Oxidation Potential Values Research Articles

Determining the Oxidation Stability of Electrolytes for Lithium-Ion Batteries Using Quantum Chemistry and Molecular Dynamics

Determining the Oxidation Stability of Electrolytes for Lithium-Ion Batteries Using Quantum Chemistry and Molecular Dynamics

Integrated Fenton-like and ozonation based advanced oxidation processes for treatment of real-time textile effluent containing azo reactive dyes

The treatment of real-time textile effluent, collected from the Common Effluent Treatment Plant (CETP) of Kerala Industrial Infrastructure Development Corporation (KINFRA) at Kannur (District), Kerala (State), India, have been studied by utilizing the Fenton-like and ozone (O3) based advanced oxidation processes (AOPs). The Fenton-like AOP has been conducted as the pre-treatment of textile effluent involving the activation of persulfate (PS) and hydrogen peroxide (H2O2) as a single and the mixed oxidants by using the Flyash (FA)-Pd composite particles as the activator. The maximum chemical oxygen demand (COD) removal of 84% has been observed for a stand-alone O3 based treatment at an O3 flow rate of 5–6 g h−1. By conducting the pre-treatment of textile effluent with the PS, H2O2, and mixed oxidants (PS and H2O2) based Fenton-like AOPs, the COD removal after an O3 based post-treatment has been observed to be 83, 87, and 93% respectively at an O3 flow rate of 2, 3, and 5 g h−1. Hence, the Fenton-like pre-treatment involving the activation of mixed oxidants has been determined to be the best method for the highest COD removal of real-time textile effluent. The optimum values of initial oxidant-ratio (initial [H2O2]:initial [PS]), initial oxidant-dosage, and ozonation time, for the mixed oxidants based Fenton-like pre-treatment, have been determined to be 3 wt% mM−1, 6:2 wt% mM−1, and 60 min respectively. Under the most optimum conditions, the COD removal has been attributed to the combination of O2•- (for the pre-treatment) and •OOH (for the post-treatment) which possess relatively lower oxidation potential values.

A Computational Study on the Impact of Anchoring Groups on the Optical and Electronic Properties of Triphenylamine-Based Dyes for Dye-Sensitized Solar Cell Applications

Anchoring groups are crucial for enhancing the performance of dye-sensitized solar cells (DSSCs). For instance, cyanoacrylic acid serves as the primary anchoring group in DSSC due to its crucial elements required for effective electron transport. However, it suffers from degradation. To address this limitation, this study proposes alternative cyano-based anchoring groups for sensitizers. Density functional theory (DFT) and time-dependent DFT were used to investigate the optical and electronic properties of the dyes. The studied dyes (excluding the dye containing OH group) displayed three absorption bands within the visible and NIR regions. Low-energy peaks ranged from 498 to 576 nm, corresponding to excitation from ground state to first excited state. Moderate intensity bands appeared at 376 to 418 nm, with the highest energy bands falling within 351 to 384 nm. Ground state oxidation potential values for the dyes were lower than the redox potential of the iodide/triiodide pair. Similarly, excited state oxidation potential values were higher than or equal to the conduction band of TiO2, except for NO2 and CHO containing dyes. Ionization potential values ranged from 6.24 eV to 6.40 eV, while electron affinity values were within 1.21 eV to 2.74 eV. Chemical potential values ranged from 3.75 to 4.57 eV, and chemical hardness of the dyes fell between 1.83 to 2.54 eV. The proposed cyano-based anchoring groups show promising potential for enhancing DSSC performance.

