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AbstractFive new copper(II) complexes of substituted quinoxaline ligands have been prepared and characterized via single crystal X-ray diffraction, including [Cu(5-Mequinox)2(NO3)2] (2), [Cu(5-Mequinox)(NO3)(H2O)(μ-1,3-NO3)]n (3), the chloride salt (5-MequinoxH)2[Cu3Cl8] (4), the complex [Cu(6-Mequinox)2(NO3)2] (5) and [(2-carboxylato-3-methylquinox)(2-hydroxymethyl-3-methylquinox)nitratocopper(II)]. CH3CN (6) [quinox = quinoxaline; 5-Mequinox = 5-methylquinoxaline; 6-Mequinox = 6-methylquinoxaline]. None of the complexes produced diazine bridged chain structures (as seen in [(quinox)Cu(NO3)2]n (1)), although 3 forms chains via a bridging nitrate ion. Crystal packing is controlled primarily through hydrogen bonding and π-stacking of nitrate ions. The temperature dependent magnetic susceptibility data of the parent compound [(quinox)Cu(NO3)2]n are also reported and discussed. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study is to investigate the metal catalyst-free synthesis and antimicrobial activity of quinoxaline-based oxazole derivatives (IVa–IVp), confirming their structure through spectral analyses. These compounds are evaluated for their in vitro antimicrobial efficacy against both Gram-negative and Gram-positive bacteria, suggesting their potential as therapeutic agents for treating microbial diseases, particularly bacterial infections. Methods: As a part of our efforts on determination of effect of antibacterial agents, in this study, we focused on the metal catalyst-free synthesis and antimicrobial activity of quinoxaline-based oxazole derivatives (IVa–IVp). Results and Discussion: The synthesized quinoxaline-based oxazole derivatives (IVa–IVp) exhibited significant antimicrobial activity against both Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae) and Gram-positive (Staphylococcus aureus) bacteria. This suggests the potential of these compounds as therapeutic agents for microbial diseases, particularly in the treatment of bacterial infections. The presence of pharmacologically active groups in these derivatives further enhances their therapeutic relevance. These findings underscore the importance of exploring novel synthetic approaches and chemical structures in the development of antimicrobial agents with improved efficacy and potential clinical applications. Conclusions: The metal catalyst-free synthesis produced effective quinoxaline-based oxazole derivatives (IVa–IVp) with confirmed structures and significant antimicrobial activity against Gram-negative and Gram-positive bacteria, indicating their potential as therapeutic agents for bacterial infections, warranting further investigation for clinical application. [ABSTRACT FROM AUTHOR]

Abstract Impaired wound healing in diabetic individuals creates huge social and financial burdens for both diabetic patients and the health system. Unfortunately, the current treatment has not resulted in consistently lower amputation rates. Quinoxalines are heterocyclic compounds with multiple important pharmacological properties. Their effect on wound healing have not been closely studied. In the current work, the wound healing effect of 3-hydrazinylquinoxaline-2-thiol hydrogel is tested topically in a full-thickness excision wound in streptozotocin-induced type 1 diabetic rats. We examined the wound closure rate, expression of inflammatory factors, growth factors in addition to the histological analysis. The results revealed a significant acceleration in wound closure in the treated group compared with the control experimental animals. Histological data demonstrated enhanced re-epithelialization and collagen disposition. The healing effect was additionally evaluated by the inhibition of the inflammatory response of interleukin (IL)—1β interleukin (IL)—6, tumor necrosis factor (TNF-α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) with a marked improvement of the transforming growth factor beta (TGFβ-1), antioxidant markers and collagen-1. In silico study indicated a favorable drug-like properties and toxicity profile. The present work showed that 3-hydrazinylquinoxaline-2-thiol holds great potential for the treatment of diabetic wounds.

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.

The quinoxaline moiety in the title molecule, C13H13ClN2O3, is almost planar (r.m.s. deviation of the fitted atoms = 0.033 Å). In the crystal, C—H...O hydrogen bonds plus slipped π-stacking and C—H...π(ring) interactions generate chains of molecules extending along the b-axis direction. The chains are connected by additional C—H...O hydrogen bonds. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (37.6%), H...O/O...H (22.7%) and H...Cl/Cl...H (13.1%) interactions.

