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A few computational studies indicated that some inhibitors of viral RNA–polymerase such as favipiravir could also inhibit cysteine proteases. The potential dual action of favipiravir as an inhibitor for both RNA–polymerase and proteases promises enhanced therapeutic efficacy of the drug against coronaviruses. To shed more light on this phenomenon, in view of the chemical structure of favipiravir and the recent advances in this field, six novel derivatives of 3-methyl quinoxaline were synthesized. In silico methods confirmed the abilities of these compounds to occupy the active-site clefts of both 3CLpro and PLpro with favorable interactions, while the ADMET evaluations predicted low toxicity and high bioavailability for them. Then, due to the high similarities between PLpro and papain, the inhibitory impacts of favipiravir and the synthesized quinoxalines on the kinetics of papain were thoroughly investigated. The outcome revealed that the potential dual-action of favipiravir-like compounds is a possibility that should be taken into account in designing more effective and safe drugs against coronavirus. [ABSTRACT FROM AUTHOR]

Halogenation of Y‐series small‐molecule acceptors (Y‐SMAs) is identified as an effective strategy to optimize photoelectric properties for achieving improved power‐conversion‐efficiencies (PCEs) in binary organic solar cells (OSCs). However, the effect of different halogenation in the 2D‐structured large π‐fused core of guest Y‐SMAs on ternary OSCs has not yet been systematically studied. Herein, four 2D‐conjugated Y‐SMAs (X‐QTP‐4F, including halogen‐free H‐QTP‐4F, chlorinated Cl‐QTP‐4F, brominated Br‐QTP‐4F, and iodinated I‐QTP‐4F) by attaching different halogens into 2D‐conjugation extended dibenzo[f,h]quinoxaline core are developed. Among these X‐QTP‐4F, Cl‐QTP‐4F has a higher absorption coefficient, optimized molecular crystallinity and packing, suitable cascade energy levels, and complementary absorption with PM6:L8‐BO host. Moreover, among ternary PM6:L8‐BO:X‐QTP‐4F blends, PM6:L8‐BO:Cl‐QTP‐4F obtains a more uniform and size‐suitable fibrillary network morphology, improved molecular crystallinity and packing, as well as optimized vertical phase distribution, thus boosting charge generation, transport, extraction, and suppressing energy loss of OSCs. Consequently, the PM6:L8‐BO:Cl‐QTP‐4F‐based OSCs achieve a 19.0% efficiency, which is among the state‐of‐the‐art OSCs based on 2D‐conjugated Y‐SMAs and superior to these devices based on PM6:L8‐BO host (17.70%) and with guests of H‐QTP‐4F (18.23%), Br‐QTP‐4F (18.39%), and I‐QTP‐4F (17.62%). The work indicates that halogenation in 2D‐structured dibenzo[f,h]quinoxaline core of Y‐SMAs guests is a promising strategy to gain efficient ternary OSCs. [ABSTRACT FROM AUTHOR]

Demonstrated here is an external photo‐sensitizer‐free (auto‐sensitized) singlet oxygen‐enabled solvent‐dependent tertiary hydroxylation and aryl‐alkyl spiro‐etherification of C3‐maleimidated quinoxalines. Such "reagent‐less" photo‐oxygenation at Csp3‐H and etherification involving Csp3‐H/Csp2‐H are unparalleled. Possibly, the highly π‐conjugated N‐H tautomer allows the substrate to get excited by irradiation, and subsequently, it attains the triplet state via ISC. This excited triplet‐state sensitized molecule then transfers its energy to a triplet‐state oxygen (3O2) generating reactive singlet oxygen (1O2) for hydroxylation and spirocyclization depending on the solvent used. In HFIP, the generated alkoxy radical accepts a proton via HAT giving hydroxylated product. In contrast, in an aprotic PhCl it underwent a radical addition at the ortho‐position of the C2 aryl to provide spiro‐ether. An unprecedented orthogonal spiro‐etherification was observed via the displacement of o‐substitutents for ortho (−OEt, −OMe, −F, −Cl, −Br) substituted substrates. The order of ipso substitution follows the trend −OMe>−OEt>−F>−H>−Cl>−Br. Both these oxygenation reactions can be carried out with nearly equal ease using direct sunlight without the requirement of any elaborate reaction setup. Demonstration of large‐scale synthesis and a few interesting transformations have also been realized. Furthermore, several insightful control experiments and quantum chemical computations were performed to unravel the mechanism. [ABSTRACT FROM AUTHOR]

The nano size Cu-Zn ferrite particles substituted to Mg2+ and La3+ having general chemical formula MgxCu0.3Zn0.7-xLayFe2-yO4 (x = 0.1, 0.2, 0.3, 0.4, 0.5; and y = 0.0, 0.025, 0.050, 0.075, 0.10) prepared through sol-gel method. The prepared mixed metal oxide nanoparticles were characterized employing techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) analyses. The prepared MgxCu0.3Zn0.7-xLayFe2-yO4 magnetic nanoparticles were used as a efficient, recoverable and heterogeneous catalyst for the one-pot synthesis of quinoxalines 3(a–g) and 1,5-benzodiazepines 5(a–h) under mild reaction conditions in good yields. The recyclability of catalyst was tested for five times without significant decrease in the catalytic activity. Catalyst has been used for the synthesis of different derivatives of quinoxalines in short time (20 to 30 min) with 90 -97% yield. Also, different derivatives of 1,5-benzodiazepines have been synthesized in short time (15 to 30 min) with 89 -98% yield using the catalyst. [ABSTRACT FROM AUTHOR]

In this study, electrochemical copolymerization of 6,7-diphenyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline and 3,3'-didecyl-3,4-propylenedioxythiophene is carried out to obtain a copolymer namely poly(6,7-diphenyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline-co-3,3'-didecyl-3,4-propylenedioxythiophene). Two distinct copolymers, PC1 and PC2, were produced as a result of the utilization of two different feed ratios. Copolymers were examined electrochemically and spectroelectrochemically after the copolymerization procedure. This study's major goal is to combine the exceptional characteristics of homopolymers P1 and P2 (P1 has a low band gap but is not soluble, and P2 is soluble and has a larger band gap) into a single copolymeric material. [ABSTRACT FROM AUTHOR]

