Quinone Compounds Research Articles

Triplet Energy Gap‐Regulated Room Temperature Phosphorescence in Host‐guest Doped Systems

The organic room temperature phosphorescence (RTP) materials via host‐guest doped method receive considerable attention in the fields of optoelectronics, bioimaging, and information encryption. Despite many host‐guest doped materials with excellent RTP properties have been developed, their luminous mechanism is still limited. Here, a series of host‐guest doped materials, using Benzophenone as the host and quinone compounds as the guests, were constructed to investigate the effect of the triplet energy gap (ΔET) between the host and guest on triplet states population. The guest’s triplet state is proposed to be a “triplet energy reservoir”, gathering the triplet excitons to emit RTP when ΔET is large and returning triplet excitons to the host when ΔET is small. By combining the results of steady‐state and delayed emission spectra, time‐resolved transient absorption, and theoretical calculations, A bidirectional energy transfer process is proved, which are triplet‐triplet energy transfer and reverse triplet‐triplet energy transfer processes. The thermal equilibrium of these two energy transfer processes can be regulated by the ΔET and temperature. The potential applications of these RTP properties are also realized in data encryption and anti‐counterfeiting. This work provides valuable insight into the design of host‐guest doped materials based on energy transfer mechanisms.

Triplet Energy Gap-Regulated Room Temperature Phosphorescence in Host-guest Doped Systems.

The organic room temperature phosphorescence (RTP) materials via host-guest doped method receive considerable attention in the fields of optoelectronics, bioimaging, and information encryption. Despite many host-guest doped materials with excellent RTP properties have been developed, their luminous mechanism is still limited. Here, a series of host-guest doped materials, using Benzophenone as the host and quinone compounds as the guests, were constructed to investigate the effect of the triplet energy gap (ΔET) between the host and guest on triplet states population. The guest's triplet state is proposed to be a "triplet energy reservoir", gathering the triplet excitons to emit RTP when ΔETis large and returning triplet excitons to the host when ΔETis small. By combining the results of steady-state and delayed emission spectra, time-resolved transient absorption, and theoretical calculations, A bidirectional energy transfer process is proved, which are triplet-triplet energy transfer and reverse triplet-triplet energy transfer processes. The thermal equilibrium of these two energy transfer processes can be regulated by the ΔETand temperature. The potential applications of these RTP properties are also realized in data encryption and anti-counterfeiting. This work provides valuable insight into the design of host-guest doped materials based on energy transfer mechanisms.

A High-capacity Benzoquinone Derivative Anode for All-organic Long-cycle Aqueous Proton Batteries.

Quinone compounds, with the ability to uptake protons, are promising electrodes for aqueous batteries. However, their application is limited by the mediocre working potential range and inferior rate performance. Herein, we examined quinones bearing different substituents, and for the first time introduce tetraamino-1,4-benzoquinone (TABQ) as anode material for proton batteries. The strong electron-donating amino groups can effectively narrow the band gap and negatively shift the redox potentials of quinone material. The protonation of amino groups and the amorphization of structure result in the formation of an intermolecular hydrogen-bond network, supporting Grotthuss-type proton conduction in the electrode with a low activation energy of 192.7 meV. The energy storage mechanism revealed by operando FT-IR and ex-situ XPS features a reversible quinone-hydroquinone conversion during cycling. TABQ demonstrates a remarkable specific capacity of 307 mAh g-1 at 1 A g-1, which is the highest among organic proton electrodes. An all-organic proton battery of TABQ//TCBQ has also been developed, achieving exceptional stability of 3500 cycles at room temperature and excellent performance at sub-zero temperatures.