2D-ReS2 & diamond nanoparticles-based sensor for the simultaneous determination of sunset yellow and tartrazine in a multiple-pulse amperometry FIA system

We present a flow injection system with a multiple pulse amperometric detection (FIA-MPA)-based methodology for the simultaneous analysis of sunset yellow and tartrazine. As transducer, we have developed a novel electrochemical sensor based on the synergistic effect of ReS2 nanosheets and diamond nanoparticles (DNPs). Among several transition dichalcogenides for the sensor development, we have selected ReS2 nanosheets since it yields a better response towards both colourants. Scanning probe microscopy characterization shows that the surface sensor is composed by scattered and stacked ReS2 flakes and large aggregates of DNPs. With this system, the gap between the oxidation potential values of sunset yellow and tartrazine is wide enough to allow the simultaneous determination of both dyes. Under the optimum potential pulse conditions (0.8 and 1.2 V) during 250 ms, a flow rate of 3 mL/min and a volume injection of 250 μL, detection limits of 3.51 × 10−7 M and 2.39 × 10−7 M for sunset yellow and tartrazine, respectively, were obtained. This method exhibits good accuracy and precision with Er minor than 13% and RSD lower than 8% with a sampling frequency of 66 samples per hour. Pineapple jelly samples were analyzed by the standard addition method, obtaining 53.7 mg/kg and 29.0 mg/kg of sunset yellow and tartrazine, respectively. From the analysis of fortified samples, recoveries of 94% and 105% were obtained.

High electrochemical response of TiO2@C-dots nanocomposites as electrode modifiers for Pb (II) detection

The synthesis of new modifiers based on nanomaterials as Pb (II) sensing electrode composites has attracted much attention in recent years. Modifiers are believed to produce stable electrodes with good sensitivity. In this study, we synthesized TiO2-incorporated carbon dots (TiO2@C-dots) and tested their performance as modifiers in the detection of Pb (II) using a carbon paste electrode (CPE). The fabrication of TiO2@C-dots-decorated CPE (CPE/TiO2@C-dots) has been carried out using several methods including electrochemical, hydrothermal impregnation, and mechanical homogenization at low temperatures. Based on the results of SEM, XRD, and FTIR characterization, the morphology of the nanocomposites is known to consist of uniform solid particles. Also, there are voids on the nanocomposite surface. The nanocomposite has an average particle size of 22.61 nm and a specific 2θ angle of 26.33°. The nanocomposites actively absorb IR at specific wavenumbers of 3600 cm−1 (-OH stretch) and 1759 cm−1 (CO stretch). Performance test results for Pb (II) detection showed that decorative modifiers (TiO2@C-dots) and CPE affected the peak redox current of Pb (II). This effect correlates with the mass of TiO2@C-dots, with a mass of 10.0 mg being the best mass for TiO2@C-dots. During the detection process, Pb (II) underwent redox reactions with oxidation (Epa) and reduction (Epc) potential values of −0.38 V and −0.50 V, respectively. During application, it is controlled by the interaction diffusivity with the Pb (II) molecule, yielding an accuracy of 0.36%.

How To Enhance the Efficiency of Breslow Intermediates for SET Catalysis

Oxidative carbene organocatalysis, which proceeds via single electron transfer (SET) pathways, has been limited by the moderately reducing properties of deprotonated Breslow intermediates BI-s derived from thiazol-2-ylidene 1 and 1,2,4-triazolylidene 2. Using computational methods, we assess the redox potentials of BI-s based on ten different types of known stable carbenes and report our findings concerning the key parameters influencing the steps of the catalytic cycle. From the calculated values of the first oxidation potential of BI-s derived from carbenes 1 to 10, it appears that, apart from the diamidocarbene 7, all the others are more reducing than thiazol-2-ylidene 1 and the 1,2,4-triazolylidene 2. We observed that while the reducing power of BI-s significantly decreases with increasing solvent polarity, the redox potential of the oxidant can increase at a greater rate, thus facilitating the reaction. The cation, associated with the base, also plays an important role when a nonpolar solvent is used; large and weakly coordinating cations such as Cs+ are beneficial. The radical-radical coupling step is probably the most challenging step due to both electronic and steric constraints. Based on our results, we predict that mesoionic carbene 3 and abnormal NHC 4 are the most promising candidates for oxidative carbene organocatalysis.

Dyes from the Southern Lands: An Alternative or a Dream?

