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Conical intersections (CIs) play a crucial role in photochemical reactions, offering an efficient channel for ultrafast non-adiabatic relaxation of excited states. This significantly influences the reaction pathways and the resulting products. In this work, we utilize the non-Markovian stochastic Schrödinger equation with complex modes method to explore the dynamics of electronic transitions through conical intersections (CIs) in pyrazine. The linear vibronic coupling model serves as the foundational framework, incorporating both intra-state and inter-state electron–vibrational interactions. The dynamics of the excited electronic transitions are analyzed across varying strengths of system–bath coupling and different bath relaxation times. The accuracy of this method is demonstrated by comparing its predictions with those from the hierarchical equations of motion method. [ABSTRACT FROM AUTHOR]

The exploration of cyclo‐N5ˉ‐based energetic cocrystals represents a noteworthy avenue within pentazolate chemistry, focusing on leveraging cocrystallization to enhance stability. Recently, a novel cocrystal explosive, N2H5N5/PDO, was developed by combining N2H5N5 with pyrazine 1,4‐dioxide (PDO), exhibiting promising detonation characteristics and reduced sensitivity. This study endeavors to elucidate how the structure and noncovalent interactions impact the performance of N2H5N5/PDO through a first‐principles investigation. The results indicate that the enhanced hydrogen bonding and wave‐like crystal packing structure within the cocrystal effectively bolster its stability compared to N2H5N5. The N···H and O···H interactions, in conjunction with π–π interactions, emerge as critical elements driving cocrystal formation. Compared to the pure N2H5N5, the detonation performance of the cocrystal exhibits a slight decline, albeit with a noticeable reduction in sensitivity. [ABSTRACT FROM AUTHOR]

In this paper, a series of Zr metal‐organic frameworks, whose hexanuclear clusters of Zr are connected with luminescent rodlike dicarboxylic acids, are used for the construction of a sensor array to selectively detect various analyte vapors. The chemical functionalization of the ligand (HOOC[PE‐aryl‐EP]COOH) (which alternates phenylene(P) and ethynylene(E) units) through the aryl core, is focused on obtaining six Porous Interpenetrated Zirconium‐Organic Frameworks (PIZOFs) with distinctive luminescent properties. Particularly, the synthesis of two new ligands (aryl = nitrobenzene;metal‐organic frameworks aryl = pyrazine) enabled the preparation of new PIZOFs (UPO‐1 and UPO‐2) with submicron sizes, thanks to the use of a microwave‐assisted synthetic method. The fluorescence properties of these two new PIZOFs, along with four others already reported, are thoroughly evaluated and noticeable changes are observed in their optical properties based on variations in the aryl core of the ligands. Furthermore, the presence of various volatile analyte vapors particularly modified their characteristic emission, resulting in multiple optical responses that are combined to achieve selectivity in detecting these analytes. Specifically, the construction of a fluorescent sensor array is proposed, incorporating the six PIZOFs into polyvinylidene‐fluoride (PVDF) films, capable of producing unique identification patterns for each analyte by leveraging the cross‐responsiveness of these sensing materials. [ABSTRACT FROM AUTHOR]

The reduction of oximes was recently identified as a promiscuous activity of Old Yellow Enzymes (OYEs). This reaction involves a two‐step reduction of α‐oxime‐ß‐ketoesters to the corresponding amines, which spontaneously dimerise to yield pyrazine derivatives. This biotransformation is currently limited to substrates with small substituents like methyl/ethyl on the keto moiety. We used a structure‐based approach to engineer 12‐oxophytodienoate reductase 3 (OPR3) from Solanum lycopersicum as a prototypical OYE to accept oximes with bulkier substituents. To this end, three single and two double variants were prepared and tested on six oxime substrates. The engineered variants indeed showed activity on some of the bulkier substrates, which had not been converted at all by the wild‐type enzyme, including the diester compound diethyl‐2‐(hydroximino) malonate. While we were unable to identify variants capable of converting substrates with branched and aromatic substituents, the results demonstrate the validity of our engineering approach, suggesting potential pathways for expanding the substrate scope of OYEs. [ABSTRACT FROM AUTHOR]

d‐Allulose, a C‐3 epimer of d‐fructose, is a rare sugar with ∼70% of the sweetness of sucrose but a caloric content of only 0.4 kcal/g. Due to its low‐calorie nature, d‐allulose has garnered increasing interest in the food industry. This study was the first attempt to explore the effect of d‐allulose as a sucrose replacer on the properties of sponge cake, a widely consumed high‐sugar product. Substituting sucrose with d‐allulose generated negligible impact on the batter system, while pronounced differences in physicochemical properties of cakes were detected, including specific volume, texture, microstructure, color, and antioxidant activity. In addition, sponge cake containing d‐allulose displayed a distinctive aroma volatile profile, with more furans and pyrazines generation. Furthermore, correlations of physicochemical properties across all formulations were depicted, and the potential mechanism behind the property alterations modulated by d‐allulose was revealed from the perspectives of starch gelatinization and browning reactions. Overall, this study provides insights into the application potential of d‐allulose as a sucrose substitute in bakery product. Practical Application: This study elucidates the effect of d‐allulose as a low‐calorie sugar substitute on sponge cakes. This finding is valuable for the food industry, providing insights into a healthier alternative to traditional sugar in baked goods. [ABSTRACT FROM AUTHOR]