Chemical speciation and oxidative potential of PM10 in different residential microenvironments: Bedroom, living room and kitchen

Exposure to particulate matter (PM) and its chemical constituents in residential microenvironments has become a major health concern worldwide. The oxidative potential (OP) has been proposed as a metric for estimating the PM capacity to induce oxidative stress and, consequently, health effects. In the present study, PM10 was daily monitored simultaneously in the bedroom, living room and kitchen of three dwellings for one week in a small town of Portugal, to perform a detailed characterisation of its organic and inorganic constituents and the determination of the OP. Bedrooms (B) were found to be a hotspot of PM10 concentrations (B1 = 22.7 μg m−3; B2 = 19.5 μg m−3; B3 = 68.1 μg m−3). PM10-bound elements varied significantly between microenvironments in all dwellings. Lower molecular weight polycyclic aromatic hydrocarbons (PAHs) were found to be between 14 and 72 times higher than high molecular weight PAHs in bedrooms. The mean volume-normalised OP determined by the dithiothreitol and ascorbic acid assays varied within the 0.01–0.38 nmol min−1 m−3 and 0.03–0.53 nmol min−1 m−3 ranges, respectively. Quinones, oxy-aromatic, aromatic and alkyl-aromatic compounds stood out in bedrooms. Strong and significantly positive relationship between OP and black carbon, Cu and Br were observed, indicating common redox active species mainly associated with traffic emissions. Sr, Fe, Zn and Zr presented higher concentrations in dwelling 3, exhibiting excellent positive correlation with OP, indicating that the Sahara dust intrusion recorded in that house may have contributed to the formation of more redox active species thought to drive antioxidant depletion responses.

Bioinspired coassembly of peptide, imidazolecarboxaldehyde, and copper for nanozyme with laccase-like activity for colorimetric detection of epinephrine

Epinephrine plays a vital role in the central nervous system, but its abnormal levels will result in various diseases. Therefore, facile, rapid and accurate detection of epinephrine is essential for clinical application. Due to its phenolic structure, epinephrine can be detected through colorimetric assays as it is oxidized by laccase to form a colored quinone compound. In this work, a laccase-like nanozyme, diphenylalanine peptide/4-imidazolecarboxaldehyde-Cu (FF/ICA-Cu), was designed to mimic the active center of natural laccase. The as-synthesized FF/ICA-Cu nanozyme showed high laccase-like activity because of its structural similarity to the natural laccase active center. Moreover, it exhibited excellent stability and recyclability, even under harsh conditions. Based on its laccase-like activity, a sensitive and selective sensing strategy for epinephrine was developed. This approach offers a promising avenue for accurately detecting epinephrine and designing catalysts with potential for future industrial applications.

The Effects of Ceric Ammonium Nitrate in the Oxidation of 2-Benzyl-1,4-dimethoxybenzene Derivatives

The one- or two-electron reduction in quinone compounds gives rise to semiquinones and hydroquinones, respectively, which, in turn, can be oxidized back to quinones, generating a cyclic redox system with the production of reactive oxygen species (ROS). For these reasons, quinone derivatives participate in various biological processes in metabolic pathways, such as oxidative reactions and electron transport. In addition, natural quinone compounds as well as their semisynthetic and/or synthetically produced derivatives are of great pharmacological interest for the discovery and design of new drugs. As a result, their chemical reactivity as well as new methods for their synthesis are being investigated on an ongoing basis. Herein, a mild and efficient synthesis to obtain 2-(4-benzyl substituted)-1,4-dimethoxybenzene derivatives is reported. In addition, an evaluation of the effects on the quinone/diquinone ratio in the reaction product in relation to different ways of adding the oxidant CAN to the arene solution is discussed.

