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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]

[Display omitted] • Thieno[2,3- b ]quinoxaline derivatives were synthesized via thiolative cyclization. • Primary thioamides are great sulfur sources in these reactions. • Primary thioamides provide only a sulfur atom without unnecessary appendages. An efficient synthesis of thieno[2,3- b ]quinoxalines by thiolative cyclization of 2-chloro-3-(phenylethynyl)quinoxalines using primary thioamides as sulfur sources has been proposed. The reactions provided moderate to good yields under mild conditions. [ABSTRACT FROM AUTHOR]

This work reports on the synthesis of fluorescent dimethyl quinoxaline derivatives QXD1–QXD5. These D–π–A type organic blue-light emitters were fine-tuned by varying the electron donating strengths of donor (D) groups appended on quinoxaline acceptor (A) through a π-spacer. These compounds are emissive in both solid and solution states. This D–π–A arrangement resulted in intramolecular charge transfer (ICT), which led to positive solvatochromism. The analysis of single crystals of QXD1 and QXD3 revealed a twisted structure with herringbone packing arrangement. AIEE behavior could be seen in THF-H 2 O mixtures in these compounds. Adding trifluoroacetic acid (TFA) solution to these QXD s led to fluorochromic changes from blue to yellow fluorescence in solution, which was reversed upon adding triethylamine (TEA). A similar reversible fluorochromic change was observed upon the exposure of solid QXD s to TFA vapors, followed by TEA vapors. The distinguishable fluorocolorimetric responses of QXD3 and QXD4 towards TFA were employed for data protection through encryption and decryption. [Display omitted] • Synthesis of D–π–A type novel blue-emissive quinoxaline derivatives. • Single crystal X-ray diffraction analysis revealed twisted structure with herringbone packing arrangement. • AIEE observed in THF-H 2 O mixtures. • Reversible acidofluorochromic response toward TFA in solid and solution state. • Successful encryption and decryption of data observed. [ABSTRACT FROM AUTHOR]

G-quadruplexes (G4s) are commonly formed in the G-rich strand of telomeric DNA. Ligands targeting telomeric G4 induce DNA damage and telomere dysfunction, which makes them potential antitumor drugs. New telomeric G4 ligands with drug-likeness are still needed to be exploited, especially with their antitumor mechanisms thoroughly discussed. In this study, a novel series of quinoxaline analogs were rationally designed and synthesized. Among them, R1 was the most promising ligand for its cytotoxic effects on tumor cells and stabilizing ability with telomeric G4. Cellular assays illustrated that R1 stabilized G4 and induced R-loop accumulation in the telomeric regions, subsequently triggering DNA damage responses, cell cycle arrest in G2/M phase, apoptosis and antiproliferation. Moreover, R1 evoked immunogenic cell death (ICD) in tumor cells, which promoted the maturation of bone marrow derived dendritic cells (BMDCs). In breast cancer mouse model, R1 exhibited a significant decrease in tumor burden through the immunomodulatory effects, including the increase of CD4+ and CD8+ T cells in tumors and cytokine levels in sera. Our research provides a new idea that targeting telomeric G4 induces DNA damage responses, causing antitumor effects both in vitro and in vivo, partially due to the enhancement of immunomodulation. [Display omitted] • A new series of drug-like quinoxaline analogs binding telomeric G4 were developed. • The ligand could stabilize telomeric G4 and induce R-loop formation, leading to DNA damage responses and ICD effects. • This study provides a novel strategy to develop G4-targeted antitumor agents with the activation of immune responses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chromophores with Quinoxaline core in the bridge are used as guests in PMMA matrix. • Effect of electric field strength on chromophore alignment in composite is considered. • Material glass transition temperature is estimated with ESP charges as 470 K. • Acentric order parameter is used to characterize chromophores orientation. • Free volume distribution in the material with density 1.07 g/cm3 is 0.3 % The effect of applied electric field strength on the chromophore alignment in composite PMMA-based material is studied by atomistic modeling. Polymer material of real density (1.07 g/cm3), established in the course of modeling using NPT protocol, is considered along with model materials with reduced density (0.6 and 0.9 g/cm3), applied fields ranging from 100 to 1000 V/μm. Glass transition temperature, at which materials simulation was performed, was estimated in the course of multistage simulation. Simulation was performed with OPLS3e force field. Both centric, 〈P2〉, and acentric, 〈cos3Θ〉, chromophores order parameters were estimated. For the polymer material with high density, ρ = 1.07 g/cm3, the value of the order parameter 〈cos3Θ〉 grows from 0.25 to 0.30 for field strength varying from 300 to 1000 V/μm; the values of 〈P2〉 for chromophores are in agreement with the results of measurements by UV–vis spectroscopy. The obtained values of order parameters (both 〈P2(ch)〉 and 〈cos3Θ〉 for model materials with decreased density (0.6 and 0.9 g/cm3) are quite close to each other and seem to be overestimated compared to the values for the material with high density; this observation is in agreement with calculated values of free volume in the composite. The applied approach may provide guidelines for the elaboration of optimal poling protocols used at the development of composite polymer materials with quadratic nonlinear optical properties, containing quinoxaline chromophores-guests possessing high dipole moments (more than 20 D). [ABSTRACT FROM AUTHOR]

Variety of 2-aryl quinoxaline derivatives 1–23 were synthesized in good yields, by reacting 1,2-phenylenediamine with varyingly substituted phenacyl bromides in the presence of pyridine catalyst. All molecules 1–23 were characterized by spectroscopic techniques and evaluated for their diverse biological potential against α -amylase (α -AMY), α -glucosidase (α -GLU), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) enzymes. Synthetic derivatives possess enhanced inhibitory potential against all enzymes at nanomolar concentrations. In particular, compound 14 was found much superior with IC 50 = 294.35, 198.21, 17.04, and 21.46 nM against α -AMY, α -GLU, AChE, and BChE, respectively, as compared to standard inhibitors. Furthermore, selected potent compounds, including 3 , 4 , 8 , 14 , 15 , 17 , and 18 , were subjected to molecular docking studies to decipher the binding energies and interactions of ligands (synthetic molecules) with all four target enzymes. [Display omitted] • Synthetic 2-aryl quinoxaline derivatives as potential leads for anti-diabetic and anti-Alzheimer diseases. • Compounds evaluated against α -amylase, α -glucosidase, acetylcholinesterase, and butyrylcholinesterase enzymes. • Compounds exhibited potent inhibitory activities at nanomolar concentration. • Compounds with good inhibition constant, Ki value, were selected for molecular docking studies. [ABSTRACT FROM AUTHOR]

Alkyl chains can not only provide a shielding effect but also hinder the interaction between dye and [Cu(tmby) 2 ]2+. By strategically positioning alkyl chains to control the preferred conformation of dyes, targeted dyes with decreased charge recombination process can be designed. [Display omitted] • Dye-[Cu(tmby) 2 ]2+ interaction and its impact on charge recombination are studied. • The interaction of Dye-[Cu(tmby) 2 ]2+ can be regulated. • A new strategy for targeted design of dyes towards high performance is proposed. • A further optimization has been made on the basis of the champion dye ZS4. Two quinoxaline dyes utilized in copper-electrolyte-based dye-sensitized solar cells (Cu-DSSCs) are theoretically investigated to analyze the impact of alkyl chains on dye performance. The investigation shows that ZS4 , known for its record efficiency of up to 13.2 %, exhibits higher electron coupling and fewer binding sites for dye-[Cu(tmby) 2 ]2+ interaction compared to ZS5. Contrary to common belief, alkyl chains are found to not only provide shielding but also hinder the interaction between dye and [Cu(tmby) 2 ]2+ by influencing the optimal conformation of dyes, thereby impeding the charge recombination process. It is crucial to consider the influence of alkyl chains on dye conformation when discussing the relationship between dye structure and performance, rather than oversimplifying it as often done traditionally. Building on these findings, eight dyes are strategically designed by adjusting the position of the alkyl chain to further decrease charge recombination compared to ZS4. Theoretical evaluation of these dyes reveals that changing the alkyl chain on the nitrogen atom from 2-ethylhexyl (ZS4) to 1-hexylheptyl (D3-2) not only reduces the charge recombination rate but also enhances light harvesting ability. Therefore, D3-2 shows potential as a candidate for experimental synthesis of high-performance Cu-DSSCs with improved efficiency. [ABSTRACT FROM AUTHOR]