DSSC technology based on natural dyes still constitutes a tempting alternative to explore. Besides the ease of extraction, most natural dyes fulfill the characteristics to be applied as sensitizers. The presented results summarize the exploration of the features of several southern dyes, mostly coming from the Antarctic region. The explored pigments showed good absorption capacity within the visible region of the light spectra, and their molecules possess functional moieties to coordinate with the TiO2 semiconductor, oxidation potential value near 1 V and reduction potential near −0.8 V, adequate thermal stability, and low fluorescence emission.

Effects of Different Rootstocks and Storage Temperatures on Postharvest Quality of Eggplant (Solanum melongena L. cv. Madonna)

In addition to mitigating biotic and abiotic stress, grafting may influence the fruit quality and postharvest quality of eggplants. Few studies have been published on the influence of grafting on the postharvest performance of eggplant fruit. The current work examined the postharvest behavior of grafted and non-grafted eggplant cv. Madonna at 0 and 10 °C storage. Rootstocks include Solanum grandiflorum × Solanum melongena (SH), Solanum torvum (ST), Solanum melongena × Solanum integrifolium (SI), Solanum integrifolium (A), and Solanum lycopersicum cv. Optifort (O) and Emperador (E). The values for soluble solids, L*, and b* of pulp declined throughout storage. The pH of the fruit pulp decreased during storage at 10 °C. The lowest firmness was observed in fruit grafted onto E and O. The oxidation potential (OP) value decreased for fruit harvested from the O rootstock. At 0 °C, the oxidation potential (OP) value increased in fruit harvested from the A rootstock. Fruit firmness reduction at the end of storage in fruit grafted onto SH was less than in the other rootstocks and control plants. Overall, we found that the storage temperature had a more significant effect than the applied rootstock on the studied parameters of the eggplant fruits.

Photo- and electrochemical properties of di(cymantrenylalkyl) disulfides

Photolysis of di(cymantrenylalkyl)disulfides was studied by IR, 1H NMR and UV-vis spectroscopy. Irradiation of cymantrenes with a disulfide bridge results in the formation of two type dicarbonyl chelates with Mn-S bond. The first type is formed due to removal of one CO ligand from one cymantrenyl moiety to give a 5-membered chelate cycle; the other is formed due to removal of two CO ligands from two cymantrenyl moieties to form a bicyclic chelate. The latter was isolated and characterized by X-ray analysis. For the first time, unstable fulvenes were prepared in situ by irradiation of cymantrenyl derivatives or their dicarbonyl complexes. Electrochemical properties of disulfides were studied before and after photolysis in acetonitrile. The manganese oxidation potential value increased on going from tricarbonyls to dicarbonyls.

Fabrication and Characterization of Acute Myocardial Infarction Myoglobin Biomarker Based on Chromium-Doped Zinc Oxide Nanoparticles.

In this article, we describe the fabrication and characterization of a sensor for acute myocardial infarction that detects myoglobin biomarkers using chromium (Cr)-doped zinc oxide (ZnO) nanoparticles (NPs). Pure and Cr-doped ZnO NPs (13 × 1017, 20 × 1017, and 32 × 1017 atoms/cm3 in the solid phase) were synthesized by a facile low-temperature sol-gel method. Synthesized NPs were examined for structure and morphological analysis using various techniques to confirm the successful formation of ZnO NPs. Zeta potential was measured in LB media at a negative value and increased with doping. XPS spectra confirmed the presence of oxygen deficiency in the synthesized material. To fabricate the sensor, synthesized NPs were screen-printed over a pre-fabricated gold-coated working electrode for electrochemical detection of myoglobin (Mb). Cr-doped ZnO NPs doped with 13 × 1017 Cr atomic/cm3 revealed the highest sensitivity of ~37.97 μA.cm−2nM−1 and limit of detection (LOD) of 0.15 nM for Mb with a response time of ≤10 ms. The interference study was carried out with cytochrome c (Cyt-c) due to its resemblance with Mb and human serum albumin (HSA) abundance in the blood and displayed distinct oxidation potential and current values for Mb. Cr-doped ZnO NP-based Mb biosensors showed 3 times higher sensitivity as compared to pure ZnO NP-based sensors.