Isolation, structural elucidation and biosynthetic pathway of bioactive prenyl quinone compounds from Panus lecomtei based on untargeted metabolomics combined with molecular networking

Panus lecomtei is a relatively unfamiliar and undeveloped mushroom. This study generated ethyl acetate extracts of P. lecomtei intracellular (I), extracellular (E) and total fermentation broth (T). Both E and T extracts demonstrated antioxidant and antibacterial activities at 100 to 200 μg/mL. The composition differences of metabolites of these extracts were further studied based on comparative metabolomics by LS/MS and molecular network analysis. The results revealed that there were over 2000 significantly distinct metabolites among the three extracts, with abundant prenyl quinone compounds. Furthermore, the molecular network clarified the conversion relationship of P. lecomtei metabolites. Seven known prenyl quinone derivatives (1–7) were isolated from the E extract. Among them, compound 3 displayed excellent antioxidant activity and modest antibacterial activity. Compound 5 was discovered in fungi for the first time. Finally, a potential biosynthetic route for prenyl quinone in P. lecomtei was suggested.

Oxygen‐Stable Electrochemical CO2 Capture using Redox‐Active Heterocyclic Benzodithiophene Quinone

Electrochemical carbon capture offers a promising alternative to thermal amine technology, which serves as the traditional benchmark method for CO2 capture. Despite its technological maturity, the widespread deployment of thermal amine technologies is hindered by high energy consumption and sorbent degradation. In contrast, electrochemical methods, with their inherently isothermal operation, address these challenges, offering enhanced energy efficiency and robustness. Among emerging strategies, electrochemical carbon capture systems using redox‐active materials such as quinones stand out for their potential to capture CO2.However, their practical application is currently limited by their low stability in the presence of oxygen. We demonstrate that benzodithiophene quinone (BDT‐Q), a heterocyclic quinone, exhibits high stability in electrochemical carbon capture processes with oxygen‐containing feed gas. Conducted in a cyclic flow system with a simulated flue gas mixture containing 13% CO2 and 3.5% O2 for over 100 hours, the process demonstrates high oxygen stability with an electron utilization of 0.83 without significant degradation, indicating a promising approach for real world applications. Our study explores the potential of new heterocyclic quinone compounds in the context of carbon capture technologies.

Oxygen-Stable Electrochemical CO2Capture using Redox-Active Heterocyclic Benzodithiophene Quinone.

Electrochemical carbon capture offers a promising alternative to thermal amine technology, which serves as the traditional benchmark method for CO2capture. Despite its technological maturity, the widespread deployment of thermal amine technologies is hindered by high energy consumption and sorbent degradation. In contrast, electrochemical methods, with their inherently isothermal operation, address these challenges, offering enhanced energy efficiency and robustness. Among emerging strategies, electrochemical carbon capture systems using redox-active materials such as quinones stand out for their potential to capture CO2.However, their practical application is currently limited by their low stability in the presence of oxygen. We demonstrate that benzodithiophene quinone (BDT-Q), a heterocyclic quinone, exhibits high stability in electrochemical carbon capture processes with oxygen-containing feed gas. Conducted in a cyclic flow system with a simulated flue gas mixture containing 13% CO2and 3.5% O2for over 100 hours, the process demonstrates high oxygen stability with an electron utilization of 0.83 without significant degradation, indicating a promising approach for real world applications. Our study explores the potential of new heterocyclic quinone compounds in the context of carbon capture technologies.

AQDS-functionalized biochar enhances the bioreduction of Cr(VI) by Shewanella putrefaciens CN32