AbstractDye-sensitized solar cells (DSSCs) have garnered significant attention due to their exceptional ability to convert solar energy into electricity at a relatively low cost. Novel organic photosensitizers (FZB1-FZB9) from the pyrazine-based aromatic dye (E)-3-(5-(2,3-bis(40-(diphenylamino)-[1,10-biphenyl]-4-yl)-7 (trifluoromethyl)quinoxalin-5-yl)thiophen-2-yl)-2-cyanoacrylic acid (TPPF) have been quantum chemically modeled for their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). The electrochemical and photovoltaic features of modeled dyes are investigated by performing DFT insights, i.e. FMOs, absorption maxima, DOS, TDM, NBO, exciton and binding energy, radiative lifetime analysis (ꚍ), electron-injection (ΔGinject) and regeneration analysis (ΔGdyeregen)@TiO2. FMO analysis confirmed the better electron injection as HOMO of designed dyes was found to be more positive than redox potential I/I3 (-4.8 eV), and the LUMO appeared more negative than the conduction band of TiO2 (-4.0 eV). The modeled photosensitizers exhibited red shift λmax from 338-494 nm with a lower energy gap from 5.62 eV in FZB (R) to 5.17 eV in FZB9. Bridging modification reduces the exciton and binding energy for designed dye FZB9 and FZB7 compared to reference FZB. The designed dyes appeared with a lower radiative lifetime of up to 1.32 than the reference dye of 1.63, better light harvesting efficiency (LHE), and the highest NBO charge on bridges of designed photosensitizers for enhanced light emitting efficiency. The investigated dyes exhibited more negative values for electron injection, i.e. −0.003 and the highest values of dye regeneration (ΔGregedyeregen) up to 11.717, which unveils innovative and effective injection of electrons toward semiconductor TiO2. Among all dyes, FZB8 proved best with the novel bridging modification that enables quick charge transfer as exhibited the lowest gap (5.17 eV), lowest excitation energy, better LHE, highest charge on LUMO and more negative electron injection (ΔGinject). The outcomes of this computational study confirmed that this research established a new benchmark for achieving novel and efficient photosensitizers, thus recommending them for future DSSC applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Herein, we have developed palladium‐trifluoroacetate‐catalyzed carbo‐palladation reaction of pyrrole‐2‐carbonitriles and aryl boronic acids leading to functionally diverse pyrrolo[1,2‐α]pyrazines under thoroughly optimized reaction conditions. The reaction proceeded smoothly and allowed the diversity‐oriented synthesis of pyrrolo[1,2‐α]pyrazines with broad substrate scope with respect to pyrrole‐2‐carbonitriles and aryl boronic acids. [ABSTRACT FROM AUTHOR]

An organic cathode material for zinc-ion batteries shows a reliable proton transport mechanism. It uses a pyrazine ring as the energy storage unit and H+ as the shuttle ion, enabling high functionality utilization with rapid redox kinetics. [ABSTRACT FROM AUTHOR]

An unexpected nitro group displacement during a nitro-Mannich reaction led to the one-pot formation of the octahydro-2H-pyrazino[1,2-a]pyrazine core, representing the shortest access to date to this pharmacologically relevant heterobicyclic system. A mechanistic hypothesis is suggested and supported by specific experiments and HRMS analysis of reaction mixtures. [ABSTRACT FROM AUTHOR]

The emergence of extensively drug-resistant Salmonella Typhi (XDR-S. Typhi) poses a grave public health threat due to its resistance to fluoroquinolones and third-generation cephalosporins. This resistance significantly complicates treatment options, underscoring the urgent need for new therapeutic strategies. In this study, we synthesized pyrazine carboxamides (3, 5a–5d) in good yields through the Suzuki reaction. Afterward, we evaluate their antibacterial activities against XDR-S. Typhi via the agar well diffusion method; 5d has the strongest antibacterial activity with MIC 6.25 (mg/mL). Moreover, in vitro Alkaline Phosphatase inhibitor activity was also determined; 5d is the most potent compound, with an IC50 of 1.469 ± 0.02 µM. Further, in silico studies were performed to find the type of interactions between synthesized compounds and target proteins. [ABSTRACT FROM AUTHOR]

This study investigated the composition of the aroma substances and the physicochemical properties of lyophilized coffee produced from Ecuador Arabica and robusta coffee beans. In the present study, we propose a fast method of analyzing volatile compounds in coffee using the headspace solid phase extraction method (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). According to the results, 25 aroma compounds were detected in coffee, the most important of which are 2-acetylfuran, 2-furanmethanol, 2,3-dimethylpyrazine, 2,3,5-trimethylpyrazine, and 2-methoxy-4-vinylphenol. As is known, furans and pyrazines are associated with "roasted, cocoa, coffee, and hazelnut" odours. The most important organic acids detected in the study are citric, maleic, and succinic. [ABSTRACT FROM AUTHOR]

In this study, the volatile flavour compounds of baked potatoes from different cultivars were identified and analysed via headspace–gas chromatography–ion mobility spectrometry (HS-GC-IMS) together with principal component analysis (PCA). Totally, 89 signal peaks were detected, and 64 compounds were identified and classified into 25 aldehydes, 14 alcohols, 11 ketones, 5 esters, 2 furans, 1 pyrazine and others. Based on the signal intensity of the identified compounds, topographic plots and fingerprints were established to investigate the differences caused by cultivars. The main compounds including aldehydes, alcohols, ketones, esters, furan and pyrazine varied with cultivars; they were more abundant in B5 and B6 cultivars. Moreover, PCA and fingerprint similarity analysis clearly showed that these samples are independent and distinguishable. Results also showed that the GC-IMS technique might be helpful and useful in the rapid detection of volatile compounds in cooked potatoes and provide support for the domestic and industrial products. The obtained information could serve for breeding projects of new varieties with specific flavour profiles which comply with consumer demand. [ABSTRACT FROM AUTHOR]

By employing the doorway-window (DW) on-the-fly simulation protocol, we performed ab initio simulations of peak evolutions and beating maps of electronic two-dimensional (2D) spectra of a polyatomic molecule in the gas phase. As the system under study, we chose pyrazine, which is a paradigmatic example of photodynamics dominated by conical intersections (CIs). From the technical perspective, we demonstrate that the DW protocol is a numerically efficient methodology suitable for simulations of 2D spectra for a wide range of excitation/detection frequencies and population times. From the information content perspective, we show that peak evolutions and beating maps not only reveal timescales of transitions through CIs but also pinpoint the most relevant coupling and tuning modes active at these CIs. [ABSTRACT FROM AUTHOR]

Covalent triazine frameworks (CTFs) are promising battery electrodes owing to their designable functional groups, tunable pore sizes, and exceptional stability. However, their practical use is limited because of the difficulty in establishing stable ion adsorption/desorption sites. In this study, a melt‐salt‐stripping process utilizing molten trichloro iron (FeCl3) is used to delaminate the layer‐stacked structure of fluorinated covalent triazine framework (FCTF) and generate iron‐based ion storage active sites. This process increases the interlayer spacing and uniformly deposits iron‐containing materials, enhancing electron and ion transport. The resultant melt‐FeCl3‐stripped FCTF (Fe@FCTF) shows excellent performance as a potassium ion battery with a high capacity of 447 mAh g−1 at 0.1 A g−1 and 257 mAh g−1 at 1.6 A g−1 and good cycling stability. Notably, molten‐salt stripping is also effective in improving the CTF's Na+ and Li+ storage properties. A stepwise reaction mechanism of K/Na/Li chelation with C═N functional groups is proposed and verified by in situ X‐ray diffraction testing (XRD), ex‐situ X‐ray photoelectron spectroscopy (XPS), and theoretical calculations, illustrating that pyrazines and iron coordination groups play the main roles in reacting with K+/Na+/Li+ cations. These results conclude that the Fe@FCTF is a suitable anode material for potassium‐ion batteries (PIBs), sodium‐ion batteries (SIBs), and lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

