Microwave-assisted Synthesis Research Articles

Microwave-assisted green synthesis of Cassia alata-mediated gold nanoparticles and evaluation of its antioxidant, anti-inflammatory, and antibacterial activities

Microwave-assisted green synthesis of Cassia alata-mediated gold nanoparticles and evaluation of its antioxidant, anti-inflammatory, and antibacterial activities

Green synthesis of nanostructured 1T/2H-MoS2 hybrid phase with polyol solvents and microwave heating

Green synthesis approaches have attracted greatly of attention in recent years since they address the issues associated with sustainability than conventional synthesis methods. New research fields in green nanoscience are being developed as a result of the incorporation of green chemistry principles into nanoscience. In this paper, the successful microwave-assisted green synthesis of MoS2 nanoparticles in a single pot using polyol solvents such as ethylene glycol and glycerol is demonstrated. The coexistence of 1T and 2H phases in MoS2 nanomaterials was determined using advanced techniques such as XRD, Raman, XPS, and TEM images. The highest 1T proportion obtained was 84.5% when compared to the 2H phase. The reaction mechanism and the phase transition between 1T and 2H were described and illustrated. The role of polyol solvents in the practical synthesis of nano MoS2 under microwave heating is also evaluated and explained. Due to the ability of the metallic 1T phase to enhance electrical conductivity, it is believed that hybrid nanostructures exhibit superior electrochemical performance for energy storage and conversion applications.

Microwave-Assisted Synthesis of Argyrodite Solid Electrolytes and Their Use in Solid-State Batteries

Microwave-Assisted Synthesis of Argyrodite Solid Electrolytes and Their Use in Solid-State Batteries

Microwave-assisted synthesis of highly uniform Prussian Blue@Carbon cathode materials for sodium-ion batteries

Prussian blue (PB) and its analogues (PBAs) as cathode material for sodium-ion batteries suffer from poor cycling stability because of crystal defects and sluggish ion diffusion kinetics. Composite with carbon materials is an effective solution to alleviate this problem. However, this is typically achieved through simple physical mixing or encapsulation, which relies heavily on the compatibility between carbon and PB, often resulting in composites that are neither stable nor uniform. Herein, we have developed a facile strategy that utilizes microwave radiation to anchor PB onto the surface of polyvinylpyrrolidone (PVP) functionalized graphene oxide (GO-PVP) through stable, uniform covalent bonds via the amide groups in PVP, in order to obtain an excellent composite material with Prussian blue and carbon materials for sodium-ion batteries. The as-prepared composite materials exhibit lower content of crystallization water and higher crystal integrity, delivering a high initial specific capacity of 165.2 mAh g−1 at 1 C rate and maintaining a capacity of 120.1 mAh g−1 after 500 cycles. This composite approach offers novel insights into the creation of uniform and stable PB/carbon materials as the cathode of sodium-ion batteries.

One-step microwave-assisted synthesis of MgO-modified magnetic biochar for enhanced removal of lead and phosphate from wastewater: Performance and mechanisms

Herein, magnesium oxide (MgO) and ferroferric oxide (Fe3O4) functionalized biochar (MgO@MBC) was synthetized through one-step pyrolysis method, which was used to decontaminate lead (Pb) and phosphate in contaminated water. Characterization results exhibited that MgO and Fe3O4 particles were successfully loaded on MgO@MBC, and the magnetism of MgO@MBC was in favor of recycling materials. Experimental results showed that MgO@MBC possessed outstanding adsorption performance with 556.62/303.08 mg/g for Pb(II)/phosphate. Furthermore, MgO@MBC had excellent anti-interference performance under the coexistence of various ions, and superior reusability with over 82 % adsorption efficiency for Pb(II)/phosphate after four regeneration cycles. It demonstrated that the high-efficiency capacity of Pb(II) adsorbed on MgO@MBC was attributable to complexation, electrostatic attraction, precipitation, and pore-filling, while the efficient uptake of phosphate was due to precipitation, pore-filling, and ligand exchange. Based on the above analysis, MgO@MBC was believed to be an outstanding adsorbent for remediating Pb(II)/phosphate wastewater.