Various strategies are being explored to reduce the formation of undesirable compounds during the thermal processing of foods. This study investigates the impact of incorporating annatto seed powder (Bixa orellana L.) into beef patties to reduce the formation of heterocyclic amines (HAs) during charcoal-grilling and pan-frying. A three-level full factorial design was used to assess the effect of both annatto seed powder concentration and cooking times on HAs formation. The results showed that HA formation increased with longer cooking times and decreased with higher concentrations of annatto seed powder. A significant reduction in HA content was observed in both charcoal-grilled and pan-fried beef patties when annatto seed powder was added, with a particularly notable 91 % reduction at the 1 % addition level. These findings demonstrate that the addition of annatto seed powder is a highly effective strategy for reducing HA formation in beef patties. 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline (MeIQx) (PubChem CID: 62275); 2-amino-3,4,8-trimethylimidazo[4,5- f ]quinoxaline (4,8-DiMeIQx) (PubChem CID: 104739); 2-amino-3,7,8-trimethylimidazo[4,5- f ]quinoxaline (7,8-DiMeIQx) (PubChem CID: 104855); 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP) (PubChem CID: 1530); 3-amino-1,4-dimethyl-5 H -pyrido[4,3- b ]indole (Trp-P-1) (PubChem CID: 5284474); 3-amino-1-methyl-5 H -pyrido[4,3- b ]indole (Trp-P-2) (PubChem CID: 5284476); 2-amino-9 H -pyrido[2,3- b ]indole (AαC) (PubChem CID: 62805); 2-amino-3-methyl-9 H -pyrido[2,3- b ]indole (MeAαC) (PubChem CID: 62244); Bixin (PubChem CID: 5281226). [Display omitted] • Annatto seed powder reduces heterocyclic amines (HAs) in grilled beef patties. • HAs formation increases with longer cooking times, decreases with more annatto. • Annatto seed powder is a highly effective strategy to minimize HAs in cooked meat. • 91% reduction in HAs achieved with 1 % annatto seed powder addition. [ABSTRACT FROM AUTHOR]

• The SIRT1 inhibition of 1-thiocyanatopyrrolo[1,2- a ]quinoxalines was studied. • Synthesis involved sonochemical thiocyanation of pyrrolo[1,2- a ]quinoxalines. • Docking into SIRT1 showed good interactions and selectivity for top compounds. • The thiocyanato (NCS-) group played an important role in their interactions. • In silico , in vitro studies and ADME predictions suggested 3h, 3i and 3j as hits. A series of compounds based on the 1-thiocyanatopyrrolo[1,2- a ]quinoxaline framework were designed and assessed as potential inhibitors of SIRT1. A convenient access to this class of compounds was achieved via the sonochemical thiocyanation of pyrrolo[1,2- a ]quinoxalines. The methodology involved use of N -thiocyanatosaccharin as a key agent under mild reaction conditions. The reaction proceeded with high regioselectivity affording the desired compounds in good to acceptable yields. The in silico docking studies suggested good interactions of these compounds with SIRT1 when majority of them formed an H-bond with GLN 345 though the most promising 3h formed H-bond with ILE347. The thiocyanato (NCS-) group of these compounds seemed to have played a key role in their interactions that formed either an H-bond through its nitrogen atom and/or participated in a pi-sulfur interaction via its sulfur atom. Moreover, the analysis of in silico structure-interaction of all the 1-thiocyanatopyrrolo[1,2- a ]quinoxalines suggested that compound with –CN, -Cl (dichloro) and –OH substitutions had better binding interactions with SIRT1. Accordingly, 3h, 3i and 3j were identified as top molecules that also showed probable selectivity towards SIRT1 over SIRT2 in silico. Correlating the outcome of in silico studies, these compounds displayed encouraging inhibition of SIRT1 in vitro with IC 50 ∼2.6–3.4 µM when 3h appeared as the most active molecule. The SAR (Structure-Activity-Relationship) analysis indicated good inhibition of compounds possessing the C-4 aryl group represented by the phenyl ring containing a 4-cyano or 2,4-dichloro or 2‑hydroxy group. Based on in silico and in vitro studies along with ADME predictions the 1-thiocyanatopyrrolo[1,2- a ]quinoxaline 3h, 3i and 3j were selected as initial hits for further pharmacological evaluation. 1-Thiocyanatopyrrolo[1,2- a ]quinoxalines prepared via the sonochemical thiocyanation in a regioselective manner were explored as potential inhibitors of SIRT1. [Display omitted] [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) has become a candidate treatment for breast cancer due to its non-invasive, specific and controllable properties. However, there are few strategies to develop photothermal agents with high photothermal conversion efficiency, adequate tumor accumulation, and the molecular design theory is not perfect. Thus, to obtain the photothermal agent with better comprehensive performance, a novel conjugated polymer PAPQ-Th , comprising quinoxaline derivative 10,11-bis(4-(octyloxy) phenyl)acenaphtho[1,2- b ]pyrazino[2,3- g ]quinoxaline (PAPQ) as the acceptor and thiophene (Th) as the donor, was designed and synthesized. The PAPQ-Th exhibited the high non-radiative rate of 7.3 × 1011 s−1 and faint fluorescence emission. And PAPQ-Th nanoparticles exhibited strong NIR absorption from 650 nm to 900 nm, negligible ROS generation, and an impressively high photothermal conversion efficiency of 61 % under an 808 nm laser irradiation. Furthermore, PAPQ-Th nanoparticles can be successfully used for both in vitro and in vivo experiments, and exhibited remarkable photothermal antitumor efficacy. After intravenous administration and 808 nm laser irradiation, 4T1 tumor-bearing mice achieve complete tumor remission without recurrence. The results demonstrate that the design of new quinoxaline derivative and construction of novel donor-acceptor conjugated polymer are the effective strategy for the synthesis of efficient photothermal agent. A novel near-infrared photothermal material for efficient breast cancer therapy was developed. [Display omitted] • A novel near-infrared photothermal material (PAPQ-Th) for efficient breast cancer therapy was developed. • The PAPQ-Th exhibited the high non-radiative rate of 7.3 × 1011 s−1 and faint fluorescence emission. • The PAPQ-Th nanoparticles exhibited strong NIR absorption from 650 nm to 900 nm and negligible ROS generation. • The PAPQ-Th nanoparticles an impressively high photothermal conversion efficiency of 61 % under an 808 nm laser irradiation. • The PAPQ-Th nanoparticles can be successfully used for both in vitro and in vivo experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ratiometric detection of o-phenylenediamine (OPD) was successfully realized by combinatorial principles of in-situ fluorogenic reaction and in-situ generation of metal nanoparticles. • OPD can react with AA to produce blue fluorescent quinoxaline (OXD) in the presence of Cu2+. • The unreacted Cu2+ can react with dithiothreitol (DTT) to yield red-emitting DTT-copper nanoparticles (DTT-CuNPs). Herein, a novel ratiometric strategy for ultra-sensitive detection of o-phenylenediamine (OPD) was proposed based on combinatorial reactions of in-situ fluorogenic reaction and in-situ formation of red fluorescent dithiothreitol-copper nanoparticles (DTT-CuNPs). Here, Cu2+ is used both as an oxidant and as a precursor. Dehydroascorbic acid (DHAA) is formed via redox reaction of AA and Cu2+. Then, DHAA reacts with OPD to yield blue fluorescent quinoxaline (OXD) with emission peak at 434 nm through in-situ fluorogenic reaction. Red emitting DTT-CuNPs with emission peak at 666 nm is instantly generated due to the coordination reaction between DTT and the residual Cu2+ which is not consumed by AA. The fluorescence intensity (FI) of OXD at 434 nm is closely relied on the concentration of OPD, which can be used as a response signal for OPD detection. Meanwhile, FI of DTT-CuNPs at 666 nm has no significant change, which can be used as a reference signal for OPD detection. Thus, the ratio (F 434 /F 666) of the Cu2+/AA/DTT sensing system is successfully employed to quantify OPD, exhibiting a wide linear range from 0.2 µM to 60 µM, with LOD of 0.09 µM. [ABSTRACT FROM AUTHOR]