We describe herein a method for transition‐metal‐free (hetero)arylsulfonylation of 1‐iodopyrrolo[1,2‐a]quinoxalines with sodium arylsulfinates. The corresponding aryl iodides were in situ prepared from eletrophilic iodination of C1−H bonds in pyrrolo[1,2‐a]quinoxalines with N‐iodosuccinimide. The ensuing sulfonylation only required DMSO as solvent and completed after 15 min. Many arylsulfinates bearing chloro, bromo, methylsufonyl, acetamide, and nitro groups were competent substrates. Heteroarylsulfonylation of pyrrolo[1,2‐a]quinoxalines were also feasible. [ABSTRACT FROM AUTHOR]

A series of pyrrolo[3,2‐f]quinoxaline derivatives have been obtained by a three‐component domino reaction of quinoxalin‐6‐amine, arylglyoxal monohydrates, and cyclic 1,3‐dicarbonyl compounds in ethanol medium at 80°C catalyzed by acetic acid. The notable features of this synthesis are excellent regioselectivity, operational simplicity, relatively mild reaction conditions, and good yields. [ABSTRACT FROM AUTHOR]

Herein, we report the design and synthesis of a novel series of 6-((1H-1,2,3-triazol-4-yl)methyl)-6H-indolo[2,3-b]quinoxalines (22–29) via the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction. The target compounds formed through two pathways (A and B). The structures of the newly click synthesised 1,2,3-triazole-6H-indolo[2,3-b]quinoxalines (22–29) were confirmed on the basis of their elemental analysis and spectral data. Some of these compounds exhibited significant antiproliferative effects against tested cancer cells, including hepatocellular carcinoma (Hep-G2), breast cancer (MCF-7), and colon cancer (HCT116), relative to healthy noncancerous control skin fibroblast cells (BJ-1) to evaluate their cytotoxic effects. Among the tested compounds, compound 27 exhibited strong activity with IC50 = 9.3 ± 1.1, 1.5 ± 0.1, 2.4 ± 0.2, and 17.3 ± 1.2 against cancer cell lines HCT-116, HepG-2, MCF-7, and BJ-1, respectively. Therefore, compound 27 was selected for further investigation. Cell cycle analysis of liver cancer (HepG-2) cells treated with 27 showed cell cycle arrest in the S and G0/G1 phases and strong apoptotic activity, as indicated by Annexin V-FITC staining. Compound 27 was also found to fit in the ATP binding pocket during docking experiments combined with molecular dynamics simulation. Lastly, we conducted a Petra/Osiris/Molinspiration (POM) study on the synthesized compound. The most promising candidates were identified by evaluating primary in silico parameters, which showed considerable differences among individual synthesized compounds. These features can promote future drug candidate design to produce better derivatives in the search for anticancer agents, particularly those with favorable ADME parameters, low toxicity, anticipated bioactivity, and bright futures. [ABSTRACT FROM AUTHOR]

The integration of photovoltaic technologies within agricultural settings, also known as agrivoltaics, is attracting increasing attention as a sustainable approach to ensure both clean energy and food supply. The success of this strategy relies on the development of innovative materials that can selectively convert specific wavelengths into energy while being transparent to photosynthetically relevant light. To this aim, here we report our endeavors in the synthesis of a new class of D‐π‐A‐π‐D quinoxaline fluorophores and their use in the preparation of wavelength‐selective luminescent solar concentrators. The dyes were expeditiously prepared following a direct arylation protocol and extensively characterized by spectroscopic analyses and computational studies. They present high light harvesting ability in the green region of the visible spectrum and good emission properties, which were fully retained in the solid state when embedded into a poly methyl methacrylate (PMMA) matrix. These materials were employed to construct LSC devices of promising efficiency, fostering further developments for the use of wavelength‐selective LSC in agrivoltaic systems. [ABSTRACT FROM AUTHOR]

Photochemical properties of terarylenes with quinoxalines bridge unit and allomaltol fragment was investigated. We have demonstrated that starting compounds with hydroxyl group in 3‐hydroxy‐4‐pyranone substituent does not undergo any photoinduced transformations. Wherein, conversion to methoxy derivatives allows one to realize photochemical 6π‐electrocyclization for considered quinoxalines. Based on data of x‐ray analysis the observed difference in reactivity is connected with the presence of hydrogen bond in hydroxyl derivatives. As a result of carried out research photochemical approach to novel benzo[a]pyrano[3,2‐c]phenazin‐4‐ones was implemented. [ABSTRACT FROM AUTHOR]

We report two methods for selective morpholinomethylation and formylation of C1 − H bonds in pyrrolo[1,2-a]quinoxalines. Reaction of pyrrolo[1,2-a]quinoxalines and morpholine using CuI catalyst, (bis(trifluoroacetoxy)iodo)benzene oxidant, and DMSO solvent yielded the morpholinomethylation products. Meanwhile, formylation of C1 − H bonds in pyrrolo[1,2-a]quinoxalines progressed in the presence of CuI catalyst, trifluoroacetic acid, and DMSO solvent. Compounds bearing halogen, methylsulfonyl, pyridine, and thiophene groups were isolated in moderate yields. [ABSTRACT FROM AUTHOR]

An eco‐conscious, metal‐free protocol has been developed to synthesize a diverse collection of biologically and pharmacologically active quinoxaline and pyrazine derivatives. The protocol involves a one‐pot condensation of various 1,2‐diamines with 1,2‐diones using thiourea dioxide as a catalyst and water as a solvent at ambient temperature. Notably, the catalyst can be reused up to five times without any significant loss of efficacy. The green aspects of this method involved milder reaction conditions, higher yields with shorter reaction times, simple work‐up, non‐chromatographic separations, good reusability, and easy catalyst recovery by simple filtration. Moreover, the reaction is successfully accelerated to a multigram scale, making it favourable for production at a larger scale. [ABSTRACT FROM AUTHOR]