The synthesis of substituted pyrazines from readily available methyl aryl/heteroaryl ketones and 1,2‐diamines was achieved using highly stable and reusable ferrite‐stabilized copper nanoparticles (Fe3O4‐CuO) as a catalyst. The reaction proceeds through a cascade imine formation–oxidative cyclization method under an oxygen atmosphere. The nanocatalysts were readily recovered and reused up to three consecutive cycles without any significant decrease in particle size, catalytic activity and reaction yield, as evidenced by analytical techniques such as transmission electron microscopy (TEM) and powder X‐ray diffraction (PXRD). The synthesized pyrazines exhibited photophysical behaviour, displayed large Stokes shifts, and were explored as fluorescent probes for the sensitive as well as selective "turn‐off" detection of iron with a limit of detection of 0.63 μM. The sensing method is also useful for the quantification of iron in spiked water samples. Furthermore, the application of luminescent pyrazines as fluorescent ink was successfully demonstrated. [ABSTRACT FROM AUTHOR]

High‐efficiency and long‐lifetime near‐infrared (NIR) organic light‐emitting diodes (OLEDs) are rarely reported. Herein, three efficient NIR Ir(III) complexes 1–3 are developed with specially designed cyclometallated ligands based on pyrido[3,4‐b]pyrazine and oriented substitutions along the Ir─N bond axis. Electron‐deficient pyrazine ring effectively stabilizes LUMO energy, leading to significant emission bathochromic shift. Importantly, for complexes 2 and 3, oriented substitutions along the direction of the Ir─N bond axis considerably enhance the horizontal emitting dipole orientation ratio up to 90%. Their OLEDs demonstrate high maximum external quantum efficiencies (EQEs), negligible efficiency roll‐offs, superior radiance, and long lifetimes. The maximum EQEs and radiances of devices are 9.84% and 158 W Sr−1 m−2 at 725 nm for 1, 6.98% and 14.03 W Sr−1 m−2 at 760 nm for 2, and 12.49% and 18.94 W Sr−1 m−2 at 735 nm for 3, respectively. The device lifetime LT97 at 10 mA cm−2 is 453 h for complex 2, which sets a champion lifetime for NIR‐OLEDs. This work demonstrates that pyrido[3,4‐b]pyrazine is a desired building block for robust NIR emitting Ir(III) complexes, providing a superior paradigm to combine high efficiency, negligible roll‐off, and long device lifetime simultaneously toward practical applications. [ABSTRACT FROM AUTHOR]

π‐Conjugated materials are highly attractive owing to their unique optical and electronic properties. Covalent organic frameworks (COFs) offer a great opportunity for precise arrangement of building units in a π‐conjugated crystalline matrix and tuning of the properties through choice of functionalities or post‐synthetic modification. With this review, we aim at summarizing both the most representative as well as emerging strategies for the synthesis of π‐conjugated COFs. We give examples of direct synthesis using large, π‐extended building blocks. COFs featuring fully conjugated linkages such as vinylene, pyrazine, and azole are discussed. Then, post‐synthetic modification methods that result in the extension of the COF π‐system are reviewed. Throughout, mechanistic insights are presented when available. In the context of their utilization as film devices, we conduct a concise survey of the prominent COF layer deposition techniques reported and their aptness for the deposition of fused aromatic systems. [ABSTRACT FROM AUTHOR]

The applicability of SNH and click reactions in the series of 2-amino-5-bromomethyl-3-(ethoxycarbonyl)pyrazine 1-oxide and its derivatives for the synthesis of distant analogs of folic acid and fluorophores was studied. The target products were synthesized in the yields up to 81%, and their structures were proved by 1H NMR spectroscopy and mass spectrometry. [ABSTRACT FROM AUTHOR]

As one of the most essential types of heterocyclic compounds, pyrazines have a characteristic smell and taste and have a wide range of commercial applications, especially in the food industry. With the development of the food industry, the demand for pyrazines has increased. Therefore, understanding the properties, functions, and synthetic pathways of pyrazines is one of the fundamental methods to produce, control, and apply pyrazines in food or medical systems. In this review, we provide an overview of the synthesis pathways and physiological or pharmacological functions of naturally occurring pyrazines. In particular, we focus on the biosynthesis and pharmacological effects of 2,3,5,6-Tetramethylpyrazine (TTMP), 2,5-Dimethylpyrazine (2,5-DMP), and 2,3,5-trimethylpyrazine (TMP). Furthermore, areas where further research on pyrazines is needed are discussed in this work. [ABSTRACT FROM AUTHOR]

BACKGROUND: Biogenic amines (BA) are hazardous components in Huangjiu (HJ). To ensure the quality of Dangshen Huangjiu (DSHJ), an orthogonal experiment L9 (33) was proposed to optimize the process by the main brewing factors (pre‐fermentation temperature, pre‐ and post‐fermentation time) that may affect BA and functional factors in DSHJ. DSHJ was produced with low BA content and high functional factors. Gas chromatography–ion mobility spectrometry combined with a multivariate statistical method (GC‐IMS‐MSM) was used to analyze the volatile components in the brewing process of DSHJ. RESULTS: The optimum brewing process parameters of DSHJ were as follows: pre‐fermentation temperature, 28 °C; pre‐fermentation time, 9 days; post‐fermentation time, 18 days. The average content of BA in DSHJ was 33.12 mg L−1, and the sensory score, total phenol content and DPPH free radical scavenging rate of DSHJ were significantly higher than those of HJ. A total of 14 esters, 7 acids, 7 alcohols, 1 ketone, 5 aldehydes and 1 pyrazine in DSHJ and HJ were identified by GC‐IMS. There were no significant differences (P > 0.05) in DSHJ and HJ in the soaking rice and saccharification stage. 11 components, such as ethyl acetate, and 12 components, such as acetic acid, were the different components of HJ and DSHJ in pre‐fermentation and post‐fermentation stages, respectively. In the post‐fermentation stage, the contents of 8 components in DSHJ such as ethyl acetate were higher than in HJ. CONCLUSION: The preparation process parameters of DSHJ optimized by orthogonal experiments can ensure that DSHJ has the advantages of low BA content, high total phenol content and good antioxidant activity. Sensory score and GC‐IMS‐MSM analysis found that DSHJ prepared using the optimal process had the characteristics of good taste and rich aroma. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hot compressed water (HCW), also known as subcritical water (SCW), refers to high‐temperature compressed water in a special physical and chemical state. It is an emerging technology for natural product extraction. The volatile organic compounds (VOCs) generated from the Maillard reaction between l‐ascorbic acid (ASA) and l‐cysteine (Cys) have attracted significant interest in the flavor and fragrance industry. This study aimed to explore the formation mechanism of VOCs from ASA and Cys and examine the effects of reaction parameters such as temperature, time, and pH in HCW. RESULTS: The identified VOCs were predominantly thiophene derivatives, polysulfides, and pyrazine derivatives in HCW. The findings indicated that thiophene derivatives were formed under various pH conditions, with polysulfide formation favored under acidic conditions and pyrazine derivative formation preferred under weak alkaline conditions, specifically at pH 8.0. CONCLUSION: The Maillard reaction between ASA and Cys mainly produced thiophene derivatives, polysulfides, and pyrazine derivatives in HCW. The generation mechanism was significantly dependent on the surrounding pH conditions. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In series‐connected tandem organic solar cells (TOSCs), various light‐harvesting molecules with complementary absorptions are explored with the aim of collaboratively utilizing solar light to the maximum extent. In sharp contrast to the small molecular acceptors that possessing almost the successively tunable bandgaps, high‐performance wide‐bandgap (WBG) polymer donors in TOSCs are quite scarce, with only PM6 (optical bandgaps, Egopt = 1.80 eV) and D18 (Egopt = 1.98 eV) being widely used. Herein, to develop WBG polymer donors with large open‐circuit voltages (VOC) and high‐energy photon absorption, two pyrazinyl polymer donors, PPy1 and PPy2, are synthesized with branched 2‐butyloctyl and n‐dodecyl chains on polymeric backbones, respectively, demonstrating the downshifted highest occupied molecular orbital energy levels of ≈−5.60 eV and thus afford Egopt over 2.0 eV. Consequently, when blending with a WBG acceptor F‐ThCl, PPy2:F‐ThCl‐based devices exhibit a higher power conversion efficiency (PCE) of 14.50% and fill factor of 77.66%. In light of its large VOC of 1.07 V, TOSCs based on PPy2 are further fabricated and exhibit an impressive PCE of 19.35% by using a narrow bandgap blend of PM6:CH1007:F‐2F as a rear cell. This work demonstrates the great potential of pyrazine units in constructing WBG polymer donors for achieving record‐breaking TOSCs. [ABSTRACT FROM AUTHOR]