• Tautomeric and geometric equilibria in solution of quinoxalines derivatives. • Use of NMR to study the behavior of quinoxaline derivatives. • Correlation between experimental and computationally calculated NMR δ values. The understanding of the prototropic lactam/lactim/enol equilibrium and the E / Z isomerism around the N-C(O) bond in amides is important for the determination of different physicochemical properties in compounds, moreover in compounds with more than one equilibrium. In this work, these equilibria were studied for N -acyl and N -carbamoyl-3,4-dihydroquinoxalin-2(1 H)-ones using mono- and bi-dimensional NMR experiments , at different temperatures. For both types of derivatives, the lactam form was the only tautomer detected. The results obtained from molecular modelling experiments agree with the experimental results. For the N -acyl derivative, the E isomer is the predominant, while for the N -carbamoyl derivative both geometric isomers are present in a similar ratio. The theoretical calculations allowed the signal assignment for each isomer from the chemical shift values estimated for both geometric isomers corresponding to the studied N -acyl and N -carbamoyl derivatives. [Display omitted] [ABSTRACT FROM AUTHOR]

• A lead-free perovskite Cs 3 Bi 2 Br 9 is employed as a photocatalyst. • Cs 3 Bi 2 Br 9 exhibits a high catalytic activity for visible-light-mediated C3 arylation of quinoxalin-2(1 H)-ones. • Various 3-arylquinoxalin-2(1 H)-one derivatives are obtained with high yields. • The reaction is performed in dimethyl carbonate with oxygen in air as oxidant at room temperature. • The catalytic system can be effectively operated in gram-scale, and the catalyst is stable and recyclable. A facile, practical and attractive approach has been developed for the C3 arylation of quinoxalin-2(1 H)-ones with phenylhydrazines using the lead-free perovskite Cs 3 Bi 2 Br 9 as heterogeneous photocatalyst. The reaction proceeded smoothly in dimethyl carbonate with oxygen in air as oxidant under light irradiation, furnishing 3-arylquinoxalin-2(1 H)-one derivatives in high yields. The developed recyclable system showed a broad substrate range, good functional group compatibility, mild conditions, photocatalyst recyclability, and gram-scale reactivity. [Display omitted] [ABSTRACT FROM AUTHOR]

• Late-stage derivatization of valuable molecules. • Simple and green conditions. • Broad FG tolerance & scale-up. • Absence of metal/oxidant & high atom economy. Given the pivotal importance of sulfoximines in the field of medicine, they have garnered considerable attention in synthetic chemistry, and the development of novel catalytic methods to achieve their functionalization is highly valuable. Herein, a direct and practical electrochemical strategy for the synthesis of heteroaromatic-substituted products was developed using NH -sulfoximines and quinoxalin-2(1 H)-ones as starting materials. The direct construction of the N C(sp2) bonds of NH -sulfoximines is achieved through the cleavage of the C3 H bonds of quinoxalin-2(1 H)-ones. This protocol features good functional group tolerance, simplicity in operation, and easy to scalability. By utilizing this electrochemical strategy, the structural modification of biomolecular derivatives has been successfully carried out, which is unattainable with other traditional oxidants. The mechanistic investigation demonstrates that quinoxalin-2(1 H)-ones serve dual roles as both substrates and redox mediators, thereby avoiding the addition of extra hydrogen atom transfer (HAT) reagents. An environmentally friendly electrochemical system for the construction of N C(sp2) bonds from easily available sulfoximines has been reported. Various heteroaromatic-substituted sulfoximines were successfully obtained in moderate to excellent yields, which are not easily accessible through other methods. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Transition-metal-free functionalization of C1-H bonds in pyrrolo[1,2- a ]quinoxalines. • Sulfenylation of fused heterocycles with sulfonyl hydrazides. • Broad scope of functionalities. A method for transition-metal-free sulfenylation of pyrrolo[1,2- a ]quinoxalines was developed. Selective functionalization of C1 H bonds was achieved via an electrophilic substitution with thiodiazonium adduct presumably derived from combination of sulfonyl hydrazides and molecular iodine. The conditions were well tolerated with a wide range of functionalities as well as heterocycles. Our method would offer a rare example for direct sulfenylation of C1 H bonds in pyrrolo[1,2- a ]quinoxalines in the absence of transition metals or strong oxidants. [ABSTRACT FROM AUTHOR]

• Molecular structure of synthetized hydrazinylidene based quinoxaline effect was investigated. • The anti-corrosion performance depends on the molecular structure and the concentration. • The investigated inhibitors take their performance at high temperature. • EIS measurements and SEM analysis indicated the formation of a protective layer. • Theoretical investigated confirm the molecular structure effect. In this paper, the anti-corrosion effect of two synthesized and characterized hydrazinylidene based quinoxaline derivatives, namely (2E,3E)-2,3-dihydrazono-1,2,3,4-tetrahydroquinoxaline (QX-F) and (2E,3E)-2,3-dihydrazono-6-methyl-1,2,3,4-tetrahydroquinoxaline (QX-N)resistance, on mild steel (MS) substrate in 1.0 M HCl medium was investigated electrochemical measurements, scanning electron microscopy (SEM) coupled with functional density theory (DFT) and molecular dynamics simulation (MD). The EIS measurements discovered that the QX-N and QX-F compounds raise the charge transfer resistance value, and reduce the double-layer capacity value, indicating the establishment of a defensive film on the MS area. In addition, the I-E curves designated that both products react as mixed-type inhibitors, and their inhibition values increase with their concentration to reach a maximum of 90.5 % and 91.8 % at 10−3 M QX-N and QX-F, respectively. The best performance of QX-F than QX-N was attributed to the molecular structure nature. In the same way, it is founded that the investigated hydrazinylidene based quinoxaline derivatives adhere on the MS area according to the Langmuir isotherm, and they take their anti-corrosion performance at high temperature solution. These findings were confirmed by SEM analysis. Finally, the experimental results were justified and explained by the DFT calculations and the MD simulation. [Display omitted] [ABSTRACT FROM AUTHOR]

• The Quinoxaline-based Schiff base serves as effective colorimetric chemosensor for CN͞ ion sensing. • By using 1H NMR and DFT calculations, the hypothesized sensing mechanism of HG-1 towards CN͞ ion was verified. • A combinatorial logic gate circuit was built using HG-1's reversibility towards CN͞ ion and MeOH. • The HG-1 was used to detect CN͞ ion in test strips. Cyanide ion is very toxic for both environment and human being, so it is necessary to design a chemosensor for cyanide ion detection. For this purpose, Two novel chemosensors based on 3-hydrazinylquinoxalin-2(1H)-one and aromatic aldehydes were synthesized named as (E)-3-(2-(5-fluoro-2-oxo-1H-indol-3(2H,3aH,7aH)-ylidene)hydrazinyl)quinoxalin-2(1H)-one (HG-1) and (Z)-3-(2-(4-morpholinobenzylidene)hydrazinyl)quinoxalin-2(1H)-one (HG-2) for selective detection of cyanide ion. The structural characterization was done by analytical techniques such as UV/Visible, FTIR, 1HNMR, 13CNMR, EI-MS and UPLC. Further confirmation of chemosensor sensing was done by DFT and TDDFT calculations with B3LYP/6-31G (d, p) method by performing QTAIM, FMO, UV/Vis and global reactivity parameters (GRPs) elucidation. The binding constant was calculated as 4.14 × 106 M−1 and detection limit was calculated as 21 × 10−6 M. In the presence of CN͞ ion, chemosensor HG-1 generated a noticeable color change from light yellow to orange. To build a combinatorial logic circuit gate, the reverse reaction of chemosensor with methanol is useful. Overall results shows that chemosensor HG-1 has greater selectivity for CN͞ ion than HG-2. Test strips were made for CN͞ ion detection. A simple quinoxaline based Schiff bases have been created. The chemosensor HG-1 has a rapid response time, good sensitivity, and high selectivity towards CN͞ ions. The chemosensor served analytical purposes well. [Display omitted] [ABSTRACT FROM AUTHOR]

