Anthraquinone Research Articles

Rational Design of Hierarchical Structure Electrodes to Suppress Shuttle Diffusion in Redox-Enhanced Supercapacitors.

In carbon-based supercapacitors, redox couples can effectively improve the energy density of supercapacitors; however, most redox couples still suffer from serious shuttle diffusion. Currently, there is no universal strategy to effectively constrain their shuttle diffusion. Therefore, developing a simple, effective, and universal method to suppress shuttle diffusion remains a great challenge. Herein, we designed and prepared a hierarchical structure electrode composed of three functional layers (inner conductive layer, intermediate storage layer, and outer confinement layer) for redox-enhanced supercapacitors. The hierarchical electrode can be fabricated on a large scale in three simple steps based on commercial carbon felt. The rationally designed three functional layers endow the hierarchical structure electrode with excellent conductivity, adsorption capacity, and confinement ability. Long-term charge-discharge cycle results prove that the hierarchical structure electrode exhibits an outstanding restriction effectiveness on three redox media with different molecular sizes (anthraquinone (AQ), naphthoquinone (NQ), and p-benzoquinone (PQ)). Specifically, for AQ, NQ, and PQ, the hierarchical structure electrodes showed CV peak current attenuation rates of only 5.64%, 3.54%, and 10.34% after 5,000 cycles of charge-discharge, while common electrodes exhibited attenuation rates of 10.44%, 15.02%, and 20.20%, respectively. Moreover, the soft-pack supercapacitors composed of hierarchical electrodes still had a capacitance retention of 86.6% after 5,000 cycles of charge-discharge. All the results demonstrate that the structure design is reasonable and the hierarchical structure electrode has a great potential to be the universal electrode for suppressing the shuttle diffusion of redox media in supercapacitors and other energy storage devices.

Synergistic Regulation of Bidirectional Conversion of LiPSs and Li2S Using Anthraquinone as a Redox Mediator.

Lithium-sulfur (Li-S) batteries are strong contenders as energy storage options in the next-generation, primarily because of their potential for delivering high energy densities. Nonetheless, their widespread commercialization faces several obstacles, including sluggish sulfur redox kinetics, the insulating properties of the Li2S discharge product, and significant reaction energy barriers. In this work, anthraquinone (AQ) was introduced as a redox mediator and incorporated onto Co-doped carbon materials through π-π interactions. The results showed that synergistic effect between AQ and Co atoms facilitated the bidirectional conversion of lithium polysulfides (LiPSs) and Li2S. During charging, AQ lowered the reaction energy barrier for Li2S oxidation and thereby enhanced the reversibility of sulfur redox reactions. Density functional theory (DFT) calculations showed that AQ-Li2Sx exhibits a lower energy for the lowest unoccupied molecular orbital (LUMO) and a higher energy for the highest occupied molecular orbital (HOMO). Experimental results demonstrated that an impressive initial discharge specific capacity of 1290 mAh g-1 was achieved by the fabricated S@AQ/Co-N-C electrode at 0.1 C. After 600 cycles at 1 C, it retained 64% of this capacity and exhibited a minimal 0.06% capacity decay rate per cycle.

Intersystem Crossing, Photo-Induced Charge Separation and Regioisomer-Specific Excited State Dynamics in Fully Rigid Spiro Rhodammine-Naphthalene/Anthraquinone Electron Donor-Acceptor Dyads.

We prepared a series fully rigid spiro electron donor-acceptor orthogonal dyads, with closed form of rhodamine (Rho) as electron donor and naphthalene (Np)/anthraquinone (AQ) as electron acceptor, to access the long-lived triplet charge separation (3CS) state, via the electron spin control method. We found strong dependency of the photophysical property of the dyads on the amino substitution positions of the Np chromophores in the dyads 1,8-DaNp-Rho and 2,3-DaNp-Rho. Nanosecond transient absorption (ns-TA) spectra show the population of the 3LE state (lifetime: 47 μs) for 2,3-DaNp-Rho, however, long-lived 3CS state was observed (τCS = 0.62 μs) for AQ-Rho, with a CS quantum yield of ΦCS = 58%. Based on femtosecond transient absorption (fs-TA) spectra, spin orbit charge transfer ISC (SOCT-ISC) is proposed to be responsible for the formation of the triplet states. Time-resolved electron paramagnetic resonance (TREPR) spectra of AQ-Rho indicate the presence of two states, a 3LE state with zero field splitting (ZFS) D parameter of 1400 MHz and E parameter of -410 MHz, formed via radical pair ISC (RP-ISC) and SOCT-ISC mechanism; and a 3CS state with the electron spin-spin interaction in the regime of spin-correlated radical pair (SCRP).