The bioreduction of toxic chromium(VI) to sparingly soluble chromium(III) represents an environmentally friendly and cost-effective method for remediating Cr contamination. Usually, this bioreduction process is slow and requires the addition of quinone compounds as electron shuttles to enhance the reaction rate. However, the dissolved quinone compounds are susceptible to loss with water flow, thereby limiting their effectiveness. To address this challenge, this study loaded anthraquinone-2,6-disulfonate (AQDS), a typical quinone compound, onto biochar (BC) to create a novel solid-phase electron mediator (BC-AQDS) that can sustainably promote Cr(VI) bioreduction. The experimental results demonstrated that BC-AQDS significantly promoted the bioreduction of Cr(VI), where the reaction rate constant increased by 4.81 times, and the reduction extent increased by 38.31%. X-ray photoelectron spectroscopy and Fourier-Transform Infrared Spectroscopy analysis revealed that AQDS replaced the –OH functional groups on the BC surface to form BC-AQDS. Upon receiving electrons from Shewanella putrefaciens CN32, BC-AQDS was reduced to BC-AH2DS, which subsequently facilitated the reduction of Cr(VI) to Cr(III). This redox cycle between BC-AQDS and BC-AH2DS effectively enhanced the bioreduction rate of Cr(VI). Our study also found that a lower carbonization temperature of BC resulted in a higher surface –OH functional group content, enabling a greater load of AQDS and a more pronounced enhancement effect on the bioreduction of Cr(VI). Additionally, a smaller particle size of BC and a higher dosage of BC-AQDS further contributed to the enhancement of Cr(VI) bioreduction. The preparation of BC-AQDS in this study effectively improve the utilization of quinone compounds and offer a promising approach for enhancing the bioreduction of Cr(VI). It provides a more comprehensive reference for understanding and solving the problem of Cr pollution in groundwater.

STUDY THE EFFECT OF HYLOCEREUS POLYRHIZUS SOME ANTIOXIDANT FACTORS IN CHRONIC KIDNEY DISEASE PATIENTS

The current work was aimed to study the effect of Hylocereus polyrhizus some antioxidant factors in CKD patients and healthy persons. An overall total of (80) CKD patients were included in this study. The patients were between the ages of 20 and 60. Each patient's case information sheet was compiled with information on their name, age, sex, marital status, place of residence, history of chronic diseases, history of drug use, history of smoking, and type of operation. These patients were hospitalized to Kirkuk, Iraq's Kirkuk Teaching Hospital between April and July 2022. 50 healthy individuals served as the control group in this experiment. testing for a few biological elements. The analysis of the peel extract from H. polyrhizus revealed the presence of saponin, flavonoid, tannin, polyphenol, alkaloid, quinone, and terpenoid compounds. Total antioxidant capacity level in male and female were showed significant (P≤0.05) reduced in comparison to the heath group. After using dragon fruits extract, Total antioxidant capacity level were improved and there was non-significant (P≤0.05) changes in comparison to the heath group. Total oxidant status level in male and female were showed significant (P<0.05) elevated in comparison to the heath group. After using dragon fruits extract, Total oxidant status level (951.8±57.4) were improved and there was non-significant (P≤0.05) changes in comparison to the heath group. Based on the results of the current study, it was found that dragon fruits extract has an effective role as an antioxidant.

Chemical constituents with antioxidant activity from the branches and leaves of Hultholia mimosoides

Four undescribed homoisoflavanoids (1–4), one homoflavonoid (5), ten dibenzoxocin derivatives (6a–10a and 6b–10b), one dibenzoxocin-derived phenolic compound (11), one diterpenoid (13), three aliphatic dicarboxylic acid derivatives (14–16), together with the known diterpenoid 12-O-ethylneocaesalpin B (12) were obtained from the branches and leaves of Hultholia mimosoides. Their structures were elucidated by extensive spectroscopic techniques. Notably, each of the dibenzoxocins 6−10 existed as a pair of interconvertible atropisomers and the conformation for these compounds was clarified by NMR and ECD analyses. Protosappanin F (11) was a previously undescribed dibenzoxocin-derived compound in which one of the benzene rings was hydrogenated to a polyoxygenated cyclohexane ring and an ether linkage was established between C-6 and C-12a. The isolated polyphenols were tested for induction of quinone reductase and compounds 3 and 8 showed potent QR-inducing activity in Hepa-1c1c7 cells.

