Acid Anions Research Articles

1H and 13C NMR and FTIR Spectroscopic Analysis of Formic Acid Dissociation Dynamics in Water.

The formation and transport of ionic charges in formic acid-water (HCOOH-H2O) mixtures with initial water mole fractions ranging from XH2Oi = 0 to 1 were investigated using 13C and 1H NMR, FTIR spectroscopy, viscosity, conductivity, and pH measurements. The maximum molar concentration of ions (H3O+ and HCOO-), along with the relative differences between theoretical and experimental densities, spin-lattice relaxation times (T1), activation energies (Ea), viscosity (η), and conductivity (σ), were identified within the range of XH2Oi ≈ 0.5-0.7. These results indicate that pure formic acid (FA) solutions predominantly consist of cyclic dimers at room temperature. As the water mole fraction increases up to 0.6, a structural shift occurs from cyclic dimers to a mixture of linear and cyclic dimers, driven by the formation of strong hydrogen bonds. Beyond a water mole fraction of 0.6, the structure transitions to linear dimers, with FA molecules behaving as free entities in the water. Furthermore, the acidity was found to increase approximately 2-fold with every 0.1 increment in water mole fraction. These findings are critical for understanding the kinetics of formic acid anions in body fluids, the structure of the hydrogen bonding network, and ionization energies.

Discovery of calcium sulfate at different hydration states on Mars - based on perseverance SHERLOC analysis

Organic matter on planets is often co-deposited with evaporites, and evaporation of lakes in the Jezero region of Mars may have led to the deposition of abundant organic matter and minerals such as sulfates, making sulfates important minerals for preserving the remains of potential life on Mars, especially in different hydration states, will help to invert the variability of the Martian environment and provide guidance for the exploration of life on Mars. Raman spectroscopy can detect the molecular composition of organic matter and acid anion information of the target of interest, thus enabling in situ analysis of life information and its living environment. In order to realize the detection of life remains on Mars, The Perseverance rover is equipped with SHERLOC in situ material detection payload, which adopts a 248.6 nm deep ultraviolet (DUV) laser to simultaneously excite Raman and fluorescence signals of the target. In this paper, five scans in three modes (survey scan, HDR scan and detail scan) from two sites on Mars (Quartier and Bellegarde) were selected for preliminary analysis, and the presence of sulfate minerals at these two sites was confirmed. The detail scans at Quartier were analyzed in depth, and the presence of four calcium sulfate minerals, gypsum (CaSO4∙2 H2O), bassanite (CaSO4∙0.5 H2O), anhydrite (β-CaSO4) and gamma-calcium sulfate (γ-CaSO4)was inferred from the states of ν1 (SO4), ν3 (SO4) and hydrated peaks. The differences in the degree of hydration of calcium sulfate minerals suggest that there may have been active water activity on Mars. By comparing data collected by SHERLOC with spectra from spectral libraries, the composition of small-scale structures on Mars may be assessable. However, due to the complexity of the Martian geology, more accurate water activity will need to be combined with more detailed ions, temperatures, humidity, and other conditions for a more precise analysis.

Effect of the Introduction of ZnII and CdII Ions on EuIII and TbIII Emission in M2Ln2 Heterometallic Molecules With 2‐Furoic Acid Anions

ABSTRACTHeterometallic d‐4f coordination complexes are of paramount interest in modern coordination chemistry because of their potential applications in organic light‐emitting devices and spintronic materials. Here we report the synthesis and thorough investigation of Ln and MLn (M = Zn, Cd; Ln = Sm, Eu, Gd, Tb) molecular complexes based on 2‐furancarboxylic acid anion (Hfur): [Ln2(NO3)2(fur)4(DME)2] (Ln = Eu, Gd, Tb; DME is dimethoxyethane) and [M2Ln2(NO3)2(fur)8(bpy)2] (M = Zn, Cd; Ln = Eu, Gd, Tb, Sm; bpy is 2,2′‐bipyridyl). The structure and isostructural nature of compounds were determined based on the single‐crystal and powder X‐ray diffraction data. The photophysical properties of the obtained compounds were studied in detail: The energies of the triplet levels of the furoate anion and d‐blocks {M(fur)2(bpy)} (M = Zn, Cd), the relaxation times of the excited states, and the quantum yields were determined. Critical step from Ln complexes to ZnLn and CdLn (Ln = Eu, Tb) is accompanied by an increase in quantum yields, which correlates with a change in the energy of the triplet level of the aromatic part of the complexes and with the results of quantum chemical calculations indicating different schemes for the origination of triplet levels in MLn compounds.