Plant pathogenic fungi pose a major threat to global food security, ecosystem services, and human livelihoods. Effective and broad-spectrum fungicides are needed to combat these pathogens. In this study, a novel antifungal 2-oxyacetate hydrazide quinoxaline scaffold as a simple analogue was designed and synthesized. Their antifungal activities were evaluated against Botrytis cinerea (B. cinerea), Altemaria solani (A. solani), Gibberella zeae (G. zeae), Rhizoctonia solani (R. solani), Colletotrichum orbiculare (C. orbiculare), and Alternaria alternata (A. alternata). These results demonstrated that most compounds exhibited remarkable inhibitory activities and possessed better efficacy than ridylbacterin, such as compound 15 (EC50 = 0.87 μg/mL against G. zeae, EC50 = 1.01 μg/mL against C. orbiculare) and compound 1 (EC50 = 1.54 μg/mL against A. alternata, EC50 = 0.20 μg/mL against R. solani). The 3D-QSAR analysis of quinoxaline-2-oxyacetate hydrazide derivatives has provided new insights into the design and optimization of novel antifungal drug molecules based on quinoxaline. [ABSTRACT FROM AUTHOR]

A novel quinoxaline-based phthalonitrile monomer, namely, 4,4′-(((quinoxaline-2,3-diylbis (oxy))bis (3,1-phenylene))bis (oxy))di-phthalonitrile (QDOP), was successfully synthesized by nucleophilic substitution reaction, which exhibits a low melting point (85°C) and a wide processing window (150°C). The QDOP monomer was cured with 4-aminophenoxy phthalonitrile (APPH) as catalyst by different temperature programs, and the curing process and kinetics were discussed in detail by non-isothermal differential scanning calorimetric (DSC). The QDOP polymer mainly forms triazine, isoindoline and phthalocyanine structure, as revealed by Fourier transform infrared (FTIR) spectroscopy, and its properties improved with the increase of post-curing temperature and curing time. After post-curing at 380°C, the polymer exhibited high storage modulus (3731 MPa), high glass-transition temperature (>400°C), and outstanding thermal stability and thermal oxidation stability. [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]

Adjusting the energy levels and fibrillar morphology is paramount to enhancing the power conversion efficiency (PCE) of organic solar cells (OSCs). In the present study, an increase in the open‐circuit voltage (VOC) is facilitated through the elongation of the alkyl chain within AQx (namely AQx‐8), aiming to decrease the free volume ratio (FVR). This reduction in FVR attenuates electron‐phonon coupling, thereby augmenting emission efficiency and diminishing the non‐radiative energy loss (ΔEnr). To further refine the energy levels and morphological characteristics, the external undecyl chain of AQx‐8 is substituted with a shorter carbon chain and cyclohexane noted for its considerable steric hindrance (AQx‐H). This alteration significantly mitigates intermolecular aggregation, expands the bandgap, and elevates the lowest unoccupied molecular orbital (LUMO) energy level, culminating in an elevated VOC of 0.923 V in devices based on AQx‐H. Morphological analysis reveals that blends based on AQx‐H exhibit an enhanced multi‐length‐scale fibrillar structure, which is conducive to exciton dissociation and charge transport, thereby contributing to a high fill factor (FF) nearing 80%. Consequently, this study reports one of the highest binary PCEs documented, standing at 19.5% (with certification at 19.0%). [ABSTRACT FROM AUTHOR]

The cytotoxic activity, EGFR/VEGFR2 target inhibition, apoptotic activity, RT-PCR gene expression, in vivo employing a solid-Ehrlich carcinoma model, and in silico investigations for highlighting the binding affinity of eight quinoxaline derivatives were tested for anticancer activities. The results showed that compound 8 (N-allyl quinoxaline) had potent cytotoxicity against A594 and MCF-7 cancer cells with IC50 values of 0.86 and 1.06 µM, respectively, with noncytotoxic activity against WISH and MCF-10A cells having IC50 values more than 100 µM. Furthermore, it strongly induced apoptotic cell death in A549 and MCF-7 cells by 43.13% and 34.07%, respectively, stopping the cell cycle at S and G1-phases. For the molecular target, the results showed that compound 8 had a promising EGFR inhibition activity with an IC50 value of 0.088µM compared to Sorafenib (IC50 = 0.056 µM), and it had a promising VEGFR2 inhibition activity with an IC50 value of 0.108µM compared to Sorafenib (IC50 = 0.049 µM). Treatment with compound 8 ameliorated biochemical and histochemical parameters near normal in the in vivo investigation, with a tumor inhibition ratio of 68.19% compared to 64.8% for 5-FU treatment. Finally, the molecular docking study demonstrated the binding affinity through binding energy and interactive binding mode inside the EGFR/VEGFR2 proteins. Potent EGFR and VEGFR2 inhibition of compound 8 suggests its potential for development as a selective anticancer drug. [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.