Microwave-assisted one-pot synthesis of carbon dots from biomass: Fe(III) ion sensing and in-situ methylene blue reduction catalytic activity

In this study, zero-dimensional fluorescent carbon dots were synthesized from affordable organic bio-precursors derived from chayote seeds using a one-pot microwave-assisted carbonization process. These biomass-derived carbon dots display excellent fluorescence properties, with an average size of approximately 3.3 nm and a fluorescence quantum yield about 9.56 %. The fluorescence emission spectra were recorded at different excitation peaks, with the highest intensity emission peak observed at 387 nm with an excitation wavelength of 320 nm. These carbon dots effectively detect Fe3+ ions, with a detection limit of 4.5 µmol. Carbon dots show strong catalytic reduction activity against a reduction of Methylene Blue dye, achieving an 81 % reduction in a short period. These biomass-derived carbon dots presents sustainable and promising option for applications in metal sensing and catalytic degradation.

Microwave assisted synthesis, photoisomerization study and antioxidant activity of a series of N-acylhydrazones

A series of N-acylhydrazone 4(a-f) were prepared by condensation of 2-hydroxybenzohydrazide with substituted benzaldehyde derivatives and catalytic amount of acetic acid via a simple method using microwave-assisted synthesis. Reaction conditions such as temperature (60 °C), irradiation power (150 w), and catalyst were optimized. Target compounds were obtained in prompt time (4–10 min) and with excellent yields reaching 98 %. Structural characterization was accomplished using FTIR, 1H NMR, 13C NMR and EIS-MS spectrometry. Reversible light-induced E/Z isomerization at the C = N bond of the synthetized compounds was achieved as function of time in two solvents: dimethylsulfoxide (DMSO) and methanol. The photodynamical E/Z conversion revealed the influence of the solvent on this process that took about 30 min in methanol and 45 min in DMSO. Moreover, antioxidant activity was evaluated for all the synthetized N-acylhydrazones using the 2,2 Dipheny-1-picrylhydrazyl (DPPH) assays. Results showed promising antioxidant effects for compounds 2-hydroxy-N′-(2-hydroxy-4-(p-tolyldiazenyl)benzylidene)benzohydrazide (4e) and 2-hydroxy-N′-(2-hydroxy-3-methoxy-4-(p-tolyldiazenyl)benzylidene)benzohydrazide (4f) that are combining both the acylhydrazone function and an azo fragment in their structures.

Recently Adopted Synthetic Protocols for Piperazines: A Review

Piperazines, a class of heterocyclic compounds, have garnered significant attention in the field of organic synthesis due to their diverse pharmacological activities and widespread applications in medicinal chemistry. This review provides a comprehensive overview of the recent advancements in the synthesis of piperazines, highlighting innovative methodologies, novel reagents, and green synthesis approaches adopted by researchers. The synthesis of piperazines has witnessed remarkable progress, with a focus on developing efficient and sustainable synthetic routes. Various strategies, such as transition-metal-catalyzed reactions, microwave-assisted synthesis, photo-redox reactions, and bio-inspired methods, have emerged as powerful tools for constructing piperazine scaffolds. The review also encompasses discussions on the stereochemistry and regioselectivity issues associated with piperazine synthesis, shedding light on the intricacies of achieving specific substitution patterns. The impact of newly synthesized piperazines in drug discovery and development is also explored, emphasizing the therapeutic potential of these compounds in various disease areas. In conclusion, this review provides a comprehensive and up-to-date account of the recent advancements in piperazine synthesis, offering insights into the current state of the field and guiding future research directions. The integration of innovative methodologies and the exploration of sustainable practices underscore the ongoing efforts to streamline the synthesis of piperazines, contributing to the expansion of their applications in medicinal chemistry and related disciplines.

