-
Inorganic Chemistry May 2024One of the crucial metabolic processes for both plant and animal kingdoms is the oxidation of the amino acid tryptophan (TRP) that regulates plant growth and controls...
One of the crucial metabolic processes for both plant and animal kingdoms is the oxidation of the amino acid tryptophan (TRP) that regulates plant growth and controls hunger and sleeping patterns in animals. Here, we report revolutionary insights into how this process can be crucially affected by interactions with metal oxide nanoparticles (NPs), creating a toolbox for a plethora of important biomedical and agricultural applications. Molecular mechanisms in TRP-NP interactions were revealed by NMR and optical spectroscopy for ceria and titania and by X-ray single-crystal study and a computational study of model TRP-polyoxometalate complexes, which permitted the visualization of the oxidation mechanism at an atomic level. Nanozyme activity, involving concerted proton and electron transfer to the NP surface for oxides with a high oxidative potential, like CeO or WO, converted TRP in the first step into a tricyclic organic acid belonging to the family of natural plant hormones, auxins. TiO, a much poorer oxidant, was strongly binding TRP without concurrent oxidation in the dark but oxidized it nonspecifically via the release of reactive oxygen species (ROS) in daylight.
Topics: Cerium; Metal Nanoparticles; Models, Molecular; Oxidation-Reduction; Oxides; Titanium; Tryptophan
PubMed: 38684718
DOI: 10.1021/acs.inorgchem.3c03674 -
Environmental Science & Technology Nov 2015Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation,...
Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide and assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM.
Topics: Bromides; Forests; Halogenation; Humic Substances; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Light; New Jersey; Oxidation-Reduction; Pinus; Quercus; Soil; Soil Microbiology; X-Ray Absorption Spectroscopy
PubMed: 26468620
DOI: 10.1021/acs.est.5b03937 -
Molecules (Basel, Switzerland) Dec 2022The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their...
The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their natural oxidative degradation in clay soils and to evaluate the ecotoxicity of mixtures partially oxidized on the species , a biodiversity representative of plants in the aquatic environment. Kinetic data showed that the adsorption of organic pollutants on clay particles obeys the pseudo-second-order model, while the adsorption isotherms satisfactorily fit the Langmuir model. Adsorption reduces the dispersion of the organic pollutant in the environment and prolongs its persistence and its natural degradation probability. Measurements of the Zeta potential and particle size as a function of pH demonstrate that the catalytic activity of clay depends on its cation, its silica/alumina ratio, and therefore on its permanent and temporary ion exchange capacities. These factors seem to govern its delamination and dispersion in aqueous media, its hydrophilic-hydrophobic character, and its porosity. Tests conducted on in contact with ozonation mixtures revealed that the toxicity could be due to pH decrease and to the toxicity of the intermediates yielded. Ecotoxicity would depend on the structure of the organic molecules, the chemical composition of the clay surface and ozonation time, which determines the oxidation progress. These results are of great importance for further research because they allow concluding that the negative impact of the persistence of an organic molecule in clay-containing media depends on the type and composition of the very clay mineral.
Topics: Clay; Aluminum Silicates; Environmental Pollutants; Water; Molecular Structure; Catalysis; Ozone; Adsorption; Water Pollutants, Chemical; Bentonite
PubMed: 36615416
DOI: 10.3390/molecules28010222 -
Nature Chemistry Mar 2019Despite significant progress in the development of site-selective aliphatic C-H oxidations over the past decade, the ability to oxidize strong methylene C-H bonds in the...
Despite significant progress in the development of site-selective aliphatic C-H oxidations over the past decade, the ability to oxidize strong methylene C-H bonds in the presence of more oxidatively labile aromatic functionalities remains a major unsolved problem. Such chemoselective reactivity is highly desirable for enabling late-stage oxidative derivatizations of pharmaceuticals and medicinally important natural products that often contain such functionality. Here, we report a simple manganese small-molecule catalyst Mn(CF-PDP) system that achieves such chemoselectivity via an unexpected synergy of catalyst design and acid additive. Preparative remote methylene oxidation is obtained in 50 aromatic compounds housing medicinally relevant halogen, oxygen, heterocyclic and biaryl moieties. Late-stage methylene oxidation is demonstrated on four drug scaffolds, including the ethinylestradiol scaffold where other non-directed C-H oxidants that tolerate aromatic groups effect oxidation at only activated tertiary benzylic sites. Rapid generation of a known metabolite (piragliatin) from an advanced intermediate is demonstrated.