Effect of magnetic field on the behavior of Electrochemical oxidation of Aluminum in 3.5% NaCl solution

An irreversible electrochemical reaction from material interaction with the environment and causing degradation is known as corrosion. The electrolyte changes significantly affect the corrosion's reaction kinetics. Unknown factors and various notable factors influence the corrosion rate of a particular material in the environmental system. Significant interest in magnetic fields and their effects on electrochemical reactions have recently been gained. This paper studies the effect of an external magnetic field on the electrochemical oxidation of Aluminum (Al) in a 3,5% NaCl solution. The magnetic field 0; 0,8; 1,4; and 2,1 Tesla were used to expose the samples during corrosion testing. We found that the effect of a magnetic field on electrochemical oxidation shifts the oxidation potential to higher or lower than the oxidation potential without a magnetic field. Moreover, the oxidation potential's value depends on the magnetic field's intensity.

Study of the electrochemical betanidin oxidation path using computational methods.

Betalains can be used in the food, drug, and cosmetic industries and have shown their bioactive potential. For these reasons, unraveling their oxidation mechanism is of high importance and demands a systematic and multidisciplinary study. Moreover, the properties mentioned above are drastically influenced by pH and other physicochemical conditions. Betanidin (1) is a relevant molecule of this family and is crucial to elucidating the oxidation mechanism in which its pigment is involved. In the present study, the pKas and oxidation potential values for all protic groups of 1 were analyzed using B3LYP/6-31+G(d,p)/SMD as the computational methodology. Moreover, six explicit water molecules were added to improve the solvation-free energy values. The oxidation mechanism at each pH was constructed and analyzed in depth. On the other hand, cyclic voltammetry simulations allowed obtaining electrochemical data from experiments and support the proposed mechanism. In the present work, the main oxidation path of 1 is described and consists of a concerted electron-proton transfer followed by a sequential electron and proton transfer to obtain the o-quinone product or a quinone methide molecule.

Diarylamines with the Neighboring Pyridyl Group: Synthesis and Modulation of the Amine Functionality via Intramolecular H-Bonding

AbstractNew pyridyl-containing diarylamines were obtained via Cu-assisted reductive amination of the ortho-2-pyridylarylboronic acids. Comparative analysis of the spectral and electrochemical data obtained for new diarylamines and their pyridyl-free counterparts revealed the intramolecular H-bond (IMHB) formation which significantly influences the properties of the amino group. The electron density at the N atom of the amino group is increased due to partial weakening of the N–H bond, although the BDE and activation energy for the H-atom abstraction is increased due to the chelating effect of two N atoms. The ortho-pyridyl-containing diarylamines are more prone to be oxidized as compared to their pyridyl-free counterparts; the shift in the oxidation potential values correlates with the strength of the intramolecular H-bonding which can be tuned by inserting substituents in the pyridyl or phenyl rings. The IMHB is reserved even in polar solvents having a significant H-acceptor ability (such as DMSO) but can be destroyed in methanol, testifying in favor of the dynamic nature of the H-bonding.

Anodic Oxidation of Iodobenzene and Iodobenzoic Acids in Acetic Acid Environment – Electrochemical Investigation and Density Functional Theory Study

AbstractKinetic and mechanistic aspects of an anodic oxidation of iodobenzene and its selected derivatives leading to the corresponding iodosyl compounds, were investigated in anhydrous acidic acetic acid environment using boron‐doped diamond electrode. The first electron removal leading to the formation of radical cation was identified as the rate determining step of the process. Oxidation potential values of the investigated compounds were rationalised by their solution phase ionisation energies (in conformation of the radical cations as products of the first electron removal), calculated by advanced DFT methods. Unexpectedly low oxidation potential of 2‐iodobenzoic acid and its functional derivatives compared to iodobenzene, 3‐iodo and 4‐iodobenzoic acids was explained by decreased electron density at iodine atom leading to planar 2‐iodobenzoic acid radical cation. This is connected with reordering of its frontier molecular orbitals compared to non‐planar neutral molecule.