The crop mined phosphorus nutrition via modifying root traits and rhizosphere micro‐food web to meet the increased growth demand under elevated CO2

AbstractElevated CO2 (eCO2) stimulates productivity and nutrient demand of crops. Thus, comprehensively understanding the crop phosphorus (P) acquisition strategy is critical for sustaining agriculture to combat climate changes. Here, wheat (Triticum aestivum L) was planted in field in the eCO2 (550 µmol mol−1) and ambient CO2 (aCO2, 415 µmol mol−1) environments. We assessed the soil P fractions, root morphological and physiological traits and multitrophic microbiota [including arbuscular mycorrhizal fungi (AMF), alkaline phosphomonoesterase (ALP)‐producing bacteria, protozoa, and bacterivorous and fungivorous nematodes] in the rhizosphere and their trophic interactions at jointing stage of wheat. Compared with aCO2, significant 20.2% higher shoot biomass and 26.8% total P accumulation of wheat occurred under eCO2. The eCO2 promoted wheat root length and AMF hyphal biomass, and increased the concentration of organic acid anions and the ALP activity, which was accompanied by significant decreases in calcium‐bound inorganic P (Ca‐Pi) (by 16.7%) and moderately labile organic P (by 26.5%) and an increase in available P (by 14.4%) in the rhizosphere soil. The eCO2 also increased the growth of ALP‐producing bacteria, protozoa, and bacterivorous and fungivorous nematodes in the rhizosphere, governed their diversity and community composition. In addition, the eCO2 strengthened the trophic interactions of microbiota in rhizosphere; specifically, the eCO2 promoted the associations between protozoa and ALP‐producing bacteria, between protozoa and AMF, whereas decreased the associations between ALP‐producing bacteria and nematodes. Our findings highlighted the important role of root traits and multitrophic interactions among microbiota in modulating crop P‐acquisition strategies, which could advance our understanding about optimal P management in agriculture systems under global climate changes.

Hierarchical ion interactions in the direct air capture of CO2 at air/aqueous interfaces.

The direct air capture (DAC) of CO2 using aqueous solvents is plagued by slow kinetics and interfacial barriers that limit effectiveness in combating climate change. Functionalizing air/aqueous surfaces with charged amphiphiles shows promise in accelerating DAC; however, insight into these interfaces and how they evolve in time remains poorly understood. Specifically, competitive ion interactions between DAC reagents and reaction products feedback onto the interfacial structure, thereby modulating interfacial chemical composition and overall function. In this work, we probe the role of glycine amino acid anions (Gly-), an effective CO2 capture reagent, that promotes the organization of cationic oligomers at air/aqueous interfaces. These surfaces are probed with vibrational sum frequency generation spectroscopy and molecular dynamics simulations. Our findings demonstrate that the competition for surface sites between Gly- and captured carbonaceous anions (HCO3-, CO32-, carbamates) drives changes in surface hydration, which in turn tunes oligomer ordering. This phenomenon is related to a hierarchical ordering of anions at the surface that are electrostatically attracted to the surface and their ability to compete for interfacial water. These results point to new ways to tune interfaces for DAC via stratification of ions based on relative surface propensities and specific ion effects.

Sonocatalysis Regulates Tumor Autophagy for Enhanced Immunotherapy.

Immunotherapy stands as a groundbreaking strategy for cancer treatment, due to its ability to precisely and safely detect and eradicate tumors. However, the efficacy of immunotherapy is often limited by tumor autophagy, a natural defense mechanism that tumors exploit to resist immune attacks. Herein, we introduce a spatiotemporally controlled method to modulate tumor autophagy via sonocatalysis, aiming to improve immunotherapeutic outcomes. Specifically, we synthesized a tumor-targeting nanocatalyst based on a semiconductor heterojunction composed of Barium Titanate (BTO), Black Phosphorus (BP) integrated with Hyaluronic Acid (HA), referred to as BTO/BP-HA. Compared to traditional catalysts, the heterojunction structure enhances energy band bending and rapid electron-hole separation under ultrasonic stimulation, splitting water to generate H2. This promotes tumor cell apoptosis by inhibiting mitochondrial respiration and induces immunogenic cell death, triggering immune responses to eliminate tumor cells. However, the concurrent activation of autophagy mitigates the cytotoxic effectiveness of nanocatalysts. Within the nanocatalyst, BP undergoes lysosomal degradation to generate PO43-, which subsequently interacts with H+ to generate a conjugated acidic anion, increasing the lysosomal pH. This research ingeniously combines sonocatalysis with tumor autophagy, disrupting the activity of acidic hydrolases to inhibit autophagy, thereby enhancing the immune response and improving the effectiveness of immunotherapy.