Enzalutamide (Enz), sold under the brand name "XTANDI", belongs to a group of drugs known as androgen receptor inhibitors and functions by suppressing androgen's actions, which in turn helps in treating castrate-resistant prostate cancer. The current study focuses on the solvates and cocrystals of enzalutamide. Firstly, we obtained single crystals of 1,4-dioxane (Dox) solvate in two different stoichiometric ratios, Enz–Dox 1 : 0.5 and Enz–Dox 2 : 0.5. Based on this, we chose the coformer pyrazine (Pyrz), which is structurally similar to the Dox solvate. Crystallization of Pyrz with Enz also yielded 1 : 0.5 and 2 : 0.5 stoichiometries like the Dox solvate, but these existed as cocrystals (Enz–Pyrz 1 : 0.5 and Enz–Pyrz 2 : 0.5). Despite the solvate and cocrystal of the same stoichiometry (1 : 0.5/2 : 0.5) exhibiting identical sorts of interactions, the inclusion of a coformer in the cocrystal prompted a few additional bonds to form, but the overall crystal environment is still preserved. From the packing similarity analysis, it was found that Enz–Dox 1 : 0.5 and Enz–Pyrz 1 : 0.5 have similar packing indexes; however, the former generates a 2D hydrogen bonded network and the latter leads to a 3D network. The same trend is observed in the cases of Enz–Dox 2 : 0.5 and Enz–Pyrz 2 : 0.5. Hirshfeld analysis was performed to evaluate the prominence of various intermolecular interactions. Void map analysis enabled us to understand the roles of solvent and coformer in the crystal packing. Periodic DFT computations and DSC studies were performed to correlate thermal stabilities of solvates and cocrystals. Accelerated stability experiments revealed the better stability of cocrystals over solvates. This study provides valuable insights into solvate formation, which can be used as an effective strategy for attaining cocrystals with desired entities. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) materials are expected to address triplet‐related losses in electrically driven organic lasers, as the electrically generated triplets in the materials can be converted to radiative singlets through reverse intersystem crossing (RISC). This offers a way to bypass triplet absorption and annihilation in organic semiconductor lasers (OSLs). In this work, two versatile TADF emitters 4tCzPz and 4αCbPz for application in organic light‐emitting diodes (OLEDs) and OSLs are presented. Both emitters possess moderately high singlet‐triplet energy gap, ΔEST (≈0.30 eV) and show high photoluminescence quantum yields, ΦPL, in solution and solid‐state and prominent stimulated emission features in solution. Films of 4tCzPz and 4αCbPz doped in mCBP show an amplified spontaneous emission (ASE) threshold of 41.0 and 44.9 µJ/cm2, respectively. The OLEDs with 4tCzPz and 4αCbPz emit with peak wavelengths of 492 and 475 nm, respectively, and show corresponding maximum external quantum efficiencies, EQEmax, of 24.6 and 21.3%. The research shows that D‐A TADF materials hold significant potential not only as emitters for OLEDs but also in OSLs. [ABSTRACT FROM AUTHOR]

The direct two‐step synthesis of new coordination polymer [Co2(pyz)(tfa)2(dmf)6(H2O)][Co3(μ3‐F)(tfa)6(pyz)(dmf)]2 ⋅ 2dmf, (where pyz=pyrazine, Htfa=trifluoroacetic acid, dmf=dimethyl formamide) containing the fluoro‐centered secondary building block [Co3(μ3‐F)(tfa)6], is reported. The substance characterization using single‐crystal XRD, powder XRD, IR‐spectroscopy and thermogravimetry was performed. SCXRD data revealed the presence of cationic and anionic subsystems, both containing cobalt(II) ions and pyrazine bridging ligands. The magnetic proper‐ties of the compound were collected and discussed. Temperature dependence of magnetic susceptibility shows Curie–Weiss like behavior at all studied temperatures. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) is an emission mechanism whereby both singlet and triplet excitons can be harvested to produce light. Significant attention is devoted to developing TADF materials for organic light‐emitting diodes (OLEDs), while their use in other organic electronics applications such as sensors, has lagged. A family of TADF emitters, TPAPyAP, TPAPyBP, and TPAPyBPN containing a triphenylamine (TPA) donor and differing nitrogen‐containing heterocyclic pyrazine‐based acceptors is developed and systematically studied. Depending on the acceptor strength, these three compounds emit with photoluminescence maxima (λPL), of 516, 550, and 575 nm in toluene. Notably, all three compounds show a strong and selective spectral response to the presence of ZnCl2, making them the first optical TADF sensors for this analyte. It is demonstrated that these three emitters can be used in vacuum‐deposited OLEDs, which show moderate efficiencies. Of note, the device with TPAPyBPN in 2,8‐bis(diphenyl‐phoshporyl)‐dibenzo[b,d]thiophene (PPT) host emits at 657 nm and shows a maximum external quantum efficiency (EQEmax) of 12.5%. This electroluminescence is significantly red‐shifted yet shows comparable efficiency compared to a device fabricated in 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (CBP) host (λEL = 596 nm, EQEmax = 13.6%). [ABSTRACT FROM AUTHOR]