We reported two butterfly-shaped monomers TTCQF and TTCQH consisting of camphor-substituted quinoxaline units as π-spacers, and their electrochemical polymerizations for electrochromic energy storage devices. [Display omitted] • Two conjugated polymers PTTCQH and PTTCQF were developed for electrochromic and energy storage devices. • The present polymers showed efficient electrochromic performance with large optical contrast over 75 % around 1100 nm. • PTTCQH exhibited large areal specific capacitance of 12 mF/cm2 at a current density of 0.1 mA/cm2. Two new butterfly-shaped monomers TTCQF and TTCQH consisting of camphor-substituted quinoxaline units as π-spacers were designed and synthesized, which were further electrochemical polymerized and deposited on ITO substrates for electrochromic energy storage devices. The present cross-linked polymer thin films PTTCQF and PTTCQH displayed prominent color changes with significant optical contrast in both the visible and near-infrared regions under external electrical stimuli. These two polymers showcased superior electrochromic performance, involving high optical contrast, fast switching speed, and good coloration efficiency. Additionally, both polymers demonstrated a high areal specific capacitance (12 mF/cm2 for PTTCQH and 9.97 mF/cm2 for PTTCQF) at a current density of 0.1 mA/cm2. Electrochromic energy storage devices based on these polymers were fabricated, and not only illuminated an LED bulb but also visually indicated the energy storage state, guaranteed their potential for applications in energy-saving smart windows. This work may provide valuable insights into the development of efficient cross-linked electrochromic energy storage polymers. [ABSTRACT FROM AUTHOR]

[Display omitted] • α-Zr(HPO 4) 2.H 2 O synthesized successfully using a conventional hydrothermal method and characterized by different techniques. • Zr(HPO 4) 2 ·H 2 O has been used as an effective and recoverable catalyst for the preparation of a family of quinoxalines. • The preparation of quinoxalines was obtained with good yields (97–98 %) and a short stirring time (8 min). • α-Zr(HPO 4) 2 ·H 2 O continued to be highly active even once it had been recycled several times, with no decrease in catalytic performance. In our work, we have established a straightforward and friendly process for the preparation of a family of quinoxaline. This method relies on using α-Zr(HPO 4) 2 ·H 2 O as a catalyst and an ethanol/water mixture as an ecological solvent. Firstly, we prepared α-Zr(HPO 4) 2 ·H 2 O by a simple hydrothermal procedure and conducted comprehensive characterization employing various analytical methods. On the other hand, we produced the quinoxalines by means of a condensation reaction between 1,2-dicarbonyl compounds and various 1,2-diamines. The synthesized quinoxaline and its derivative products were characterized by melting point, proton, and carbon nuclear magnetic resonance analysis. As a result, the optimal reaction conditions that resulted in a high yield (97–98 %) were an amount of catalyst of 0.03 g, a stirring time of 8 min, a volume of solvent of 2 mL, and a reaction temperature of 50 °C. This approach is advantageous due to its simple and eco-friendly procedure, green solvent, quick reaction time, low cost, and high yields. Additionally, it offers the possibility to recycle the catalyst for a minimum of five cycles with no decrease in its catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Immunological detection methods for quinoxalines were reviewed for the first time. • The designs of haptens for quinoxalines and their metabolites were discussed. • Immunological detection methods for quinoxalines residues are prospected. Quinoxalines are a class of veterinary drugs with antibacterial and growth-promoting functions. They are often widely used to treat and prevent animal diseases and are illegally used as animal growth promoters to increase economic benefits. Quinoxalines could be easily metabolized in animals to various residue markers and remain in animal-derived foods, which would pose a serious threat to human health. Consequently, it is necessary to detect the residues of quinoxalines and their metabolites. This article reviewed and evaluated immunoassays for quinoxalines and their metabolites in animal-derived foods, mainly including enzyme-linked immunosorbent assays, fluorescence immunosorbent assays, immunochromatography, and surface plasmon resonance biosensors. In addition, we deeply explored the design of haptens for quinoxalines and their metabolites and analyzed the effect of haptens on antibody performance. This paper aims to provide guidance and references for their accurate and sensitive detection, thereby ensuring food safety and human public health. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyamides with D-A segments for electrochromic and memory storage performance improvements. • The triphenylamine moiety with substituted methoxyl group improves the switching cycle stability. • Polyamides exhibit high optical contrast, outstanding coloration efficiency, fast response and long-term cycle. • Polyamides also serve as memristors with accessible threshold voltage and long retention time. With the aim to obtain multifunctional durable electrochromic (EC) devices, we propose an effective strategy by introducing weak electron acceptor segment with suitable bandgap and oxidation potential. A series of quinoxaline-based units polyamides (PAs) (denoted as T 2 BPA-CA, T 2 BPA-OA, T 2 BPA-TP, and T 2 BPA-SA) were prepared from a novel donor–acceptor-donor (D-A-D) type diamine with weak electron acceptor quinoxaline and connected with two methoxyl-substituted donor triphenylamine, 10,13-bis[4-aminophenyl (4-methoxyphenyl) amino]-dibenzo[a,c]phenazine, and four dicarboxylic acids, which are high soluble in various organic solvents and exhibit excellent thermostability. Furthermore, the T 2 BPA-SA thin film exhibits excellent EC performance with outstanding optical contrast (50 %), high coloration efficiency (230 cm2 C−1) and impressive cycle stability (optical contrast remains 80 % over 1400 cycles) in the NIR range. Meanwhile, all of these PAs are served as memristors and exhibit typical nonvolatile ternary memory, realizing an accessible threshold voltage of −0.65 V, a retention time of more than104 s and high current switch ratio (103.52:102.43:1). Overall, this work implies the great potential of these PAs in EC displays and memory storage devices. [ABSTRACT FROM AUTHOR]

• A novel series of indolo[2,3- b ]quinoxaline incorporating triazole moiety was prepared via click chemistry protocol. • The structure of the new compounds was confirmed on the basis of their elemental analysis and spectral data. • The newly synthesized compounds' cytotoxicity and in vitro anticancer activities were assessed against selected human cancerous cell lines. • All the newly synthesized compounds showed superior cytotoxic activities against hepatocellular carcinoma (Hep-G2). • Some compounds were found to fit in the ATP binding pocket during docking experiments combined with molecular dynamic simulation. In the pathway of anticancer drug development, we designed and synthesized a novel series of 6-((1 H -1,2,3-triazol-4-yl)methyl)-1,2,3,4,4a,11a-hexahydro-6 H -indolo[2,3- b ]quinoxalines 13-20 through a simple multi-step protocol starting from Isatin. Initially, 6 H -indolo[2,3- b ]quinoxaline (3) was prepared by the condensation of isatin (1) with o-cyclohexyldiamine (2) then the obtained product was reacted with propargyl bromide resulting in the formation of N -propargyl derivatives 4. The latter compound was subjected to cycloaddition with a series of substituted aromatic azides 5-12 in the presence of copper (I) as catalyst to give the target molecules 13-20. The structure of the newly clicked 1,2,3-triazole-1,2,3,4,4a,11a-hexahydro-6 H -indolo[2,3- b ]quinoxalines 13-20 was confirmed on the basis of their elemental analysis and spectral data. Moreover, these compounds are screened against selected human cancerous cell lines: 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 effect. All the compounds showed superior cytotoxic activities against HepG2 while, compounds 15 and 18 exhibited significant in vitro activity against MCF-7 and HCT116, respectively. In addition, compound 15 was found to fit in the ATP binding pocket during docking experiments combined with molecular dynamic simulation. Lastly, we conducted a Petra/Osiris/Molinspiration (POM) study on the recently 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 designing to produce better derivatives in the search for the anticancer agents, particularly those with favorable ADME parameters, low toxicity, anticipated bioactivity, and bright futures. [Display omitted] [ABSTRACT FROM AUTHOR]

Cancer is a leading cause of death and a major health problem worldwide. While many effective anticancer agents are available, most drugs currently on the market are not specific, raising issues like the common side effects of chemotherapy. However, recent research hold promises for the development of more efficient and safer anticancer drugs. Quinoxaline and its derivatives are becoming recognized as a novel class of chemotherapeutic agents with activity against different tumors. The present review compiles and discusses studies concerning the therapeutic potential of the anticancer activity of quinoxaline derivatives, covering articles published between January 2018 and January 2023. [Display omitted] • Despite the advent of immunotherapy, cancer remains a leading cause of death worldwide. • Quinoxalines result from the fusion of a pyrazine and a benzene ring and possess multiple biological properties. • Quinoxalines target hallmarks of cancer by a multitude of mechanisms of action. • Quinoxalines are good providers of tyrosine kinase inhibitors as well as conventional chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

[Display omitted] 2,3-Bis- and 2,3,5,6-tetrakis(diphenylphosphoryl)-substituted pyrazines have been synthesized from the corresponding polychloropyrazines and ethyl diphenylphosphinite. They may serve as new N , O -bidentate organophosphorus ligands for extraction and recovery of f -block metal ions from nitric acid solutions. [ABSTRACT FROM AUTHOR]

