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2,5‐disubstituted N,N'‐alkylpiperazines represent an interesting target in organic synthesis both for pharmaceutical or agrochemical applications and as a promising class of ligands in coordination chemistry. We report here a microwave‐enhanced synthesis of these compounds starting from non‐activated N‐alkyl aziridines in the presence of catalytic amounts of simple ammonium metallates. A remarkable TOF of 2787.9 h−1 has been observed in the case of [TBA]2[ZnI4] as the catalyst (catalyst loading 0.1 mol %) and with an almost complete selectivity (up to 97 %) in favor of both diastereoisomers (meso and chiral form) of the target 2,5‐disubstituted piperazines, obtained in 1 : 1 ratio. The two isomers are easily separated, because the meso form precipitates in pure from the reaction crude. A stereochemical investigation and the unprecedented isolation of 2,6‐disubstituted N,N'‐alkylpiperazines allowed us to shed light on the reaction mechanism. [ABSTRACT FROM AUTHOR]

We describe the synthesis and computational investigation of N‐heterocycle‐substituted hexa‐peri‐hexabenzocoronenes (HBCs). Following our method for the preparation of thioether‐substituted HBCs, we prepared pyrrole‐, indole‐, carbazole‐, and 1H‐benz[g]indole‐substituted HBCs from the corresponding fluorinated precursors under microwave irradiation. A series of polysubstituted benzoindole‐HBCs with windmill architectures was also synthesized using the polyfluorinated HBC analogs, and the substituent effects on the electronic properties of the HBC core were investigated. Similar to the thioether substituted HBCs, the nature of the heterocycle does not influence the optoelectronic properties of the HBC core. The attachment of multiple benzoindole substituents leads to a bathochromic shift of the absorption and emission spectra, comparable to our previous studies. Due to the circular arrangement of the benzoindole moiety, the attachment of multiple substituents results in the presence of multiple conformers at room temperature. The rotation barrier can be overcome by heating the compounds to 323–333 K. Additionally, the investigation of the relaxed geometries shows two π‐stacking motifs within the conformers. [ABSTRACT FROM AUTHOR]

A microwave‐assisted synthesis of 7‐amino‐1,2,4‐triazolo[1,5‐a][1,3,5]triazine‐2‐propanamides was developed using a three‐component, catalyst‐free reaction of cyanamide and trimethyl orthoformate with 3‐(5‐amino‐1H‐1,2,4‐triazol‐3‐yl)propanamides (3). The reaction tolerated structurally diverse substrates and proceeded chemo‐ and regio‐selectively, affording the target compounds in high purity in 5–10 minutes. The convenient chromatography‐free isolation and purification of the products add practicality to this method. The structural features of the prepared compounds were investigated using dynamic NMR spectroscopy, X‐ray crystallography and computational chemistry calculations. X‐ray crystallography performed on a representative compound, 3‐(7‐amino‐1,2,4‐triazolo[1,5‐a][1,3,5]triazin‐2‐yl)‐N‐(4‐benzyl)propanamide (4 l), showed the overall molecular conformation to adopt the shape of the letter C. Notable localisation of π‐electron density is found within the 1,2,4‐triazolo[1,5‐a][1,3,5]triazine system; a relatively short C−NH2 bond is consistent with restricted rotation about this bond. This study also presents a detailed analysis of the molecular interactions in 4 l using DFT and QTAIM methods with a focus on the hydrogen‐bonding and π‐stacking interactions that influence the molecular packing of 4 l. The findings reveal the significant roles of N−H⋅O, N−H⋅N and C−H⋅N interactions, along with electrostatically enhanced π⋅π contacts. A broad screening for insecticidal, fungicidal and herbicidal properties identified several compounds with potent herbicidal activity against Matricaria inodora. [ABSTRACT FROM AUTHOR]

This work uses green sustainable reactions twice. Firstly, it is microwave synthesis: 2,4,6‐tribiphenyl‐4‐yl‐1,3,5‐triazine and similar compounds were prepared in a closed microwave reactor in n‐octane by the Friedel‐Crafts reaction. Second, a hybrid electrocatalyst for the highly demanded electrochemical reaction of nitrate reduction to ammonia (NO3RR) was prepared based on this material. This reaction has great potential to replace the energy‐intensive Haber‐Bosch process, and in addition, has independent value for the elimination of nitrate contamination of water resources. As shown in the work, microwave synthesis is an eco‐friendly method for the synthesis of complex organic compounds; fast, selective and with a high yield of the target product. The electrocatalyst deposited on the graphite electrode consisted of a layer of 2,4‐bis([1,1′‐biphenyl]‐4‐yl)‐6‐hydroxy‐1,3,5‐triazine and related compounds coated with cobalt oxide. The hybrid catalyst was firmly retained on the graphite electrode during NO3RR and the material showed impressive stability with almost no decrease in catalytic activity even after the fifth cycle. Both 2,4‐bis([1,1′‐biphenyl]‐4‐yl)‐6‐hydroxy‐1,3,5‐triazine and the catalyst based on this substance were characterized by SEM, XPS, XRD, UV‐vis spectra, cyclic (and linear) voltammetry, and chronoamperometry. This work can serve as a starting point for the development of stable and durable electrocatalysts for NO3RR using triazine derivatives. [ABSTRACT FROM AUTHOR]

