distribution on both surfaces by energy-dispersive X-ray spectroscopy. The antibiofilm assays of clinical multidrug-resistant Pseudomonas aeruginosa showed significant effects at the concentrations of 0.167 and 0.500 M, with a log reduction of 1.3 and 2.6, respectively. Additionally, viability experiments with human dermal fibroblasts (HDF) exposed to AgNPs released from functionalized porcine skin showed favorable tolerance, with retention of viability more significant than 90% for concentrations of 0.05 and 0.167 M after 24 h exposure. Antibacterial activity combined with excellent biocompatibility makes this biomaterial a candidate for antibacterial protection by inhibiting bacterial biofilms in deep burns during early stages of development.

Hydrogen Oxidation and Oxygen Reduction Reactions on an OsRu-Based Electrocatalyst Synthesized by Microwave Irradiation.

This work presents an OsRu-based electrocatalyst synthesis, by a rapid and efficient method through microwave irradiation. The outstanding electrocatalyst shows a dual catalytic activity, demonstrating both: hydrogen oxidation and oxygen reduction reactions. The material is structural and morphologically characterized by FT-IR, X-ray diffraction, EDS, and SEM, indicating nanoparticulated Os and Ru metallic phases with a crystallite size of ∼6 nm, calculated by the Scherrer equation. The metal nanoparticles are apparently deposited on a carbonaceous sponge-like morphology structure. Its electrochemical characterization is performed in 0.5 M H2SO4 by the rotating disk electrode technique, employing cyclic and linear sweep voltammetry. Two different ink treatments have been studied to improve the obtained polarization curves. The material is also tested in the presence of methanol for the oxygen reduction reaction, showing an important resistance to this contaminant, making it viable for its use in direct methanol fuel cells (DMFCs) as a cathode and in polymer electrolyte fuel cells (PEMFCs) as an anode as much as a cathode.

Green by Design: Convergent Synthesis, Computational Analyses, and Activity Evaluation of New FXa Inhibitors Bearing Peptide Triazole Linking Units.

Green chemistry implementation has led to promising results in waste reduction in the pharmaceutical industry. However, the early sustainable development of pharmaceutically active compounds and ingredients remains a considerable challenge. Herein, we wish to report a green synthesis of new pharmaceutically active peptide triazoles as potent factor Xa inhibitors, an important drug target associated with the treatment of diverse cardiovascular diseases. The new inhibitors were synthesized in three steps, featuring cycloaddition reactions (high atom economy), microwave-assisted organic synthesis (energy efficiency), and copper nanoparticle catalysis, thus featuring Earth-abundant metals. The molecules obtained showed FXa inhibition, with IC50-values as low as 17.2 µM and no associated cytotoxicity in HEK293 and HeLa cells. These results showcase the environmental potential and chemical implications of the applied methodologies for the development of new molecules with pharmacological potential.

2,4-Thiazolidinedione as Precursor to the Synthesis of Compounds with Anti-glioma Activities in C6 and GL261 Cells.

BACKGROUND: Thiazolidinediones (TZDs) represent an important class of heterocyclic compounds that have versatile biological activities, including anticancer activity. Glioma is one of the most common primary brain tumors, and it is responsible for most of the deaths caused by primary brain tumors. In the present work, 2,4-thiazolidinediones were synthesized via a multicomponent microwave one-pot procedure. The cytotoxicity of compounds was analyzed in vitro using rat (C6) and mouse (GL261) glioblastoma cell lines and primary cultures of astrocytes. OBJECTIVE: This study aims to synthesize and characterize 2,4-thiazolidinediones and evaluate their antitumor activity. METHODS: TZDs were synthesized from three components: 2,4-thiazolidinedione, arene-aldehydes, and aryl chlorides. The reactions were carried out inside a microwave and monitored using thinlayer chromatography (TLC). Compounds were identified and characterized using gas chromatography coupled to mass spectrometry (CG-MS) and hydrogen (1H-NMR) and carbon nuclear magnetic resonance spectroscopy (13C-NMR). The antitumor activity was analyzed using the 3-(4,5- dimethyl)-2,5-diphenyltetrazolium bromide (MTT) reduction test, in which cell viability was verified in the primary cultures of astrocytes and in rat and mouse glioblastoma cells exposed to the synthesized compounds. The cytotoxicity of all derivatives was analyzed at the 100 µM concentration, both in astrocytes and in the mouse and rat glioblastoma cell lines. The compounds that showed the best results, 4CI and 4DI, were also tested at concentrations 25, 50, 100, 175, and 250 µM to obtain the IC50. RESULTS: Seventeen TZD derivatives were easily obtained through one-pot reactions in 40 minutes with yields ranging from 12% to 49%. All compounds were cytotoxic to both glioblastoma cell lines without being toxic to the astrocyte primary cell line at 100 µM, thus demonstrating a selective activity. Compounds 4CI and 4DI showed the best results in the C6 cells: IC50 of 28.51 µM and 54.26 µM, respectively. CONCLUSION: The compounds were not cytotoxic in astrocyte culture, demonstrating selectivity for malignant cells. Changes in both rings are important for anti-glioma activity in the cell lines tested. TZD 4CI had the best anti-glioma activity.