In this investigation, a quantitative structure-property relationship (QSPR) model coupled with a quantum neural network (QNN) was used to explore the corrosion inhibition efficiency (CIE) of quinoxaline compounds. Integrating quantum chemical properties (QCP) features reduced computational burden by strategically reducing the features from 11 to 4 while maintaining prediction accuracy. QNN models outperform traditional methods like artificial neural networks (ANN) and multilayer perceptron neural networks (MLPNN), with a coefficient of determination (R2) value of 0.987, coupled with diminished root mean square error (RMSE), mean absolute error (MAE), and mean absolute deviation (MAD) values of 0.97, 0.92, and 1.10, respectively. Predictions for six newly synthesized quinoxaline derivatives: quinoxaline-6-carboxylic acid (Q1), methyl quinoxaline-6-carboxylate (Q2), (2E,3E)-2,3-dihydrazono-1,2,3,4-tetrahydroquinoxaline (Q3), (2E,3E) 2,3-dihydrazono-6-methyl-1,2,3,4-tetrahydroquinoxaline (Q4), (E)-3-(4-methoxyethyl)-7-methylquinoxalin-2(1 H)-one (Q5), and 2-(4-methoxyphenyl)-7-methylthieno[3,2-b] quinoxaline (Q6), show remarkable CIE values of 95.12, 96.72, 91.02, 92.43, 89.58, and 93.63 %, respectively. This breakthrough technique simplifies testing and production procedures for new anti-corrosion materials.

The quinoxaline moiety in the title molecule, C13H13ClN2O3, is almost planar (r.m.s. deviation of the fitted atoms = 0.033 Å). In the crystal, C--H⋯O hydrogen bonds plus slipped π-stacking and C--H⋯π(ring) interactions generate chains of molecules extending along the b-axis direction. The chains are connected by additional C--H⋯O hydrogen bonds. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (37.6%), H⋯O/O⋯H (22.7%) and H⋯Cl/Cl⋯H (13.1%) interactions. [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]

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]

Unfused‐ring acceptors with different electron‐deficient central units, dithieno[3,2‐f:2′,3′‐h]quinoxaline (KS40) and dithieno[3,2‐e:2′,3′‐g]‐2,1,3‐benzoxadiazole (KS41) are synthesized and characterized. When blended with PM6, KS40 with a weaker electron‐accepting quinoxaline exhibits a much higher open‐circuit voltage (VOC) of 0.945 V. As a result, the KS40‐based device achieves a power conversion efficiency (PCE) of 12.2%. PM6:KS41‐based devices, in contrast, afford improved charge mobilities as well as suppressed recombination behavior, which eventually leads to an improvement in the fill factor (72.4%). Consequently, the device is able to achieve a PCE of 11.6%. [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]

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]

In recent years, heterogeneous catalysts have led to environment‐friendly transformations with better yields and reusability. Pd, one of the initial metals employed in heterogeneous organic synthesis, suffered from limitations like its high cost. This justifies the need for development of catalysts with abundant, low‐cost metals, which has been receiving a lot of attention in the scientific community. In this work, a bimetallic oxide catalyst, CeO2–ZrO2, is synthesized by a sol–gel route. The structure and morphology of the catalyst are investigated using X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray analysis, thermogravimetric analysis, Brunauer–Emmett–Teller measurements, and temperature‐programmed desorption. It is utilized for obtaining quinoxaline derivatives at room temperature. 2,3‐Diphenylquinoxaline is obtained via a simple condensation reaction between 1,2‐diaminobenzene and 1,2‐diketones, catalyzed by CeO2(50)–ZrO2(50) with 87% yield in 15 min. Quinoxalines are known for their biological and therapeutic activities; hence, they are essential molecules. The biological activity of the synthesized quinoxaline derivatives has been evaluated against bacterial and fungal strains. © 2023 Society of Chemical Industry. [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]

The newly synthesized quinoxaline-1,2,4-triazole-3-amide conjugates through a multistep method. The prepared compounds were screened for their anticancer activity against secreted human cancer cell lines such as DU-145 (prostate), MCF-7 (breast), and A549 (lung) by applying the MTT method, and the standard drug etoposide was used as a reference drug. The activity results show that two compounds, namely 3,5-dimethoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide and 4-methoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide exhibited more potent activity than the standard drug. Whereas, two compounds, 3-methoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide, and 3,4-dimethoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide showed very similar activity against tested cell lines to that of the standard drug IC50 value. The in vitro tyrosine kinase EGFR inhibitory activity results indicate that two compounds, 3,5-dimethoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide and 4-methoxy-N-(5-{[2-oxoquinoxalin-1(2H)-yl]methyl}-4H-1,2,4-triazol-3-yl)benzamide exhibited more activity than the standard drug etoposide. [ABSTRACT FROM AUTHOR]