Microwave-assisted synthesis of molecularly imprinted polymers for smartphone-based luminescent hemoglobin one-pot detection

This work introduces a novel strategy to selectively and sensitively determine Hemoglobin (Hb) using a microwave-synthesized molecularly imprinted polymer (MIP) and chemiluminescence (CL) as the detection method. Studies conducted on both MIP and non-imprinted polymer (NIP) evidenced that the MIP material exhibits a high adsorption capacity (48 µg/mg) and an imprinted factor of about 3, in addition to a selective adsorption property towards Hb in the presence of other proteins, whose structures are very similar to that of Hb. The high selectivity and sensitivity of the proposed biosensor were also assured by the CL detection, whose mechanism is based on Hb's ability to enhance luminol oxidation in an alkaline medium in the presence of hydrogen peroxide, emitting a blue light whose intensity is related to the Hb concentration. The emitted light intensities from the CL reaction, directly proportional to Hb concentration, were captured and analyzed using a smartphone and RGB Color application, avoiding the use of sophisticated equipment and facilitating the measurement process. In order to streamline and speed up the detection process, all the experimental steps including Hb adsorption on MIPHb, supernatant removal, CL reaction, and smartphone readout occur in a single 8-well strip. Therefore, the proposed approach offers one-pot detection for the sensitive (LOD = 0.03 µg.mL−1, equivalent to 1.5 nmol.L−1) and selective determination of Hb in blood samples, for biomedical or forensic applications, through a rapid, low-cost, simple, and affordable approach.

Green Synthesis of Thiazoles and Thiadiazoles Having Anticancer Activities under Microwave Irradiation

Abstract: Sulfur and nitrogen-containing heterocycles have received a great deal of attention due to their unique structures and therapeutic relevance. Thiazoles and thiadiazoles are important five-membered heterocycles containing sulfur and nitrogen atoms that draw the special attention of re-searchers due to their synthetic diversity and potent pharmacological properties. Thiazoles and thi-adiazoles are used in agrochemicals, liquid crystals, sensors, the cosmetic industry, cyanine dyes, etc. Sometimes, organic synthesis, including thiazoles and thiadiazoles syntheses with the help of conventional methods, is laborious work, while synthesis of promising organic molecules using microwave irradiation provides better yields, diminishes the reaction time, and reduces unwanted side products. The major causes of death worldwide are due to cancer. Current research demands the design and preparation of novel compounds, including thiazoles and thiadiazoles, that may help to combat cancer, as chemotherapy or chemo drugs suffer from some demerits, including toxicity, lack of selectivity, resistance, and side effects. Hence, the review focuses on the microwave-assisted synthesis of thiazoles and thiadiazoles as a sustainable technique for the first time, and it also aims to highlight the anticancer activities of thiazoles and thiadiazole derivatives elegantly.

Microwave-assisted click synthesis, characterisation, and In silico studies of novel 2H-chromene-1,2,3-triazolyl glycoconjugates as potent anticancer and antibacterial agents

A series of novel 2H-chromene-1,2,3-triazolyl glycoconjugates 10a-w were synthesized, well characterized and evaluated for their in vitro antimicrobial and anticancer activities. Among the tested compounds, 10a, 10b, 10u, 10v, and 10w exhibited the most excellent potency against both gram-positive (S. aureus) and gram-negative (E. coli) bacterial strains relative to the standard drug, Gentamicin. The anticancer results showed that in MCF-7 cell line all the tested compounds exhibited better activity as compared to other two cancer cell lines (MDA-MB-231 and A549). Compounds 10t, 10u, 10v, and 10w showed significant cytotoxicity against MCF-7 cell line. The molecular docking studies suggested that all the four potent compounds exhibited a greater affinity for the selected receptors. Experimentally and computationally observed structure-activity relationships indicates, -OCH3 group at R2 position in benzopyran ring with tosyl-protected sugar containing compound 10b and benzyl-protected sugar containing compound 10t enhanced the antibacterial and anticancer activity respectively. Frontier molecular orbital analysis of compounds using the global reactivity parameters indicated that benzyl-protected sugar and acetyl-protected sugar containing compounds are stable and exhibits low reactivity. Moreover, molecular electrostatic potential analysis plots clearly showed that the compounds have strong electrophonic reaction potential. Moreover, the assessment of ADMET predictions revealed favourable pharmacokinetic properties of the investigated compounds. Collectively, it was observed that compounds 10u, 10v, and 10w could be considered as promising dual anticancer antibiotic inhibitors.