• A novel developed ester-substituted quinoxaline EF-Qx unit was applied to construct polymer donors in PSCs. • D-A type polymer and D-A 1 -D-A 2 type polymer both exhibit an a relatively low band gap and wide absorption spectrum. • Due to the superior morphology, D-A type polymer shows the optimal PCE of 5.37%. Two narrow bandgap conjugated polymers, PTT-EFQX and PT-DFBT-T-EFQX, comprising a novel bis(2-alkyl) 5,8-dibromo-6,7-difluoroquinoxaline-2,3-dicarboxylate (EF-Qx) unit, are designed and synthesized through palladium-catalyzed Stille coupling reaction. The ester groups and difluorine substituents are introduced into the EF-Qx unit to improve the electron affinity. The polymers containing EF-Qx unit exhibit a relatively narrow bandgap of around 1.6 eV. To optimize the effects of solubility and molecular packing, D-A structure and D-A 1 -D-A 2 structure synthesis strategies are adopted in this work and the structure-property relationship is systematically studied. The results morphology characterizations indicate that the active layer based on D-A structure polymer PTT-EFQX has a superior morphology compared to active layer based on D-A 1 -D-A 2 structure polymer PT-DFBT-T-EFQX, which helps PTT-EFQX-based polymer solar cells (PSCs) to obtain better PCEs of up to 5.4%. Our work demonstrates that the effective design strategy for development of quinoxaline-based polymer donor is necessary for controlling the morphology and thus achieving high-performance PSCs. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is a multifactorial disease and its effective therapy often demands several drugs with different modes of action. Herein, we report a rational design and synthesis of multi-targeting novel molecular hybrids comprised of EGCG and quinoxaline derivatives that can effectively inhibit α-glucosidase, α-amylase as well as control oxidative stress by scavenging ROS. The hybrids showed superior inhibition of α-glucosidase along with similar α-amylase inhibition as compared to standard drug, acarbose. Most potent compound, 15c showed an IC 50 of 0.50 μM (IC 50 of acarbose 190 μM) against α-glucosidase. Kinetics studies with 15c revealed a competitive inhibition against α-glucosidase. Binding affinity of 15c (−9.5 kcal/mol) towards α-glucosidase was significantly higher than acarbose (−7.7 kcal/mol). 15c exhibited remarkably high antioxidant activity (IC 50 = 18.84 μM), much better than vitamin C (IC 50 = 33.04 μM). Of note, acarbose shows no antioxidant activity. Furthermore, α-amylase activity was effectively inhibited by 15c with an IC 50 value of 16.35 μM. No cytotoxicity was observed for 15c (up to 40 μM) in MCF-7 cells. Taken together, we report a series of multi-targeting molecular hybrids capable of inhibiting carbohydrate hydrolysing enzymes as well as reducing oxidative stress, thus representing an advancement towards effective and novel therapeutic approaches for diabetes. [Display omitted] • Molecular hybrids of EGCG and quinoxaline were synthesized using Click reaction • All the hybrids effectively inhibited α-glucosidase, α-amylase, and quenched ROS • 380-fold better α-glucosidase inhibition by most potent hybrid, 15c than acarbose • All the hybrids showed strong antioxidant activity superior/similar to vitamin C • 15c showed no cytotoxicity in MCF-7 cell line up to 40 μM concentration [ABSTRACT FROM AUTHOR]

• Photoinduced Rapid Chloropropylation of Quinoxalin-2(1H)-Ones with Cyclopropane and HCl. • SAS was used as the photocatalyst, HCl was used as the chlorine source. • This synthetic method provides a green and efficient way to realize the chloropropylation of quinoxalin-2(1H)-ones and afford a series of chlorinated quinoxalin-2(1H)-one derivatives in good to excellent yields with a high functional group tolerance and a broad substrate scope. Herein, a photoinduced three-component reaction of aryl cyclopropane, quinoxalin-2(1H)-ones and HCl has been developed to introduce chloroalkyl motifs into N -heteroarenes. This synthetic method provides a green and efficient way to realize the chloropropylation of quinoxalin-2(1H)-ones and afford a series of chlorinated quinoxalin-2(1H)-one derivatives in moderate to good yields with the broad functional-group tolerance. [Display omitted] [ABSTRACT FROM AUTHOR]

• The protocol shows scope simple condition, environment-friendly protocol and good functional group tolerance, providing an array of methylation products within 20 min in good to high yields. Notably, DMSO was used as both a methylation reagent and as the optimal reaction solvent. The synthesis of iron-catalyzed N -methylation of quinoxalin-2(1 H)-ones using dimethyl sulfoxide as the methylating reagent is described herein. The cross-coupling reactions proceeded smoothly under visible-light irradiation, which generated the corresponding products in moderate to good yields. Further investigation on the application of the methylation reaction using readily available DMSO as the methylation reagent is currently underway. [Display omitted] [ABSTRACT FROM AUTHOR]

In organic solar cells, the absorption range and extinction coefficient of the active layer not only affect the charge separation and carrier transfer efficiency of excitons, but also influence the J SC , and thus the device efficiency. Herein, an efficient nonfullerene polymer solar cells (NF–PSCs) based on a medium-bandgap (MBG) polymer donor PBDTTS-TClQx comprising chlorinethiophene quinoxaline (Qx) unit and a small molecule nonfullerene acceptor (SM-NFA) Y6 is developed. The PBDTTS-TClQx shows a strong absorption in the wavelength region of 330∼750 nm with an optical band gaps (E g opt) of 1.68 eV, which is well complementary with that of Y6 (1.33 eV) and facilitates achieving of high short-circuit current (J SC) in PSCs. As a result, the PBDTTS-TClQx:Y6-based PSCs achieved a power conversion efficiency (PCE) of 14.28% with a J SC of 25.9 mA cm−2. The J SC of 25.9 mA cm−2 achieved is among the highest reported for Qx-based polymer donors in PSCs. The PBDTTS-TClQx:Y6 blend has a broad and complementary absorption spectrum (300–950 nm) with well-matched energy levels. The PSCs achieves a PCE of 14.28% with a J SC of 25.9 mA cm−2. The impressive J SC of 25.9 mA cm−2 is by far one of the highest values for the PSCs from the Qx-based copolymers as donor. [Display omitted] • The PBDTTS-TClQx polymer donor and Y6 acceptor were employed to fabricate a high-performance photovoltaic device. • The PBDTTS-TClQx:Y6 blend has a broad and complementary absorption spectrum with well-matched energy levels. • The PSCs based on PBDTTS-TClQx:Y6 exhibits a PCE of 14.28% with a J SC of 25.9 mA cm−2. • The J SC of 25.9 mA cm−2 achieved is among the highest reported for Qx-based polymer donors in PSCs. • Chlorothiophene side-chains Quinoxaline; Medium bandgap polymer; Organic solar cells. [ABSTRACT FROM AUTHOR]

We reported two donor–acceptor (D-A) monomers consisting of two 2,5-dithiophen-2-yl-pyrrole units and camphor substituted quinoxaline-based linkers, and their electrochemical polymerizations for electrochromic energy storage devices. [Display omitted] • Two conjugated polymers SNSCQH and SNSCQF were developed for electrochromic and energy storage devices. • The present polymers showed efficient electrochromic performance, involving large optical contrast over 50 %, short response time less than 1.5 s, and high coloration efficiency over 220 cm2/C. • The present polymers exhibited large areal specific capacitance over 9 mF/cm2 at a current density of 0.1 mA/cm2. In this work, two donor–acceptor monomers SNSCQH and SNSCQF consisting of two 2,5-dithiophen-2-yl-pyrrole units and camphor substituted quinoxaline-based linkers were developed for electrochromic and energy storage applications. The cross-linked conjugated polymer thin films PSNSCQH and PSNSCQF were successfully prepared through electrochemical polymerization of the corresponding monomers and deposited on ITO substrates, which exhibited remarkable electrochromic performance, involving large optical contrast over 50 %, short response time less than 1.5 s, and high coloration efficiency over 220 cm2/C. Moreover, both PSNSCQH and PSNSCQF demonstrated large areal specific capacitance, with values of 9.27 mF/cm2 and 10.13 mF/cm2 at a current density of 0.1 mA/cm2, respectively. Additionally, electrochromic energy storage devices based on PSNSCQH and PSNSCQF thin films in a sandwich configuration were fabricated, enabling visualization of the energy storage state through color changes. This study provided valuable insights into the behavior of cross-linked two-dimensional conjugated polymers with intermolecular interactions between layers for electrochemical devices. [ABSTRACT FROM AUTHOR]