In this study, we developed sodium alginate-chitosan hydrogels using a microwave-assisted synthesis method, aligning with green chemistry principles for enhanced sustainability. This eco-friendly approach minimizes chemical use and waste while boosting efficiency. A curcumin:2-hydroxypropyl-β-cyclodextrin complex was incorporated into the hydrogels, significantly increasing the solubility and bioavailability of curcumin. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed the structure and successful incorporation of curcumin, in both its pure and complexed forms, into the polymer matrix. Differential scanning calorimetry revealed distinct thermal transitions influenced by the hydrogel composition and physical cross-linking. Hydrogels with higher alginate content had higher swelling ratios (338%), while those with more chitosan showed the lowest swelling ratios (254%). Scanning Electron Microscopy (SEM) micrographs showed a porous structure as well as successful incorporation of curcumin or its complex. Curcumin release studies indicated varying releasing rates between its pure and complexed forms. The chitosan-dominant hydrogel exhibited the slowest release rate of pure curcumin, while the alginate-dominant hydrogel exhibited the fastest. Conversely, for curcumin from the inclusion complex, a higher chitosan proportion led to the fastest release rate, while a higher alginate proportion resulted in the slowest. This study demonstrates that the form of curcumin incorporation and gel matrix composition critically influence the release profile. Our findings offer valuable insights for designing effective curcumin delivery systems, representing a significant advancement in biodegradable and sustainable drug delivery technologies. [ABSTRACT FROM AUTHOR]

Background: Lamivudine is an Anti-Viral Drug belongs to BCS Class II Drug which exhibits limited solubility and high permeability through oral route. Aim: The study was designed to predict the solubility potential of Lamivudine loaded Metal Organic Framework complexed with MIL 100 by using microwave assisted chemistry through topical route. Materials and Methods: In combination of MIL 100 (Fe) we utilize Ferric chloride hexahydrate as metal particle and benzene 1,3,5-carboxyl corrosive as natural linker. The anti-viral drug Lamivudine was used to load in the MIL 100 (Fe). The specific proportion of FeCl3.6H2O and benzene 1,3,5-carboxylic acid was weakened with deionized water. Above combination is put in microwave at 130ºC for 6 min which prompts development of complex called MIL 100 (Fe). Various proportions of Lamivudine medication and MIL 100 (Fe) were taken to prepare the formulations and the effect of drug loading with various ratios were interpreted. Evaluation of MOF was done for drug-excipient compatibly studies and surface morphology for structural analysis. Results and Discussion: Spectral studies conforms the purity of the sample and from drug-excipient compatibility studies no interactions were noticed. Microwave Assisted Technology can be proven as a best fit model for synthesis of advanced 2D Materials called MOF and drug loading was found to be high at a ratio of Lamivudine: MIL (1:0.5). The particulate studies conform the nanonisation of drug which results in enhanced solubility due to increased surface area of drugs. Conclusion: Lamivudine loaded Metal Organic Frameworks (MOF) with MIL 100 (Fe) was successfully fabricated with high loading and decreased particle size authenticates the utilization of microwave assisted technology as a promising tool for MOF and with the result of increase in solubility, Lamivudine can be used in a best way as an anti-viral drug in the form of MOF through topical route. [ABSTRACT FROM AUTHOR]

Tempted by the unique medicinal and biological potential of indole‐containing heterocycles, chemists, especially those specializing in heterocycle synthesis and drug discovery, are actively pursuing their efficient construction. This review spotlights the latest advancements in microwave‐assisted (M. W.) synthesis of diverse indole‐based heterocyclic compounds. We systematically categorize the reported methods based on the specific indole substitution patterns. This review concise the microwave assisted synthesis of indole based‐pyridine derivatives, indole based‐pyrimidine, indole based‐oxindole, spiro‐oxindole, Fischer indole Heck‐isomerization derivatives, functionalized indole, substituted indoles, indolyl quinoline, indole triazole and indolylnicotinonitriles derivatives. Ultimately, this review aims to provide organic and medicinal chemists with a concise yet informative guide to recent methodologies employing indole derivatives in the microwave‐powered synthesis of heterocycles. [ABSTRACT FROM AUTHOR]

β‐Carbolines represent a large class of bioactive natural products, whereby most of these alkaloids bear residues at C1, and occasionally at C3, and only limited examples of 1,4‐disubstituted β‐carbolines are known. In this project we worked out a novel approach to 1,4‐disubstituted β‐carbolines and performed a comprehensive analysis of the scope and limitations of this methodology. The 1,4‐disubstituted β‐carbolines were synthesized via 3‐substituted 2‐acylindoles, for which effective synthesis procedures were developed. Our studies revealed that a broad range of target compounds with electron‐withdrawing substituents at C4 are accessible. Limitations of this method arose from competing CH and NH acidities of precursors. Nevertheless, the work described herein provides a unique approach to highly substituted β‐carbolines. In addition, intermediates from this route opened a novel approach to 1‐substituted β‐carbolines utilizing a chemoselective Mo(CO)6‐catalyzed amide reduction with tetramethyldisiloxane. [ABSTRACT FROM AUTHOR]

Herein we report the first microwave‐assisted one‐pot three‐step metal‐free [4+2] procedure for the synthesis of 5,6‐substituted‐3‐hydrazinyl‐1,2,4‐triazines directly from commercially available aromatic and heteroaromatic ketones. The 3‐hydrazinyl‐1,2,4‐triazine can be isolated or further elaborated, after a simple work‐up, by direct condensation with different aldehydes or ketones to provide highly functionalized hydrazone‐derivatives. This protocol represents a rapid, efficient, and sustainable approach for the development of new highly functionalized 1,2,4‐triazine derivatives with potential biological interest. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of new 4-thiazolidinones with a fructose scaffold through a microwave-assisted cascade multicomponent reaction. The study focuses on the incorporation of carbohydrates in the synthesis of bioactive molecules and drugs, as well as the design of new green methodologies for the preparation of pharmacologically valuable structural motifs. The article provides detailed information on the experimental procedures and results, including yields and analysis of the synthesized compounds. The compounds were also tested for their inhibitory activity against FXa blood protein, with moderate inhibitory efficiency observed. The authors conclude that this synthetic strategy is a promising method for accessing pure and interesting stereoisomeric macromolecules. [Extracted from the article]

This document discusses the importance of computational models in various industries, such as the food industry, green chemistry, microwave chemistry, and microwave processing of materials. The models are based on differential equations that describe heating phenomena in microwave processing. The document emphasizes the need for accurate parameters and their interactions in the models, as well as the validation of the models through quantitative predictions. It also highlights the importance of understanding the calculations behind the models and the limitations of using simulators without proper validation. The document concludes by emphasizing the interdisciplinary nature of computer modeling and the importance of theoretical support in the modeling process. [Extracted from the article]