A series of benzamide derivatives containing quinoxaline and benzoxazole fragments were synthesized and characterized by 1H NMR and mass spectra. The antibacterial activity of the synthesized derivatives was tested in vitro against gram-positive and gram-negative bacterial strains using an agar well diffusion assay. The molecular docking study showed good docking scores between –9.85 and –7.8 kcal/mol against DNA gyrase (PDB ID: 4KTN). [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]

Quinoxaline is a fused heterocycle system of a benzene ring and pyrazine ring. It has earned considerable attention due to its importance in the field of medicinal chemistry. The system is of extensive importance due to its comprehensive array of biological activities. Quinoxaline derivatives have been used as anticancer, anticonvulsant, anti-inflammatory, antidiabetic, antioxidant, antibacterial, anti-TB, antimalarial, antiviral, anti-HIV, and many other uses. Variously substituted quinoxalines are significant therapeutic agents in the pharmaceutical industry. This review spotlights on the chemistry, physiochemical characters, synthesis, pharmaceutical products, and medicinal chemistry of various anticancer quinoxaline derivatives that were developed in the last period. It covers the period from 2016 to 2023.

The asymmetric unit of the title compound, C12H13N3O4, consists of two molecules differing to a small degree in their conformations. In the crystal, layers of molecules are connected by weak C—H...O hydrogen bonds and slipped π-stacking interactions. These layers lie parallel to (10\overline{1}) and are stacked along the normal to that plane. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing arise from H...H (43.5%) and H...O/O...H (30.8%) contacts. The density functional theory (DFT) optimized structure of the title compound at the B3LYP/ 6–311 G(d,p) level agrees well with the experimentally determined molecular structure in the solid state.

Treatment of 1‐azido‐2‐(2,2‐dihalovinyl)arenes with a catalytic amount of Rh2(esp)2 afforded various 2,3‐dihaloindoles in 51–74% yields. This reaction progressed via the intramolecular cyclization of rhodium nitrene generated in situ and the rearrangement of one halogen group. For the 2‐chloro‐2‐iodovinyl group, the iodo group selectively rearranged to yield 2‐chloro‐3‐iodoindoles as single isomers. Moreover, 1‐azido‐2‐[(2,2‐dihalomovinyl)(Boc)amino]arenes were reacted with a catalytic amount of Rh2(oct)4, which produced 2‐haloquinoxaline in 55–92% yields. [ABSTRACT FROM AUTHOR]

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]

Upon reaction with N-substituted pyrroloquinoxalinetriones, isatin hydrazone is oxidized to diazooxindole and enters into a formal [4+1] cycloaddition reaction with N-substituted pyrroloquinoxalinetriones to form compounds containing a spiro[dihydrofuran-2,3′-oxindole] fragment, which is interesting for medicinal chemistry. The reaction of diazooxindoles with N-unsubstituted pyrroloquinoxalinetriones afforded analogous substituted spiro[dihydrofuran-2,3′-oxindoles]. The resulting compounds show moderate antimicrobial activity. [ABSTRACT FROM AUTHOR]

This article, published in the Russian Journal of Bioorganic Chemistry, presents the results of a study on the design, synthesis, and evaluation of quinoxaline derivatives for their antibacterial activity. The researchers synthesized a series of compounds and tested their efficacy against various bacteria, including drug-resistant strains. One compound, IVk, showed excellent antibacterial activity and a lower tendency for developing bacterial resistance compared to positive controls. The compound also demonstrated strong bactericidal activity and minimal cytotoxicity. These findings suggest that IVk may have potential as a drug and warrant further study. The study was supported by the Science and Technology Research Project of Chongqing Education Commission. [Extracted from the article]

Quinoxaline is a fused heterocycle system of a benzene ring and pyrazine ring. It has earned considerable attention due to its importance in the field of medicinal chemistry. The system is of extensive importance due to its comprehensive array of biological activities. Quinoxaline derivatives have been used as anticancer, anticonvulsant, anti-inflammatory, antidiabetic, antioxidant, antibacterial, anti-TB, antimalarial, antiviral, anti-HIV, and many other uses. Variously substituted quinoxalines are significant therapeutic agents in the pharmaceutical industry. This review spotlights on the chemistry, physiochemical characters, synthesis, pharmaceutical products, and medicinal chemistry of various anticancer quinoxaline derivatives that were developed in the last period. It covers the period from 2016 to 2023. [ABSTRACT FROM AUTHOR]