Topics: Chemical Phenomena; Chemistry, Organic; Hydrocarbons, Aromatic; Oxidation-Reduction
PubMed: 30559371
DOI: 10.1038/s41557-018-0175-8 -
Ecotoxicology and Environmental Safety May 2022The frequent use of antibiotics allows them to enter aqueous environments via wastewater, and many types of antibiotics accumulate in the environment due to difficult... (Review)
Review
The frequent use of antibiotics allows them to enter aqueous environments via wastewater, and many types of antibiotics accumulate in the environment due to difficult degradation, causing a threat to environmental health. It is crucial to adopt effective technical means to remove antibiotics in aqueous environments. The Fenton reaction, as an effective organic pollution treatment technology, is particularly suitable for the treatment of antibiotics, and at present, it is one of the most promising advanced oxidation technologies. Specifically, rapid Fenton oxidation, which features high removal efficiency, thorough reactions, negligible secondary pollution, etc., has led to many studies on using the Fenton reaction to degrade antibiotics. This paper summarizes recent progress on the removal of antibiotics in aqueous environments by Fenton and Fenton-like reactions. First, the applications of various Fenton and Fenton-like oxidation technologies to the removal of antibiotics are summarized; then, the advantages and disadvantages of these technologies are further summarized. Compared with Fenton oxidation, Fenton-like oxidations exhibit milder reaction conditions, wider application ranges, great reduction in economic costs, and great improved cycle times, in addition to simple and easy recycling of the catalyst. Finally, based on the above analysis, we discuss the potential for the removal of antibiotics under different application scenarios. This review will enable the selection of a suitable Fenton system to treat antibiotics according to practical conditions and will also aid the development of more advanced Fenton technologies for removing antibiotics and other organic pollutants.
Topics: Anti-Bacterial Agents; Catalysis; Hydrogen Peroxide; Oxidation-Reduction; Wastewater; Water; Water Pollutants, Chemical; Water Purification
PubMed: 35395600
DOI: 10.1016/j.ecoenv.2022.113464 -
International Journal of Environmental... Mar 2022Cadmium (Cd)-contaminated paddy soils are a big concern. However, the effect of irrigation with acid water on the migration and transformation of Cd and the effect of...
Cadmium (Cd)-contaminated paddy soils are a big concern. However, the effect of irrigation with acid water on the migration and transformation of Cd and the effect of alternating redox conditions caused by intermittent irrigation on Cd aging processes in different depths of paddy soils are unclear. This study revealed Cd fractionation and aging in a Cd-contaminated paddy soil under four irrigation periods with acid water and four drainage periods, by applying a soil columns experiment and a sequential extraction procedure. The results showed that the dynamic changes of soil pH, oxidation reduction potential (ORP), iron (Fe) oxides and dissolved organic carbon (DOC) throughout the intermittent irrigation affected the transformation of Cd fractions. After 32 days, the proportion of exchangeable Cd (F1) to the total Cd decreased with a reduction of 24.4% and 20.1% at the topsoil and the subsoil, respectively. The labile fractions of Cd decreased, and the more immobilizable fractions of Cd increased in the different depths of soils due to the aging process. Additionally, the redistribution of the Fe and Mn oxide-bound Cd (F3) and organic matter and secondary-sulfide-bound Cd (F4) occurred at different depths of soils during the incubation time. Overall, the bioaccessibility of Cd in the subsoil was higher than that in the topsoil, which was likely due to the leaching and accumulation of soluble Cd in the deep soil. In addition, the aging processes in different depths of soils were divided into three stages, which can be mainly described as the transformation of F1 into F3 and F4.
Topics: Cadmium; Environmental Pollution; Oryza; Oxides; Soil; Soil Pollutants; Water
PubMed: 35329022
DOI: 10.3390/ijerph19063339 -
Angewandte Chemie (International Ed. in... May 2022This work reports an aqueous dye-sensitized photoelectrochemical cell (DSPEC) capable of oxidizing glycerol (an archetypical biobased compound) coupled with H...
This work reports an aqueous dye-sensitized photoelectrochemical cell (DSPEC) capable of oxidizing glycerol (an archetypical biobased compound) coupled with H production. We employed a mesoporous TiO photoanode sensitized with the high potential thienopyrroledione-based dye AP11, encased in an acetonitrile-based redox-gel that protects the photoanode from degradation by aqueous electrolytes. The use of the gel creates a biphasic system with an interface at the organic (gel) electrode and aqueous anolyte. Embedded in the acetonitrile gel is 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), acting as both a redox-mediator and a catalyst for oxidative transformations. Upon oxidation of TEMPO by the photoexcited dye, the in situ generated TEMPO shuttles through the gel to the acetonitrile-aqueous interface, where it acts as an oxidant for the selective conversion of glycerol to glyceraldehyde. The introduction of the redox-gel layer affords a 10-fold increase in the conversion of glycerol compared to the purely aqueous system. Our redox-gel protected photoanode yielded a stable photocurrent over 48 hours of continuous operation, demonstrating that this DSPEC is compatible with alkaline aqueous reactions.
Topics: Acetonitriles; Coloring Agents; Cyclic N-Oxides; Glycerol; Oxidation-Reduction; Photosynthesis; Solar Energy; Water
PubMed: 35266261
DOI: 10.1002/anie.202200175 -
The Journal of Physical Chemistry. A Jun 2021The fates of organic hydroperoxides (ROOHs) in atmospheric condensed phases are key to understanding the oxidative and toxicological potentials of particulate matter....