Hypoglycaemic Effects of an Aqueous Leaves Extract of Combretum micranthum in Normoglycaemic Rats

Background: In order to promote the Ivorian pharmacopoeia, we undertook the study of Combretum micranthum (Combretaceae), a plant commonly used in Ivory Coast for the treatment of diabetes. The aim of this study was to evaluate the hypoglycemic effects of an aqueous leaves extract of Combretum micranthum (EaqCM) in Wistar rats. Methods and Materials: A phytochemical screening study was performed. The pharmacological test on normoglycaemic rats was carried out in 4 groups of 5 rats per group. Rats in group 1 received 2 ml of distilled water, and rats in the test groups received doses ranging at 100 to 300 mg/kg B.W. of the EAqCM. Tests in pre-treated temporarily hyperglycemic rats were performed in 4 groups of 5 rats per group. The rats in groups 1 and 2 received 2ml of distilled water, the rats in test groups (3 and 4) received the dose of 10-2g/kg B.W. and 100 mg/kg B.W. respectively glibenclamide and EAqCM. Thirty minutes later, all rats except those in group 1 received anhydrous glucose. The protocol for testing post-treated hyperglycaemic rats is the same as that for pretreated rats, except that in this experiment glucose is administered to the animals before the test substances. Blood glucose is measured in the rats at regular intervals of 30, 60, 90, 120, 150, and 180 minutes after administration of the substances. Results: Qualitative phytochemical analysis of EAqCM revealed the presence of polyphenols, flavonoids, catechic, tannins, quinonic compounds, alkaloids, sterols, and polyterpenes. Pharmacological tests on the glycemia of normoglycemic rats showed that EAqCM has hypoglycemic properties at a dose of 100 mg/kgB.W. with a percentage reduction of 30%. In hyperglycemic rats, EAqCM and glibenclamide exhibited anti-hyperglycemic activity with respective percentages reduction of 57.47 % and 58.82 %. Conclusion: Antihyperglycemic effect of EAqCM in post-treated rats would probably be due to the presence of polyphenols and flavonoids in this extract. These results support the use of this plant in traditional medicine for the treatment of diabetes.

Secondary Organic Aerosol Generated from Biomass Burning Emitted Phenolic Compounds: Oxidative Potential, Reactive Oxygen Species, and Cytotoxicity.

Phenolic compounds are largely emitted from biomass burning (BB) and have a significant potential to form SOA (Phc-SOA). However, the toxicological properties of Phc-SOA remain unclear. In this study, phenol and guaiacol were chosen as two representative phenolic gases in BB plumes, and the toxicological properties of water-soluble components of their SOA generated under different photochemical ages and NOx levels were investigated. Phenolic compounds contribute greatly to the oxidative potential (OP) of biomass-burning SOA. OH-adducts of guaiacol (e.g., 2-methoxyhydroquinone) were identified as components of guaiacol SOA (GSOA) with high OP. The addition of nitro groups to 2,5-dimethyl-1,4-benzoquinone, a surrogate quinone compound in Phc-SOA, increased its OP. The toxicity of both phenol SOA (PSOA) and GSOA in vitro in human alveolar epithelial cells decreased with aging in terms of both cell death and cellular reactive oxygen species (ROS), possibly due to more ring-opening products with relatively low toxicity. The influence of NOx was consistent between cell death and cellular ROS for GSOA but not for PSOA, indicating that cellular ROS production does not necessarily represent all processes contributing to cell death caused by PSOA. Combining different acellular and cellular assays can provide a comprehensive understanding of aerosol toxicological properties.

Deciphering layer formation in Red Heart Qu: A comprehensive study of metabolite profile and microbial community influenced by raw materials and environmental factors

Environmental-origin microbiota significantly influences Red Heart Qu (RH_Qu) stratification, but their microbial migration and metabolic mechanisms remain unclear. Using high-throughput sequencing and metabolomics, we divided the stratification of RH_Qu into three temperature-based stages. Phase I features rising temperatures, causing microbial proliferation and a two-layer division. Phase II, characterized by peak temperatures, sees the establishment of thermotolerant species like Bacillus, Thermoactinomyces, Rhodococcus, and Thermoascus, forming four distinct layers and markedly altering metabolite profiles. The Huo Quan (HQ), developing from the Pi Zhang (PZ), is driven by the tyrosine-melanin pathway and increased MRPs (Maillard reaction products). The Hong Xin evolves from the Rang, associated with the phenylalanine-coumarin pathway and QCs (Quinone Compounds) production. Phase III involves the stabilization of the microbial and metabolic profile as temperatures decline. These findings enhance our understanding of RH_Qu stratification and offer guidance for quality control in its fermentation process.

ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY TESTS OF BANGKAL LEAF (Nauclea subdita Leaf.) SERUM EXTRACTS

Bangkal leaves contain polyphenols, alkaloids, flavonoids, and quinone compounds that have the potential to act as antioxidants and antibacterial agents. To maximize the use of bangkal leaves, a cosmetic preparation, serum, was prepared. Serum is composed of 3 formulas: formula 1 (3% extract concentration), formula 2 (4% extract), and formula 3 (5% extract). Serum was tested for antioxidant activity using the DPPH (2,2-Diphenyl-1-Picrylhydrazyl) method at a wavelength of 518 nm. Ascorbic acid was used for comparison. Serum was also tested to evaluate its physical properties including organoleptics, pH, spreadability and viscosity. Antibacterial activity was determined using the well diffusion method. The research results showed that the IC50 value of the extract was 171.18 ppm, the bangkal leaf extract serum preparation for formula I was 174.26 ppm, formula II was 209.97 ppm, and formula III was 237.91 ppm. The antibacterial activity of bangkal leaf extract serum (Nauclea subdita) against Staphylococcus aureus formulas 1, 2, and 3 had an average zone of inhibition of 10.67, 12.00, and 14 mm. Based on the antioxidant and antibacterial activity values, bangkal leaf extract serum has moderate antioxidant and antibacterial abilities. Keywords : Bangkal leaf extract, antioxidant activity test, antibacterial test

Influences of compound age and identity in the effectiveness of insect quinone secretions against the fungus Beauveria bassiana.

Chemical defences against parasites and pathogens can be seen in a wide range of animal taxa, including insect pests such as the red flour beetle Tribolium castaneum. Antimicrobial quinone-based secretions can be used by these beetles to defend against various parasites, particularly the fungal entomopathogen Beauveria bassiana. While quinone secretions can inhibit B. bassiana growth, it is unknown how long they remain effective or how individual secretion compounds contribute to growth inhibition. Here, we tested each individual component of the quinone secretions (methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, and 1-pentadecene), as well as two mixed solutions that represent the composition range found in natural T. castaneum secretions, after aging for 0, 24, or 72h. The two quinone compounds equally contributed to B. bassiana inhibition, but their efficacy was significantly reduced after 24h, with no growth inhibition after 72h. This indicates that quinones protect insects against B. bassiana for only a limited time, perhaps requiring constant secretion into the environment to effectively defend against this fungal threat. Future investigations may consider the extent to which quinone secretions are effective against other parasites, as well as how their ability to cause parasite damage changes with compound age.

Preparation and characterization of a solid dispersion formulation of coenzyme Q10 loaded with protamine: an efficient and novel strategy to enhance bioavailability and stability

