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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]

We tested five chemically and metabolically stable prostaglandin (PG) receptor agonists in a mouse model of dexamethasone-induced ocular hypertension (OHT). Whilst all compounds significantly (p < 0.05, ANOVA) lowered intraocular pressure (IOP) after twice-daily bilateral topical ocular dosing (5 µg/dose) over three weeks, the time course and magnitude of the responses varied. The onset of action of NS-304 (IP-PG receptor agonist) and rivenprost (EP4-PG receptor agonist) was slower than that of misoprostol (mixed EP2/EP3/EP4-PG receptor agonist), PF-04217329 (EP2-PG receptor agonist), and butaprost (EP2-PG receptor agonist). The rank order of IOP-lowering efficacies aligned with the onset of actions of these compounds. Peak IOP reductions relative to vehicle controls were as follows: misoprostol (74.52%) = PF-04217329 (74.32%) > butaprost (65.2%) > rivenprost (58.4%) > NS-304 (55.3%). A literature survey indicated that few previously evaluated compounds (e.g., latanoprost, timolol, pilocarpine, brimonidine, dorzolamide, cromakalim analog (CKLP1), losartan, tissue plasminogen activator, trans-resveratrol, sodium 4-phenyl acetic acid, etc.) in various animal models of steroid-induced OHT were able to match the effectiveness of misoprostol, PF-04217329 or butaprost. Since a common feature of the latter compounds is their relatively high affinity and potency at the EP2-PG receptor sub-type, which activates the production of intracellular cAMP in target cells, our studies suggest that drugs selective for the EP2-PG receptor may be suited to treat corticosteroid-induced OHT.

UNLABELLED: The industrial amino acid production workhorse, Corynebacterium glutamicum naturally produces low levels of 2,3,5,6-tetramethylpyrazine (TMP), a valuable flavor, fragrance, and commodity chemical. Here, we demonstrate TMP production (∼0.8 g L-1) in C. glutamicum type strain ATCC13032 via overexpression of acetolactate synthase and/or α-acetolactate decarboxylase from Lactococcus lactis in CGXII minimal medium supplemented with 40 g L-1 glucose. This engineered strain also demonstrated growth and TMP production when the minimal medium was supplemented with up to 40% (v v-1) hydrolysates derived from ionic liquid-pretreated sorghum biomass. A key objective was to take the fully engineered strain developed in this study and interrogate medium parameters that influence the production of TMP, a critical post-strain engineering optimization. Design of experiments in a high-throughput plate format identified glucose, urea, and their ratio as significant components affecting TMP production. These two components were further optimized using response surface methodology. In the optimized CGXII medium, the engineered strain could produce up to 3.56 g L-1 TMP (4-fold enhancement in titers and 2-fold enhancement in yield, mol mol-1) from 80 g L-1 glucose and 11.9 g L-1 urea in shake flask batch cultivation. ONE-SENTENCE SUMMARY: Corynebacterium glutamicum was metabolically engineered to produce 2,3,5,6-tetramethylpyrazine followed by a design of experiments approach to optimize medium components for high-titer production.

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]

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]

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 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]

The market for fine-flavor cocoa provides significant benefits to farmers. However, identifying the sensory qualities of chocolate under specific environmental conditions and measuring how its chemical compounds may be affected by climate differences and postharvesting practices remain a challenge. This study investigates how fermentation time and agroclimatic conditions in Colombia's fine cocoa-producing region of Arauca influence the sensory profile and volatile compound composition (volatilome) of chocolate derived from cocoa beans. Sensory evaluation was conducted on chocolates fermented for 48, 72, 96, and 120 h, revealing that fermentation time critically affects the development of fine-flavor attributes, particularly fruitiness and nuttiness. The optimal fermentation period to enhance these attributes was identified at 96 h, a duration consistently associated with peak fruitiness under all studied climatic conditions. Analysis of 44 volatile compounds identified several key aroma markers, such as acetoin, 1-methoxy-2-propyl acetate, and various pyrazines, which correlate with desirable sensory attributes. These compounds exhibited varying amounts depending on fermentation time and specific agroclimatic conditions, with a 96 h fermentation yielding chocolates with a higher quantity of volatile compounds associated with preferred attributes. Our findings highlight the complex interaction between fermentation processes and agroclimatic factors in determining cocoa quality, providing new insights into optimizing the flavor profiles of chocolate. [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]

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]