Organic cathode materials for aqueous rechargeable zinc batteries (ARZBs) are rapidly gaining prominence, while the exploration of compounds with affordable synthesis, satisfactory electrochemical performance, and understandable mechanisms still remains challenging. In this study, 6,8,15,17‐tetraaza‐heptacene‐5,7,9,14,16,18‐hexaone (TAHQ) as an easily synthesized organic cathode material with novel quinone/pyrazine alternately conjugated molecule structure is presented. This organic electrode exhibits good capacity with highly reversible redox reactions, and the influence of multi‐active structures on the Zn2+/H+ loading behavior is systematically investigated by ex situ spectroscopy, electrochemical tests, and computation. Both experimental and theoretical studies effectively address the Zn2+/H+ intercalation/deintercalation kinetics. Benefitting from the fused active functionalities, the assembled Zn//TAHQ battery displays a maximum discharge specific capacity of 254.3 mAh g−1 at 0.5 A g−1, and it maintains remarkable cycle performance with 71% capacity retention after 1000 cycles under 5 A g−1. [ABSTRACT FROM AUTHOR]

The successful mono‐ and diprotonation of DAMN showed the first site of protonation to be an amino group, while the second protonation occurs at a nitrile group. The prepared salts were characterized by vibrational spectroscopy and single crystal X‐ray crystallography. Under strong superacidic conditions and with sufficient time cyclization of two (di)protonated molecules of DAMN is observed, yielding a tetracationic pyrazine species. Quantum chemical calculations are employed to explain reactivity and properties of compounds shown in the manuscript. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel AIE-TADF photosensitizer was constructed based on triphenylamine and pyrazine. • The control of singlet oxygen and superoxide radical can be realized by using AIE-TADF molecule as photosensitizers. • The AIE-TADF can be used as photocatalysts for photocatalytic oxidation of phosphine and hydroazobenzenes in water. Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4′-(12-(pyridin-4-yl)dibenzo[ f , h ]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N, N -diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (Δ E ST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O 2 , which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly. [ABSTRACT FROM AUTHOR]

Forty-five "4H, 8H difurazano[3,4-b;3′,4′-e] pyrazine (DFP) based energetic derivatives" were designed, and their heat of formation, stability, detonation performance, and impact sensitivity properties were comprehensively studied using density functional theory. The changes in these properties caused by changes in the type and quantity of substituents were analyzed. The results showed that the density range of DFP based energetic derivatives was 1.62–2.02 g/cm, the detonation velocity range was 7.02–9.18 km/s, and the detonation pressure range was 20.99–38.72 GPa. The introduction of –NH2 and –NHNH2 groups can effectively reduce the chemical reactivity of the compounds, while the introduction of –NHNH2 groups can efficiently improve the heat of formation and detonation performance of the compounds and reduce the sensitivity of the derivatives. Compounds B8 (4H, 8H bis ([1,2,5] oxadiazolo) [3,4-b:3′,4′-e] pyrizine-4,8-diyl nitrate), C8 (8-(trinitromethyl)-4H, 8H bis ([1,2,5] oxadiazolo) [3,4-b:3′,4′-e] pyrizin-4-yl nitrate), E4 (N-(8-hydrazine-4H, 8H bis ([1,2,5] oxadiazolo) [3,4-b:3′,4′-e] pyrizin-4-yl) nitrate, E8 (8-(nitroamino)-4H, 8H bis([1,2,5] oxadiazolo) [3,4-b:3′,4′-e] pyrizin-4-yl nitrate) can be used as candidates for high-energy density materials. [ABSTRACT FROM AUTHOR]

The electrophilic activation of 2H‐azirines with triflic anhydride (Tf2O) for an addition/cyclization reaction producing 2‐aryl‐pyrido[2,3‐b]pyrazines regioselectively is described. This reaction proceeds via nucleophilic addition of 3‐amino‐2‐fluoropyridines onto 1‐trifloyl‐aziridin‐2‐yl triflates and subsequent cyclization via SNAr. Desulfonylation and oxidation provides a single regioisomer of the aza‐bicyclic heterocycle after treatment with Et3N. Optimization of the reaction conditions lead to a range of 2‐aryl‐pyrido[2,3‐b]pyrazines in isolated yields of 20 % to 60 %. [ABSTRACT FROM AUTHOR]

The development of reaction pathways and ancillary ligand scaffolds is essential in the pursuit of higher nuclearity rare earth metal clusters that are relevant in storage materials and catalysis. Guanidinate anions represent attractive ligands due to their high degree of customizability allowing for facile alterations of both their steric and electronic properties. Here, we demonstrate an unprecedented bridge splitting reaction that shifts chloride anions in favor of a bridging neutral pyrazine to give pyrazine‐bridged dinuclear guanidinate rare earth complexes, [{(Me3Si)2NC(NiPr)2}2RECl]2(μ‐pyz) (RE =Y (1) and Er (2), pyz=pyrazine). Each six‐coordinate metal center is ligated by two guanidinates, one chloride ligand, and one nitrogen atom from the bridging pyrazine unit. The molecules were characterized by X‐ray crystallography, IR, NMR, and UV‐Vis spectroscopy. DFT calculations conducted on 1 provide insight into both the bonding picture and the mechanism of complex formation. This type of reaction constitutes a seminal application of a bridge splitting mechanism to the rare earth metals. [ABSTRACT FROM AUTHOR]

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

1,2,4‐triazolo‐[4,3‐a]pyrazine was prepared via a two‐step electrochemical, photochemical process. First, a 5‐substituted tetrazole is electrochemically coupled to 2,6‐dimethoxypyrazine to yield 1,5‐ and 2,5‐ disubstituted tetrazoles. Subsequent photochemical excitation of the 2,5‐disubstituted tetrazole species using an ultraviolet lamp releases nitrogen gas and produces a short‐lived nitrilimine intermediate. Subsequent cyclization of the nitrilimine intermediate yields a 1,2,4‐triazolo‐[4,3‐a]pyrazine backbone. The scope of this reaction was explored using various tetrazoles and pyrazines. Materials produced were identified using chemical analytical techniques and computationally studied for potential application as an insensitive energetic material. [ABSTRACT FROM AUTHOR]