Tartaric acid anion intercalated layered double hydroxides constructed a CO2-favorable transport channel in PIM-1 mixed matrix membranes for CO2/N2 separation

As a unique polymer of intrinsic microporosity, PIM-1 has great potential in mixed matrix membranes (MMMs) for gas separation with ultra-high permeability. However, the separation performance, e.g. CO2/N2 separation, is still limited by its poor selectivity. In this work, PIM-1-based MMMs containing tartaric acid anion intercalated layered double hydroxides (TA-LDH) nanofillers are successfully prepared. The uniformly dispersed TA-LDH in the PIM-1 matrix contributes to optimizing the stacking of polymer chains for accessible pores, which is conducive to CO2 diffusion. In addition, the assistant experiment and theoretical calculation point out that the -COO-, –OH between the TA-LDH layers had an affinity for CO2, creating a two-dimensional fast transport channel between the enlarged interlayer space. Compared with the pristine PIM-1 membrane, the CO2 permeability and CO2/N2 selectivity of 0.7 % TA-LDH/PIM-1 membrane is increased by 43.19 % and 105.48 %. The excellent gas separation performance with CO2 permeability of 8343.18 Barrer and CO2/N2 selectivity of 39.02 exceeds the 2019 Robson upper limit. This paves a new way to improve the gas separation performance of PIM-1-based MMMs and suggests high perspectives for real applications.

Multifunctional polymeric stationary phases with enhanced hydrophilicity grafted with polyethyleneimine and polyglycidol

Two methods for increasing the degree of hydrophilization and screening of the sorbent matrix based on a copolymer of styrene and divinylbenzene grafted with polyethyleneimine quaternized with glycidol are proposed. The first method involves the polymerization of glycidol in the functional layer by varying the pH of the reaction medium, and the second method involves modifying the matrix by oxidizing the double bonds on its surface to obtain anchor epoxy groups. It was demonstrated that in the first method, the optimal approach is the twofold addition of glycidol before and after the addition of alkali, as in this case, the first addition of glycidol is consumed for the quaternization of polyamine, and the second for polymerization in ion-exchange centers. The new method of matrix modification, combined with the developed method of creating hydrophilic layers, significantly reduced the retention of oxyhalides, haloacetic acids, and polarizable anions in ion chromatography with suppressed background conductivity and amino acids in hydrophilic chromatography up to the point of changing the elution order. The obtained stationary phases are suitable for the simultaneous determination of standard inorganic anions, oxyhalides, and anions of haloacetic or alkylphosphonic acids in ion chromatography, as well as for the separation of amino acids, sugars, and vitamins in hydrophilic chromatography.

Effect of the length of TiO2 nanotubes on the photoelectrochemical oxidation of phenylacetic acid anions

Effect of the length of TiO2 nanotubes on the photoelectrochemical oxidation of phenylacetic acid anions

Unravelling molecular origins of improved tribological properties of amino acid ionic liquid water-based lubricants

In the quest for sustainable lubrication, this study explores the potential of water-based lubricants (WBLs) with amino acid ionic liquid (AAIL) additives. The research combines experimental and reactive molecular dynamics (MD) simulations to assess the tribological and rheological enhancements provided by AAILs. Specifically, tetrabutylphosphonium (P4444) cations paired with Serine (Ser) and Tryptophan (Trp) anions were mixed into water to create AAIL WBLs. The introduction of AAILs significantly improved the lubricants’ rheological properties and reduced the coefficient of friction by up to 34 %. This reduction is attributed to the formation of hydration shells around the amino acid anions, which create a chemically adsorbed tribofilm on iron oxide surfaces, and P4444 cations that establish a load-bearing layer in the middle regions of the lubricant. This dual-layer structure, supported by hydration lubrication, effectively maintains lubricant fluidity while bearing substantial loads. Among the AAIL WBLs tested, those with a thicker, more stable, hydrated amino acid tribofilm demonstrated more significant friction reduction. These insights into the molecular mechanisms behind AAIL WBLs’ tribological behaviour underscore their promise as eco-friendly lubricants, contributing to advancing a circular economy in industries reliant on lubrication.