Potassium 6-oxo-7,13,16,22-tetraazatetracyclo[12.6.2.18,12.017,21]tricosa-1(20),8(23),9,11,14,16,18,21-octaen-2-yne-15-carboxylate was synthesized through a multi-step pathway, starting from commercially available 3-iodo-1,2-phenylenediamine. Structure characterization of this new substituted macrocyclic quinoxaline compound was achieved using 1H NMR, 13C NMR, and HRMS spectral analysis. This new macrocyclic derivative demonstrated submicromolar potency on both Pim-1 and Pim-2 isoforms, with an interesting selectivity profile against a selected panel of human kinases. [ABSTRACT FROM AUTHOR]

Conjugated microporous polymers (CMPs) have been widely used in various fields as a new class of porous materials. In this study, a quinoxaline-based CMP (BQP-CMP) was prepared and used as the coating in SPME for the extraction and enrichment of nine phthalate esters (PAEs) in juice, soya sauce, cooking wine, and blended edible oil samples. Several parameters affecting solid-phase microextraction (SPME) were optimized. The feasibility of the developed method was verified using real samples, which showed low LODs (0.014–0.032 µg L−1), wide linearities (0.05–50 µg L−1), good repeatability (2.8–6.6%), and a long service life. The real liquid samples were successfully analyzed using this proposed method and spiked recoveries of 70.16–96.36% were obtained. Moreover, the interaction model and binding energies between BQP-CMP and the PAEs were explored using molecular docking. Satisfactory extraction efficiency was achieved owing to the high specific surface area (601.62 m2 g−1), high hydrophobicity, and the conjugated planar structural unit distribution of BQP-CMP. This study demonstrates that BQP-CMP is excellent as a rapid and sensitive analysis material for PAEs at trace levels in various types of samples and that CMP materials are also excellent candidates for SPME coatings. [ABSTRACT FROM AUTHOR]

Material design of guest acceptor is always a big challenge for improving the efficiency of ternary organic solar cells (OSCs). Here, a pair of isomeric nonfullerene acceptors based on quinoxaline core, Qx–p‐C7H8O and Qx–m‐C7H8O, is designed and synthesized. By moving the alkoxy chain attached on side phenyl from meta‐position to para‐position, both π–π stacking distance and crystallinity are enhanced simultaneously. They obtain the uplifted lowest unoccupied molecular orbital level. Compared to Qx–m‐C7H8O, Qx–p‐C7H8O exhibits wider absorption spectrum and higher extinction coefficient. Using D18‐Cl:N3 as host materials, the addition of guest acceptor Qx–p‐C7H8O significantly improves the power conversion efficiency (PCE) from 17.61% to 18.49% because of higher open‐circuit voltage (0.875 V) and short‐circuit current density (27.85 mA cm−2). This can be attributed to the faster exciton dissociation, more balanced carrier mobility, fine fiber morphology, and lower energy loss in the ternary devices. However, Qx–m‐C7H8O‐based ternary device achieves relatively low PCE of 17.17% because this device shows extremely low electron mobility. The results indicate that molecular stacking, film morphology, etc., can be effectively modulated by fine‐tuning the side chains of guest materials, which may be an effective design rule for further improving the PCE of OSCs. [ABSTRACT FROM AUTHOR]

A library of functionalized pyrrolidine‐based triazolium salts containing a BF4 counterions have been prepared from readily accessible 2‐pyrolidinone via one‐pot reaction protocol. By separating imine‐ether intermediates, a detailed mechanistic pathway has been investigated. Studied mechanistic investigation improved the synthetic process, resulting in higher yields for pyrrolidine‐based triazolium NHC structures and the large‐scale synthesis of chiral NHCs pre‐catalyst with free OH‐group. The presence of a hydroxyl functional group on the NHCs has the potential for further functionalization and for non‐covalent control over catalytic reactions in which the NHCs can serve as organocatalysts or donor ligands for organometallic catalysis. This benzoin catalytic system was investigated by testing different solvents and aldehydes, NHC‐catalysts loading and time variation effects to prepare a broad range of functionalized benzoin compounds with high yields. The highly reactive pyrrolidine‐based triazolium salts (TACF5) showed significant potential application of organocatalysts in benzoin condensation‐oxidation. EDG and EWG substituted α‐hydroxy ketone derivatives were directly converted to corresponding benzil scaffolds from an aldehyde through one‐pot reaction condition with MnO2 acting as an oxidating reagent in open‐air atmosphere. Selective heterocycles, quinoxaline, imidazole and pyrazine precursor were achieved from simple benzil under green conditions. [ABSTRACT FROM AUTHOR]