Candida ranks as among the most frequently encountered fungal infections that associated with high morbidity and mortality. Quinoxaline derivatives are a group of small molecules that showed a promising antimicrobial activity. This study aimed to investigate the fungicidal effects of 3-hydrazinoquinoxaline-2-thiol against Candida in comparison with Amphotericin B in vitro as a reference. Also, we aim to assess the efficacy of 3-hydrazinoquinoxaline-2-thiol in vivo using mice oral candidiasis model. Fifty-six Candida isolates were subjected to susceptibility testing by broth microdilution method for 3-hydrazinoquinoxaline-2-thiol and Amphotericin B. Therefore, Minimal inhibitory concentrations (MIC) were assessed and compared. The oral candidiasis mice model was used to evaluate the activity of 3-hydrazinoquinoxaline-2-thiol in vivo. Microbiological evaluation of progression and ELISA were used in this study. 3-hydrazinoquinoxaline-2-thiol was more effective than Amphotericin B against most clinical isolates of Candida albicans. Higher effectiveness was seen against Candida glabrata and Candida parapsilosis isolates. However, the efficiency against Candida tropicalis isolates varies. 3-hydrazinoquinoxaline-2-thiol was also effective against Pichia kudriavzevii and Clavispora lusitaniae. 3-hydrazinoquinoxaline-2-thiol showed a good efficacy in mice model against C. albicans cells ATCC 10231. 3-hydrazinoquinoxaline-2-thiol has shown promising antifungal and anti-inflammatory activity against different Candida species. More tests and experiments are needed. [ABSTRACT FROM AUTHOR]

A new series of quinoxaline‐sulfonamide derivatives 3–12 were synthesized using fragment‐based drug design by reaction of quinoxaline sulfonyl chloride (QSC) with different amines and hydrazines. The quinoxaline‐sulfonamide derivatives were evaluated for antidiabetic and anti‐Alzheimer's potential against α‐glucosidase, α‐amylase, and acetylcholinesterase enzymes. These derivatives showed good to moderate potency against α‐amylase and α‐glucosidase with inhibitory percentages between 24.34 ± 0.01%–63.09 ± 0.02% and 28.95 ± 0.04%–75.36 ± 0.01%, respectively. Surprisingly, bis‐sulfonamide quinoxaline derivative 4 revealed the most potent activity with inhibitory percentages of 75.36 ± 0.01% and 63.09 ± 0.02% against α‐glucosidase and α‐amylase compared to acarbose (IP = 57.79 ± 0.01% and 67.33 ± 0.01%), respectively. Moreover, the quinoxaline derivative 3 exhibited potency as α‐glucosidase and α‐amylase inhibitory with a minute decline from compound 4 and acarbose with inhibitory percentages of 44.93 ± 0.01% and 38.95 ± 0.01%. Additionally, in vitro acetylcholinesterase inhibitory activity for designed derivatives exhibited weak to moderate activity. Still, sulfonamide‐quinoxaline derivative 3 emerged as the most active member with inhibitory percentage of 41.92 ± 0.02% compared with donepezil (IP = 67.27 ± 0.60%). The DFT calculations, docking simulation, target prediction, and ADMET analysis were performed and discussed in detail. [ABSTRACT FROM AUTHOR]

A series of 3-chloro-1-aryl-4-dihydro-2H-pyrrolo[2,3-b]quinoxalin-2-ones and 3-chloro-1-aryl-6,7-dimethyl-1,4-dihydro-2H-pyrrolo[2,3-b]quinoxalin-2-ones was prepared by the condensation of o-phenylenediamine or 4,5-dimethyl-1,2-aminobenzene with N-aryl-3,4-dichloro-maleimides. All the prepared quinoxalines were tested for their antitumor activity against three human cancer cell lines (prostate cells PC3, colorectal cells Caco-2, and cervical cells HeLa), and a mammalian cell line (Vero cells). The compounds were also tested for their antibacterial properties against three different bacterial cells Escherichia coli, Bacillus spizizenii, and Pseudomonas aeruginosa. The compounds 3c, 3d, 3g, 3h, 3i and 4a, 4b, 4h showed anti-proliferative activity against the tested cell lines. Regarding their antibacterial activity, compounds 3a, 3g, 4a, and 4h showed inhibitory activity against E. coli, and B. spizizenii only. [ABSTRACT FROM AUTHOR]

Context: Due to the widely known positive contributions of the quinoxaline group in organic semiconductors, we conducted a fully computational study using quantum mechanical methods to investigate the effect of quinoxaline in the electron acceptor unit with the combination of different chalcogen atoms on the band gap of a series of donor–acceptor-donor type conjugated polymers. Using density functional theory, we mainly calculated the electronic band gap values of the structures containing four different chalcogen atoms (O, S, Se, and Te) in the electron donor and acceptor units. While chalcogendiazoloquinoxaline groups were used as the electron acceptor units, furan, thiophene, selenophene, and tellurophene were used as the donor units. Our theoretical results showed that the use of heavy chalcogen atoms in both donor and acceptor units resulted in a low band gap. Besides this, the effect of heavy chalcogen atoms used in the electron donor units is much more pronounced compared to the ones used in the acceptor units. More importantly, our findings proved that the inclusion of the chalcogendiazoloquinoxaline group instead of benzochalcogenadiazole as the acceptor unit significantly decreases the electronic band gap of the conjugated polymer. The lowest band gap was found to be 0.10 eV for the 4,9-di(tellurophen-2-yl)-[1,2,5]telluradiazolo[3,4-g]quinoxaline polymer. Methods: Conformational analysis of the monomers and their corresponding oligomers was performed at the B3LYP/LANL2DZ level of theory. Then, long-range corrected hybrid functional LC-BLYP in a combination with the LANL2DZ basis set was utilized for the calculation of electronic properties and HOMO and LUMO energy gaps of monomers and oligomers through the reoptimization of the lowest energy conformers obtained from the B3LYP/LANL2DZ calculations in the previous step. All energy minimum structures were confirmed through vibrational frequency analysis at both calculation levels. The Gaussian 09 rev. D.01 software was used for all calculations, and GaussView 5.0.9 for visualizations. [ABSTRACT FROM AUTHOR]