Imminent prognosis for piperazinium-based ionic liquids applications for coal desulfurization

Sulfur is one of the most important quality parameters for coal rank and utility in power generation. Combustion of coal having high sulfur content leads to SOx emissions which have detrimental impacts on the environment and human health. For sulfur remediation, N-methyl piperazinium-based room temperature ionic liquids (RTILs) were synthesized with two acidic anions precursors’ dimethyl sulfate and Perchloric acid. These novel RTILs were characterized using standardized analytical techniques of FTIR, 1H NMR, 13C NMR, HPLC, and TGA/DSC. Thermal stability of dimethyl piperazinium methyl sulfate [DMPI+][MeSO4−] and methyl piperazinium perchlorate [MPI+][ClO4−] was 284 °C and 256 °C. The proximate and ultimate analysis of coal samples collected from block II of the Thar coal field shows high moisture content (29–47 %) and gross calorific value between 5006–6660 Btu/lb suggesting it is Lignite-B type fuel. Total sulfur content in coal samples was 1–4.1 % reflecting variable degree of sulfurization. Coal cleansing through oxidative extractive desulfurization theme using nifty combinations of these acidic RTILs was verified by HPLC, FTIR, CHNS Elemental Analyzer, and X-ray Florescence (XRF) techniques. Sulfur leaching from the coal matrix was higher for methyl piperazinium perchlorate and an 85 % decrease in the sulfur part of coal along with increased heat content through this study suggests cleaner and sustainable use of coal.

Effects of anions on the electrospray ionization of proteins in strong acids.

The effect of anions on the positive electrospray ionization (ESI) of proteins in different strong acids with varying pH values from 3 to 1 is studied using high-pressure ESI. Reducing the pH from ∼2 to 1 caused a drastic shift in charge state from a high-charge-state distribution (HCSD) to a narrow low-charge-state distribution (LCSD). The shift in charge state was consistent with the circular dichroism result that showed a conformational change due to the "acid-induced folding" of proteins from an unfolding state to a compact molten globule state. Acids of different anions produced noticeable differences in the average charge for HCSD and LCSD. For HCSD, the average charge was lower than the value typically observed using formic and acetic acids. As for LCSD, the average charge was lower than the "native" charge. The high abundance of acid anion that induces the protein compaction was believed to play a role in charge reduction. The effectiveness of anions to "refold" a highly unfolded protein to a compact state and the propensity to reduce the charge of HCSD for proteins appeared to follow the selectivity series of anions towards the stationary phase in ion chromatography. However, the propensity of anions to reduce the charge for LCSD follows quite an opposite trend. The presence of ammonium salt in the acidic solution was found to increase the charge of LCSD. The simple mass spectrum with a narrow distribution of charge state obtained with perchloric acid at pH 1 was demonstrated to facilitate the counting of basic sites.

Advanced Functional Photochromic Wearables with Superior Durability and Stability for Sustainable Applications

AbstractThe rewritable wearables based on photochromism have emerged as attractive candidates in inkless printing applications. Among various photochromic materials, polyoxometalates have great potential for rewritable wearables, with major advantages in fast response upon UV irradiation, long‐term photochemical stability, and excellent fatigue resistance. However, the development of rewritable wearables based on polyoxometalates is limited by low combining fastness, weak stability, and poor scalability. Here, a scalable strategy is reported to fabricate an ideal rewritable wearable based on fundamental charge balance mechanism. The pristine cotton substrate is grafted by cationic polymer brushes to incorporate photochromic phosphomolybdic acid (PMoA) anions through electrostatic attraction, and then the cationic surfactants with alkyl chains are introduced to encapsulate the PMoA anions to achieve charge balance subsequently. The resultant rewritable wearables display the long‐awaited properties, such as high color contrast, favorable reversibility (>10 cycles), long color retention (>15 days) and high stability against detergent and sweat (pH 6.5–8.0) during repeated washing (50 cycles) and wearing. As a demonstration, a rewritable T‐shirt is scalably fabricated, and excellent antibacterial activity and biocompatibility are demonstrated as well, which is expected to be a sustainable solution for regular fabric printing in household products and public display.