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True morels (Morchella spp.) are renowned for their aroma and taste, and hot air drying is widely used to extend the shelf life of harvested morels. However, the effects of different drying temperatures on volatile flavor compounds and non-volatile metabolites in the morel are poorly understood. Here, fresh morels (Morchella sextelata) were air-dried at low (45 °C, LT), medium (55 °C, MT), and high temperatures (65 °C, HT). The volatile flavor compounds and non-volatile metabolites were analyzed using GC-IMS and LC-MS/MS, respectively. The GC-IMS revealed that aldehydes, hydrocarbons, and pyrazines increased at greater temperatures, while acids, alcohols, and esters decreased. Random forest machine learning indicated that 1-hexanol and ethyl 3-methylbutanoate were indicative flavor compounds at LTs, while those at MTs and HTs were hexanal and valeraldehyde, respectively. Greater temperatures reduced acetic acid, an unpleasant sour flavor. The LC-MS/MS showed that the relative abundance of amino acids and nucleotides increased with the temperature, with the same trend in 5′-nucleotides and flavor amino acids. Sorbitol 6-phosphate was indicative of the non-volatile metabolites at LTs, while several amino acids were indicative at MTs and HTs. This study revealed the flavor and taste characteristics of morels dried at different temperatures, providing a theoretical reference for establishing a standardized postharvest morel drying process and maintaining morel quality. [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]

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]

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]

[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]

A new fire retardency APD was synthesized successfully by the condensation between 2‐aminopyrazine and DOPO, and target product APD was characterized by NMR. Absorption peak at 12.6 ppm in 31P NMR verified complete consumption of the reactant DOPO and further confirmed the structure of APD. The safety of epoxy resin (EP) in fire disaster was dramatically improved by introduction of APD. Epoxy resin modified with 8% APD succeeded in vertical burning (UL‐94) test with V‐0 rating and limited oxygen index (LOI) of EP/8% APD was also improved to 33.9%. Cone calorimeter (CC) test further exhibited fire resistant effect of APD on EP in detail. 11.0 g APD reduced total heat release of 100 g EP to 35.1% and reduced total smoke product of 100 g EP to 19.9%. Char residue from CC test of EP/8% APD was analyzed by Raman, XPS, SEM, and FTIR tests. The results of these tests indicated that compact morphology of char residue from EP/8% APD possessed a positive effect in blocking fire spread. Highlights: APD was synthesized and fire resistant EP was made.EP/APD acquired outstanding fire resistance and moderate mechanical properties.APD played fire resistant role in gas phase and condensed phase. [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]

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]

Cocoa is the third most important global agricultural export commodity. However, because it is a crop sensitive to climatic change, there has been an active search for cocoa substitutes worldwide. Roasted jackfruit seeds were previously described as having a chocolate aroma and are affordable and accessible. In this study, we characterized and identified by SPME-GC-O and SPME-GC-MS the aroma profile of cocoa-based beverages formulated with jackfruit seed flour as a natural cocoa substitute. Our analysis tentatively identified 71 odor-active aroma descriptors with some similarities between formulations. Overall, 15 odor-active aromas were present in all beverages. The formulation containing only cocoa/chocolate showed the following aroma descriptors: cocoa, hazelnut, peanut butter, earthy, and roast, which are mostly related to the presence of 2,3-dimethylpyrazine and 2,3-diethyl-5-methylpyrazine. The fermented beverage had a content of complex pyrazines such as 2,3,5-trimethyl-6-isopentylpyrazine and methylpropylpyrazine. Our data indicated that both the control and fermented beverages showed a similar aromatic profile, mainly earthy, pyrazine, and chocolate. Qualitative similarities in the pyrazine content were observed between the fermented jackfruit seed flour and cocoa beverages. In conclusion, fermented jackfruit seed flour can be incorporated into cocoa-based beverages as a natural chocolate substitute, offering the potential to elevate the chocolate aroma. [ABSTRACT FROM AUTHOR]