2,3-Bis[5-(pyren-1-yl)thiophen-2-yl]quinoxalines and 2,3-bis{5-[4-(9H-carbazol-9-yl)phenyl]thiophen-2-yl}pyrazino[2,3-f][1,10]phenanthroline were synthesized. One- and two-photon absorption and emission of the compounds were studied, the cross sections of the two-photon absorption were found to be equal to 101–476 GM in THF. Fluorescent responses of pyrene-containing fluorophores and dipyrido-annelated quinoxaline to nitroaromatic compounds and metal cations, respectively, were investigated. [ABSTRACT FROM AUTHOR]

A simple synthetic route to poorly available polycyclic systems with a [1,2,5]oxadiazolo-[3,4-b]quinoxaline backbone has been developed, which is based on the sequence of nucleophilic aromatic substitution of hydrogen and the Scholl cross-coupling. According to the data from electrochemical and photophysical measurements, the synthesized compounds can be potentially considered as the narrow-gap (from 1.97 to 2.34 eV) n-type organic semiconductors, the energy levels of which are comparable to those of top commercially available electronic semiconductors. [ABSTRACT FROM AUTHOR]

We report the efficient, sustainable one‐pot synthesis of a wide variety of N‐polyheterocycles, such as imidazo‐quinolines and quinoxalines, and furoquinolines, from easily available nitroaromatics and glycols via a molybdenum catalytic domino reduction‐imine formation‐intramolecular cyclization‐oxidation sequence. It is worth highlighting that the recycling and incorporation of the waste carbonyl byproduct, generated in the reduction step, into the final compound is realized. In addition, the overall efficiency and atom economy of the process are further improved owing to the participation of one reaction intermediate as reductant that allows lowering the amount of external reducing agent employed. [ABSTRACT FROM AUTHOR]

Background: Candida represents a prevalent fungal infection, notable for its substantial implications on morbidity and mortality rates. In the landscape of prospective treatments, quinoxaline derivatives emerge as a category of compact compounds exhibiting notable potential in addressing infections. These derivatives showcase promising antimicrobial efficacy coupled with favorable pharmacokinetic and safety characteristics. Aims: The central aim of this investigation was to examine the antifungal characteristics of 2-Chloro-3-hydrazinylquinoxaline against diverse strains of Candida and Aspergillus in vitro. Additionally, we endeavored to assess the in vivo efficacy of 2-Chloro-3-hydrazinylquinoxaline using a murine model for oral candidiasis induced by C. albicans cells ATCC 10231. Results: 2-Chloro-3-hydrazinylquinoxaline demonstrated noteworthy effectiveness when tested against various reference strains of Candida species. It exhibited heightened efficacy, particularly against Candida krusei isolates. However, its performance against Candida albicans, Candida tropicalis, Candida glabrata, Candida parapsilosis, and Candida auris isolates exhibited variability. Notably, 2-Chloro-3-hydrazinylquinoxaline manifests variable efficacy against Aspergillus fumigatus, Aspergillus niger, Aspergillus terreus and Aspergillus flavus and no effect against Aspergillus brasiliensis. In a murine model, 2-Chloro-3-hydrazinylquinoxaline exhibited significant efficacy in combating the C. albicans cells ATCC 10231 strain, underscoring its potential as a viable treatment option. Conclusion: 2-Chloro-3-hydrazinylquinoxaline has demonstrated substantial potential in effectively addressing various Candida and Aspergillus species, showcasing dual attributes of antifungal and anti-inflammatory properties. However, to attain a more comprehensive understanding of its therapeutic capabilities, further investigations, incorporating additional tests and experiments, are imperative. [ABSTRACT FROM AUTHOR]

Heterocycles are very common in many naturally occurring bioactive compounds as well as in the commercially available drug molecules. Very recently spiroheterocycles have gained considerable attention due to their wide range of pharmacological applicability. Among many others, 11H‐indeno[1,2‐b]quinoxalin‐11‐one in recent time have gained significant attention as an important building block to prepare structurally diverse biologically promising spiroheterocycles under various reaction conditions. On the other hand, it was found that one‐pot three‐component reaction strategy plays an important role in the preparation of spiroheterocycles starting from 11H‐indeno[1,2‐b]quinoxalin‐11‐one as it has many advantages including high atom economy, operational simplicity, easy workup procedures, reduction of byproducts, energy and reaction step efficiency etc. In this review, we have discussed all the recent developments related to the one‐pot three‐component synthesis of biologically promising indenoquinoxaline fused spiroheterocycles starting from 11H‐indeno[1,2‐b]quinoxalin‐11‐ones under diverse reaction conditions. [ABSTRACT FROM AUTHOR]

The main objective of the present work is to synthesize and identify the potential breast cancer medication of 2-aryl quinoxaline -derivatives via in silico investigations. Synthesis of 2-aryl quinoxaline derivatives have been achieved via the reaction of 3-aroylmethylene-2H-indol-2-ones 1 with various 1,2-diamines. Good yields were obtained at 60 °C in methanol by using graphene oxide (GO) as catalyst, however, the regio selectivity in case of unsymmetrically substituted diamines were low to moderated. This is the first report of the oxidative cleavage of C = C bond during the course of the reaction. Molecular docking study of these synthesized compounds were employed to calculate the binding affinity with human epidermal growth factor receptor 2 (HER2). 6-Bromo-3-phenylpyrido[2,3-b]pyrazine 3k showed highest binding energy of −7.70 kcal/mol depicting the potential inhibitor of HER2 receptor protein. However, this study needs to be supported by in vitro and in vivo studies. [ABSTRACT FROM AUTHOR]

This study introduces novel Liquid Organic Hydrogen Carriers (LOHCs) derived from quinoxaline. It shows that strategically incorporating N atoms and methyl groups markedly improves the hydrogen release kinetics. This structural modulation optimizes the adsorption properties and enables low-temp C–H bond activation, providing valuable insights for developing efficient LOHCs. [ABSTRACT FROM AUTHOR]