Innovating an amphoteric collector derived from dodecylamine molecular structure: Facilitating the selective flotation separation of apatite from quartz and dolomite

This paper introduces a novel amphoteric collector, N-dodecyl-β-alanine (DDALA), derived from the molecular structure of dodecylamine, with the incorporation of a propionic acid group. In the study, flotation experiments are undertaken to examine the selectivity of DDALA in apatite flotation. Results demonstrate that DDALA, in combination with xanthan gum (XG) depressant and oleic acid collector successfully accomplishes the reverse flotation separation of apatite from quartz and dolomite. In addition, the synergistic application of zeta potential experiments, X-ray photoelectron spectroscopic tests, and first-principles calculations has been employed to delve into the action mechanisms of DDALA collector and XG depressant. By combining the results with existing research, the paper proposes that the selective adsorption of XG between apatite and quartz surfaces facilitates the selective separation of these two minerals by DDALA collector. Moreover, the intermediate collecting ability of DDALA/oleic acid combined collector for dolomite results from the competitive adsorption of DDALA neutral molecules and oleic acid anions on dolomite surface. Furthermore, the formation of hydrophilic molecular aggregates between DDALA neutral molecules and oleic acid anions on apatite surface diminishes the collecting ability of DDALA/oleic acid combined collector for apatite compared to the individual use of each collector.

Vibrational Spectra Simulations in Amino Acid-Based Imidazolium Ionic Liquids.

We present maximally localized Wannier functions and Voronoi tessellation to obtain dipole moment distributions for vibrational spectra in several important ionic liquids calculated by using ab initio molecular dynamics simulations. IR and Raman spectra of various imidazolium-based ionic liquids (ILs) paired with six amino acid anions are shown herein. For IR spectra, two approaches (Wannier and Voronoi) are in agreement with respect to the relative intensities and the overall shapes for the main peaks. Under Raman spectra, the polarizability of the covalent bonds is shown to affect the strength of the Raman scattering signal. The advantage of the Voronoi tessellation method, being that it does not have strong spikes in its time development, is demonstrated by the comparison of two theoretical methods (Wannier and Voronoi) with experimental data. We analyze the errors between theoretical and experimental spectroscopic data, with the Voronoi method shown to accurately reproduce experimental values. In addition, theoretical spectroscopy shows the ability to accurately separate components of a mixture. The combination of theoretical and experimental methods is utilized to understand the spectroscopic properties of amino acid-based imidazolium ILs.

Brønsted acidity of bis(trifluoromethanesulfonyl)amide and trifluoromethanesulfonic acid in ionic liquids of ternary ammonium

Bis(trifluoromethanesulfonyl)amide (Tf2N−) and triflate (TfO−) are commonly used anions of protic ionic liquids (PILs). They are the conjugate anions of strong acids, Tf2NH and TfOH, whose Brønsted acidities crucially influence the performance of the PILs. In this study, the Brønsted acidity of Tf2NH and TfOH was compared directly through potentiometric titrations carried out in the ionic liquids of ternary ammonium salts. As a result, Tf2NH exhibits stronger Brønsted acidity than TfOH by approximately 2 pH units. Furthermore, calorimetric titrations revealed that this difference originates from differences in their entropy states. This suggests that the solvation state, rather than the properties in their isolated state, has a more significant impact on the acidities of Tf2NH and TfOH. Besides, ionization thermodynamics turned out to be governed by both the constituent cations and anions of the PILs. Therefore, once the acid-base natures of the constituent ions are characterized, the overall acid-base behavior of the PIL may become predictable.

Anions regulation strategy in simulated seawater: A sustainable and efficient approach for on-site hydrolysis hydrogen generation from Mg alloy waste