The direct palladium‐catalyzed C−H arylation of 1,3,4‐oxadiazoles with challenging aryl chloride substrates is promoted by the use of a specifically designed electron‐rich ferrocenyl diphosphane. This protocol employs 0.5 to 1.0 mol % catalyst loading without any additives such as copper or ammonium salts, and equally tolerates electron‐donating and electron‐withdrawing substituents on the (heteroaryl)aryl halides, as illustrated by the efficient synthesis in 86 % yield of the anti‐tubercular agent PHOXPY (2‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)pyrazine) by a late‐stage arylation using 2‐chloropyrazine. [ABSTRACT FROM AUTHOR]

This article discusses the design and synthesis of heterocyclic core scaffolds for drug discovery research. The researchers were able to generate unique heterocyclic skeletons from a common derivative and discovered that an amino moiety could be added to the ring system through annulative reactions with quinones. The target compound possesses both carbonyl and amino groups, similar to biologically active quinones. The researchers optimized the reaction conditions and found that the use of Cu(OAc)2 as a catalyst provided the desired product in high yield. The synthesis of various compounds was also explored. These compounds were tested for their anticancer effects and showed good inhibitory activities against human hepatocellular cells and prostate adenocarcinoma cells. The study suggests that these compounds could be further developed as potential anticancer agents for the treatment of liver and prostate cancer. The given text provides data and information related to the synthesis and characterization of compounds 4a, 4b, 4c, 4d, and 4e. The compounds were synthesized using a general procedure involving the reaction of naphthoquinone with different reagents. The compounds were obtained in good yields and characterized using various techniques such as NMR and HRMS. The data presented in the text can be used by researchers studying the cytotoxic effects of these compounds on HepG2 and PC-3 cells. The document provides information on the synthesis and characterization of various compounds. The compounds are described in terms of their chemical structures [Extracted from the article]

In the last past twenty years, research on luminescent platinum (II) complexes has been intensively developed for useful application such as organic light emitting diodes (OLEDs). More recently, new photoluminescent complexes based on diazine ligands (pyrimidine, pyrazine, pyridazine, quinazoline and quinoxaline) have been developed in this context. This review will summarize the photophysical properties of most of the phosphorescent diazine Pt(II) complexes described in the literature and compare the results to pyridine analogues whenever possible. Based on the emission color, and the photoluminescence quantum yield (PLQY) values, the relationship between structure modification, and photophysical properties are highlighted. Tuning of emission color, quantum yields in solution and solid state and, for some complexes, aggregation induced emission (AIE) or thermally activated delayed fluorescence (TADF) properties are described. When emitting OLEDs have been built from diazine Pt(II) complexes, the external quantum efficiency (EQE) values and luminance for different emission wavelengths and in some cases, chromaticity coordinates obtained from devices, are given. Finally, this review highlights the growing interest in studies of new luminescent diazine Pt(II) complexes for OLED applications. [ABSTRACT FROM AUTHOR]

Context: The compounds of the "565" parent ring structure have received much attention from researchers because of their excellent detonation performance. In the present study, 81 derivatives were designed by introducing different substituents based on 6-dinitrophenyl-5,6,7,8-tetrahydro-4-imidazo[4,5-e]furazano[3,4-b] pyrazine (DIOP), which is a compound of the parent ring structure of 565, and the performance of these derivatives, such as the electronic structure, energy gap, heat of formation, and detonation performance, were investigated. Among these energy-containing derivatives, the density ranges from 1.70 to 2.17 g/cm3, the detonation velocity ranges from 8.01 to 10.26 km/s, and the detonation pressure ranges from 27.99 to 49.88 GPa. Through comprehensive analysis of several properties of DIOP derivatives, it was found that the oxygen balance of derivatives with the -ONO2 group was greater than zero and close to zero, while the oxygen balance of derivatives with other groups was almost all less than zero. Among them, G8 (D = 10.1 km/s, P = 47.72 GPa), H8 (D = 10.11 km/s, P = 47.92 GPa), and I8 (D = 10.26 km/s, P = 49.88 GPa) had higher detonation velocity and pressure among all derivatives, and their impact sensitivity was better than RDX. Therefore, three potential high-energy and less sensitive energy-containing derivatives, G8, H8, and I8, were screened out. The intramolecular interactions of the three derivatives were further analyzed, and it was found that there were intensive van der Waals interactions and significant spatial steric effects within the molecules, which had a positive effect on reducing the shock sensitivity of the compounds. Moreover, the three derivatives have a large degree of stacking, which leads to a high density. Methods: All calculations in this paper are performed using Gaussian16 based on density functional theory. Firstly, the structures of the derivatives were optimized at the level of B3LYP-D3/6-311G**, and then single-site energy calculations were carried out at the level of M06-2X-D3/def2-TZVPP, to reveal the effects of single substituents versus multiple substituents and isomerism on the properties of the DIOP-based energetic derivatives. Multiwfn was used to plot the density of states (DOS) of the derivatives and to calculate the molecular surface electrostatic potential at 0.001 e/Bohr3 electron density, 0.25 Bohr lattice spacing surface. [ABSTRACT FROM AUTHOR]

Nitrogenous heterocyclic rings are present in a wide range of drugs, natural compounds, and fine chemicals and are considered privileged scaffolds in medicinal chemistry. Seeking novel anti‐protozoal drugs acting on new targets or by novel mechanisms of action, we focused on a preliminary evaluation of the potential of "linear‐shaped" diaryl pyrazines. To this purpose, a two‐enzyme chemoenzymatic synthesis of this heteroaromatic core was carried out. Specifically, starting from simple, commercially available aromatic aldehydes, the target pyrazines were obtained through a sequence of biocatalytic benzoin condensation, chemical oxidation and a transaminase‐mediated tandem process of transamination and cyclization. The profiles of the compounds as antiprotozoal agents were evaluated in vitro against parasites cultures of the Leishmania and Plasmodium genera and using the human cell line HepG2. [ABSTRACT FROM AUTHOR]

Two new coordination polymers, [Cu(pz)(L)2(H2O)2](ClO4)2 (L = 2-Cl- (1) or 2-Br-4-pyridone (2); pz = pyrazine), have been synthesized and characterized by X-ray diffraction, EPR and variable temperature magnetic measurements. Both compounds crystallize as well isolated pyrazine-bridged chains with the heterocyclic ligands in the pyridone tautomer and coordinated via the oxygen atom. The Cu ions possess Jahn-Teller elongated octahedral geometries with the Jahn-Teller axis along the Cu-O axis. The water molecules in 2 are inequivalent with one molecule semi-coordinate (dCu...O = 3.225(6) Å) at an occupancy of 0.72. Both compounds exhibited axial powder EPR spectra, as expected. Variable temperature magnetic measurements are well fit by the uniform chain Heisenberg antiferromagnetic model with J = −10.74(4) K (1) or = −10.64(2) K (2). Comparison with the known 3-halo-4-pyridone compounds suggests an inverse relationship between the Cu-pz-Cu distance and the strength of the magnetic exchange. [ABSTRACT FROM AUTHOR]