A central nervous system (CNS)‐oriented compound collection was screened to find hit compounds for human glioblastoma T98G cell growth inhibition. A series of quinoxaline‐based derivatives were identified as hit compounds having one‐ to two‐digit micromolar GI50 values. Anti‐glioblastoma activity was improved in structure–activity relationship studies varying the substituents on the quinoxaline ring system, resulting in the discovery of four compounds exhibiting sub‐micromolar GI50 values. The potentials of the four compounds to induce apoptosis were confirmed by annexin V staining assay. The development potential of the four compounds as CNS drug leads was evaluated by in vitro MDR‐MDCK cell permeability and in vivo brain disposition in mice. The mouse pharmacokinetic and kinome profiling studies for compound 10g, which showed high brain‐penetrating ability, revealed that the compound is orally bioavailable and inhibits the kinase activities of anaplastic lymphoma kinase (ALK) and Erb‐B2 receptor tyrosine kinase (ERBB3). [ABSTRACT FROM AUTHOR]

In this study, we present a highly efficient and environmentally benign protocol for synthesizing biologically important quinoxaline derivatives. The synthesis involves the reaction of 1,2-diamines with substituted phenacyl bromides or benzil, taking place at room temperature in N,N-dimethylformamide (DMF) solvent. The reaction is facilitated by a bifunctional heterogeneous catalyst composed of Al2O3–ZrO2 binary metal oxide. Our method offers numerous advantages, including excellent product yield, renewable catalytic conditions, minimal catalyst usage, safer chemistry, short reaction time, and a simple work-up procedure. To determine the chemical structure of the synthesized derivatives, we employed characterization techniques such as nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). Additionally, the Al2O3–ZrO2 catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX), and thermogravimetric analysis (TGA). [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, C12H13N3O4, consists of two molecules differing to a small degree in their conformations. In the crystal, layers of molecules are connected by weak C--H• • •O hydrogen bonds and slipped π-stacking interactions. These layers lie parallel to (101) and are stacked along the normal to that plane. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing arise from H• • •H (43.5%) and H• • •O/O• • •H (30.8%) contacts. The density functional theory (DFT) optimized structure of the title compound at the B3LYP/ 6-311 G(d,p) level agrees well with the experimentally determined molecular structure in the solid state. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [C14H18N2)2Ag2](NO3)2, contains subtle differences in ligand, metal, and counter-anion coordination. One quinoxaline ligand uses one of its quinoxaline N atoms to bond to one silver cation. That silver cation is bound to a second quinoxaline which, in turn, is bound to a second silver atom; thereby using both of its quinoxaline N atoms. A nitrate group bonds with one of its O atoms to the first silver and uses the same oxygen to bond to a silver atom (related by symmetry to the second), thereby forming an extended network. The second nitrate group on the other silver bonds via two nitrate O atoms; one silver cation therefore has a coordination number of three whereas the second has a coordination number of four. One of the quinoxaline ligands has a disordered ethyl group.

Plant pathogenic fungi pose a major threat to global food security, ecosystem services, and human livelihoods. Effective and broad-spectrum fungicides are needed to combat these pathogens. In this study, a novel antifungal 2-oxyacetate hydrazide quinoxaline scaffold as a simple analogue was designed and synthesized. Their antifungal activities were evaluated against Botrytis cinerea (B. cinerea), Altemaria solani (A. solani), Gibberella zeae (G. zeae), Rhizoctonia solani (R. solani), Colletotrichum orbiculare (C. orbiculare), and Alternaria alternata (A. alternata). These results demonstrated that most compounds exhibited remarkable inhibitory activities and possessed better efficacy than ridylbacterin, such as compound 15 (EC50 = 0.87 μg/mL against G. zeae, EC50 = 1.01 μg/mL against C. orbiculare) and compound 1 (EC50 = 1.54 μg/mL against A. alternata, EC50 = 0.20 μg/mL against R. solani). The 3D-QSAR analysis of quinoxaline-2-oxyacetate hydrazide derivatives has provided new insights into the design and optimization of novel antifungal drug molecules based on quinoxaline.