Dyes based on quinoline and quinoxaline skeletons were designed for application as visible light photoinitiators. The obtained compounds absorb electromagnetic radiation on the border between ultraviolet and visible light, which allows the use of dental lamps as light sources during the initiation of the photopolymerization reaction. Their another desirable feature is the ability to create a long-lived excited state, which enables the chain reaction to proceed through the mechanism of intermolecular electron transfer. In two-component photoinitiating systems, in the presence of an electron donor or a hydrogen atom donor, the synthesized compounds show excellent abilities to photoinitiate the polymerization of acrylates. In control tests, the efficiency of photopolymerization using modified quinoline and quinoxaline derivatives is comparable to that obtained using a typical, commercial photoinitiator for dentistry, camphorquinone. Moreover, the use of the tested compounds requires a small amount of photoinitiator (only 0.04% by weight) to initiate the reaction. The research also showed a significant acceleration of the photopolymerization process and shortening of the reaction time. In practice, this means that the new two-component initiating systems can be used in much lower concentrations without slowing down the speed of obtaining polymer materials. It is worth emphasizing that these two features of the new initiating system allow for cost reduction by reducing financial outlays on both materials (photoinitiators) and electricity. [ABSTRACT FROM AUTHOR]

We present a new category of quinoxaline di-N-oxides (QdNOs) containing amino acid side chains with dual antituberculosis and antileishmanial activity. These compounds were synthesized by combining a regioselective 2,5-piperazinedione opening and a Beirut reaction and were screened for their activity against Mycobacterium tuberculosis and the promastigote and amastigote forms of representative species of the Leishmania genus. Most QdNOs exhibited promising antitubercular activity with IC50 values ranging from 4.28 to 49.95 μM, comparable to clinically established drugs. Structure–activity relationship analysis emphasized the importance of substituents on the aromatic ring and the side chain. Antileishmanial tests showed that some selected compounds exhibited activity comparable to the positive control miltefosine against promastigotes of Leishmania amazonensis and Leishmania donovani. Notably, some compounds were found to be also more potent and less toxic than miltefosine in intracellular amastigote assays against Leishmania amazonensis. The compound showing the best dual antitubercular and leishmanicidal profile and a good selectivity index, 4h, can be regarded as a hit compound that opens up new opportunities for the development of integrated therapies against co-infections. [ABSTRACT FROM AUTHOR]

Here, a cyclometalated Pt(II) clamshell dimer (complex 2) has been synthesized with the primary ligand of dibenzo(f,h)quinoxaline and an ancillary ligand of N,N′-diphenylformamidine. In addition, a mononuclear Pt(II) complex 1a and a binuclear Pt(II) complex 1b were also prepared. Complex 1a was coordinated by one cyclometalated ligand of dibenzo(f,h)quinoxaline, one chloride ion, and one N,N′-diphenylformamidine. Complex 1b was coordinated by one cyclometalated ligand of dibenzo(f,h)quinoxaline, two chloride ions, and two N,N′-diphenylformamidines. All of these three complexes were characterized by nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectrometry (HRMS), elemental analyses, and single-crystal X-ray diffraction (XRD). The Pt–Pt distance in complex 2 was 2.8439(2) Å. It also exhibited a near-infrared (near-IR) emission at 887 nm in the pure solid state. On the other hand, complexes 1a and 1b exhibited triplet emission at 589 and 660 nm, respectively, in the pure solid state. Furthermore, in 2 wt% poly(Me methacrylate) (PMMA) films, complex 1a showed a triplet emission at 548 nm (with Φ = 84% and τ = 5.53 μs) and complex 1b showed an emission at 627 nm (with Φ = 79% and τ = 4.07 μs). Due to its great photophysical properties, complex 1b was deposited onto quartz plates for the detection of organic solvent vapors and it showed unique emission quenching for the vapor of tetrahydrofuran. [ABSTRACT FROM AUTHOR]

This manuscript describes the development of alkyne addition to the aziridine moiety of aziridinoquinoxalines using dual Ir(III)/Cu(I) catalytic system under green light‐emitting diode (LED) photolysis (λmax=525 nm). This mild method features high levels of chemo‐ and regioselectivity and was used to generate 30 highly functionalized substituted dihydroquinoxalines in 36–98 % yield. This transformation was also carried asymmetrically using phthalazinamine‐based chiral ligand to provide 9 chiral addition products in 96 : 4 to 86 : 14 e.r. The experimental and quantum chemical explorations of this reaction suggest a mechanism that involves Ir(III)‐catalyzed triplet energy transfer followed by a ring‐opening reaction ultimately leading to the formation of azomethine ylide intermediates. These azomethine intermediates undergo sequential protonation/copper(I) acetylide addition to provide the products. [ABSTRACT FROM AUTHOR]

This manuscript describes the development of alkyne addition to the aziridine moiety of aziridinoquinoxalines using dual Ir(III)/Cu(I) catalytic system under green light‐emitting diode (LED) photolysis (λmax=525 nm). This mild method features high levels of chemo‐ and regioselectivity and was used to generate 30 highly functionalized substituted dihydroquinoxalines in 36–98 % yield. This transformation was also carried asymmetrically using phthalazinamine‐based chiral ligand to provide 9 chiral addition products in 96 : 4 to 86 : 14 e.r. The experimental and quantum chemical explorations of this reaction suggest a mechanism that involves Ir(III)‐catalyzed triplet energy transfer followed by a ring‐opening reaction ultimately leading to the formation of azomethine ylide intermediates. These azomethine intermediates undergo sequential protonation/copper(I) acetylide addition to provide the products. [ABSTRACT FROM AUTHOR]

In the title compound, C17H12N2O,the quinoxaline moiety shows deviations of 0.0288 (7) to -0.0370 (7) Å from the mean plane (r.m.s. deviation of fitted atoms = 0.0223 Å). In the crystal, corrugated layers two molecules thick are formed by C--H⋯N hydrogen bonds and π-stacking interactions. [ABSTRACT FROM AUTHOR]