Low-temperature sintered La 2−x Y x Mo 2 O 9 ceramics (x = 0–0.12) were synthesized by solid-state method. XRD analysis confirmed pure La 2 Mo 2 O 9 with a cubic structure (space group P 21 3). Sintering at 925 °C resulted in La 2 Mo 2 O 9 ceramic with favorable microwave dielectric properties: ε r = 17.8, Q × f = 24300 GHz, τ f = −35.1 ppm/°C. Notably, adding Y3+ greatly improved Q × f and τ f. Sintering La 1.88 Y 0.12 Mo 2 O 9 at 900 °C significantly enhanced microwave dielectric properties: ε r = 17.4, Q × f = 34100 GHz, τ f = −5.5 ppm/°C. ε r was primarily influenced by ionic polarizability, while Q × f correlated positively with packing fraction. Analysis based on P-V-L theory showed that increased ionicity, lattice energy, and bond energy led to higher ε r , Q × f , and τ f values. Raman spectroscopy revealed that most observed peaks were associated with Mo-O bond vibrations. These findings highlight La 2−x Y x Mo 2 O 9 ceramics as promising candidates for LTCC materials. [ABSTRACT FROM AUTHOR]

Guanidine is a privileged scaffold in drug discovery. Herein we report our investigations into the acid promoted amination of pyrimidine‐bearing cyanamide to produce N, N'‐disubstituted guanidines. Hydrochloric acid was found to be a suitable catalyst, and the substrate scope using conventional heating was investigated with 23 aniline derivatives. The highest yield was obtained with anilines having pKa in the range of 2–4. Further, a microwave synthesis was developed using 3‐chloroaniline as a model substrate increasing the yield from 68 to 93 %. The microwave method was especially suited for increasing yields with anilines having pKa > 3. The structure of the pyrimidine‐bearing guanidines was confirmed by NMR spectroscopy, and one representative compound has been evaluated by X‐ray crystallography, showing the trans‐isomer as the only tautomer in solid form. [ABSTRACT FROM AUTHOR]

To achieve environmentally benign synthesis and develop pharmacologically active compounds, a library of novel thiophene‐clubbed pyrazole‐1,2,3‐triazole hybrids was designed and successfully synthesized using L‐ascorbic acid as a green acid catalyst and ethanol as a green solvent. The reaction was carried out using microwave and ultrasonic irradiation methods to achieve a highly efficient reaction route. All title compounds were characterized and evaluated for their potential in vitro antimicrobial activity using Ciprofloxacin and Nystatin as standard drugs, in which compounds with chloro and naphthyl substitutions exhibited excellent antibacterial activity at concentrations of 25 μg/mL and compounds with methyl and methoxy substitutions exhibited excellent antifungal activity at concentrations of 100 μg/mL. Additionally, the molecular docking study showed that all compounds examined had excellent binding energies ranging from −9.3 to −10.3 kcal/mol, and naphthyl substitution displayed the highest binding energy (−10.3 kcal/mol) on the target protein of E. coli DNA gyrase subunit B. Furthermore, the final moieties were evaluated for in silico ADMET prediction to examine their drug‐likeness profile and toxic effects. The present study revealed that this structural information will be helpful in future antimicrobial drug design and development. [ABSTRACT FROM AUTHOR]

The water-mediated mineral carbonation represents a promising solution for the capture and the storage of atmospheric CO2. Even though this reaction might be spontaneous for a number of Mg- and Ca-rich mineral phases, it is characterized by considerable activation barriers. In order to make it effective, associated energy costs related to the achievement of adequate reaction conditions must be minimized. Microwave chemistry is known to provide for substantial increments of the reaction rate for several systems. We applied here microwave chemistry to the process of carbonation of aqueous slurries of brucite, a model system of Mg-rich mineral, subjected to partial pressures of CO2 as low as 6 bar and to no other additive. The temperature of the reactor was finely varied while the radiation power and the reactor pressure were monitored in real-time. The radiation power was used to estimate the radiation energy budget needed to complete the carbonation process, whereas the reactor pressure was used as a proxy of reaction progression. We show a detailed evolution of the carbonate products obtained in terms of mineral phases, morphological properties, and degree of crystallinity, both as precipitate and as solid residue in the exsiccated supernatant reaction liquid.

A literature survey showed that different derivatives with the 9‐phenyl‐9H‐carbazole or the dihydroindoline scaffold may be of biological activity including cytotoxic effect. Driven by this experience, P‐functionalized derivatives of these N‐heterocycles were synthesized. Three N‐heterocycles, 9‐(4‐bromophenyl)‐9H‐carbazole, 3‐bromo‐9‐phenyl‐9H‐carbazole and 1‐(5‐bromoindolin‐1‐yl)ethan‐1‐one, were coupled with dialkyl phosphites and diarylphosphine oxides using Pd(OAc)2 (10 %) as the catalyst precursor and triethylamine as the base in ethanol under microwave irradiation. The excess of the Y2P(O)H reagent (Y=alkoxy, aryl) (30 %) served as the P‐ligand in its trivalent tautomeric form (Y2POH), hence there was no need for the usual P‐ligands meaning cost and environmental burden. Hence, the presented method is a "green" approach that proved to be more efficient than the preparation by the traditional method. The products, dialkyl phosphonates and tertiary phosphine oxides obtained in 58–84 % yields were characterized, one of them also by single crystal X‐ray analysis, and were subjected to in vitro biological activity evaluation. A (carbazol)yl‐phenylphosphonate, an N‐phenyl‐(carbazol)yl‐phosphonate, a (carbazol)yl‐phenylphosphine oxide and an N‐phenyl‐(carbazol)ylphosphine oxide revealed a significant cytotoxic activity on A549 human non‐small‐cell lung carcinoma and MonoMac‐6 acute monocytic leukemia cancer cells. The cytotoxic effect was significant as compared to that of the reference compounds. [ABSTRACT FROM AUTHOR]