Metabolomic characteristics and anthraquinones accumulation patterns of Rhubarb in different tissues and roots from different developmental stages

Rhubarb's multifaceted value in culinary and medicine is renowned, especially Rheum tanguticum (Rhubarb), whose bountiful content of anthraquinones (AQs) makes it increasingly attractive in the realms of dietary supplements and natural edible pigments. Current understanding of the spatiotemporal dynamics of AQs accumulation in Rhubarb remains limited, and the knowledge of other valuable metabolites is even more scarce. This gap limits the ability to fully explore Rhubarb's potential as a food ingredient and hinders its efficient use in food development, potentially leading to unnecessary resource waste. This study integrated widely targeted metabolomics and AQs quantification to determine the metabolic profiles in four tissues and the roots at three developmental stages in Rhubarb. The high levels of malic and citric acids in the stems paved the way for their use in flavored beverages and substantiated the practice of traditional consumption. The abundance of flavonoids in the leaves and seeds, and the AQs, phenolic acids of the seeds, which potentially bestowed upon them exceptional antioxidant capabilities, underscore the significant potential of edible product development. The widespread traditional use of roots was mirrored by the preferential accumulation of AQs, and the roots' value escalated in tandem with the time-accumulated increase of AQs. The root bark and root tip with high AQs should be given attention in production and not simply discarded. This research clarifies the chemical composition and spatiotemporal variation patterns of Rhubarb's characteristic components, offering valuable scientific insights for their efficient use and value enhancement in the food industry.

Quinone Quest: Unraveling electrochemical performance in quinone-anchored 3D graphene architectures for high-energy supercapacitors

In the pursuit of advancing energy storage technologies, the exploration of novel electrode materials for supercapacitors, specifically organic materials, has garnered significant attention. This work delves into the electrochemical performance of quinone-anchored three-dimensional (3D) graphene (3DG) architectures as potential electrode materials for high-energy supercapacitors, focusing on elucidating the influence of different quinone types including 1,4-naphthoquinone (NQ), anthraquinone (AQ), duraquinone (DQ), p-benzoquinone (BQ), 2,5-dimethyl-1,4-benzoquinone (DMBQ), and sodium anthraquinone-2-sulfonate (SAQS). To that end, various quinone-anchored three-dimensional graphene (Q_3DG) architectures were synthesized via a chemical reduction-induced self-assembly technique in the presence of l-ascorbic acid, a green reducing agent. The physicochemical characterizations confirmed the successful incorporation of quinones to the carbon structure, without the presence of any impurities. Different interaction mechanisms between graphene oxide (GO) and quinone molecules during the synthesis led to different surface morphologies, which affected their electrochemical behavior. The 3-electrode electrochemical characterizations in 1.0 M Na2SO4 electrolyte revealed that all Q_3DG structures exhibited superior electrochemical performance compared to GO, as well as to a Bare_3DG sample synthesized without quinone molecules. NQ anchored 3DG (NQ_3DG) network yielded the highest specific capacitance value of 386.3 F.g−1 at 10 mV.s−1, which was almost 50 times larger than that of Bare_3DG. The findings not only shed light on the fundamental mechanisms governing charge storage and transfer within these unique architectures but also provide valuable insights for the rational and green design of next-generation organic electrode-based supercapacitors with enhanced energy storage capabilities.

Y-Shaped Acceptor-π-Donor-π-Acceptor Configured Anthraquinone-Tethered Phenothiazine Molecular Scaffold for High-Performance Organic Pseudocapacitors.