Hemilabile Properties of Sulfur‐Containing Cymantrene Derivatives

AbstractSulfur‐containing cymantrene derivatives having one or two organometallic moieties were studied by NMR, IR, UV/Vis spectroscopic methods and CVA under irradiation conditions. Photolysis of compounds 1–3 leads to the formation of rare 4‐membered chelates 4, 5 and 8. In the presence of external ligand (L), dissociation of the Mn−S bond occurred to form new dicarbonyl complexes with the Mn−L bond, which demonstrates the hemilabile character of the chelates obtained. The results were confirmed by DFT calculations. CVA method showed manganese oxidation potential value increased in the case of dicarbonyls (1313 mV for 4) as compared to that of tricarbonyls (1067 mV for 1).

Electrochemical Detection of Tryptophan Metabolites via Kynurenine Pathway by Using Nanocarbon Films

AbstractWe studied nanocarbon film electrodes with the aim of detecting tryptophan metabolites via the kynurenine pathway. The nanocarbon films were formed by using unbalanced magnetron sputtering, and they exhibited superior electrode properties including a wide potential window and a low background current as a result of the sp3‐containing structure and ultraflat surface. These properties allowed us to detect certain tryptophan metabolites such as kynurenic acid (KYNA), which has a relatively high oxidation potential. We also investigated the effect of the sp2/sp3 ratio of the nanocarbon film as regards the electrode activity in relation to target molecules. We found that the sp2/sp3 ratio played important roles in both widening the potential window and obtaining superior electrode performance for the metabolites. The nanocarbon film with a high sp3 content was beneficial as regards the electrode performance with respect to the detection limit and sensitivity. Compared with conventional carbon‐based electrodes, the nanocarbon film electrode with a high sp3 content exhibited higher electrode activity against KYNA while maintaining a low background current. Computational experiments revealed that the theoretical oxidation potential (Eox) value for some targets coincided with that obtained in electrochemical experiments using our nanocarbon film electrode.

Mestranol moieties clicked to Zn(II)phthalocyanine for controllable photosensitized oxidation of cholesterol

Four mestranol moieties were chemically linked to Zn(II) phthalocyanine (4) by cycloaddition “Click” reaction using a tetra-azidoethoxy substituted Zn(II)-phthalocyanine (3). The alkyl-azido coupling reaction was realized between azido groups of 3 and alkyl group of mestranol. The alkylation reaction was carried out to obtain cationic Zn(II) phthalocyanine derivative (5). The new compounds were chemically characterized by the known analytical methods. The absorption and fluorescence properties were studied in comparison. The absorption maxima of phthalocyanines 3, 4 and 5 were recorded at approx. shifts of 8 - 12 nm in the far- red region (680 - 684 nm) and the fluorescence maxima (692 - 693 nm) as compared to unsubstituted ZnPc (672 nm, 680 nm) in DMSO. The studies of singlet oxygen generation of 3, 4 and 5 showed relatively high values such as 0.52 for 3; 0.51 for 4 and 0.46 for 5. The fluorescence lifetime of 3.15 ns (3), 3.25 ns (4) and 3.46 ns (5) were determined with lower than the value than for the used standard ZnPc (3.99 ns). The high photo stability was observed for compounds 3, 4 and 5. In addition, the photosensitized oxidation of cholesterol was compared for 3 and 4 with much lower values of oxidation potential than for unsubstituted ZnPc which suggests that the substitution groups influenced on the photooxidation index of the target molecule.