The fates of organic hydroperoxides (ROOHs) in atmospheric condensed phases are key to understanding the oxidative and toxicological potentials of particulate matter. Recently, mass spectrometric detection of ROOHs as chloride anion adducts has revealed that liquid-phase α-hydroxyalkyl hydroperoxides, derived from hydration of carbonyl oxides (Criegee intermediates), decompose to geminal diols and HO over a time frame that is sensitively dependent on the water content, pH, and temperature of the reaction solution. Based on these findings, it has been proposed that H-catalyzed conversion of ROOHs to ROHs + HO is a key process for the decomposition of ROOHs that bypasses radical formation. In this perspective, we discuss our current understanding of the aqueous-phase decomposition of atmospherically relevant ROOHs, including ROOHs derived from reaction between Criegee intermediates and alcohols or carboxylic acids, and of highly oxygenated molecules (HOMs). Implications and future challenges are also discussed.
Topics: Atmosphere; Hydrogen-Ion Concentration; Mass Spectrometry; Peroxides; Thermodynamics; Water
PubMed: 33904735
DOI: 10.1021/acs.jpca.1c01513 -
International Journal of Environmental... Mar 2023NO is a greenhouse gas and a candidate oxidant. Volatile organic pollutants (VOCs) have caused great harm to the atmospheric ecological environment. Developing the...
NO is a greenhouse gas and a candidate oxidant. Volatile organic pollutants (VOCs) have caused great harm to the atmospheric ecological environment. Developing the technique utilizing NO as the oxidant to oxidize VOCs to realize the collaborative purification has significant importance and practical value for NO emission control and VOC abatement. Therefore, the study of NO catalytic oxidation of tert-butanol based on zeolite catalysts was carried out. A series of molecular sieves, including FER, MOR, ZSM-5, Y, and BEA, were selected as the catalyst objects, and the 1.5% wt Fe and Co were, respectively, loaded on the zeolite catalysts via the impregnation method. It was found that the catalytic performance of BEA was the best among the molecular sieves. Comparing the catalytic performance of Fe-BEA under different load gradients (0.25~2%), it was found that 1.5% Fe-BEA possessed the best catalytic activity. A series of characterization methods showed that Fe content in 1.5% Fe-BEA was the highest, and more active sites formed to promote the catalytic reaction. The α-O in the reaction eventually oxidized tert-butanol to CO over the active site. The Co mainly existed in the form of Co cations over Co-BEA samples; the 2% Co-BEA possessing higher amounts of Co exhibited the highest activity among the prepared Co-BEA samples.
Topics: tert-Butyl Alcohol; Zeolites; Oxidants; Oxidation-Reduction
PubMed: 36981811
DOI: 10.3390/ijerph20064902 -
Environmental Science & Technology Apr 2016Oscillations between reducing and oxidizing conditions are observed at the interface of anaerobic/oxic and anaerobic/anoxic environments, and are often stimulated by an...
Oscillations between reducing and oxidizing conditions are observed at the interface of anaerobic/oxic and anaerobic/anoxic environments, and are often stimulated by an alternating flux of electron donors (e.g., organic carbon) and electron acceptors (e.g., O2 and NO3(-)). In iron (Fe) rich soils and sediments, these oscillations may stimulate the growth of both Fe-reducing bacteria (FeRB) and Fe-oxidizing bacteria (FeOB), and their metabolism may induce cycling between Fe(II) and Fe(III), promoting the transformation of Fe (hydr)oxide minerals. Here, we examine the mineralogical evolution of lepidocrocite and ferrihydrite, and the adaptation of a natural microbial community to alternating Fe-reducing (anaerobic with addition of glucose) and Fe-oxidizing (with addition of nitrate or air) conditions. The growth of FeRB (e.g., Geobacter) is stimulated under anaerobic conditions in the presence of glucose. However, the abundance of these organisms depends on the availability of Fe(III) (hydr)oxides. Redox cycling with nitrate results in decreased Fe(II) oxidation thereby decreasing the availability of Fe(III) for FeRB. Additionally, magnetite is detected as the main product of both lepidocrocite and ferrihydrite reduction. In contrast, introduction of air results in increased Fe(II) oxidation, increasing the availability of Fe(III) and the abundance of Geobacter. In the lepidocrocite reactors, Fe(II) oxidation by dissolved O2 promotes the formation of ferrihydrite and lepidocrocite, whereas in the ferrihydrite reactors we observe a decrease in magnetite stoichiometry (e.g., oxidation). Understanding Fe (hydr)oxide transformation under environmentally relevant redox cycling conditions provides insight into nutrient availability and transport, contaminant mobility, and microbial metabolism in soils and sediments.
Topics: Bacteria; Ferric Compounds; Geobacter; Glucose; Iron; Minerals; Nitrates; Oxidation-Reduction; Oxides; Oxygen; Soil Microbiology
PubMed: 26949922
DOI: 10.1021/acs.est.5b05519