For the first time acceptor-π-donor-π-acceptor (A-π-D-π-A) based Y-type organic electrode material have been designed and successfully utilized in supercapacitor (SC) application. This Y-type molecular architecture coined as AQ-Im-PTZ-Im-AQ based on anthraquinone (AQ) (A)-imidazole (Im) (π)-phenothiazine (PTZ) (D)-imidazole (Im) (π)-anthraquinone (AQ) (A) in combination with graphite foil (GF). As-fabricated PTZ-Im-AQ/GF and AQ-Im-PTZ-Im-AQ/GF electrode have shown the good energy storage properties in three-electrode supercapacitor system. Moreover, two-electrode symmetric supercapacitor (SSC) device based on AQ-Im-PTZ-Im-AQ/GF electrode exhibited specific capacitance (Csp) of 68.97 F g-1 at 1 A g-1 current density. The specific electron density (ED) of SSC was observed to be 12.06 Wh kg-1 at a specific power density (PD) of 1798.50 W kg-1. The SSC device exhibited 81.62 % of Csp retention after 5000 galvanostatic charge-discharge (GCD) cycles. For real world applications, AQ-Im-PTZ-Im-AQ/GF electrode was tested in symmetric Csp coin cell with applied potential voltage window of -0.4 to 1.0 V was found to be 112.32 F g-1 at 0.5 A g-1. Moreover, it realized high specific capacitance and high energy density of 19.66 Wh kg-1 at 891.94 W kg-1 power density. As a results, AQ-Im-PTZ-Im-AQ/GF make as an attractive electrode material for application in next-generation SCs.

Contribution of Protonation to the Dielectric Relaxation Arising from Bacteriopheophytin Reductions in the Photosynthetic Reaction Centers of Rhodobacter sphaeroides.

The pH dependence of the free energy level of the flash-induced primary charge pair P+IA- was determined by a combination of the results from the indirect charge recombination of P+QA- and from the delayed fluorescence of the excited dimer (P*) in the reaction center of the photosynthetic bacterium Rhodobacter sphaeroides, where the native ubiquinone at the primary quinone binding site QA was replaced by low-potential anthraquinone (AQ) derivatives. The following observations were made: (1) The free energy state of P+IA- was pH independent below pH 10 (-370 ± 10 meV relative to that of the excited dimer P*) and showed a remarkable decrease (about 20 meV/pH unit) above pH 10. A part of the dielectric relaxation of the P+IA- charge pair that is not insignificant (about 120 meV) should come from protonation-related changes. (2) The single exponential decay character of the kinetics proves that the protonated/unprotonated P+IA- and P+QA- states are in equilibria and the rate constants of protonation konH +koffH are much larger than those of the charge back reaction kback ~103 s-1. (3) Highly similar pH profiles were measured to determine the free energy states of P+QA- and P+IA-, indicating that the same acidic cluster at around QB should respond to both anionic species. This was supported by model calculations based on anticooperative proton distribution in the cluster with key residues of GluL212, AspL213, AspM17, and GluH173, and the effect of the polarization of the aqueous phase on electrostatic interactions. The larger distance of IA- from the cluster (25.2 Å) compared to that of QA- (14.5 Å) is compensated by a smaller effective dielectric constant (6.5 ± 0.5 and 10.0 ± 0.5, respectively). (4) The P* → P+QA- and IA-QA → IAQA- electron transfers are enthalpy-driven reactions with the exemption of very large (>60%) or negligible entropic contributions in cases of substitution by 2,3-dimethyl-AQ or 1-chloro-AQ, respectively. The possible structural consequences are discussed.

Anthraquinone/Activated Carbon Electrochemical Sensor and its Application in Ofloxacin Analysis

AbstractOfloxacin (OFL) has antibacterial and anti‐inflammatory effects on respiratory tract infection, skin soft tissue infection and urogenital tract infection caused by sensitive bacteria. In this study, an electrochemical sensor on account of glassy carbon electrode (GCE) and anthraquinone (AQ)/Vulcan XC‐72 (C) composite was prosperity prepared for the determination of ofloxacin (OFL) drug. The morphology and structure of C/20%AQ composites were characterized by SEM. The electrochemical behavior of OFL on the C/20%AQ/GCE sensor was tested using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The consequences indicate that the linear response of the sensor to OFL at pH 6.5 in 0.2 M phosphate buffer solution (PBS) was in the scope of 0.1–550.0 μM (R2=0.998) with the limit of detection of 0.01 μM. The prepared C/20%AQ/GCE sensor exhibited good anti‐interference ability and repeatability against OFL. The sensor presents a sensitive, simple and low cost OFL detection method, and has been successfully applied to real samples.