An innovative design of hydrazine hydrate electrochemical sensor based on decoration of crown ether/Nafion/carbon nanotubes composite with gold nanoparticles

Abstract For the first time an efficient electrochemical sensor is presented for electrochemical sensing of hydrazine hydrate (HH) in real water samples. A layer-by-layer stacked composite sensor is fabricated based on carbon nanotubes (CNTs), Nafion (NF), 15-crown-5 (CW) and gold nanoparticles; GC/CNT/NF/CW/Aunano. Each of the sensor components’ unique property contributes in synergism to the current signal enhancement. CNTs offer large surface area, and good electrical conductivity; NF has a great cationic selectivity which facilitates the preconcentration of HH; crown ether allows good binding ability, stable supramolecular complexes, and excellent host–guest interaction. Besides, the presence of Aunano over the electrode composite surface provides large electroactive surface for HH oxidation process. Thermodynamically the conversion process of HH is more preferred over the composite sensor surface with oxidation potential value of + 135 mV against a value of + 630 mV over GC/CNT electrode. Amperometry determination of HH in wastewater sample in the concentration range (0.005–200 µM) is successfully achieved with low detection limit (0.132 nM) in the low concentration range. Practical application of the GC/CNT/NF/CW/Aunano sensor is efficiently assessed in wastewater sample for HH determination with acceptable recovery, excellent anti-interference ability and long-term stability.

Polyhedral oligomeric silsesquioxanes appended conjugated soluble polymers based on thieno[3,4-c]pyrrole-4,6‑dione acceptor unit

A series of new donor-acceptor-donor type fluorescent molecules incorporating thieno[3,4-c]pyrrole-4,6‑dione (TPD) as the acceptor unit were synthesized. TPD acceptor unit was modified with polyhedral oligomeric silsesquioxanes (POSS) cages and integrated with thiophene and alkylenedioxythiophene derivatives (3,4-ethylenedioxythiophene (EDOT) and 3,4-propylenedioxythiophene (ProDOT)) using Stille coupling reaction. The monomers, T2-POSS, E2-POSS, and P2-POSS, were polymerized successfully via electrochemical and chemical polymerization techniques. As a fingerprint of d-A-D monomers, all monomers showed dual band characteristics due to intramolecular charge transfer. Soluble polymers exhibited reversible electrochromic responses electrochemically and chemically with fast switching times and high coloration efficiencies. E2-POSS and its polymer PE2-POSS exhibited the lowest oxidation potential and band gap values as compared to their thiophene and ProDOT analogs. Also, P2-POSS and its chemically obtained fluorescent polymer PP2-POSS-C represented high sensitivity towards Fe2+ and Fe3+ ions, which makes them potential candidates to be amenable for use in ion sensing.

Fine-Tuning the Biological Profile of Multitarget Mitochondriotropic Antioxidants for Neurodegenerative Diseases.

Neurotransmitter depletion and mitochondrial dysfunction are among the multiple pathological events that lead to neurodegeneration. Following our previous studies related with the development of multitarget mitochondriotropic antioxidants, this study aims to evaluate whether the π-system extension on the chemical scaffolds of AntiOXCIN2 and AntiOXCIN3 affects their bioactivity and safety profiles. After the synthesis of four triphenylphosphonium (TPP+) conjugates (compounds 2–5), we evaluated their antioxidant properties and their effect on neurotransmitter-metabolizing enzymes. All compounds were potent equine butyrylcholinesterase (eqBChE) and moderate electric eel acetylcholinesterase (eeAChE) inhibitors, with catechols 4 and 5 presenting lower IC50 values than AntiOXCIN2 and AntiOXCIN3, respectively. However, differences in the inhibition potency and selectivity of compounds 2–5 towards non-human and human cholinesterases (ChEs) were observed. Co-crystallization studies with compounds 2–5 in complex with human ChEs (hChEs) showed that these compounds exhibit different binging modes to hAChE and hBChE. Unlike AntiOXCINs, compounds 2–5 displayed moderate human monoamine oxidase (hMAO) inhibitory activity. Moreover, compounds 4 and 5 presented higher ORAC-FL indexes and lower oxidation potential values than the corresponding AntiOXCINs. Catechols 4 and 5 exhibited broader safety windows in differentiated neuroblastoma cells than benzodioxole derivatives 2 and 3. Compound 4 is highlighted as a safe mitochondria-targeted antioxidant with dual ChE/MAO inhibitory activity. Overall, this work is a contribution for the development of dual therapeutic agents addressing both mitochondrial oxidative stress and neurotransmitter depletion.