• Optical study of 2,3-bis(aryl)-quinoxaline-6-carboxylic acid 1a, 1b and 2 are reported. • Compounds exhibit blue to green luminescence in solution and aggregate states. • Alkyl chains, electron donor capacity, and acidic group impact greatly on AIEE. • Carboxylic acid quinoxalines exhibit solvatochromism in emission spectra and AIEE. • Carboxylate salts of final compounds show AIE in water-THF with increasing f THF. We report an optical study of quinoxaline-based luminogens derived from 2,3-bis(aryl)-quinoxaline-6-carboxylic acid (1a, 1b , and 2) in solution and solid state. These compounds were fluorescent in solid films and in solutions with emission bands ranging from blue to green (445–517 nm). They showed a positive solvatochromism in the PL spectra, indicative of intramolecular charge transfer (ICT) in the excited state. 1a, 1b , and 2 exhibited Aggregation-Induced Enhanced Emission (AIEE) characteristics with a drastic change in properties by increasing alkyl chains and donor alkoxy groups. Their carboxylate potassium salts had a blueshift emission compared to the acid carboxylic form and a significant quenching in PL intensity in protic polar solvents. The salt of 1a presented an Aggregation-Induced Emission (AIE) profile, its weak fluorescence in water had an expressive enhancement by adding THF. Theoretical calculations were also carried out considering implicit solvent effects. The optimized structures of compounds and their simulated UV–vis absorption spectra showed no significant differences in water and acetonitrile. These results are in good agreement with the solvatochromism experiments. The calculated HOMO-LUMO energy gaps were 3.47 eV in both solvents, and the energy levels for HOMO and LUMO are slightly lower in water. [Display omitted] [ABSTRACT FROM AUTHOR]

• Quinoxalin-2(1 H)-ones act as reagent and photocatalyst in this reaction system. • This methodology features simple, conventional photocatalyst-free, practical and sustainable. • Diverse azidoalkylated quinoxalinones with potential use in medical and pharmaceutical were obtained. A photoinduced, self-catalyzed three-component reaction of quinoxalinones with unactivated alkenes and IBA-N 3 was developed. Quinoxalin-2(1 H)-ones act as both reagent and photocatalyst in this reaction system. This methodology provides a simple, practical and sustainable method to access diverse azidoalkylated quinoxalinones with potential use in medical and pharmaceutical. A photoinduced, self-catalyzed three-component reaction of quinoxalinones with unactivated alkenes and IBA-N 3 has been developed. Quinoxalin-2(1 H)-ones serve as both reagent and photocatalyst in this reaction system. This methodology offers a straightforward, practical, and sustainable approach to producing a range of azidoalkylated quinoxalinones with potential applications in medicine and pharmaceuticals. [Display omitted] [ABSTRACT FROM AUTHOR]

The cell cycle includes two checkpoint arrests allowing to repair of damaged DNA. Many cancer cell lines exhibit weak G1 checkpoint mechanisms relying significantly more on the G2 checkpoint than do healthy cells. Inhibition of Myt1 kinase (PKMYT1), a forgotten member of the Wee family, cyclin-dependent kinase 1 (Cdk1) inhibitory kinase, target for G2 checkpoint abrogation, whose inhibition forces cells into premature unchecked mitosis resulting in cell death, is a promising concept for anticancer therapy. There are not many inhibitors of this emerging, potentially clinically important kinase. Herein, the valuable insight into structural features and binding mechanisms of diaminopyrimidines, aminoquinolines, quinazolines, pyrido[2,3- d ]pyrimidines, pyrazolo[3,4- d ]pyrimidines, and pyrrolo[2,3- b ]quinoxalines, as well as finally made a general scheme of fragmented structures of Myt1 inhibitors with the enzyme, offer potential frameworks useful for future directions, for further chemical optimizations, in the discovery and the design of novel effective structures, potential therapeutics. [Display omitted] • Inhibition of Myt1 kinase is promising concept for anticancer therapy. • Inhibitors of Myt1, regulator of G2/M transition, were reviewed and classified. • The most common scaffolds are diaminopyrimidine, aminoquinoline and 7-azaindole. • Fragmented schemes with common interaction patterns of inhibitors were consolidated. • Analyzed structural features offer potential frameworks for further optimizations. [ABSTRACT FROM AUTHOR]

Improving the light-harvesting efficiency and boosting open circuit voltage are crucial challenges for enhancing the efficiency of organic solar cells. This work introduces seven new molecules (SA1-SA7) to upgrade the optoelectronic and photovoltaic properties of Q-C-F molecule-based solar cells. All recently designed molecules have the same alkyl-substituted Quinoxaline core and CPDT donor but vary in the end-capped acceptor subunits. All the investigated molecules have revealed superior properties than the model (R) by having absorbance ranging from 681 nm to 782 nm in the gaseous medium while 726 nm–861 nm in chloroform solvent, with the lowest band gap ranging from 1.91 to 2.19 eV SA1 molecule demonstrated the highest λ max (861 nm) in chloroform solvent and the lowest band gap (1.91 eV). SA2 molecule has manifested highest dipole moment (4.5089 D), lower exciton binding energy in gaseous (0.33 eV) and chloroform solvent (0.47 eV), and lower charge mobility of hole (0.0077693) and electron (0.0042470). At the same time, SA7 showed the highest open circuit voltage (1.56 eV) and fill factor (0.9166) due to solid electron-pulling acceptor moieties. From these supportive outcomes, it is inferred that our computationally investigated molecules may be promising candidates to be used in advanced versions of OSCs in the upcoming period. [Display omitted] • A series of seven molecules SA1-SA7 is derived from Q-C-F molecule. • Various optoelectronic and photovoltaic properties of molecules were studied using DFT. • A narrow bandgap, low excitation energy and improved light absorption was observed in newly presented molecules. • SA7 showed significantly improved open circuit voltage and fill factor. • Results demonstrate that new molecules have potential to be used as advanced organic solar cells. [ABSTRACT FROM AUTHOR]

A ultrasound assisted two-step approach was developed for the general synthesis of 4-substituted pyrrolo[1,2- a ]quinoxalines for the identification of potential inhibitors of SIRT1. [Display omitted] • First sonochemical approach to pyrrolo[1,2- a ]quinoxalines is reported. • This involves Cu-catalyzed N -arylation and Wang resin/air promoted oxidative cyclization. • Shorter duration, eco-friendly energy and wider substrate scope are key features. • Compound 4 k , 4 m and 4p showed SIRT1 inhibition better than nicotinamide in vitro. The 4-substituted pyrrolo[1,2- a ]quinoxaline framework was explored for the identification of possible inhibitors of SIRT1. To access the target compounds a general and ultrasound assisted two-step approach was developed for the first time involving the Cu-catalyzed N -arylation followed by Wang resin/air promoted oxidative cyclization strategy. Thus, C N coupling of 2-iodoanilines with pyrrole gave the 1-(2-aminophenyl)pyrrole derivatives in the first step which on C N/C C bond formation with aldehydes afforded the desired products. The second step proceeded in pure water under open air and recovery as well as reuse of the Wang resin catalyst was demonstrated. The methodology offers advantages such as shorter duration, use of eco-friendly energy and wider substrate scope. Further application of this sonochemical method was also demonstrated via Suzuki coupling of a bromo product. Some of the pyrrolo[1,2- a ]quinoxalines showed encouraging (52–77 %) inhibition of SIRT1 in vitro (better than nicotinamide) and were identified as initial hits. [ABSTRACT FROM AUTHOR]