Opportunistic infections like tuberculosis (TB) are prevalent in HIV‐infected individuals. In an approach to introducing an industrial‐scale microwave‐assisted production of agents having both antiviral and antibacterial properties, a set of hydrophilic 2,3‐substituted quinazolinones, 4‐oxo‐2‐phenylquinazoline‐3(4H)‐carboximidamide (Qg) and 4‐oxo‐2‐phenylquinazoline‐3(4H)‐carboxamide (Qu), were afforded in encouraging yields. They were obtained by treating 2‐benzamidobenzoyl chloride with guanidine hydrochloride or urea in the presence of potassium carbonate in DMF. DFT calculations were employed for geometrical optimization and vibrational frequency analysis of the compounds. Free energies of solvation (ΔGsol) of Qg, and Qu calculated using DFT lend evidence in support of their hydrophilicity The anti‐HIV‐1 activities of the small‐molecule quinazolinone derivatives Qg and Qu were investigated. The synthons under in vitro conditions inhibit the entry of HIV in receptor cells with low cytotoxicity (EC50=50.53 nM for Qu and EC50=97.92 nM for Qg). The study identifies the antiviral properties of the two benzo‐fused pyrimidine derivatives, which were earlier reported to have antitubercular activity. Our findings indicate the scope for further synthetic explorations of these quinazolinone scaffolds that can lead to developing promising alternatives in drug design, pharmaceutics, and clinical research. [ABSTRACT FROM AUTHOR]

SP 1 sp H NMR (600 MHz, acetone- I d i SB 6 sb + D SB 2 sb O): = 7.09 (d, I J i = 1.94 Hz, 1 H, H-2'), 7.02 (dd, I J i = 1.94, 8.22 Hz, 1 H, H-6'), 6.94 (d, I J i = 8.22 Hz, 1 H, H-5), 6.13 (d, I J i = 2.27 Hz, 1 H, H-6), 5.97 (d, I J i = 5.97 Hz, 1 H, H-8), 4.91 (d, I J i = 10.26 Hz, 1 H, H-2), 4.86 (d, I J i = 3.69 Hz, 1 H, H-4), 3.84 (dd, I J i = 3.69, 10.26 Hz, 1 H, H-3), 3.813 (s, 3 H, 5-OCH SB 3 sb ), 3.806 (s, 6 H, 3', 5'-OCH SB 3 sb ), 3.73 (s, 3 H, 7-OCH SB 3 sb ). SP 13 sp C NMR (151 MHz, CDCl SB 3 sb ): = 159.9 (C-4'), 153.7 (C-7), 149.5 (C-8a), 137.8 (C-8), 130.1 (C-1'), 128.8 (C-2', 6'), 125.3 (C-5), 114.6 (C-4a), 114.1 (C-3', 5'), 109.2 [ I C i (CH SB 3 sb ) SB 2 sb ], 106.4 (C-6), 77.7 (C-2), 75.9 (C-3), 71.6 (C-4), 61.1 (4'/8-OCH SB 3 sb ), 56.4 (7-OCH SB 3 sb ), 55.4 (4'/8-OCH SB 3 sb ), 28.6 (CH a/b), 26.1 (CH SB 3 sb a/b). SP 13 sp C NMR (151 MHz, CDCl SB 3 sb ): = 169.0 [3/2"/4"/6"-O I C i (O)CH SB 3 sb ], 168.5 [3/2"/4"/6"-O I C i (O)CH SB 3 sb ], 168.4 [3/2"/4"/6"-OC(O)CH SB 3 sb ], 167.8 [3/2"/4"/6"-OC(O)CH SB 3 sb ], 160.3 (C-5/7), 159.1 (C-5/7), 156.5 (C-8a), 149.8 (C-1'), 149.7 (C-3'/4'), 149.0 (C-3'/4'), 148.8 (C-2"/6"), 148.6 (C-2"/6"), 129.1 (C-4"), 124.0 (C-1"), 120.7 (C-6'), 114.6 (C-3"/5"), 113.4 (C-3"/5"), 111.0 (C-5'), 110.8 (C-2'), 105.5 (C-4a), 94.2 (C-6/8), 93.9 (C-6/8), 80.5 (C-2), 72.7 (C-3), 56.1 (3'/4'-OCH SB 3 sb ), 56.0 (3'/4'-OCH SB 3 sb ), 55.6 (5/7-OCH SB 3 sb ), 55.5 (5/7-OCH SB 3 sb ), 36.7 (C-4), 21.3 [3/2"/4"/6"-OC(O) I C i H SB 3 sb ], 21.2 [3/2"/4"/6"-OC(O) I C i H SB 3 sb ], 20.7 [3/2"/4"/6"-OC(O) I C i H SB 3 sb ], 20.4 [3/2"/4"/6"-OC(O) I C i H SB 3 sb ]. [Extracted from the article]

In this work, we report the regiospecific and stereoselective synthesis of novel pyrrolo thioxoimidazolidinones with promising biological activities due to the inherent pharmaceutical properties of thioxoimidazolidinone core. The reaction of different thioxoimidazolidinones with trans‐4‐ethoxy‐1,1,1‐trifluorobut‐3‐en‐2‐one (ETFBO) yields bicyclic 1,3‐diaza heterocycles bearing the trifluoromethyl (CF3) moiety. Our investigation involved both depth experimental analysis and theoretical calculations to fathom out the mode of reaction of this building block and elucidate the underlying mechanism operating for the observed reactions. Remarkably, this unusual mechanism retained the ethanol moiety from the building block in the final products, deviating from conventional nucleophilic reactions reported in the literature. [ABSTRACT FROM AUTHOR]