In this study, a new series of 1,2,4-triazine and 1,2-diazine derivatives was prepared in four and three steps, respectively. In the preparation of 1,2,4-triazine derivatives. The first step included a reaction between 2-phenyl-3- aminoquinazoline-4-(3H)-one and chloroacetyl chloride in the presence of Et3N as a base to produce (1) in 83% yield. Compound (1) was then reacted in the second step with hydrazine hydrate to yield the corresponding hydrazide (2) in 80% yield. The third step of our work included a reaction of compound (2) with different compounds: α-Naphthan isocyanate to give compound (3) (90% yield); phenyl isocyanate to afford compound (4) (80% yield); phenyl isothiocyanate to yield compound (5) (85% yield); and CS2 in basic medium to provide compound (9) in 85% yield. In the fourth step, the products (3-5) were then cyclized in alkaline medium to give substituted trizines as six-membered rings (6-8) in 78-85% yields. The reaction of compound (9) with hydrazine hydrate afforded compound (10) in 80% yield. In the preparation of 1,2-diazine derivatives, compound (2) was treated with cyclic and aromatic anhydrides to give (11-15) in yields ranging from 75 to 86%. The prepared compounds were characterized by FT-IR, 13C NMR, and ¹H NMR spectroscopy and measured for a number of their physical characteristics. Also, certain tests have been performed on their anti-microbial activities on fungal strains, bacterial strains, and gram-negative and gram-positive bacteria for the identification of the most sufficient of the biologically active complexes. Finally, the anticancer activity of three prepared compounds (2, 12, and 13) was tested, and the results showed good effects of these compounds against prostate cancer PC3. [ABSTRACT FROM AUTHOR]

Thin films with thicknesses in the range between ca. 10–50 nm of the spin crossover (SCO) compound {Fe(pyrazine)[μ4-M(CN)4]} (M = Ni, Pt) have been deposited on fused silica substrates using a sequential assembly method and 4-pyridinecarboxylic acid as anchoring layer. Film morphology and crystallinity were assessed by means of atomic force microscopy and grazing incidence X-ray diffraction, respectively. The intensity of the π–π* transition of the pyrazine ligand at 270 nm, being rather insensitive to the spin state of the complex, was used to follow the film growth as a function of different deposition parameters. On the other hand, the spin state changes were inferred from the temperature dependence of absorption bands appearing at 540, 490 and 310 nm in the low spin state. In line with their amorphous nature, each film displays a very gradual thermal spin crossover between ca. 100–300 K, independently of its thickness and deposition conditions. These results are not only interesting to better understand the effects of size reduction and organization on the SCO phenomenon, but the deposition of these SCO compounds on electrically insulating and/or optically transparent oxide surfaces opens also the door for various photonic or electronic applications. [ABSTRACT FROM AUTHOR]

A series of 8‐(piperazin‐1‐yl) imidazo [1,2‐a] pyrazine derivatives were designed and synthesized as acetylcholinesterase inhibitors (AChEIs) and antioxidants for the treatment of Alzheimer's disease (AD). Moreover, the biological evaluation results demonstrated that these synthesized compounds exhibited moderate inhibitory activities toward acetylcholinesterase (AChE) and radical scavenging activities. Among them, the compound with the strongest inhibitory activity against AChE had an IC50 value of 0.55 μM, which was higher than that of galantamine as the reference compound (IC50 value=5.01 μM). The compound with the strongest antioxidant activity had an IC50 value of 57.94 μM, which was lower than that of the ascorbic acid (IC50 value=25.70 μM) as the control drug. Furthermore, the results of molecular docking studies indicated that the compound could simultaneously bind to both catalytic active site (CAS) and peripheral anionic site (PAS) of AChE, which was consistent with the mixed inhibition pattern shown by enzyme kinetic studies. The interaction's stability was also assessed using a conventional atomistic 100 ns dynamics simulation study, which revealed the conformational stability of representative compound in the cavity of the AChE. In addition, the molecular properties of all compounds were predicted online through the SwissADME, and most compounds matched the properties of most orally administered drugs. Based on the biological activity and molecular properties, 8‐(piperazin‐1‐yl) imidazo[1,2‐a] pyrazine derivatives as AChEI were valuable for further development. [ABSTRACT FROM AUTHOR]

A facile and atom‐efficient route via a new aqueous synthetic protocol for the greener and more efficient preparation of 3‐phenylpyrrolo[1,2‐a]pyrazine and 3‐phenylpyrazino[1,2‐a]indole by the one‐pot, three‐component method under mild reaction conditions is developed with substituted phenacyl bromides, aqueous ammonium hydroxide, and the corresponding 1H‐pyrrole‐2‐carbaldehyde and 1H‐indole‐2‐carbaldehyde. A reaction cascade consisting of N‐alkylation, imine formation, and annulation by condensation produces a sequence of three C−N bonds. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of novel hetrometallic complexes [{cis‐PtCl(NH3)2(μ‐4,4′‐bipyridyl)ZnCl(terpy‐Cl)}](ClO4)2 (C1a), [{trans‐PtCl(NH3)2(μ‐4,4′‐bipyridyl)ZnCl(terpy)}](ClO4)2 (C2a), [{cis‐PtCl(NH3)2(μ‐pyrazine)ZnCl(terpy‐Cl)}](ClO4)2 (C3a) and [{trans‐PtCl(NH3)2(μ‐pyrazine)ZnCl(terpy‐Cl)}](ClO4)2 (C4a) (where terpy‐Cl = 4′‐chloro‐2,2′:6′,2′′‐terpyridine) was done. Acid–base titrations were performed by UV–Vis spectrophotometric method to evaluate the pKa values of corresponding aqua complexes. Interactions between complexes and important biomolecules, guanosine‐5′‐monophosphate (5′‐GMP) and glutathione (GSH) were examined by 1H NMR spectroscopy. The chloride substituent at the 4′ position on the middle pyridine ring of terpyridine ligand significantly affects the coordination of biomolecules, as well as overall stability of complexes. The complexes were evaluated in vitro for the antioxidant prevention of DNA damages. All tested novel complexes demonstrated a significant reduction in DNA damage against oxidative modifications of DNA caused by the hydroxyl and peroxyl radicals. Also, cytotoxicity evaluation showed that significant cytotoxicity occurs only after long‐term effect of C1a, C2a and C3a, complexes in HCT‐116 cells. Molecular docking studies predict results in agreement with experimental research. [ABSTRACT FROM AUTHOR]