• The electrochemical conversion of quinoxaline and 1,2,3,4-tetrahydroquinoxaline reached 90% and 100%, respectively. • The established hydrogen storage system exhibited excellent reversibility under mild conditions. • Dendritic P-WO 3 /NF was employed as an efficient dual-functional electrode. • The hydrogenation reaction was completed without an external hydrogen supply. Liquid organic hydrogen carrier (LOHC) has been recognized as a highly promising candidate for hydrogen storage materials in addressing hydrogen utilization issues. However, the hydrogenation and dehydrogenation of LOHC typically require noble metal catalysts and harsh reaction conditions. In this paper, we proposed an efficient reversible electrochemical hydrogen storage system based on a nitrogen heterocyclic organic hydrogen carrier, quinoxaline, in which water was used as the solvent and hydrogen source for quinoxaline hydrogenation, and a self-supporting dendritic P-WO 3 /NF electrode was employed as the electrocatalyst. The catalytic properties of P-WO 3 /NF for electrochemical hydrogenation of quinoxaline and dehydrogenation of 1,2,3,4-tetrahydroquinoxaline were studied in 1 M KOH solution under mild conditions. The results showed that the hydrogenation conversion of quinoxaline was 90%, the selectivity was 99%, and the dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline was 100%, the selectivity was 100%. This indicates that the system has high conversion efficiency, outstanding selectivity, and good reversibility. Meanwhile, the P-WO 3 /NF electrode adapted to the system exhibited good catalytic stability. In addition, no pre-prepared external hydrogen was required in the electrochemical hydrogenation reaction involving water, which gave the system an excellent safety profile. The reversible electrochemical hydrogen storage system established by this work broadens the vision of LOHC in hydrogen storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hedychium gardnerianum biomass was successfully transformed into highly porous acid ACs. • Acid biomass-derived carbons efficiently catalyze the synthesis of nitrogen heterocycles. • Reaction is mainly controlled by a combination of acid functions strength and textural properties. • Experimental and theoretical results suggest a new reactive route for the synthesis of quinoxalines. We report herein for the first-time acid biomass-derived carbons from vegetal biomass, with high developed porosity, prepared through integrating method comprising pyrolysis and surface phosphonation, able to efficiently catalyze the synthesis of quinoxalines from 1,2-diamines and α-hydroxi ketones, under aerobic conditions. The obtained results indicate that the reaction is mainly driven by a combination of acid function strength and textural properties in terms of conversion and selectivity. Furthermore, our experimental and theoretical observations suggest that the preferred reaction pathway for this transformation, in the presence of the investigated acid carbon catalysts, involves cascade reactions including imination reaction between reactants, successive imine-enamine and keto-enol tautomerisms, heterocyclization followed by dehydration, and aromatization. While the acid sites seem to be a relevant role in each reaction step, the system formed by activated carbon and molecular oxygen could be behind the last oxidative reaction to give the corresponding nitrogen heterocycles. [ABSTRACT FROM AUTHOR]

• Commercial Basolites efficiently catalyze the synthesis of quinoxalines. • Acidity and texture are key factors influencing the observed reactivity. • New reaction pathway in the quinoxaline synthesis is proposed. We report here efficient synthesis of quinoxalines from o-phenylendiamine and α-hydroxy ketones over commercial Basolites. The concentration and type of acid centres, as CUS sites, together with the porosity of the samples strongly influence the resulting conversion and selectivity. Our results indicate that the formation of quinoxalines preferentially follows a new route, in which tautomerization reactions are also involved. [ABSTRACT FROM AUTHOR]

A rapid, simple and highly efficient method for the synthesis of a variety of 2-aryl-benzimidazoles, 2-aryl-benzothiazoles and quinoxalines has been developed using Koser's reagent [PhI(OH)OTs] as catalyst. The present work highlights the potential of Koser's reagent ([PhI(OH)OTs]) for the synthesis of benzimidazoles, benzothiazoles and quinoxalines, etc. Short reaction time, high yields, importantly low catalyst loading, broad substrate scope and scalability are the salient features of this methodology. Particularly, this method has been employed successfully to synthesize highly structured indole-benzimidazole and quinoxaline-6-carboxamide derivatives as well as biologically important benzimidazole-imidazo[1,2- a pyridine conjugates in moderate to good yields. These remarkable features make the present methodology a valid contribution to the existing precedents for the synthesis of benzimidazoles, etc. In the MTT assay, benzimidazole-imidazo[1,2- a pyridine conjugates 3 s , 3t and 3 v were found to be active on MCF-7 (IC 50 values of 5.10 ± 0.10, 8.23 ± 0.02, and 10.75 ± 0.03 µM, respectively) and MDA-MB-231 cell lines (IC 50 values of 10.83 ± 0.13, 7.68 ± 0.05, and 7.87 ± 0.24 µM, respectively). Flow-cytometry analysis revealed that the treatment of MCF-7 cells with compound 3 s showed moderate effect on the progression of G0/G1 phase of the cell cycle. [ABSTRACT FROM AUTHOR]

• It was the first time that the structural motif, D-D|A-π-A, was proposed. • Three sensitizers were designed according to the aforementioned motif. • Indolo [2,3- b ]quinoxaline was chosen as the main chromophore. • FS08 gave the best DSSC performance and the best co-sensitization effect. • The improved V OC was related to the suppression of the undesired charge recombination. A new structural motif, D-D|A-π-A, was suggested for the design of novel metal-free organic sensitizers, where "D|A" represents a fused donor-acceptor conjugated building block. Three organic dyes, coded FS07 , FS08 and FS09 , were synthesized accordingly with the incorporation of indolo [2,3- b ] quinoxaline (IQ) as the main building block but different additional donors. The synthesized dyes were well-characterized and their photophysical and electrochemical properties were well-studied. Additionally, molecular modeling via DFT method was employed to probe their photovoltaic behaviors as sensitizers/co-sensitizers. The isodensity of the molecular orbitals displays the distinguished intramolecular charge delocalization in the IQ moiety, even though its donor and acceptor sections are coplanar-fused. In the photovoltaic characterization, FS08 exhibited the best DSSC performance. Moreover, FS07 , FS08 and FS09 were co-sensitized along with a typical high efficient bipyridyl Ru(II) sensitizer, HD-2 , in order to induce the light harvesting over expanded spectral region and hence improve the efficiency. The solar cell co-sensitized with FS08 displayed improved efficiency of 7.94% with J SC of 19.37 mA⋅cm−2, V OC of 0.654 V and FF of 62.7%, which outperformed the device employing HD-2 alone (efficiency of 7.46%). Owing to the appropriate dye loading of FS08 in the presence of HD-2 and CDCA mixed dye solution, the benign coordination for light harvesting was guaranteed and the photoexcitation was maximized, the co-sensitized J SC was improved; due to the well-modified TiO 2 surface coverage with the tight attachment of FS08 and HD-2 , the dye aggregation was diminished and the undesired charge recombination was suppressed, the co-sensitized V OC was improved. [ABSTRACT FROM AUTHOR]

The one-pot synthesis of nine novel polyfunctionalized quinoxaline derivatives starting from l -ascorbic acid is described. Reaction products were obtained in moderate to good yields (65–84%) for an interesting scope of aldehydes after four synthetic transformations. Structural characterization of the molecules was performed by combined NMR (1H, 13C, DEPT-135 COSY and HSQC) techniques, infrared spectroscopy and theoretical calculations. Two selected target-compounds were evaluated as chromogenic chemosensors for ionic species in solution. One of the compounds was effective in the selective detection of Cu2+ in methanol-water 4:1 v/v solution. The other compound was applied as a chemosensor for F− in DMSO and aqueous DMSO solution. Binding mechanisms were proposed based on spectroscopic and theoretical data. Image 1 • The one-pot synthesis of polyfunctionalized quinoxaline derivatives is described. • Two selected compounds were evaluated as chemosensors for ions. • Structural analysis using experimental and theoretical techniques. • Compounds 1a and 1b , respectively, were selective for Cu2+ and F−. • Binding models were proposed based on spectroscopic and computational data. [ABSTRACT FROM AUTHOR]