Multi-component reactions for the construction of heterocycles have been fascinated by microwave energy as an alternative technique of heating, owing to the advantages over traditional reflux methods. The heterogeneous catalysts contribute significantly towards recycling, harmless, easy filtration, catalyst preparation, more life span, abundance, and product yields. With novel and creative uses in organic and peptide synthesis, polymer chemistry, material sciences, nanotechnology, and biological processes, the usage of microwave energy has rapidly increased during the past 20 years. This article covers multicomponent reactions involving construction of chromenes, pyridines, pyrroles, triazoles, pyrazoles, tetrazoles, trans and cis julolidines using heterogeneous catalysts under microwave. It provides an overview of contemporary microwave-assisted heterogeneous catalytic reactions. Microwave chemistry is now an established technology with several advantages regarding reaction rate and production yield, improving energy savings as confirmed by many applications. Due to the widespread curiosity in medicinal chemistry, the heterogeneously catalysed construction of heterocycles under microwave irradiation is explored to reduce time and energy. By considering various aspects of economy, eco-friendly, and user-friendly factors, this review focuses on recent advances in the multi-component construction of heterocycles using heterogeneous catalysts under microwave irradiation. This review also discusses the benefits and limitations of reaction conditions and yields from the literature reports for the past five years. [ABSTRACT FROM AUTHOR]

Carbon‐carbon bond formation in the phenanthridine 7‐position was achieved by microwave‐assisted Claisen rearrangement of 8‐allyloxyphenanthridines. The reactions took place with excellent regioselectivity and high chemical yields. If the 7‐position was substituted, rearrangement to C‐9 took place, but the reaction occurred less readily. Rearrangements of 8‐allyloxy‐5,6‐dihydrophenanthridines (phenanthridines with a saturated B‐ring) gave a mixture of 7‐ and 9‐substituted products. The experimental results were supported by DFT (density functional theory) calculations. [ABSTRACT FROM AUTHOR]

Several multicomponent synthetic approaches were elaborated for plenty of novel nitrogen or oxygen heterocycles containing a phosphonate or a phosphine oxide moiety. All multicomponent reactions were optimized through a model reaction in respect of the heating mode, molar ratio of the starting materials, atmosphere, catalyst, temperature, reaction time and solvent applied, and then, the extended preparation of small libraries of structurally-related compounds was performed. Most of the reactions could be considered as “green syntheses”, as they were carried out in the absence of any catalyst and/or solvent using microwave (MW) irradiation or even at ambient temperature. The scaling-up of a MW-assisted synthesis was also elaborated in a continuous flow MW system. Altogether more than 150 heterocyclic organophosphorus compounds were synthesized, among them several derivatives showed moderate or promising activity against the HL-60 cell line and Bacillus subtilis bacteria.

The synthesis of novel mono‐, di‐, tri‐, tetra‐, and hexafluorinated hexa‐peri‐hexabenzocoronenes (HBCs) and their conversion into their thioether‐substituted analogs is reported. The substitution reaction with the corresponding thiolates was performed microwave‐assisted to significantly reduce the reaction time. With increasing amount of fluorination or thioether‐substituents, a decreasing extinction coefficient can be observed for the HBCs. Successive addition of thioether‐moieties leads to a bathochromic shift of the absorption and emission bands, whereas the nature of the attached thioether does not affect the optoelectronical properties. To further tune the electronic environment of the HBC core, a successive oxidation to the corresponding sulfone as well as the formation of the sulfonium salts were performed. With that, the electron‐donating thioethers were transformed into electron‐withdrawing substituents, resulting in an inversed electron demand in the periphery of the core. The so obtained compounds showed decreased extinction coefficients and a broadening of the absorption and emission bands. [ABSTRACT FROM AUTHOR]

Nanomaterials have found use in a number of relevant energy applications. In particular, nanoscale motifs of binary metal sulfides can function as conversion materials, similar to that of analogous metal oxides, nitrides, or phosphides, and are characterized by their high theoretical capacity and correspondingly low cost. This review focuses on structure–composition–property relationships of specific relevance to battery applications, emanating from systematic attempts to either (1) vary and alter the dimension of nanoscale architectures or (2) introduce conductive carbon-based entities, such as carbon nanotubes and graphene-derived species. In this study, we will primarily concern ourselves with probing metal sulfide nanostructures generated by a microwave-mediated synthetic approach, which we have explored extensively in recent years. This particular fabrication protocol represents a relatively facile, flexible, and effective means with which to simultaneously control both chemical composition and physical morphology within these systems to tailor them for energy storage applications. [ABSTRACT FROM AUTHOR]

A combined experimental and theoretical study has been carried out on 4‐fluoro‐threonine, the only naturally occurring fluorinated amino acid. Fluorination of the methyl group significantly increases the conformational complexity with respect to the parent amino acid threonine. The conformational landscape has been characterized in great detail, with special attention given to the inter‐conversion pathways between different conformers. This led to the identification of 13 stable low‐energy minima. The equilibrium population of so many conformers produces a very complicated and congested rotational spectrum that could be assigned through a strategy that combines several levels of quantum chemical calculations with the principles of machine learning. Twelve conformers out of 13 could be experimentally characterized. The results obtained from the analysis of the intra‐molecular interactions can be exploited to accurately model fluorine‐substitution effects in biomolecules. [ABSTRACT FROM AUTHOR]

In catalytic reactions, trace amounts of promoters can make up for the low activity of a catalyst and significantly affect the physicochemical properties of the catalyst. Exploring a simple and efficient composite Cu‐based catalyst is essential to the Rochow‐Müller reaction. In this work, monodisperse, a hydrangea‐like 0.3Zn‐0.15Sn/CuO composite catalyst in the Rochow‐Müller reaction. The composite was synthesized via a microwave‐assisted liquid‐phase synergistic impregnation method in which Sn and Zn were used to dope the CuO surface to create strong Si interaction points. A significant increase in the catalytic activity of CuO was observed after Sn and Zn doping, attributed to the rearrangement of charges on the CuO surface and increase in the Cu atom's core electron density. This work provided a novel and efficient method for preparing efficient Cu‐based catalysts for the Rochow‐Müller reaction. [ABSTRACT FROM AUTHOR]

Abstract Carbon‐carbon bond formation in the phenanthridine 7‐position was achieved by microwave‐assisted Claisen rearrangement of 8‐allyloxyphenanthridines. The reactions took place with excellent regioselectivity and high chemical yields. If the 7‐position was substituted, rearrangement to C‐9 took place, but the reaction occurred less readily. Rearrangements of 8‐allyloxy‐5,6‐dihydrophenanthridines (phenanthridines with a saturated B‐ring) gave a mixture of 7‐ and 9‐substituted products. The experimental results were supported by DFT (density functional theory) calculations.