Designing 1-nm-Thick MOF Nanosheets with Donor-Acceptor Complexes for Photosynthesis of H2O2 Using Water and Dioxygen Only.

Artificial photosynthesis of hydrogen peroxide (H2O2) presents a promising environmentally friendly alternative to the industrial anthraquinone process. This work designed ultrathin metal-organic framework (MOF) nanosheets on which porphyrin ligand as an electron donor (D) and anthraquinone (AQ) as an electron acceptor (A) are integrated as the D-A complexes. The porphyrin component allows the MOF nanosheets to absorb full-spectrum solar light while the acceptor AQ motif promotes central aluminum ion coordination, hindering layer stacking to achieve a thickness of 1.0 nm. The ultrathin D-A design facilitates the separation of electrons from the MOF skeleton to the AQ motif, which induces the direct two-electron oxygen reduction reaction (ORR) mediated by the reversible redox couple of AQ-AQH2 and multielectron water oxidation reaction (WOR) driven by holes remaining on the porphyrin part. In O2-saturated water, the ultrathin MOF nanosheets outperformed the AQ-free bulk and multilayered counterparts by 2.9 and 2.6 times in H2O2 production, respectively, achieving the apparent quantum yield of 4.8% at 420 nm. It also surpasses other benchmark photocatalysts, including the typical MOF photocatalyst, MIL-125-NH2, and organic polymeric photocatalysts. The ultrathin D-A MOF photocatalyst generated H2O2 via both two-electron ORR as a major path and two-electron WOR as a minor path. This approach presents a promising strategy for the rational design of efficient nanostructured photocatalysts for solar fuels and chemicals.

Electron Spin Dynamics of the Intersystem Crossing in Aminoanthraquinone Derivatives: The Spectral Telltale of Short Triplet Excited States.

We studied the excited state dynamics of two bis-amino substituted anthraquinone (AQ) derivatives, with absorption in the visible spectral region, which results from the attachment of a electron-donating group to the electron-deficient AQ chromophore. Femtosecond transient absorption spectra show that intersystem crossing (ISC) takes place in 190-320 ps, and nanosecond transient absorption spectra demonstrated an unusually short triplet state lifetime (2.06-5.43 μs) for the two AQ derivatives. Pulsed laser-excited time-resolved electron paramagnetic resonance (TREPR) spectra show an inversion of the electron spin polarization (ESP) phase pattern of the triplet state at a longer delay time after laser flash. Spectral simulations show faster decay of the Ty sublevel than the other two sublevels (τx = 15.0 μs, τy = 1.50 μs, τz = 15.0 μs); theoretical computation predicts initial overpopulation of the Ty sublevel, and rationalizes the short T1 state lifetime and the ESP inversion. Theoretical computations taking into account the electron-vibrational coupling, i.e., the Herzberg-Teller effect, successfully rationalize the TREPR experimental observations.

Combination of Metabolomics, Lipidomics, and Molecular Biology for the Investigation of the Metabolic Disturbance of Short-Term Administration of Emodin.

Emodin, a natural anthraquinone derivative, is an active ingredient in many Chinese traditional herbs. Interestingly, although it is generally considered to possess hepatoprotective activity, some studies have also reported that it has a certain degree of hepatotoxicity. Additionally, the underlying metabolic regulation of emodin remains uncertain. Therefore, we conducted a nontargeted metabolomic study based on UHPLC/Q-Orbitrap-MS and NMR. Data are available via ProteomeXchange with the identifier PXD055000. The results indicated a close association between the short-term administration of emodin and lipid metabolism. Moreover, a lipidomics investigation utilizing QTRAP 6500+ UHPLC-MS/MS was conducted, with a focus on determining the position of C═C double bonds in unsaturated lipids based on Paternò-Büchi (PB) reaction to discover the metabolic disturbance more precisely. Specifically, lipidomics revealed elevated levels of free fatty acids (FFA) alongside notable reductions in sphingomyelin (SM) and triacylglycerol (TAG) levels. Furthermore, the combination of PB reaction and molecular biology results indicated that short-term administration of emodin may lead to the accumulation of n-6 polyunsaturated fatty acids by up-regulating the expression of FASN, stearyl CoA desaturase 1 (SCD1), and cytosolic phospholipase A 2 (cPLA2). Simultaneously, up-regulation of cyclooxygenase-2 (Cox-2) expression was observed, potentially fostering the production of prostaglandin E2 (PGE2) and subsequent inflammation.