Abdelbagi Elfadil,1,2 Ahmad Mandeel Alzahrani,1 Hani Abdullah,1 Hamoud Alsamhan,3– 5 Turki S Abujamel,6,7 Hafsa Elawd Ahmed,8 Asif Jiman-Fatani1 1Department of Clinical Microbiology and Immunology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia; 2Center of Research Excellence for Drug Research and Pharmaceutical Industries, King Abdulaziz University, Jeddah, Saudi Arabia; 3Department of Pharmaceutical Care, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia; 4Department of Infectious Disease Research, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia; 5Department of Pharmacy Practice, College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 6Vaccines and Immunotherapy Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia; 7Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia; 8Department of Medicine, King Abdulaziz University Hospital, Jeddah, Saudi ArabiaCorrespondence: Ahmad Mandeel Alzahrani, Department of Clinical Microbiology and Immunology, Faculty of Medicine, King Abdulaziz University, P.O. Box 80205, Jeddah, 21589, Saudi Arabia, Tel +966 54 095 9911, Email amsalzahrani4@kau.edu.saBackground: While the frequency of methicillin-resistant Staphylococcus aureus (MRSA) continues to rise globally, there is a fear regarding an increase in vancomycin resistance among S. aureus strains. As far back as the 1960s, MRSA was one of the world’s most prevalent antibiotic-resistant bacteria. Among hospitalized patients and community members, MRSA is the cause of a significant number of infections. As a result of its resistance to classical beta-lactam and, in some cases, vancomycin antibiotics, efforts must be made as soon as feasible to find a new approach to fighting MRSA.Purpose: This study is designed to evaluate the antibacterial activity of quinoxaline derivative compound against MRSA in comparison with vancomycin as a reference drug.Methods: Sixty MRSA isolates were subjected to susceptibility testing by broth microdilution method for quinoxaline derivative compound and vancomycin. Each drug’s minimal inhibitory concentration (MIC) was determined and compared.Results: Among the sixty MRSA isolates, most of the quinoxaline derivative compound MIC findings (56.7%) were 4 μg/mL compared to vancomycin MIC values (63.3%) of 4 μg/mL. In comparison, 20% of quinoxaline derivative compound MIC readings were 2 μg/mL, while the vancomycin MIC results were 6.7%. However, the overall proportion of MIC readings at ≤ 2 μg/mL for both antibacterial agents was equal (23.3%). None of the isolates were resistant to vancomycin.Conclusion: This experiment revealed that most MRSA isolates were associated with low MICs (1– 4 μg/mL) for quinoxaline derivative compound. Overall, the susceptibility of the quinoxaline derivative compound signifies a promising efficacy against MRSA and may set a novel treatment approach.Keywords: antibiotic resistance, drug discovery, methicillin-resistant Staphylococcus aureus, minimum inhibitory concentration, quinoxaline, vancomycin

The functionalization of methylated azines and diazines has aroused the interest of chemists given the structural diversity that it affords. Hindered lithium dialkylamides have been used to deprotometallate these substrates chemoselectively. In contrast, it can be observed that, despite some promising work, lithium diethylamide has been used very little for this purpose. Our objective here is on the one hand to make an inventory of what reagents have been used to deprotometallate methylpyridines, ‐quinolines and ‐quinoxalines, and on the other hand to describe the results obtained by seeking to functionalize a series of substrates with lithium diethylamide (picolines, 2,4‐lutidine, methylquinolines and 2‐methylquinoxaline). Our efforts to take advantage of the use of an in‐situ trap (a zinc chloride chelate) in these reactions are also described. [ABSTRACT FROM AUTHOR]

Recent years have witnessed marked progress in the efficient synthesis of various enantioenriched 1,2,3,4‐tetrahydroquinoxalines. However, enantio‐ and diastereoselective access to trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines remains much less explored. Herein we report that a frustrated Lewis pair‐based catalyst generated via in situ hydroboration of 2‐vinylnaphthalene with HB(C6F5)2 allows for the one‐pot tandem cyclization/hydrosilylation of 1,2‐diaminobenzenes and 1,2‐diketones with commercially available PhSiH3 to exclusively afford trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines in high yields with excellent diastereoselectivities (>20 : 1 dr). Furthermore, this reaction can be rendered asymmetric by using an enantioenriched borane‐based catalyst derived from HB(C6F5)2 and a binaphthyl‐based chiral diene to give rise to enantioenriched trans‐2,3‐disubstituted 1,2,3,4‐tetrahydroquinoxalines in high yields with almost complete diastereo‐ and enantiocontrol (>20 : 1 dr, up to >99 % ee). A wide substrate scope, good tolerance of diverse functionality and up to 20‐gram scale production are demonstrated. The enantio‐ and diastereocontrol are achieved by the judicious choice of borane catalyst and hydrosilane. The catalytic pathway and the origin of the excellent stereoselectivity are elucidated by mechanistic experiments and DFT calculations. [ABSTRACT FROM AUTHOR]