Solvothermal synthesis of mesoporous materials based on amphiphilic molecules as structure-directing agents can be enhanced using non-conventional technologies for stirring and thermal activation. Here, we disclose a green synthesis approach for the preparation of cerium-modified hexagonally ordered silica sieves. Ultrasound micromixing enabled us to obtain well-dispersed Ce in the self-assembled silica network and yielded ordered materials with high cerium content (Ce/Si molar ratio = 0.08). Microwave dielectric heating, applied by an innovative open-end coaxial antenna, was used to reduce the overall hydrothermal synthesis time and to improve the surface area and textural properties. These mesoporous materials were used as a Ni catalyst support (10 wt.% metal loading) for the ethanol steam reforming reaction. The new catalysts featured complete ethanol conversion, high H2 selectivity (65%) and better stability, compared to the same catalyst prepared with magnetic stirring and conventional heating. The Ce-promoted silica sieves offered a suitable support for the controlled growth of nanocarbon that does not result in catalyst deactivation or poisoning after 6 h on stream. [ABSTRACT FROM AUTHOR]

Three synthesis procedures for the covalent‐organic framework (COF) TpPa‐1 are studied with the purpose of setting up the most promising one in a fast and green way, leading to a more environmentally friendly and sustainable process. With conventional heating, good crystallinity and a high BET specific surface area (SSA) of up to 1007 m2 ⋅ g−1 are achieved at 170 °C for 3 days using water as the quintessential green solvent. However, the application of microwave radiation in the synthesis for this crystalline porous polymer allows reaction times to be shortened to 30 min while maintaining structural and textural properties (BET SSA of 928 m2 ⋅ g−1) and obtaining yields close to 98 % (vs. 90 % in the hydrothermal synthesis). The water‐assisted mechanochemical synthesis is also an environmentally friendly synthetic approach; with heating at 170 °C in a two‐step process (10+10 min), high crystallinity is achieved, a BET SSA of 960 m2 ⋅ g−1 and a yield of 98 % for TpPa‐1. [ABSTRACT FROM AUTHOR]

Kocaeli University, Kabaoğlu, 41380, In this work, furo[2,3‐d]pyrido[1,2‐a]pyrimidin‐4‐ones were obtained by microwave assisted radical cyclizations of 2‐hydroxy‐4H‐pirido[1,2‐a]pirimidin‐4‐ones with conjugated alkenes and phenylacetylene via Mn(OAc)3. Conventional heating and microwave irradiated reaction types were compared using parameters like temperature, time and molar ratios to determine best reaction condition. Obtained compounds were purified by chromatographic methods and characterized by spectroscopic techniques (1H NMR, 13C NMR, HRMS, FTIR). Also, to determine the exact configuration and regioselectivity of isolated compounds, XRD analysis were performed. [ABSTRACT FROM AUTHOR]

Microwave (MW)‐assisted reductive aminations of aldehydes and ketones were carried out in the presence of commercial and homemade heterogeneous Rh‐based catalysts. Ultrasound (US) was used to improve dispersion and stability of metal nanoparticles, while commercial activated carbon and carbon nanofibers were used as supports. Moreover, various bio‐derived molecules were selected as substrates, and aqueous ammonia was used as a cheap and non‐toxic reagent. MW combined with heterogeneous Rh catalysts gave a 98.2 % yield in benzylamine at 80 °C with 10 bar H2 for 1 h; and a 43.3 % yield in phenylethylamine at 80 °C and 5 bar H2 for 2 h. Carbon nanofibers proved to be a better support for the metal active phase than simple activated carbon, since a limited yield in benzylamine (10.6 %) but a high selectivity for the reductive amination of ketones was obtained. Thus, raspberry ketone was converted to raspberry amine in a 63.0 % yield. [ABSTRACT FROM AUTHOR]

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO2 nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications.

α‐Hydroxy amides are an essential class of compounds found in natural products and bioactive molecules of drug candidates. Herein we report a facile and direct approach to these compounds through oxalic acid decarbonylation/decarboxylation during the Passerini three‐component reaction (P‐3CR) under solvent‐free conditions with microwave heating. This very convenient methodology provides the title compounds through a possible concerted intramolecular decarbonylation/decarboxylation from the α‐acyloxy amide intermediate. [ABSTRACT FROM AUTHOR]

A new method for the synthesis of bis(1,3,5‐triazine‐2,4‐diamines) was developed using a one‐pot multicomponent approach. The synthesis was performed using the acid‐catalyzed reaction of cyanoguanidine with amines and aldehydes, followed by dehydrogenative aromatization of the dihydrotriazine intermediates upon heating with alkali. Two types of bis(1,3,5‐triazine‐2,4‐diamines) were prepared using either piperazine as the bifunctional amine or terephthaldehyde as the bifunctional aldehyde thus affording products with a piperazine or p‐phenylene link between two 1,3,5‐triazine rings. The microwave‐assisted method allows fast and convenient synthesis of diverse bis(1,3,5‐triazine‐2,4‐diamines). [ABSTRACT FROM AUTHOR]