This innovative study addresses a critical gap in ‘Green hydrogen’ technology by examining the impact of anions on the hydrolysis of residuary waste AZ91D alloy (Rw-AZ91D) in simulated seawater. Despite seawater's potential as an abundant resource for hydrogen production, its complex anionic composition presents efficiency challenges. Through meticulous regulation of anion types and concentrations, the results demonstrate that under ideal conditions (0.5 M NaCl at 298 K), Rw-AZ91D yields a remarkable hydrolysis capacity of 727.0 mL g−1, with a rapid onset (0.42 min) and low activation energy (27.8 kJ mol−1). Intriguingly, oxygenated acid anions notably impede both kinetics and yield. In 0.5 M NaCl solution respectively mixed with 0.1 M Na2SO4, Na2CO3 and NaNO3 solution, the hydrolysis capacities of Rw-AZ91D increase to 409.5, 514.4 and 118.6 mL g−1. When the concentration of employed anions decreases to 0.02 M, 516.5, 621.0 and 480.5 mL g−1 H2 can be obtained. Microstructural and thermodynamic assessments indicate that anions affect hydrolysis via their ionic size, chemistry, induced acidity, and solubility of Mg2+-complexed metallic compounds. This work introduces a cost-effective and eco-friendly method to manage anions during hydrogen production, thereby bolstering the feasibility of portable hydrogen generators and advancing sustainable seawater utilization in Mg alloy waste-based hydrogen generation systems.

Ionic liquid screening for lignocellulosic biomass fractionation: COSMO–RS prediction and experimental verification

The fractionation of lignocellulosic biomass is vital for advancing its applications, particularly in the extraction of high-demand cellulose. In this study, 378 ionic liquids (ILs), comprising of 18 anions and 21 cations, were selected to predict lignocellulosic biomass fractionation using COSMO–RS. The selectivity of the cellulose model to the lignin model in the prediction indicates that the dissolution and separation of lignocellulosic biomass are primarily governed by the anion, and the carboxylate and amino acid anions present the most effective separation effect among the ILs. Moreover, the pretreatment and composition analysis of cornstalk using five representative ILs indicated consistency with the predicted selectivity. The higher calculated excess enthalpy between cellulose and the IL, compared to that between lignin and the IL, led to increased cellulose dissolution by the IL, ultimately resulting in the separation of lignocellulose. This study provides a new paradigm for directly predicting the selectivity of IL to cellulose and lignin and designing ILs capable of achieving lignocellulosic biomass fractionation through COSMO–RS simulation.

Environmental impact assessment of dicationic ionic liquids with ammonium-phosphonium cations and amino acid anions

Progress in the development of biodegradable or biobased ionic liquids (ILs) has led to the design of green compounds for several applications. Herein, four biocompatible dicationic ionic liquids (DILs) with ammonium-phosphonium cations and amino acid anions were synthesized and investigated their environmental impact. The structures of the DILs were confirmed by spectral analyses (1H, 13C and 31P NMR). Furthermore, physicochemical properties such as density, viscosity and refractive index were determined. Water content, bromide content and solubility were thereafter determined as the parameters needed for further studies. Subsequently, their antifeedant activity towards economically important pests of grain in storage warehouses: the granary weevil, the confused flour beetle, and the khapra beetle was examined, showing the dependence on structure. Moreover, selected DILs were investigated for toxicity towards white mustard, Daphnia magna, and Artemia franciscana to specify the environmental impact. These studies were complemented by understand the biodegradation of DILs by bacterial communities derived from soil at the agricultural land. The result was DILs with limited environmental footprints that have great potential for further application studies.

Mechanistic Insights into the Antioxidant and Pro-oxidant Activities of Bromophenols from Marine Algae: A DFT Investigation.

Marine algae are a rich source of aromatic secondary metabolites, with bromophenols (BPs) receiving particular attention due to their health benefits. Despite extensive research on BPs, the understanding of their antioxidant potential, as well as their mechanisms of action at the molecular level, remains incomplete. This study utilized density functional theory (DFT) to systematically elucidate the antioxidant and pro-oxidant mechanisms of the main BP scaffolds under physiological conditions. It was found that BPs exhibit potent antioxidant capacity in both polar and lipid environments. In lipid media, the formal hydrogen transfer mechanism has been identified as the exclusive antiradical pathway. The position of bromine atoms significantly influenced the activity, particularly in scaffolds containing one hydroxyl group. However, no significant effect was observed in scaffolds with two hydroxyl groups. In water, monodeprotonated BPs showed key radical scavenging activity, with different mechanisms favored depending on the configuration of the hydroxyl groups. Additionally, BPs, particularly those bearing a catechol moiety, exhibit secondary antioxidant activity by reducing the production of hydroxyl radicals via the ascorbic acid anion pathway. These findings provide further validation of the potent antioxidant properties of BPs and shed light on their mechanism of action in physiological environments.