Emodin combined with 5-aminolevulinic acid photodynamic therapy inhibits condyloma acuminate angiogenesis by targeting SerRS.

Human papillomavirus (HPV) infection can cause condyloma acuminatum (CA), which is characterized by a high incidence and a propensity for recurrence after treatment. Angiogenesis plays an important role in the occurrence and development of CA. Seryl-tRNA synthetase (SerRS) is a newly identified, potent anti-angiogenic factor that directly binds to the vascular endothelial growth factor (VEGFA) promoter, thereby suppressing its transcription. Emodin is a natural anthraquinone derivative that can promote SerRS expression. This study aimed to investigate the effects of emodin on CA and explore combined treatment strategies. The HPV-infected cell line SiHa was treated with either DMSO, emodin, ALA-PDT or a combination of emodin and ALA-PDT. We observed the effects on cell proliferation, apoptosis and the SerRS-VEGFA pathway. Our findings demonstrated that emodin targets angiogenesis through the SerRS-VEGFA pathway, resulting in the inhibition of SiHa cell proliferation and promotion of apoptosis (p < 0.001). To verify the therapeutic effect of emodin combined with ALA-PDT on HPV-associated tumours invivo, we established an animal xenograft model by subcutaneously inoculating mice with SiHa cells (n = 4). The results showed that the combination of emodin and ALA-PDT significantly inhibited the expression of VEGFA to inhibit angiogenesis (p < 0.001), thus showing an inhibitory effect on tumour (p < 0.001). Furthermore, we determined that the mechanism underlying the decrease in VEGFA expression after emodin combined with ALA-PDT in CA may be attributed to the promotion of SerRS expression (p < 0.001). The combination of emodin and ALA-PDT holds promise as a novel therapeutic target for CA by targeting neovascularization in condyloma tissues.

Enhanced Cyclic Performance of Lithium-Ion Battery Based on Anthraquinone/SBA-15 Composite Cathode Prepared via Ultra-Sonication

In this study, novel organic/inorganic composites were fabricated by blending anthraquinone (AQ) with SBA-15 molecular sieve in varying ratios via ultrasonication, characterized structurally using XRD, SEM, and BET methods, and analyzed electrochemically as cathode materials for lithium-ion batteries via galvanostatic discharge/charge and electrochemical impedance spectroscopy. The composite with a 2:1 ratio of AQ and SBA-15 achieved a specific discharge capacity of 144.5 mAh/g at 0.2 C, which decreased to 63.3 mAh/g after 50 cycles, 8% higher than that of the pure AQ. The initial discharge platform of the composite was 2.28 V, which decreased to 2.10 V after 50 cycles, 50 mV higher than that of the pure AQ. This is because the loading of anthraquinone particles by the SBA-15 pore size structure facilitated the stabilization of the active materials, hindered the solubility of AQ in the electrolyte, and enhanced the cycling stability of the battery.

Efficient thermally activated delayed fluorescence materials from symmetric anthraquinone derivatives for high-performance red OLEDs

Constructing efficient red thermally activated delayed-fluorescence (TADF) materials for high-performance organic light-emitting diodes (OLEDs) remains challenging due to the formidable barrier of energy gap law. In this work, a design strategy of connecting two donor units to the adjacent positions of electron acceptor is proposed for creating red luminescent materials, and four Y-shaped TADF molecules consisting of strong electron-withdrawing anthraquinone (AQ) acceptor and triphenylamine or acridine-based donors are designed and synthesized. They exhibit strong red emissions (604−618 nm) in toluene solutions and orange/red emissions (566−608 nm) with good photoluminescence quantum yields (43−68%) in doped films, and enjoy small singlet-triplet energy gaps (0.02−0.10 eV) and fast reverse intersystem crossing processes (1.5–7.3 × 105 s−1), which are attributed to the unique Y-shape structure. A maximum external quantum efficiency of 19.5% with an electroluminescence peak at 616 nm is achieved for AQ-PTPA-based red doped device, representing the highest level for red TADF-OLEDs based on AQ acceptor in the literature. This work can provide guidance for the design of efficient red delayed-fluorescence molecules for the application in OLEDs.