Coenzyme Q10 (CoQ10) is an endogenous, lipophilic quinone compound that functions as an electron carrier in the mitochondrial respiratory chain and plays a pivotal role in cell metabolism. Despite its numerous important physiological functions, the practical application of CoQ10 is limited due to its high molecular weight, poor water solubility, photolability, chemical instability, and low bioavailability. To overcome these challenges, we developed a solid dispersion formulation of protamine loaded CoQ10 (CoQ10/Pr) using an efficient mechanochemical technology without solvents. Protamine was used as carrier and poloxamer 188 as solubilizer, while butylated hydroxytoluene (BHT) and micro powder silica gel were utilized as stabilizers and lubricants. The optimal ball milling condition to prepare CoQ10/Pr was at 100 r/min for 4 hours. The treated CoQ10/Pr has exhibited rapid-release properties, with significantly enhanced water solubility by 392,000 times, and bioavailability by 0.68 times. Furthermore, the treated CoQ10/Pr became resistant to moisture, high temperature and strong light, which makes it suitable for long-term storage. The molecular docking suggested that the solubilization mechanism of CoQ10 was closely associated with the encapsulation and complexation of protamine, as well as the formation of an intermolecular complex through hydrogen bond between CoQ10 and arginine residues on protamine. In summary, the CoQ10 solid dispersion formulation enjoys advantages such as excellent water solubility, stability, bioavailability, and low cost. This formulation also meets the stringent quality requirements of products in the food, cosmetic, and health industries. It offers dual benefits in both theoretical research and industrial development.

Interactions between Damaged Hair Keratin and Juglone as a Possible Restoring Agent: A Vibrational and Scanning Electron Microscopy Study.

Juglone, a quinonic compound present in walnut extracts, was proposed as a restoring agent for hair keratin treated with permanent or discoloration processes. The proposed mechanism of restoration by juglone involves the formation of a Michael adduct between the quinone and the thiol moieties of cysteine residues. To this purpose, the first part of the present paper involved the spectroscopic study of the product of the reaction between juglone and N-acetyl-L-cysteine as a model compound. IR spectroscopy and Scanning Electron Microscopy (SEM) monitored the chemical and morphological variations induced by applying juglone to hair keratin. In order to simulate the most common hair treatments (i.e., permanent and discoloration), juglone was applied to hair that had been previously treated with a reducing agent, i.e., methyl thioglycolate (MT) or with bleaching agents (based on hydrogen peroxide and persulfates) followed by sodium hydrogen sulfite. IR spectroscopy allowed us to monitor the formation of Michael adducts between juglone and cysteine residues: the Michael adducts' content was related to the cysteine content of the samples. In fact, MT and sodium hydrogen sulfite favored the reduction of the disulfide bonds and increased the content of free cysteine residues, which can react with juglone. SEM analyses confirmed the trend observed by IR spectroscopy since hair samples treated with juglone adopted a more regular hair surface and more imbricated scales, thus supporting the possible use of juglone as a restoring agent for damaged hair keratins.

Asymmetric Charge Distribution of Active Centers in Small Molecule Quinone Cathode Boosts High‐Energy and High‐Rate Aqueous Zinc‐Organic Batteries

AbstractSmall molecule quinone compounds are attractive cathode materials for rechargeable aqueous zinc‐organic batteries (AZOBs) because of their structural diversity and low‐cost merits. Among them, nonpolar quinones are dominant given the relatively low solubilities in aqueous electrolytes. However, their poor electronic conductivity and accumulated Coulombic repulsion lead to underutilized active sites and sluggish redox kinetics. Here, polar 2,6‐dimethoxy‐1,4‐benzoquinone (m‐DMBQ) works as an advanced AZOB cathode with unexpectedly superior performance over the nonpolar isomer of 2,5‐dimethoxy‐1,4‐benzoquinone (p‐DMBQ). The asymmetric charge distribution of active centers in the p−π conjugated backbone of m‐DMBQ induces reduced bandgap with improved electronic conductivity and redox activity, thus achieving a high specific capacity of 312 mAh g−1 approaching the theoretical limit. Additionally, the lowest unoccupied molecular orbital energy level is lowered for an increased average discharge voltage of 0.88 V. Characterizations and computational studies revealed boosted competitiveness of H+ relative to Zn2+ for significantly enhanced charge transfer kinetics and reversibility. As a result, the as‐fabricated AZOB achieves a high energy density of 275 Wh kg−1 based on m‐DMBQ along with high‐rate capability and long‐term cycling stability. This work provides a new molecular engineering strategy through regulating charge distribution symmetry for boosting charge storage in organic cathodes.