Process intensification in microwave assisted lipase catalysed solvent-free synthesis of n-nonyl caprylate

Microwave-assisted solvent free synthesis is a frequently applied mainstream tool in various enzymatic processes. Microwaves are a non-contact heat source which reduces the thermal gradient and helps to accelerate energy transfer. Microwave irradiation along with solvent free synthesis has great efficiency and efficacy in product synthesis and purification. In the present investigation, synthesis of n-nonyl caprylate was achieved by using immobilized lipases specifically Lypozyme TLIM, Novozym 435 and Lypozyme RM IM. Novozym 435 (Cal-B) was the best among these catalysts. Highest conversion of 76.8 % was achieved with following parameters: 180 min, 50 °C, 400 rpm, 50 W, 8.36 g/L catalyst loading, and 1:1 mol ratio of caprylic acid to n-nonanol. The confirmation of the product was done by GC-MS analysis.

Visible Light-Induced Photocatalytic Hydrogen Generation from Seawater Using Ternary Indium Sulfide/Indium Oxide/Gold Nanocomposites Obtained via Microwave-Assisted Synthesis

Visible Light-Induced Photocatalytic Hydrogen Generation from Seawater Using Ternary Indium Sulfide/Indium Oxide/Gold Nanocomposites Obtained via Microwave-Assisted Synthesis

Microwave-assisted bio-derived bismuth oxybromide (BiOBr) decorated polyaniline nanocomposite for highly sensitive electrochemical determination of endocrine disruptor bisphenol-A

In the presence of polyaniline (PANI), the novel nanocomposites of PANI-BiOBr bismuth oxybromide (BiOBr) were synthesized using a microwave-assisted green synthesis method and used to detect bisphenol A (BPA). By using fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and electrochemical methods, the hybrid PANI-BiOBr nanocomposite was confirmed. The higher conductivity, improve active surface-to-volume ratio, and enhanced electrochemical behaviour of the PANI-BiOBr nanoplatform can be attributed to the synergistic actions of PANI and BiOBr. With a high sensitivity of 11.7 μA (log nM)−1 cm2 and a low limit of detection of 0.19 × 10−9 μM, the constructed PANI-BiOBr sensor exhibits a broad linear range from 0.19 × 10−9 μM to 3.04 × 10−3 μM. In addition, this sensor produced adequate findings with outstanding selectivity, stability, repeatability, and reproducibility. Furthermore, the developed electrochemical PANI-BiOBr nanoplatform is essential in analysing real-world materials to detect BPA. The results obtained from these real sample analyses not only confirmed the effectiveness of the PANI-BiOBr nanocomposite sensor for BPA detection but also underscored its capability to detect other compounds with estrogenic properties, beyond just BPA.

Multifunctional persistent luminescent and photochromic hackmanite-based materials prepared by microwave-assisted solid-state synthesis