Discovery of natural anthraquinones as potent inhibitors against pancreatic lipase: structure-activity relationships and inhibitory mechanism

Obesity is acknowledged as a significant risk factor for various metabolic diseases, and the inhibition of human pancreatic lipase (hPL) can impede lipid digestion and absorption, thereby offering potential benefits for obesity treatment. Anthraquinones is a kind of natural and synthetic compounds with wide application. In this study, the inhibitory effects of 31 anthraquinones on hPL were evaluated. The data shows that AQ7, AQ26, and AQ27 demonstrated significant inhibitory activity against hPL, and exhibited selectivity towards other known serine hydrolases. Then the structure-activity relationship between anthraquinones and hPL was further analysed. AQ7 was found to be a mixed inhibition of hPL through inhibition kinetics, while AQ26 and AQ27 were effective non-competitive inhibition of hPL. Molecular docking data revealed that AQ7, AQ26, and AQ27 all could associate with the site of hPL. Developing hPL inhibitors for obesity prevention and treatment could be simplified with this novel and promising lead compound.

Efficient unsymmetric disulfide formation by molecular-scale tailoring of ortho-polyquinone-based polymer photocatalyst

Disulfide bonds, especially unsymmetric disulfide bonds, have important applications in bioactivity and drug molecules, but the synthesis of unsymmetric disulfide bonds remains challenging due to efficiency and selectivity issues. Herein, this work utilizes anthraquinone (AQ) and cyclictriphosphonononitrile through a nucleophilic substitution reaction to synthesize an organic polymer (ANTH-AMI) that incorporates an ortho-polyquinone (o-polyquinone) redox center. The anthraquinone molecule functions as a redox center, capable of accepting photoinduced electrons and subsequently transferring them to initiate an electron-coupled hydrogenation reaction (AQ to AQH). Moreover, the proximity of the o-polyquinone redox sites facilitates the catalysis of unsymmetric disulfide bond formation. Consequently, the ANTH-AMI photocatalysts demonstrate exceptional yields (up to 82 %), substrate versatility, cycling stability, and scalable preparation in promoting unsymmetric coupling reactions of thiol. This work offers a solution for designing organic polymer photocatalysts with adjacent multiple redox centers for cross-coupling reactions.

Multifunctional Bioactivity Electrospinning Nanofibers Encapsulating Emodin Provides a Potential Postoperative Management Strategy for Skin Cancer.

Skin cancer is threatening more and more people's health; its postoperative recurrence and wound infection are still critical challenges. Therefore, specialty wound dressings with multifunctional bioactivity are urgently desired. Emodin is a natural anthraquinone compound that has anti-cancer and anti-bacterial properties. Herein, we fabricated coaxial electrospinning nanofibers loaded with emodin to exploit a multifunctional wound dressing for skin cancer postoperative management, which encapsulated emodin in a polyvinylpyrrolidone core layer, combined with chitosan-polycaprolactone as a shell layer. The nanofibers were characterized via morphology, physicochemical nature, drug load efficiency, pH-dependent drug release profiles, and biocompatibility. Meanwhile, the anti-cancer and anti-bacterial effects were evaluated in vitro. The emodin-loaded nanofibers exhibited smooth surfaces with a relatively uniform diameter distribution and a clear shell-core structure; remarkably, emodin was evenly dispersed in the nanofibers with significantly enhanced dissolution of emodin. Furthermore, they not only display good wettability, high emodin entrapment efficiency, and biphasic release profile but also present superior biocompatibility and anti-cancer properties by increasing the levels of MDA and ROS in A-375 and HSC-1 cells via apoptosis-related pathway, and long-term anti-bacterial effects in a dose-independent manner. The findings indicate that the emodin-loaded nanofiber wound dressing can provide a potential treatment strategy for skin cancer postoperative management.