Diabetes Mellitus (DM) is a chronic disease that occurs when the pancreas does not produce enough insulin, or the body cannot use insulin effectively. Type 2 DM treatment can be done using antidiabetic drugs, but the continuous use of synthetic drugs will cause side effects. Empirically, the people of Nias Indonesia use palm juice (Arenga pinnata Merr.) as an antidiabetic, which can reduce blood glucose levels. This study aimed to find the active compounds in palm juice that can potentially be an antidiabetic type 2 using an in silico approach. The methods used were toxicity screening, profile pharmacokinetics, drug scanning, docking, and molecular dynamics simulation. Screening, molecular docking, and molecular dynamics of 30 compounds generated from pyrazine and furan revealed that two compounds, PF 16 and PF 30, can bind to receptors and produce lower ΔG values than metformin HCl. Molecular dynamics simulation results using the MM-GBSA calculation method showed that the PF 16 compound was more selective to the 2PDY (aldose reductase) with a value of -39.23 kcal/mol, while compound PF 30 was more selective to 1Z89 (aldose reductase) with a value of -7.36 kcal/mol. It can be concluded that the level of affinity of the PF 30 compound to the 1Z89 receptor and the PF 16 compound to the 2PDY were predicted to have the potential as antidiabetic (DM type 2). [ABSTRACT FROM AUTHOR]

To explore the effects of different preservation methods on the quality of loquat after fresh-keeping treatment, various preservation techniques were employed. These included natural preservation (NP), vacuum freezing preservation (VFP), vacuum at room temperature preservation (VP) and freezing preservation (FP). The quality assessment involved analyzing the effects of these preservation methods using physicochemical indexes, a colorimeter, an electronic nose (E-nose), an electronic tongue (E-tongue) and gas chromatography–mass spectrometry (GC–MS). The results showed minor differences in loquat quality under different preservation methods, with sensory scores ranging from 55 to 78 and ΔE values ranging from 11.92 to 18.59. Significant variations were observed in moisture content (ranging from 53.20 g/100 g to 87.20 g/100 g), calorie content (ranging from 42.55 Kcal/100 g to 87.30 Kcal/100 g), adhesion (ranging from 0.92 to 1.84 mJ) and hardness (ranging from 2.97 to 4.19 N) (p < 0.05). Additionally, the free amino acid content varied from 22.47 mg/g to 65.42 mg/g. GC–MS analysis identified a total of 47 volatile flavor substances in varieties of loquats, including 13 aldehydes, 9 esters, 6 ketones, 2 acids, 3 alcohols, 2 phenols, 3 pyrazines, 1 furan and 8 other substances. The relative content of aldehydes was significantly higher than that of other chemicals. The VFP and FP samples exhibited higher aldehyde content compared to the NP and VP samples. Moreover, Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) revealed 18 marked compounds that could differentiate between 5 loquat species. Analysis using E-nose and E-tongue indicated significant changes in the olfactory and gustatory senses of loquats following preservation. The VFP samples demonstrated the most effective preservation of loquat quality with minimal impact. This study provides some theoretical guidance for the home preservation of loquats. [ABSTRACT FROM AUTHOR]

The reactions of cage‐opened C60 derivatives with aromatic diamines are known to cause an orifice‐enlargement in association with incorporating extended π‐systems. The present work focuses on 1,2‐, 2,3‐, and 1,8‐diaminonaphthalenes for the synthesis of a series of naphthalene‐fused fullerene derivatives. For the former two, orifice enlargement proceeded by cleaving two C=C bonds to afford an opening with a ring‐atom count of 20, in which the naphthalene moiety was fused by a pyrazine ring. For the reaction with 1,8‐diaminonaphthalene, only one C=C bond was cleaved to give a 17‐membered‐ring opening where the diaminonaphthalene moiety was fused by a pyrimidine ring. [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]

Human society faces significant environmental challenges due to the rapid production and consumption of fossil fuels. Therefore, developing effective and environmentally friendly methods of generating and storing energy is essential. Hypercrosslinked polymers (HPPs) have become increasingly popular due to their diverse preparation methods, simple functionalization, large specific surface area, low cost, mild reaction conditions, high chemical and thermal stability, and small size. We synthesized two hypercrosslinked porous organic polymers using Friedel‐Crafts reactions of 2,3,5,6‐tetraphenyl pyrazine (Pyra) with 4,4′‐bis(chloromethyl)biphenyl (BP), and dimethoxymethane (DDM), resulting in Pyra‐BP‐HPP and Pyra‐DDM‐HPP, respectively. The chemical structures and thermal stability of these polymers were confirmed through solid‐state 13C NMR, FTIR, and TGA. The surface area of Pyra‐BP‐HPP and Pyra‐DDM‐HPP was determined to be 984 and 435 m2 g−1, respectively, with micro and mesoporous structures present. Pyra‐BP‐HPP displayed a high specific capacitance of 94 F g−1 at 1 A g−1, with a capacity retention of 95% after 2000 cycles, which can be attributed to its larger surface area, microporosity, and abundance of electron‐rich phenyl rings when compared to Pyra‐DDM‐HPP. [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]