Advanced optical materials inspired by natural minerals and non-toxic light elements, such as the Hackmanites (Na8Al6Si6O24(Cl,S)2), find vast possibilities of applications as they can simultaneously perform photochromism and persistent luminescence (PersL). In this work, we have explored a rapid and energy-efficient microwave-assisted (MASS) methodology for the synthesis of PersL and photochromic hackmanites. In addition, we have prepared hackmanite materials using a zeolite-free precursor to control the Na–Al–Si ratio and study its influence on the materials photoluminescent properties. The PersL hackmanites showed a white-bluish emission color, with up to 2 h of emission time. Zeolite-free photochromic materials were able to change the color from white to purple/blue efficiently with a few seconds of 254 nm excitation, but the usage of zeolite precursors enhanced the overall optical performance. Microwave synthesis times of 10–40 min were demonstrated to be optimal, as longer times boosted the formation of nepheline spurious phase, which decreases luminescence efficiency. In this way, the MASS method led to a reduction of reaction time up to 98 %, yielding hackmanite materials with similar photoluminescent or photochromic properties compared to those obtained by a 24 h conventional solid-state synthesis. This work represents a significant improvement toward coupling eco-friendly synthetic processes to eco-friendly solid-state materials for PersL illumination and PersL/photochromism optical marking.

Utilizing Pometia Pinnata leaf extract in microwave synthesis of ZnO nanoparticles: Investigation into photocatalytic properties

In this work, ZnO photocatalyst has been synthesized using matoa (Pometia pinnata) leaf extract under various microwave irradiation powers at 360, 540, and 720 Watts for 3 minutes on each. The UV-Vis absorption spectra of ZnO exhibited a peak in the ultraviolet region 300-360 nm. UV-Vis absorption analysis revealed a decrease in the band gap energy from 3.15 eV to 3.10 eV as the irradiation power increased. Field emission scanning electron microscopy (FESEM) images displayed spherical and nanoplatelet morphology with a decrease in particle size observed from 773 to 709 nm with increasing irradiation power. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO with crystallite sizes in the range of ~18-20 nm. The synthesized ZnO nanoparticles was successfully employed as a photocatalyst in 4-nitrophenol degradation, achieving the highest degradation percentage of 82.7% at 540 Watts with a corresponding reaction rate constant of 0.0126/min. In conclusion, the microwave-assisted synthesis of ZnO using on matoa leaf extract demonstrated significant potential for the degradation of organic pollutants, thereby contributing to water purification efforts.

Two-dimensional iron oxide/graphene-based nanocomposites as high-performance solid lubricants

Beyond conventional 2D layered materials such as graphene and transition metal dichalcogenides, 2D metal oxides have also received much interest in recent years. They have unique electronic (such as 2D TiO2 and MoO2), catalytic (such as 2D CeO2 and MnO2), and magnetic properties (such as 2D Fe2O3) compared with bulk metal oxides due to their atomically thin structures. Certain types of 2D metal oxides also have the potential to be a new type of high-performance solid lubricants due to the tunable interlayer interaction and possibility for 2D heterostructure formation, but this remains largely unexplored. In this work, we developed a scalable microwave-assisted solid-state synthesis of 2D Fe2O3 and their nanocomposites with reduced graphene oxide (rGO). The 2D Fe2O3/rGO nanocomposites were systematically characterized by electron microscopies and spectroscopies, and their utilization as solid lubricants was studied by pin-on-disk tribometer on both silicon and steel substrates. The results show that due to the easy sliding between 2D Fe2O3 and rGO nanosheets and their unique magnetic-induced assembled morphology, low coefficient of friction (COF) can be achieved for both steel-silicon and steel-steel interfaces. Superlubricity (COF ∼ 0.007) can be achieved for the 2D Fe2O3/rGO nanocomposite with a GO primer layer on a steel substrate. This work provides new insights into the development of functional 2D nanocomposites and expands their applications to solid lubrication and beyond.