This work demonstrates the preparation, characterization, and catalytic application of CuO@g‐C3N4 nanoparticles in synthesizing biologically and pharmaceutically important tetrasubstituted imidazole and quinoxaline derivatives. Highly substituted imidazoles of wide functionalities were synthesized in good yields (71%–85%) using EtOH as a solvent under refluxed conditions within 3–4 h. Similarly, a diverse range of quinoxaline derivatives were synthesized, which rendered moderate to good yield (65%–90%) of the products within 5–60 min in solvent‐free reaction conditions. The practical applicability of the developed protocol is shown by performing a gram‐scale reaction of quinoxaline. Furthermore, the reusability of the catalyst was studied up to the fifth consecutive cycle without much significant decrease in the activity of the catalyst. Additionally, the use of cheap metal and supported materials, shorter reaction time, high substrate scope, and easy recyclability of the catalyst are some of the salient features of the developed protocol. [ABSTRACT FROM AUTHOR]

As lung cancer was placed foremost part among other types of cancer in terms of mortality. Recent researches are widely focused on developing multi‐targeted and site‐specific targeted drug designs. In the present study, we designed and developed a series of quinoxaline pharmacophore derivatives as active EGFR inhibitors for the treatment of non‐small cell lung cancer. The compounds were synthesized through a condensation reaction between hexane‐3,4‐dione and methyl 3,4‐diaminobenzoate as a first step. Their structures were confirmed by 1H‐NMR, 13C‐NMR, and HRMS spectroscopic methods. Cytotoxicity (MTT) were applied to determine anticancer activity of the compounds against breast (MCF7), fibroblast (NIH3 T3), and lung (A549) cell lines as EGFR inhibitors. Doxorubicin was used as a reference agent, compound 4i exhibited a significant effect among other derivatives with IC50 = 3.902 ± 0.098 μM value against A549 cell line. The docking study showed that the best position on EGFR receptor could be observed with 4i. From the obtained evaluations of the designed series, compound 4i was a promising agent as EGFR inhibitor for further investigation and evaluation studies in the future. [ABSTRACT FROM AUTHOR]

We herein, described the synthesis of some new N-(thiazol-2-yl)benzamides of quinoxaline. All the synthesized compounds were evaluated for their in vitro anticancer activity against three human cancer cell lines including MCF-7 (breast cancer), A549 (lung cancer) and HepG2 (liver cancer). In this study, etoposide was used as a positive control. The results revealed that the compounds 6d, 6e, 6i, 6j and 6m exhibited promising activity against three cancer cell lines. Predominantly, compound 6i displayed greater activity than the standard drug etoposide on MCF-7, A549 and HepG2 with IC50 values of 0.95 ± 0.063, 1.32 ± 0.16 and 1.24 ± 0.10 µM respectively. The cell viability assay carried out toward a normal breast cell line (MCF-10A) for five potent compounds 6d, 6e, 6i, 6j, and 6m, did not exhibit significant cytotoxicity with IC50 values above 85 µM for all compounds. Molecular docking studies of potent compounds 6d, 6e, 6i, 6j and 6m with DNA topoisomerase II revealed that they have a good affinity toward the target protein. In addition to this, in silico pharmacokinetic profile was achieved for the potent compounds 6d, 6e, 6i, 6j and 6m using SWISS/ADME and pkCSM, whereas 6d, 6e and 6i compounds followed Lipinski, Ghose, Veber, Egan, and Muegge rules without any deviation. [ABSTRACT FROM AUTHOR]

Potassium 6-oxo-7,13,16,22-tetraazatetracyclo[12.6.2.18,12.017,21]tricosa-1(20),8(23),9,11,14,16,18,21-octaen-2-yne-15-carboxylate was synthesized through a multi-step pathway, starting from commercially available 3-iodo-1,2-phenylenediamine. Structure characterization of this new substituted macrocyclic quinoxaline compound was achieved using 1H NMR, 13C NMR, and HRMS spectral analysis. This new macrocyclic derivative demonstrated submicromolar potency on both Pim-1 and Pim-2 isoforms, with an interesting selectivity profile against a selected panel of human kinases.

Regioselective cyanation of quinoxalin‐2(1H)‐ones and quinoxalines with acetone cyanohydrin under aqueous aerobic visible‐light conditions at room temperature is described. Acetone cyanohydrin is utilized as a safe source for cyanation. In both cases, good functional group tolerance was observed with very good to quantitative yields of products under metal/base/ligand‐free conditions. Several control experiments revealed that, water and oxygen from air are crucial for the efficiency of the present transformation. These reactions proceed through a radical pathway as confirmed by radical scavengers. To validate the feasibility of the process for commercial syntheses, three products were synthesized at gram scale under the optimized conditions. The conversion of cyanated products into corresponding amides and acid was also performed and the pure products were obtained without column chromatographic separation. [ABSTRACT FROM AUTHOR]