In this work, two dendritic molecules containing an ethylenediaminetetraacetic acid (EDTA) core decorated with two and four β-cyclodextrin (βCD) units were synthesized and fully characterized. Copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) click chemistry under microwave irradiation was used to obtain the target compounds with yields up to 99%. The classical ethylenediamine (EDA) core present in PAMAM dendrimers was replaced by an EDTA core, obtaining platforms that increase the water solubility at least 80 times compared with native βCD. The synthetic methodology presented here represents a convenient alternative for the rapid and efficient construction of PAMAM analogs. These molecules are envisaged for future applications as drug carriers. [ABSTRACT FROM AUTHOR]

An effective synthesis provides a significant influence on microwave dielectric ceramics for commercial production. In this work, single-phase Li 3 Mg 2 NbO 6 ceramics were synthesized under an oxygen atmosphere to depress oxygen vacancies. Raman vibration, bond characteristics and crystal structure were analyzed to calculate the inherent features of the Li 3 Mg 2 NbO 6 ceramics. The Raman spectra and group theory indicated that the mode at 772 cm−1 reflected the symmetric vibrations of Nb–O bonds in NbO 6 octahedra and dominated the Raman vibrations. XRD patterns and Rietveld refinement indicated an orthorhombic rock-salt phase under an oxygen assisted sintering process. Well-distributed and homogeneous microstructures were obtained through SEM and grain distribution. From the chemical theory calculation, Nb–O bonds dominated the dielectric properties in consideration of their largest bond ionicity, lattice energy, and bond energy. The Li 3 Mg 2 NbO 6 ceramics sintered at 1100 °C with an oxygen atmosphere exhibited remarkable performance: ε r = 15.3, Q × f = 109,600 GHz and τ f = −17.3 ppm/°C, providing enormous potential for communication applications. [ABSTRACT FROM AUTHOR]

In this work, microstructure, composition, and microwave dielectric properties of nominal compositions (1‐x)Li2TiO3‐xZn2SiO4 (x=0.1, 0.2, 0.3, 0.4), which were prepared by conventional solid‐state ceramic route, have been investigated. Li2TiO3 and Zn2SiO4 reacted to form Li2ZnSiO4 and Zn2Ti3O8, where Zn2Ti3O8 is formed during Zn2TiO4 cooling. The microwave dielectric properties of samples are mainly affected by the characteristics and relative content of crystal phase and densification. With the increase of x, the relative dielectric constant (ϵr) decreases gradually. The quality factor (Qf) value increases at first, reaches the maximum value at x=0.2, and then decreases. The temperature coefficient of resonance frequency (τf) value has a sharp decrease due to the increase of Li2ZnSiO4. A near zero τf of about −2.0 ppm/°C was obtained in 0.8Li2TiO3–0.2Zn2SiO4 ceramic sintered at 1150 °C for 4 h with ϵr value of 17.67, Qf value of 19,600 GHz. Thus, it could be a candidate for microwave devices. [ABSTRACT FROM AUTHOR]

Several multicomponent synthetic approaches were elaborated for plenty of novel nitrogen or oxygen heterocycles containing a phosphonate or a phosphine oxide moiety. All multicomponent reactions were optimized through a model reaction in respect of the heating mode, molar ratio of the starting materials, atmosphere, catalyst, temperature, reaction time and solvent applied, and then, the extended preparation of small libraries of structurally-related compounds was performed. Most of the reactions could be considered as "green syntheses", as they were carried out in the absence of any catalyst and/or solvent using microwave (MW) irradiation or even at ambient temperature. The scaling-up of a MW-assisted synthesis was also elaborated in a continuous flow MW system. Altogether more than 150 heterocyclic organophosphorus compounds were synthesized, among them several derivatives showed moderate or promising activity against the HL-60 cell line and Bacillus subtilis bacteria. [ABSTRACT FROM AUTHOR]

Organoboron compounds are widely used in catalytic reactions, medicinal chemistry, chemosensors, and polymer applications, because of their low toxicity, high stability, Lewis acidity, chemical versatility, and ability to form covalent bonds with their nucleophilic targets, In this report, we demonstrate how to efficiently assemble tetra boronate‐containing compounds at the gram‐scale via a one‐pot modified microwave‐assisted Ugi‐4CR reaction. These boronate esters can then be transformed into the corresponding boronic acids under a reliable deprotection method, also reported herein. [ABSTRACT FROM AUTHOR]

The novel Cu−Zn−S−O nanocomposites have been successfully synthesized via a green microwave technique using preprepared ZnS and CuO nanoparticles. The Cu−Zn−S−O nanocomposites were highly sensitive to visible light. Meanwhile, Cu−Zn−S−O nanocomposites showed excellent adsorption capacity towards dye pollutants. Under the synergistic effect of adsorption and photocatalysis, various types of dye pollutants could be removed more quickly and efficiently by Cu−Zn−S−O (M=2) nanocomposite than pure CuO and ZnS nanoparticles. Furthermore, due to morphology‐controlled CuO, Cu−Zn−S−O nanocomposites were also different in the morphology and photoresponse, and even in the removal performance. The photodegradation mechanism investigation indicated that different types of dyes were mediated by different decisive reactive species. Additionally, Cu−Zn−S−O nanocomposites could be easily reused with higher activity. [ABSTRACT FROM AUTHOR]