The Y-type compound 67dTPA-FQ combining 2-phenylfuro[2,3-b]quinoxaline (FQ) with triphenylamine (TPA) demonstrated to be a green fluorescence emitter (519 nm) with a ΔES1T1 of 0.40 eV. Herein, TPA units in 67dTPA-FQ were replaced with 10-phenyl-10H-phenoxazine (Ph-PXZ) units to shift the S1 energy to a lower direction to reduce ΔES1T1 and realize thermally-activated delayed fluorescence (TADF). Thus, Y-shaped (67dPXZ-FQ) and T-shaped (58dPXZ-FQ) compounds were synthesized. As the donor changed from TPA to PXZ, the emission bands of the Y- and T-shaped compounds in toluene shifted to 585 nm and 631 nm, respectively. As we expected, ΔES1T1 for Y- and T-shaped compounds decreased to 0.12 eV and 0.15 eV, respectively, well lower than 0.3 eV. Unfortunately, the TADF feature was not observed. Theoretical calculations revealed that the HOMO and LUMO orbitals of both compounds were completely located at one of the PXZ fragment and 2-phenylfuro[2,3-b]quinoxaline moiety, respectively, yielding a complete electron separation by phenylene bridges between the acceptor FQ and PXZ. As a result, the oscillator strength (f) of the S1 → S0 transition was only 0.0001–0.0002, leading to weak radiative transition capability of the S1 state. As a result, a low fluorescent yield of 25–36% was obtained. Moreover, the calculated spin–orbital coupling value between the S1 and T1 was only 0.13 cm−1 for both 67dPXZ-FQ and 58dPXZ-FQ, suggesting weak driving capability for the reverse intersystem crossing process. As such, the TADF features of the two compounds were not observed. [ABSTRACT FROM AUTHOR]

2-Chloro-3-substituted quinoxalines (3) are significant precursors in the synthesis of 2,3-di-unsymmetrically substituted quinoxalines, including quinacillin, which has been shown to be effective against a number of transplantable diseases and cancer cells. Despite the fact that there are two ways to produce 2-chloro-3-substituted quinoxalines (3), both procedures are hampered by high temperatures, metal contamination, and toxic reagents. A visible-light-induced radical cascade cyclization of ortho-diisocyanoarenes (1) with alkyl(aryl)sulfinic acids (2) and trichloroisocyanuric acid has been developed. Also, a plausible reaction mechanism and synthetic uses of 2-chloro-3-substituted quinoxalines (3) towards a few 2,3-di-unsymmetrically-substituted quinoxalines have been described. This novel approach easily accesses 2-chloro-3-substituted quinoxalines (3) in good yields, without using elevated temperatures, or metal- or toxic reagents. [ABSTRACT FROM AUTHOR]

In this study, we synthesized sulfamic acid-functionalized Fe3O4 nanoparticles (Fe3O4@EDA-SO3H) as an effective nanomagnetic solid acid catalyst. This magnetically recoverable catalyst was well characterized by FT-IR, XRD, TGA, VSM, SEM, EDX, TEM, and CHN techniques. The prepared catalyst exhibited high efficiency in the synthesis of quinoxaline, benzothiazole, and benzoxazole derivatives such as 3,2-diphenylquinoxaline (97%), 2-phenyl-benzothiazole (97%), and 2-(4-chlorophenyl)benzoxazole (95%) via simple and mild conditions. The catalyst can be readily separated from the reaction medium by employing an external magnet and reused several times without significant loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

We designed and synthesized thirty novel quinoxaline aryl ethers as anticancer agents, and the structures of final compounds were confirmed with various analytical techniques like Mass, 1H NMR, 13C NMR, FTIR, and elemental analyses. The compounds were tested against three cancer cell lines: colon cancer (HCT‐116), breast cancer (MDA‐MB‐231), prostate cancer (DU‐145), and one normal cell line: human embryonic kidney cell line (HEK‐293). The obtained results indicate that two compounds, FQ and MQ, with IC50 values < 16 μM, were the most active compounds. Molecular docking studies revealed the binding of FQ and MQ molecules in the active site of the c‐Met kinase (PDB ID: 3F66, 1.40 Å). Furthermore, QikProp ADME prediction and the MDS analysis preserved those critical docking data of both compounds, FQ and MQ. Western blotting was used to confirm the impact of the compounds FQ and MQ on the inhibition of the c‐Met kinase receptor. The apoptosis assays were performed to investigate the mechanism of cell death for the most active compounds, FQ and MQ. The Annexin V/7‐AAD assay indicated apoptosis in MDA‐MB‐231 cells treated with FQ and MQ, with FQ (21.4%) showing a higher efficacy in killing MDA‐MB‐231 cells than MQ (14.25%). The Caspase 3/7 7‐AAD assay further supported these findings, revealing higher percentages of apoptotic cells for FQ‐treated MDA‐MB‐231 cells (41.8%). The results obtained from the apoptosis assay conclude that FQ exhibits better anticancer activity against MDA‐MB‐231 cells than MQ. [ABSTRACT FROM AUTHOR]

In the title compound, C31H24N4O2, the quinoxaline units are distinctly non-planar and twisted end-to-end. In the crystal, C--H…O and C--H…N hydrogen bonds link the molecules into chains extending along the a-axis direction. The chains are linked through π-stacking interactions between inversion-related quinoxaline moieties. [ABSTRACT FROM AUTHOR]

The pharmacological importance of quinoxaline derivatives in antibacterial research is well recognized. This study focuses on the synthesis of new 2,3‐dichloroquinoxaline derivatives containing thioether/ether groups to explore their potential as potent antibacterial agents against various pathogenic bacteria. Most of the compounds exhibited significant antibacterial properties comparable to the standard drug chlorhexidine (CHX). The derivatives of 2‐chloro‐3‐(arylthiol)quinoxaline demonstrated efficacy against Escherichia coli with minimum inhibitory concentrations (MIC) of 2.5 mg/mL and minimum bactericidal concentrations (MBC) of 2.5 to 5.0 mg/mL. These derivatives also showed similar sensitivity to Bacillus pumilus. In addition, molecular docking simulations were performed to investigate the interaction between the synthesized compounds and the DNA gyrase protein (PDB ID: 1KZN), a target for antibiotics. Among the synthesized compounds, 2,3‐bis(3‐nitrophenoxy)quinoxaline exhibited the most favourable docking score of −8.36 kcal/mol, with a binding affinity comparable to that of the reference ligand clorobiocin (−9.3 kcal/mol). [ABSTRACT FROM AUTHOR]