Herein, we report a low-metal iron-supported (0.06 wt%) catalyst (Fe20/NC-Mg), in which the FeN x site and Mg(OH) 2 nanorods are synergistic to achieve the efficient synthesis of quinoxaline (16 examples, 82–91 % yield) with water as a solvent and without additional bases. Moreover, the industrial application potential of Fe20/NC-Mg is demonstrated by gram-level synthesis and reusability of catalysts after four cycles. This protocol has high atomic and step economy, which meets with the requirement of green synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel quinoxaline derivative, 2-methyl-3-((4-nitrobenzyl)oxy)quinoxaline, has been synthesized and characterized by means of 1H NMR, 13C NMR, FTIR, Mass, XRD and single X-ray crystallographic studies. • Hirshfeld surface analysis comprehends the molecular packing and intermolecular interactions in crystals. • Molecular docking studies supported by in silico drug likeness screening suggested that MNBQ might possess potent cancer chemopreventive activity. MNBQ has been synthesized and its crystal structure was solved by direct method and refined by full matrix least squares procedure. The crystal structure is stabilized with elaborate network of intermolecular C H...O hydrogen bonds and van der-Waal's forces to form supramolecular structures. 3D Hirshfeld surfaces and allied 2D fingerprint plots were analysed for non-covalent interactions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H···H (37.5 %) and O···H/H···O (21.8 %) interactions. Theoretical (DFT) studies on the molecular structure, vibrational spectra, Mulliken charges, HOMO, LUMO, MESP surfaces have been performed at B3LYP /6-311++G (d,p) level of theory. The geometrical parameters of the optimized compound are in good agreement with the XRD experimental data. Molecular docking studies supported by in silico drug likeness screening suggested that MNBQ might possess potent cancer chemopreventive activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Time-resolved luminescence measurements are invaluable for understanding light-emitting materials but are difficult to perform on operating organic light-emitting diodes (OLEDs) because the light generated by the OLED can disturb common time-resolved techniques. We show that frequency-domain luminescence can be used to overcome this problem, and apply it to study efficiency roll-off in OLEDs. We measure the exciton lifetime of a phosphorescent OLED based on the emitter bis(2-methyldibenzo[ f , h ]quinoxaline)(acetylacetonate) iridium(III) (Ir(MDQ) 2 (acac)) whilst it is operating. By driving the OLED continuously at current densities of up to 128 mA/cm2, we observe that the exciton lifetime decreases with increasing current density as a result of triplet-polaron annihilation (TPA). The measurement presented can guide the development of new materials and device structures with improved efficiency at high brightness. [Display omitted] • Method for measuring exciton lifetime in operating OLEDs demonstrated. • Frequency-domain method gives effective rejection of unwanted light. • In-operando measurements of Ir(MDQ) 2 acac phosphorescent OLED. • Triplet-polaron annihilation dominant quenching mechanism in this material. • Method will help the development of efficient, high-brightness OLEDs. [ABSTRACT FROM AUTHOR]

Hole transport materials (HTMs) have a significant impact on the effectiveness of organic electronic devices; therefore, we present a molecular architecture of pyrazino[2,3-g]quinoxaline (PQ10)-based room-temperature organic liquid crystalline semiconductor (OLCS) as an alternative HTM. The PQ10 compound exhibits three different rectangular columnar (Col r) phases offering an impressive hole mobility of 8.8 × 10−3 cm2V−1s−1 which is found to be dexterous than most of existing polymeric hole transport materials. The charge transport mechanism is governed by the hole polarons hopping through H-aggregates of the PQ10 molecules and the hole mobility remains nearly constant throughout the mesophase range, but it decreases with increasing applied electric field. The current-voltage characteristics of the PQ10 have also been investigated in all three Col r phases and explained via the Poole-Frenkel conduction mechanism. The dielectric spectroscopy has been eventually carried out to understand the nature of dielectric permittivity and conductivity as a function of temperature and a correlation is established between the molecular architecture of the Col r phases and aforementioned physical properties. Solar cell simulation has been additionally performed to demonstrate that the PQ10 material can be a better choice as HTM for organic electronics and photovoltaic applications. • The Pyrazino[2,3-g]quinoxaline (PQ10) core-based OSC exhibits rectangular columnar phases. • PQ10 renders p-type charge carrier mobility of the order of 10−3 cm2V−1s−1. • The current conduction in PQ10 is attributed to Poole-Frenkel mechanism. • Charge carrier mobility, dielectric permittivity and conductivity remarkably depend on the mesophase ordering. • PQ10 can be designed as HTL in optoelectronic devices resulting in a better performance. [ABSTRACT FROM AUTHOR]

• A novel porous organo-catalyst made up from tragacanth gum (TG), polysulfonamide, and N,N ′-methylene- bis (acrylamide) (MBA) in the presence of SiO 2 NPs templates. • The obtained mesoporous TG-PSSA- co -ACA was used as a heterogeneous organo-catalyst in the synthesis of quinoxalines with high excellent yield. • The prepared mesoporous TG-PSSA- co -ACA was used as a novel recoverable organo-catalyst for synthesis of and 4-aryl- NH -1,2,3-triazole. A straightforward and practical method for the synthesis of 4-aryl- NH -1,2,3-triazoles and of quinoxalines is described. This method provides a new approach to prepare various N -containing heterocycles, using mesoporous polymer based on tragacanth gum (TG) and polysulfonamide (TG-PSSA- co -ACA). The notable advantages of TG-PSSA- co -ACA organo-catalyst are nontoxic, inexpensive, high surface area, and recyclabilit y. [Display omitted] [ABSTRACT FROM AUTHOR]

The simulations of π-extended systems (TQ31-TQ35) through the quantum mechanical model by the structural amendment of model TQ3R based on quinoxaline core through peripheral acceptors via thiophene bridging were conducted at PBEPBE/6-31G (d, p) level. The geometric constraints were investigated through optimization to study optoelectronic and photovoltaic parameters. The energy gap of novel molecules found to be minimized up to 0.16 eV obtained from FMO analysis possessed high charge transfer. The different reactivity parameters like ionization potential, softness, electronegativity, and electron affinity proclaimed reactivity as well as stability of all the studied systems. TD-DFT calculations declared a high absorption maximum for all the novel systems at longer wavelengths up to 1080 nm greater than model TQ3R (490 nm) in dichloromethane solvent. Low excitation energies (up to 0.23 eV) were found to be favorable for competent charge transference and elevated dipole moment (up to15.23 D) of all the newly amended molecules aided efficient solvation effect and charge separation. DOS study possessed effective contribution of the bridge, donor, as well as acceptor fragments of the novel molecular systems in HOMO to LUMO charge transfer. TDM plots exhibited high charge transition locations for electronic transitions by light absorption. Lower reorganization energy for the hole as well as for electron proclaimed efficient exciton dissociation and high charge mobility while effective values of V OC (open circuit voltage) and FF (fill factor) proclaimed increasing PCE (power conversion efficiency) of photovoltaic devices. Outcomes of the whole consideration revealed that all the innovative chromophores (TQ31-TQ35) are excellent contenders for the assembly of organic photovoltaics. [Display omitted] • Quinoxaline-based molecules were premeditated by structural amendment of TQ3. • FMO analysis exposed minimum HOMO-LUMO energy gap causing high charge transfer. • Designed novel molecules exhibited maximum absorption in visible and near IR regions up to 1080 nm. • Low values of reorganization energies for electron and hole exposed high charge mobility. [ABSTRACT FROM AUTHOR]

The development of polymer-based electrochromic devices (ECDs) with high stability and fast response time is of utmost importance for their effective utilization in ECD displays. In this study, we took inspiration from the random copolymer design strategy and successfully synthesized three solution-processable polymers, namely PTQ1, PTQ2, and PTQ3. These polymers were created using propylenedioxythiophene (ProDOT) as the donor unit and 5,8-dibromo-2-((2-ethylhexyl) oxy) quinoxaline (QX) as the acceptor unit, with varying feed ratios of ProDOT to QX (1:1, 2:1, and 3:1, respectively). Remarkably, all three polymers exhibited remarkably low oxidative initiation potentials and effective overpotentials, resulting in their respective ECDs displaying impressively fast response times of 1.8 s for PTQ1, and 0.9 s for both PTQ2 and PTQ3. Furthermore, these electrochromic polymers demonstrated exceptional stability, as indicated by their ability to maintain nearly 90% optical contrast even after 100,000 reversible switching cycles. This finding underscores the high stability of PTQ2 and PTQ3 when integrated into devices, highlighting their suitability for incorporation into future applications. Notably, owing to their fast response time and excellent reversibility, we were able to successfully fabricate two types of ECDs based on PTQ3: an inkjet-printed patterned ECD, as well as a larger 10 × 10 cm2 ECD. These achievements demonstrate the immense potential of the random copolymer strategy not only in the field of display technology but also in the development of smart windows. In conclusion, our research has successfully synthesized and characterized three solution-processable polymers for use in polymer-based ECDs. By employing the random copolymer design strategy, we have achieved impressive stability, fast response times, and high reversibility. These findings pave the way for the implementation of these electrochromic polymers in a wide range of applications, including displays and smart windows. [Display omitted] • Three solution-processable D-A copolymers were synthesized with different D:A ratios. • Increasing the ratio of D unit can effectively elevate the HOMO energy level and lower the oxidative initiation potentials. • The optical contrast still maintains over 90% after 100,000 reversible switching cycles. • An inkjet-printed large-area ECD was fabricated with vibrant electrochromic performance. [ABSTRACT FROM AUTHOR]