An effective method for the synthesis of heterocyclic steroids with the [1,2,5]oxadiazolo[3,4-b]pyrazine and [1,2,5]thiadiazolo[3,4-b]-pyrazine fragments was developed. The structure of the products was confirmed by X-ray structural analysis. The resulting compounds showed high antiproliferative activity against breast (MCF7) and prostate (22Rv1) cancer cells, which was not inferior to that of cisplatin and abiraterone acetate. [ABSTRACT FROM AUTHOR]

Aroma-active compounds in dried shrimp were investigated by aroma extract dilution analysis. Amino acids (Lys, Arg, Phe, Leu and Ile), reducing sugars (glucose, galactose, and arabinose) and total lipids were selected as precursors to construct 23 models, and then reacted at temperatures consistent with shrimp drying. The formation status and content of dried shrimp aroma-active compounds in each model were examined using gas chromatography-mass spectrometry. Twenty-seven aroma-active compounds were identified in the dried shrimp with flavour dilution (FD) factor ranges of 3 to 729, including 13 pyrazines, 5 aldehydes, 5 ketones, 2 alcohols and 2 N-containing compounds. Among them, FD factors of 5 pyrazines and trimethylamine were greater than 243. Pyrazines were the most important class of aroma-active compounds. The results of reaction model application indicated that Lys and Arg were the primary amino precursors of 13 aroma-active pyrazines and trimethylamine. Phe, Leu and Ile formed benzaldehyde, 3-methylbutanal and 2-methylbutanal, respectively. Glucose was the main carbonyl precursor. Lipids were the precursors of 2 alkylaldehydes, 4 ketones and 1-octen-3-ol, promoting the formation of pyrazines and Strecker aldehydes. This study provides a reference for improving flavour production and regulation of dried shrimp products, in particular the shrimp seasoning. [ABSTRACT FROM AUTHOR]

This article describes the synthesis and crystal structure of ten new Tc(V) complexes with pyrazine containing homologous alkoxy ligands. We carried out an analysis of the Hirshfeld surfaces for the described compounds and found out that with increasing length of the hydrocarbon substituent from CH3 to C10H21 the percentage of H⋯H interactions in crystals increases from 28% to 59%. The purpose of this article was to show the pattern of increase in interplanar distances in crystals depending on the length of the hydrocarbon substituent, and also to study the thermochemical properties of Tc(V) complexes. The mechanism of thermolysis does not depend on the length of the hydrocarbon substituent and differs only in the temperature range of the reactions. The absorption bands of the obtained complexes in IR and UV-vis spectra do not depend on the length of the hydrocarbon substituent. Using a complex with a propyl substituent as an example, the UV-vis spectral data of the mother solution are presented. Based on DFT calculations of spectra and molecular models, an indirect identification of the reaction intermediate is provided. Using a complex with a methyl substituent as an example, data on MALDI spectrometry are presented. [ABSTRACT FROM AUTHOR]

The carbonyl-rich conjugated organic compound of PTO-AQ exhibits the potential application in aqueous sodium ion batteries with wide voltage window workability. [Display omitted] Organic compounds have become an important electrode material for aqueous electrochemical energy storage. However, organic electrodes still face poor performance in aqueous batteries due to insufficient electrochemical activity. In this work, a novel conjugated quinone compound containing a rich carbonyl group was designed. The quinone compound was synthesized by a simple dehydration reaction of pyrene-4,5,9,10-tetrone (PTO) and 1,2-diaminoanthraquinone (1,2-AQ); it contains 4 pyrazines (C N) from AQ and 4 carbonyl groups (C O), as well as a large number of active sites and the excellent conductivity brought by its conjugated structure ensures the high theoretical capacity of PTO-AQ. In the context of aqueous sodium ion batteries (ASIBs), the electrode material known as PTO-AQ exhibits a notable reversible discharge capacity of 117.9 mAh/g when subjected to a current density of 1 A/g; impressively, it maintained a capacity retention rate of 74.3 % even after undergoing 500 charge and discharge cycles, a performance significantly surpassing that of pristine PTO and AQ. Notably, PTO-AQ exhibits a wide operating voltage range (-1.0–0.5 V) and a cycle life of up to 10,000 cycles. In situ Raman and ex situ measurements were used to analyze the structural changes of PTO-AQ during charge and discharge and the energy storage mechanism in NaAC. The effective promotion of Na+ storage brought by a rich carbonyl group was obtained. The structural energy level and electrostatic potential of PTO-AQ were calculated, and the active center distribution of PTO-AQ was obtained. This work serves as a guide for designing high-performance aqueous organic electrode materials that operate across a wide voltage range while also explaining their energy storage mechanism. [ABSTRACT FROM AUTHOR]

Developing low‐cost and high‐performance n‐type polymer semiconductors is essential to accelerate the application of organic thermoelectrics (OTEs). To achieve this objective, it is critical to design strong electron‐deficient building blocks with simple structure and easy synthesis, which are essential for the development of n‐type polymer semiconductors. Herein, we synthesized two cyano‐functionalized highly electron‐deficient building blocks, namely 3,6‐dibromopyrazine‐2‐carbonitrile (CNPz) and 3,6‐Dibromopyrazine‐2,5‐dicarbonitrile (DCNPz), which feature simple structures and facile synthesis. CNPz and DCNPz can be obtained via only one‐step reaction and three‐step reactions from cheap raw materials, respectively. Based on CNPz and DCNPz, two acceptor–acceptor (A–A) polymers, P(DPP‐CNPz) and P(DPP‐DCNPz) are successfully developed, featuring deep‐positioned lowest unoccupied molecular orbital (LUMO) energy levels, which are beneficial to n‐type organic thin‐film transistors (OTFTs) and OTEs performance. An optimal unipolar electron mobility of 0.85 and 1.85 cm2 V−1 s−1 is obtained for P(DPP‐CNPz) and P(DPP‐DCNPz), respectively. When doped with N‐DMBI, P(DPP‐CNPz) and P(DPP‐DCNPz) show high n‐type electrical conductivities/power factors of 25.3 S cm−1/41.4 μW m−1 K−2, and 33.9 S cm−1/30.4 μW m−1 K−2, respectively. Hence, the cyano‐functionalized pyrazine CNPz and DCNPz represent a new class of structurally simple, low‐cost and readily accessible electron‐deficient building block for constructing n‐type polymer semiconductors. [ABSTRACT FROM AUTHOR]