Addressing spoilage monitoring in packaged paneer (Indian cottage cheese): Lac dye-based intelligent indicator as an innovative solution

The study aimed to develop an intelligent real-time freshness indicator for paneer (Indian cottage cheese) by immobilizing lac dye, a natural anthraquinone dye, in situ on an agarose membrane. The indicator was characterized and evaluated for freshness monitoring of paneer. The indicator exhibited color transition from purple at pH 7 to orange-red at acidic pH (2–5). For evaluation of the indicator, it was placed inside the package headspace containing paneer and stored at ambient (25 ± 1 °C) and refrigerated (8 ± 1 °C) temperatures. Color changes in the indicator showed a correlation with quality parameters and volatile organic compounds (VOCs) emitted during storage of paneer. Initially, the indicator was purple on day 0. However, once the microbial counts in paneer exceeded acceptable limits (on day 1 at 25 ± 1 °C and day 6 at 8 ± 1 °C), indicator's color shifted to orange-red. This color transition effectively categorized paneer as: ‘fresh’, ‘moderately fresh’, and ‘spoiled’. The principal component analysis outcomes confirmed that the changes in the indicator's color were closely aligned with the variations observed in paneer quality parameters. Partial least squares models derived from indicator's color parameter data successfully predicted paneer quality. The study's findings illuminate potential of lac dye-based indicator in non-destructive real-time freshness monitoring of paneer.

Natural redox mediator anthraquinone aloe-emodin facilitated the in-situ mineralized γ-FeO(OH) membrane for the removal of tannic acid through photocatalytic-PMS activation

The growing utilization of Traditional Chinese Medicine (TCM) has resulted in an increase in wastewater. Herein, a new kind of organic-inorganic redox mediator membrane by immobilizing γ-FeO(OH) and aloe-emodin(AE) with the characteristic large π-conjugation anthraquinone structure on PVDF membrane was innovatively achieved. AE exhibiting both electron deficiency and redox activity possesses a co-catalyst role in degradation of tannic acid (TA), aiding in the separation of charge carriers through the sequential hydrogenation and dehydrogenation of AE. The removal rates of TA were 92.8 % in the tannic acid solution and 60.3 % in the simulated rhubarb wastewater by the AE-γ-FeO(OH) membrane under PMS+Vis conditions in 45 min. Also, they show a higher recovery of pure water flux and owning good fouling performance. Overall, this current work presents a novel approach for the design and preparation of organic-inorganic photocatalytic composite membrane using readily available natural products for the purification TCM wastewater.

Two-electron sulfonyl(trifluoromethanesulfonyl)imide-anthraquinone redox electrolytes for high-energy density supercapacitors

Organic redox electrolyte-enhanced electrochemical double layer capacitors (ORECs) are potentially better solution for combining both high power and energy density. The critical factor of ORECs is to develop high-performance organic redox electrolytes. Anthraquinone (AQ) derivatives are the promising organic redox electrolyte candidates because of their low redox potential and fast two-electron redox kinetics. Low solubility and poor longevity in aprotic solvents of charged AQ species are main issues for effective enhancement. Here we report two-electron redox ionic compounds by functionalizing AQ with a robustly electron-withdrawing sulfonyl(trifluoromethanesulfonyl)imide (AQSTFSI) anion and pairing counter monovalent cations for high-performance ORECs. The highly electron-conjugate substitute markedly stabilizes the radical and 2e−-charged forms of AQ by decentralizing the electron density of the CO heads, preventing the adverse reaction of electrophilic/nucleophilic attack, revealing by theoretical simulation. Also, the STFSI− substituent enables AQSTFSI-compounds significantly improved solubility, thermostability, and redox reversibility. Consequently, the AQSTFSI-K applied in OREC shows all-roundly superior performance containing 3.2 V cell voltage, specific energy of 58 Wh kg−1 with 1.8 times of corresponding electrochemical double layer capacitors (EDLCs), specific power over 8 kW kg−1, cycling stability over 12,000 cycles, low self-discharge, and wide working-temperature range. This molecular strategy grounded on electron density modulation of redox electrolyte structures provides valuable insights into the design for high-performance ORECs in practical applications.