Functional groups adjacent to the redox active center would have an uncompromising effect on the diffusion kinetics of the charge carriers. They expedite the diffusion process by extensive H-bonding, charge delocalization, and functional group polarization by tautomerism or resonance which would have long held influence on the electrochemical performance of the material. Herein, we introduced a ketonic functional group adjacent to the quinoxaline redox center which accelerates the diffusion of the charge carriers. Quinoxaline nuclei with free rotating phenyl rings (DAB) exhibited a specific capacitance of 156.4 mAhg−1 at 50 mAg−1 which was found drastically decreased due to the excessive dissolution of the material as well as the uncontrolled ring flipping of the phenyl rings. By introducing a ketone functional group and stagnant phenyl rings with a fused ring system the specific capacitance was found to be improved to a considerable extent. The quinoxaline redox center with a fused ring system and symmetrically placed ketone functional groups (TKQ) exhibited a specific capacitance of 286.7 mAhg−1 at 50 mAg−1 and remained 224.8 mAhg−1 after prolonged 1000 cycles, with 95% coulombic efficiency and 79.4% retention in the discharge capacity. The study suggests that smart molecular engineering is necessary for excellent rate performance, rate reversibility, coulombic efficiency, and capacity retention. [ABSTRACT FROM AUTHOR]

A visible-light-promoted formal [2 + 2 + 1] cyclization of N-aryl glycines with quinoxalin-2(1H)-ones to synthesize tetrahydroimidazo[1,5-a]quinoxalin-4(5H)-ones have been developed. The protocol features operational simplicity, mild reaction conditions with blue LED light employing Ru(bpy)3Cl2. 6H2O as a photoredox catalyst, a combination of O2 from air and Cu(OAc)2 as the oxidant and broad substrate applicability. [ABSTRACT FROM AUTHOR]

Due to their benefits like low cost, simple processing, mass production, and effective conversion of solar energy into electrical energy, dye-sensitized solar cell (DSSC) devices have garnered a lot of attention in the scientific community over the past few years. It is well known that the architecture and composition of the photosensitizers play a key role in improving the functioning of the DSSC. Among the many types of fundamental units, benzimidazole and quinoxaline architectures have been particularly effective in the fabrication of DSSCs due to their extreme flexibility. The main aim of this review discussion is to focus on the application of benzimidazole and quinoxaline dyes in DSSC. Incorporating benzimidazole and quinoxaline units into dyes with a D−π−A arrangement showed enhance light-harvesting, optoelectronic, electrochemical, and photovoltaic capabilities while preventing electron recombination processes. Moreover, the maximum efficiency of benzimidazole when incorporated as ancillary donor, main donor, acceptor, n-spacer and ligand have been demonstrated. Therefore, the performance of quinoxaline dyes based on internal acceptor with one donor at (5, 8), double donor at (5, 8), double donor at (2, 3) positions as well as fused quinoxaline-Indolo based donor unit have been received a particular attention in this work. This comparative and comprehensive overview provides up-to-date knowledge and may serve as a lighthouse for young aspiring researchers interested in exploring molecular engineering potential for creating and synthesizing more efficient exotic materials for solar cells. [ABSTRACT FROM AUTHOR]

A cascade one‐pot strategy to construct 31 examples of furo‐fused quinoxalines in up to 88% yields has been devised from readily accessible β‐ketothioamides and quinoxalin‐2‐ones in open flask at room temperature under TBHP mediated conditions. Mechanistic studies revealed that the overall reactivity relies on the seamless integration of intermolecular radical coupling and intramolecular cyclization via desulfhydration of C=S bond cleavage. Generation of H2S as the only by‐product makes this process highly attractive. Furthermore, the photophysical behavior of the furo‐fused quinoxalines has also been studied. [ABSTRACT FROM AUTHOR]

It is shown that the reaction of conjugated ynones containing a phosphoryl group with o‐phenylenediamines can, depending on the conditions, lead to the selective formation of phosphorylated 1,5‐benzodiazepines and quinoxalines. Phosphorylated quinoxalines can be used for synthesis of substituted vinyl quinoxalines. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed annulation of o‐phenylenediamines and internal alkynes for the synthesis of quinoxalines is developed. This method provides a variety of quinoxalines in good to high yields under a simple and mild reaction conditions with molecular O2 as a terminal oxidant. Preliminary mechanistic studies show that a novel reaction mechanism is involved in the current reaction, which is different from the previous reported dicarbonyl compound mechanism via the oxidation of the alkyne. [ABSTRACT FROM AUTHOR]

A simple method for the preparation of 2-aryl-3-(2-aminoaryl)quinoxalines from 2-alkynylnitrobenzenes and 1,2-diaminoarenes was described. The reactions could proceed under mild conditions. The 1-nitro-2-(phenylethynyl)benzenes, simple starting materials, could generate the key intermediate 3H-indole-3-ones in situ in the presence of PPh3. After a cyclization with 1,2-diaminobenzenes, the 3H-indole-3-ones were then transformed into biologically valuable quinoxalines. [ABSTRACT FROM AUTHOR]

Nitrogen heterocyclic organics are promising hydrogen storage carriers with the advantage of being capable of large-scale transportation over long distances using existing oil and gas facilities. However, traditional methods for the hydrogenation and dehydrogenation of organic hydrogen carriers usually require high temperature and pressure conditions and external hydrogen supplies, which hinder their large-scale applications, as well as having certain safety risks. In this paper, a reversible electrochemical hydrogen storage system using quinoxaline as a hydrogen carrier was developed with potential for use at room temperature and atmospheric pressure. Experiments revealed that the hydrogenation conversion of quinoxaline reached 95% within 120 min at −0.20 V vs. RHE, and the dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline reached 100% within 30 min at 1.30 V vs. RHE. This means that the system achieved quick and efficient reversible hydrogen storage. The Pd/NF dual-function electrode prepared by spontaneous redox reaction still showed high catalytic activity after 8 cycles, indicating its good long-term stability. The proton donor in the electrochemical hydrogenation process of quinoxaline was water, which completely eliminates the safety risk from the use of external hydrogen. This work provides a simple and reliable strategy for efficient hydrogen storage using nitrogen heterocyclic organics. [Display omitted] • The hydrogenation conversion of quinoxaline reached 95%. • The optimum dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline was 100%. • Pd/NF electrode was operated as a dual-function electrocatalyst. • Efficient reversible hydrogen storage was achieved at 25 °C and atmospheric pressure. • The H∗ required for the electrochemical hydrogenation of quinoxaline came from H 2 O. [ABSTRACT FROM AUTHOR]