Microwave-assisted synthesis of ZnS@CuInxSy for photocatalytic degradation of coloured and non-coloured pollutants

Copper indium sulfide (CuInS2) exhibits strong visible light absorption and thus has the potential for good photocatalytic activity; however, rapid charge recombination limits its practical usage. An intriguing strategy to overcome this issue is to couple CuInS2 with another semiconductor to form a heterojunction, which can improve the charge carrier separation and, hence, enhance the photocatalytic activity. In this study, photocatalysts comprising CuInS2 with a secondary CuS phase (termed CuInxSy) and CuInxSy loaded with ZnS (termed ZnS@CuInxSy) were synthesized via a microwave-assisted method. Structural and morphological characterization revealed that the ZnS@CuInxSy photocatalyst comprised tetragonal CuInS2 containing a secondary phase of hexagonal CuS, coupled with hexagonal ZnS. The effective band gap energy of CuInxSy was widened from 2.23 to 2.71 as the ZnS loading increased from 0 to 30%. The coupling of CuInxSy with ZnS leads to long-lived charge carriers and efficient visible-light harvesting properties, which in turn lead to a remarkably high activity for the photocatalytic degradation of brilliant green (95.6% in 5 h) and conversion of 4-nitrophenol to 4-nitrophenolate ions (95.4% in 5 h). The active species involved in these photocatalytic processes were evaluated using suitable trapping agents. Based on the obtained results, photocatalytic mechanisms are proposed that emphasize the importance of h+, O2•–, and OH− in photocatalytic processes using ZnS@CuInxSy.

Microwave-Assisted Synthesis of β-N-Aryl Glycoamphiphiles with Diverse Supramolecular Assemblies and Lectin Accessibility.

Glycoamphiphiles have attracted considerable interest in a broad range of application fields owing to their solution and bulk-state self-assembly abilities. Despite their importance, the straightforward synthesis of glycoamphiphiles consisting of a hydrophilic carbohydrate linked to a hydrophobic aglycone remains one of the major challenges in glycosciences. Here, a rapid, simple, and efficient synthetic access to chemically stable glycoamphiphiles at physiological pH, namely, N-(β-d-glycosyl)-2-alkylbenzamide, is reported. It leverages the nonreductive amination of unprotected carbohydrates with ortho-substituted aniline derivatives which could be readily obtained by reacting commercially available primary alkylamines with isatoic anhydride. This strategy avoids protection and deprotection of sugar hydroxyl groups and the use of reductive agents, which makes it advantageous in terms of atom and step economy. Moreover, in order to circumvent the cons of classical N-aryl glycosylation, we investigate the use of microwave as a heat source that provides fast, clean, and high-yield β-N-arylation of unprotected carbohydrates. Their self-assembly into water led to multiple morphologies of dynamic supramolecular glycoamphiphiles that were characterized to assess their ability to bind to lectins from pathogenic bacteria. Biophysical interactions probed by isothermal titration microcalorimetry revealed micromolar affinities for most of the synthesized glycoamphiphiles.

Microwave-assisted synthesis of novel pyrazolyl sulfones and their antimicrobial evaluation and time-resolved photoluminescence studies

This article reports an efficient and practical microwave-assisted MMPP-promoted synthesis of novel pyrazolyl sulfones from the corresponding 4-(alkyl/cycloalkylthio)-1H-pyrazoles. The reaction of 4-(alkyl/cycloalkylthio)-1H-pyrazoles with magnesium bis(monoperoxyphthalate)hexahydrate (MMPP) as an oxidizing agent afforded the corresponding 4-(alkyl/cycloalkylsulfonyl)-1,3-disubstituted-1H-pyrazoles in 85–95% yield. This method's benefits include its straightforward operation, simple workup, and use of an inexpensive, halogen-free MMPP oxidant that is easy to use and reasonably stable. All synthesized pyrazolyl sulfones were examined against bacterial and fungal strains, and notable antimicrobial activity was demonstrated by a few of the compounds. In order to investigate the prospect of connecting compounds with the highest yield and antimicrobial activity with their opto-electronic properties, time-resolved photoluminescence investigations for compounds 5a, 5b, and 5d were conducted. The tunable spectrum was observed in the micro-second time domain in all three cases, with fluorescent lifetime found higher in the compound having methyl group, intermediate with phenyl group, and lowest with the p-nitrophenyl group. Our procedures will encourage additional research into the valuable properties of pyrazolyl sulfones now that they are widely available with the structural complexity illustrated here.