New carbon dots based on glycerol and urea and its application in the determination of tetracycline in urine samples.

The current study proposes a fast one-pot microwave assisted synthesis of new carbon dots (CDs) based on glycerol and urea. The novel carbon nanoparticles (GUCDs) have been appropriately characterized and exhibited good luminescent properties with a quantum yield of about 9.8%. Interestingly, the GUCDs are able to selectively interact with tetracycline class antibiotics, which produce a decrease in the native fluorescence of the CDs. On the base of these features, a new analytical method has been developed for the determination of tetracycline. The proposed method has shown satisfactory analytical parameters, such as good linearity range -between 0.5 and 25 µM (R2 = 0.9997)- and an acceptable detection limit (165 nM). Moreover, the new method has been successfully applied for tetracycline determination in urine samples with good recoveries (94.7-103%) and precision (4.6 RSD%).

Suzuki-Type Cross-Coupling Reaction of Unprotected 3-Iodoindazoles with Pinacol Vinyl Boronate: An Expeditive C-3 Vinylation of Indazoles under Microwave Irradiation.

Herein we report an expeditive C-3 vinylation of unprotected 3-iodoindazoles under microwave irradiation. Ten C-5 substituted 3-vinylindazole derivatives, nine of them novel, were synthesized through this method, which proceeds in moderate to excellent yields starting from C-5 substituted 3-iodoindazole derivatives. In all cases, the C-3 vinylated derivative was the only isolated product. This methodology allows access to 3-vinylated indazoles selectively and directly without the need of N-protection. 3-Vinylindazoles could be interesting synthetic intermediates allowing access to biologically active molecules.

Small Molecules Derived from Thieno[3,4-c]pyrrole-4,6-dione (TPD) and Their Use in Solution Processed Organic Solar Cells.

In this work, microwave synthesis, chemical, optical and electrochemical characterization of three small organic molecules, TPA-TPD, TPA-PT-TPD and TPA-TT-TPD with donor-acceptor structure and their use in organic photovoltaic cells are reported. For the synthesis, 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione was used as electron withdrawing fragment while the triphenylamine was used as electron donating fragment. Molecular electronic geometry and electronic distribution density were established by density functional theory (DFT) calculations and confirmed by optical and chemical characterization. These molecules were employed as electron-donors in the active layer for manufacturing bulk heterojunction organic solar cells, where [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) was used as electron-acceptor. As cathode, Field's metal (FM), an eutectic alloy (Bi/In/Sn: 32.5%, 51%, and 16.5%, respectively) with a melting point above 62 °C, was easily deposited by drop casting under vacuum-free process and at air atmosphere. Prepared devices based on TPA-TPD:PC71BM (1:4 w/w ratio) presented a large VOC = 0.97 V, with JSC = 7.9 mA/cm², a FF = 0.34, then, a power conversion efficiency (PCE) of 2.6%.

(5RS)-6H-Spiro[pyrazolo[1,5-c]quinazoline-5,4'-thiochroman]: efficient synthesis under mild conditions, molecular structure and supramolecular assembly.

Pyrazolo[1,5-c]quinazolines are fused-quinazoline derivatives which have been reported as potential agents against neurological disorders. The normal synthesis routes to these compounds require harsh reaction conditions, long reaction times or multistep sequences. The title compound, C18H15N3S, has been prepared under very mild conditions by condensation of thiochroman-4-one with 5-(2-aminophenyl)-1H-pyrazole, which had itself been prepared by the reaction of hydrazine hydrate with 4-hydroxyquinoline mediated by a brief period of microwave heating. Within the molecule in the crystal structure, the reduced pyrimidine ring adopts an envelope conformation, whereas the thiane ring adopts a half-chair conformation. Molecules are linked into sheets by a combination of one N-H···S hydrogen bond and two independent C-H···π(arene) hydrogen bonds, which utilize the same aryl ring as the acceptor, with one C-H bond donating to each face of the ring. Comparisons are made with some related compounds.