Hydrogen as a new energy source, it can be made by photocatalytic technology. However, the photocatalyst is the key to the efficient decomposition of water to produce hydrogen. Functional complexes are porous materials with high crystallinity, which have the characteristics of both organic and inorganic materials. For this reason, two complexes [Mn3(Medpq)2(CIN)6]·H2O (1) and [Cd3(Medpq)2(CIN)2(Ac)4] (2) (HCIN = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]quinoxaline) were synthesized by a hydrothermal process. Combined with the unique electronic structure and group of the complex and the unique semiconductor energy band structure and excellent chemical stability of g-C3N4, the complex/g-C3N4 composite materials were constructed to solve the defect of low utilization rate of light energy and improve quantum efficiency in the internal structure. The experiment proved that complex 1/g-C3N4 photocatalytic rates of hydrogen production 715.8 μmol h−1 g−1, and complex 2 photocatalytic rates of hydrogen production 1622.9 μmol h−1 g−1, about double and fourfold that of pure g-C3N4 (407.6 μmol h−1 g−1) consequently, high-performance of the hydrogen production from water decomposition was realized. The two functional complexes [Mn3(Medpq)2(CIN)6]·H2O (1) and [Cd3(Medpq)2(CIN)2(Ac)4] (2) have the characteristics of both organic and inorganic materials and significantly enhance visible-light photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2‐chloroquinoxaline‐3‐carbonitrile 1. The compound 1 was subjected to a reaction with selenium metal in the presence of NaBH4 as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3‐cyanoquinoxaline‐2‐selenolate, which was subsequently reacted with α‐halogenated carbonyl compounds in situ. This reaction produced a series of newly synthesized 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐substituents. Ethyl 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9. This salt was then refluxed with acetic anhydride to produce oxazinone compound 10. The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3‐b]quinoxaline derivative 11. Compound 11 was then chlorinated using phosphorous oxychloride to give the corresponding chlorocompound. [ABSTRACT FROM AUTHOR]

Quinoxalines are an important group of N-heterocyclic compounds, which are present in a variety of natural and synthetic compounds possessing physicochemical properties and pharmacological activities. Since the earliest studies, their unique properties have led the chemical community, to embrace the challenge of synthesizing new Quinoxalines. This bioactive moiety can act as a versatile building block intermediate in synthesizing novel heterocyclic scaffolds and is considered as prime focus in medicinal chemistry research. This review aims to highlight the recent synthetic strategies and various routes employed to design and synthesize quinoxalines. Initially, we have discussed the classical methods of synthesis followed by modern methods and green methods, with an overview pertaining to their structure-activity-relationship (SAR). We entrust that, this mini review will offer a broad perspective and insights among the readers in the development of new quinoxalines scaffolds with rich bio-potent applications. [ABSTRACT FROM AUTHOR]

This document provides information on the synthesis and characterization of pyrido[2,3-b]quinoxaline-3-carboxylate derivatives through a one-pot Buchwald amination-cyclization method. The derivatives have potential pharmacological activities, including antibacterial, antiviral, anticancer, and antifungal properties. The study successfully achieved good yields using specific reaction conditions and explored the synthesis of these derivatives with different amines. The document includes detailed procedures, characterization data, physical properties, and spectroscopic data for specific derivatives. The research was supported by various institutions and funding sources. [Extracted from the article]

An asymmetric aza-BODIPY analogue bearing quinoxaline moiety was synthesized via a titanium tetrachloride-mediated Schiff-base-forming reaction of 6,7-dimethyl-1,4-dihydroquinoxaline-2,3-dione and benzo[d]thiazol-2-amine. This novel aza-BODIPY analogue forms a complementary hydrogen-bonded dimer due to the quinoxaline moiety in the crystal structure. It also shows intense absorption and fluorescence, with fluorescence quantum yields close to unity. The electrochemical measurements and the DFT calculations revealed the presence of the low-lying HOMO, which benefits their potential applications as an electron-transporting material. [ABSTRACT FROM AUTHOR]

The design and synthesis of strained aromatics provide an additional insight into the relationship between structure and properties. In the last years, several approaches to twist pyrene‐fused azaacenes have been developed that allow to introduce twists of different sizes. Herein, we describe the synthesis of a new set of twisted dibenzotetraazahexacenes constituted by fused pyrene and quinoxaline residues that have been distorted by introducing increasingly larger substituents on the quinoxaline residues. Their twisted structure has been demonstrated by single‐crystal X‐ray diffraction. Furthermore, absorption, fluorescence, electrochemical and theoretical studies shine light on the effects of the substituents and twists on the optoelectronic and redox properties. [ABSTRACT FROM AUTHOR]

Large‐scale production of full‐color carbon dots (CDs) at room temperature under atmospheric pressure will promote their industrial application. Herein, o‐phenylenediamine is used as a single‐precursor carbon source and hydrogen peroxide as an oxidant. Kilogram‐scale CDs are obtained by stirring these reactants at room temperature in air for 30 min. After purification and acid treatment, blue‐, green‐, and red‐fluorescence CDs with photoluminescence peaks at 481, 539, and 625 nm are obtained with quantum yields of 21.76%, 27.12%, and 13.06%, respectively. Based on chemical structural characterizations, a reasonable formation mechanism is deduced, with blue, green, and red fluorescence arising from carbon nuclei stacked in conjugate planes containing fragments of quinoxaline, 2,3‐diaminophenazine (2,3‐DAPN), and protonated 2,3‐DAPN, respectively. High‐quality multi‐color and white light‐emitting diodes are successfully fabricated to demonstrate potential commercial applications in display and illumination. [ABSTRACT FROM AUTHOR]