Traditional methods for synthesizing two-dimensional Ti 3 C 2 T x MXenes such as hydrofluoric acid (HF) or LiF/HCl based etching can be time-consuming, complex, and often result in low yields. They generally involve multi-step processes involving >40 h of preparation time that can expose the materials to harsh conditions. In this study, we demonstrate a rapid single-step microwave (MW) synthesis method that significantly reduces production time to 90 min, achieving a 90 % yield and cutting energy consumption by 75 %. For the first time, synchrotron x-ray pair distribution function (PDF) analysis conducted on MW-synthesized MXene (MW-Ti 3 C 2 T x) indicates greater structural fidelity in local atomic ordering, indicating high-quality which is comparable to conventionally synthesized counterparts (CO-Ti 3 C 2 T x). This method achieves similar or greater structural quality in less time while also enhancing electromagnetic interference shielding (EMI SE) performance. A 15 μm MW-Ti 3 C 2 T x film demonstrated an impressive EMI SE of ∼67 dB in the X-band, compared to the ∼63 dB achieved by CO-Ti 3 C 2 T x. The enhanced EMI SE performance is attributed to the presence of fluorine terminations, which provide oxidation resistance, increased conductivity and improved absorption of EM waves. The MW-induced shocks during irradiation not only help remove O 2 /OH groups, preventing oxidation, but also tunes the functional groups, enhancing charge transport and effective EM wave attenuation. The MW synthesis method presents a fast, efficient, and scalable approach for producing high-quality MXene nanosheets, paving the way for advancements in EMI shielding and other applications. [Display omitted] • Rapid MW synthesis of high-quality Ti 3 C 2 T X MXenes in under 90 minutes achieves 90% yield, and 75% less energy consumption. • Synchrotron Pair distribution analysis confirms high atomic ordering and structural fidelity compared to conventional MXene. • MW- Ti 3 C 2 T X films exhibit outstanding EMI SE of around 67 dB in the X-band. • Enhanced dielectric losses and conductivity in MW-MXenes due to increased interlayer spacing and fluorine terminations. • Scalable MW-synthesis method for MXenes eliminates the need for exfoliation or delamination. [ABSTRACT FROM AUTHOR]

In the present research, the two different systems of dye based on zinc phthalocyanine were prepared by microwave-induced synthesis and conventional methods. They were evaluated as new effective chemical-based dosimeters for gamma irradiation. The sensitivity of the prepared dosimeters was examined by studying the comparative results between them through the changes in structural and optical properties upon exposure to different gamma irradiation doses. The color bleaching of the solutions was followed spectrophotometrically. Gradual changes from blue to light yellow color of zinc phthalocyanine solution, with the increase of the gamma radiation dose, were observed due to the decomposition of the dyes based on the zinc phthalocyanine. The synthesized zinc phthalocyanine chemical-based dosimeters for measurement of gamma irradiation up to 25kGy showed excellent stability after irradiation in terms of morphology and structure, which makes them a suitable novel material as composite-based dosimeters of gamma irradiation. [Display omitted] • Development of a new and effective ZnPc dosimeter for up to 25 kGy of gamma irradiation. • Energy-efficient microwave chemistry produces stable, great fineness chemical-based dosimeter. • ZnPc/PVA composites as fine, colored films with application in gamma-ray dosimetry. [ABSTRACT FROM AUTHOR]

Nanomaterials have found use in a number of relevant energy applications. In particular, nanoscale motifs of binary metal sulfides can function as conversion materials, similar to that of analogous metal oxides, nitrides, or phosphides, and are characterized by their high theoretical capacity and correspondingly low cost. This review focuses on structure–composition–property relationships of specific relevance to battery applications, emanating from systematic attempts to either (1) vary and alter the dimension of nanoscale architectures or (2) introduce conductive carbon-based entities, such as carbon nanotubes and graphene-derived species. In this study, we will primarily concern ourselves with probing metal sulfide nanostructures generated by a microwave-mediated synthetic approach, which we have explored extensively in recent years. This particular fabrication protocol represents a relatively facile, flexible, and effective means with which to simultaneously control both chemical composition and physical morphology within these systems to tailor them for energy storage applications.

New and efficient strategies for the conversion of 4‐oxazolin‐2‐ones into 1‐methyl and 1,4‐dimethyl 3‐formylcarbazoles are herein described. Highly convergent cascade and one‐pot processes afforded the corresponding diarylamines, as in situ formed synthetic intermediates or final products in high overall yields. Special attention was given to the synthesis of methylated carbazoles by reacting 4,5‐dimethyl‐4‐oxazolin‐2‐ones with enones under microwave irradiation. The carbazole scaffold was provided by the palladium(II)‐catalyzed double C−H activation to generate oxidative cyclization of diarylamines. This methodology allowed for formal total syntheses of four naturally occurring pyrido[4,3‐b]carbazole alkaloids ellipticine, 9‐methoxyellipticine, olivacine, and 9‐methoxyolivacine. [ABSTRACT FROM AUTHOR]

The present work describes the synthesis, growth‐regulating activity, and antimicrobial behavior of ionic compounds based on 2‐diethylamino‐N‐(2,4,6‐trimethylphenyl)acetamide (trimecaine). Synthesis of ionic compounds was performed via N‐alkylation of trimecaine with alkyl halides using microwave and ultrasound activation and the results were compared with those of classical conditions (thermal activation). The synthesized ionic compounds have been tested for germination energy and capacity with the collection of different varieties and hybrids of sweet sorghum seeds. The valuable results were obtained for the seeds stored for several years for which the significant drop in germination activity is usually observed. Furthermore, the ionic compounds were used to study their biological activity – growth –regulating activity on sweet sorghum seeds and the antimicrobial behavior against E. coli, S. typhimurium, B. subtilis, S. aureus, P. aeruginosa, and C. albicans microorganisms. [ABSTRACT FROM AUTHOR]

A microwave-assisted chlorine-free direct phenol substitution is presented, which is indicated as a key green chemistry research area for pharmaceuticals manufacturers. The reaction of β-aminocarbonates (mustard carbonates) with several substituted phenols in the presence of a polar solvent (acetonitrile or butanol) led to the related aminoalkylated products via the anchimeric assistance of the nitrogen incorporated in the organic carbonate backbone. The aminoalkylation required short reaction time (7 min) and the related products were isolated in high yields (>90%) via quick liquid-liquid extraction or column chromatography depending on the solvent employed. Furthermore, microwave irradiation also promoted the one-pot aminoalkylation of phenol in excellent yield. In this approach a β-aminoalcohol was reacted with phenol in the presence of diethyl carbonate, used for the in situ formation β-aminocarbonate, key intermediate in the consequent anchimerically driven alkylation. The resulting product, namely N , N -dimethyl-2-phenoxyethanamine, was isolated as pure in almost quantitative yield. [ABSTRACT FROM AUTHOR]