Radical Reactions Research Articles

The structural characterisation of new pyridinyl alcohol Cu(II) complexes and their application as catalysts in the oxidation of n‐octane

In this study a series of pyridinyl alcohol ligands (2‐pyridinyl‐1‐cyclohexanol (1), 2‐pyridinyl‐1,1‐diphenyl methanol (2) and 2‐pyridinyl‐1‐phenyl‐1‐isopropylmethanol (3) have been coordinated to Cu (Cu 1‐3). These complexes have been characterised by single‐crystal X‐ray diffraction. The solid‐state structures of the Cu complexes obtained were dependent on the temperature and method used to grow crystals. In the selective oxidation of n‐octane the copper catalysts gave yields of up to 25% towards C8 oxygenates with predominant selectivity to C2‐C4 octanones. The exception was a chlorido‐bridged dimer, which showed high selectivity to 1‐octanol. Products from activation of the C‐1 position predominately form in higher yield in the catalytic reactions of copper(II) complexes that exhibit narrower N—Cu—O bite angles. The activity of the Cu catalysts can be attributed to metal‐ligand cooperative catalysis that involves the formation of Cu(II) peroxo intermediates. Characterisation of the recovered catalyst, in combination with the addition of a radical inhibitor during the partial oxidation reactions, indicated that the catalytic reaction progresses via a combination of an oxygen rebound mechanism and a radical chain reaction, with the latter mechanism usually dominating.

Kinetic Resolution of Racemic Radicals in Asymmetric Photoredox Minisci Reactions with Azaarenes for Precise Construction of Two Non-adjacent Stereocenters.

Despite the significant potential of photocatalysis as a robust synthetic tool, the high reactivity of radicals often presents challenges in achieving optimal chemoselectivity. In this study, we demonstrate that this inherent limitation can be strategically harnessed for asymmetric photoredox catalysis. By utilizing a chiral catalyst to facilitate kinetic resolution between the two enantiomers of racemic radical intermediates, one enantiomer selectively undergoes the desired transformation, while noncatalytic side reactions deplete the other enantiomer. Consequently, an attractive asymmetric photoredox three-component Minisci-type reaction involving bromides, racemic homoallylic tertiary alcohols or amines, and azaarenes has been developed. This approach enables efficient assembly of tertiary alcohols and amines onto the nonadjacent β-position of an azaarene-functionalized tertiary carbon stereogenic center with high levels of enantio- and diastereoselectivity. Therefore, this method not only allows for direct utilization of readily available racemic feedstocks that are challenging to convert into prochiral radicals via redox processes but also provides an efficient strategy for synthesizing complex molecules with multiple stereocenters.

Efficient Oxidation of Methylene Blue via Catalytic Activation of Peroxymonosulfate via an Engineered δ-FeOOH/Pili Nutshell Biochar Composite

This study introduces a novel composite catalyst formed by anchoring delta iron oxyhydroxide (δ-FeOOH) onto pyrolyzed Pili nutshell biochar via a room-temperature coprecipitation technique, marking the first application of Pili nutshell waste in advanced oxidation processes for wastewater treatment. This innovative methodology enhances catalyst dispersion and stability, facilitating the activation of peroxymonosulfate (PMS) to generate reactive sulfate radicals (SO4•–) for the degradation of methylene blue (MB), a thiazine dye commonly used in the medical field and the dye industry. Different techniques have been used to characterize synthesized composites in terms of their morphology, elemental composition, surface functional groups, and crystalline phase structure. The system achieved a maximum MB degradation efficiency of 90.88% within 30 min at pH 6.0 when low dosages of PMS and the δ-FeOOH/biochar composite were used, following pseudo-first-order degradation kinetics. Radical scavenging experiments confirmed that SO4•– radicals were primarily responsible for the degradation process. Notably, the composite maintained over 70% removal efficiency after four reuse cycles, indicating its potential for sustainable and cost-effective wastewater treatment. This research highlights the effectiveness of the δ-FeOOH/biochar/PMS system as a promising solution for treating MB-laden wastewater, contributing to environmental sustainability and waste valorization.

In‐Cell Fast Photochemical Oxidation Interrogates the Native Structure of Integral Membrane Proteins

AbstractIntegral membrane proteins (IMPs) are pivotal for cellular functions but challenging to investigate. Here, IC‐FPOMP (in‐cell fast photochemical oxidation of MPs) is introduced, a method enabling in situ footprinting of IMPs within live cells. IC‐FPOMP generates reactive oxygen radicals from various precursors (TiO2 nanoparticles or H2O2) near the membrane. Leveraging a laser and a 96‐well plate platform, high‐throughput and rapid footprinting of IMPs are achieved. IC‐FPOMP of two human IMPs (human glucose transporter‐hGLUT1 and human gamma‐glutamyl carboxylase‐hGGCX) are successful, providing footprinting of both the transmembrane and extramembrane regions. Comparative analysis of hGLUT1 in liposomes versus cells shows that the membrane may impact the transporter‘s conformation differently. In‐cell drug screening targeting hGLUT1 reveals drug‐binding behavior in vivo. In summary, IC‐FPOMP offers insights into IMP structure‐function relationships in cells and facilitates drug discovery.

EDA Complexation of Two Donor Molecules Initiating Radical Cation Cyclizations

AbstractIn this study, a catalyst-free EDA complexation of two donor molecules using an acidic solvent is presented. The electron-rich aromatic compound (E)-anethole is slowly protonated by the solvent hexafluoroisopropanol (HFIP), leading to the rapid formation of a photoactive EDA complex between a protonated (E)-anethole and another (E)-anethole molecule. This resulting EDA complex initiates radical chain cyclization reactions under green light irradiation.

In-situ designed Bi metal @ defective Bi2O2SO4 to enhance photocatalytic NO removal via boosted directional interfacial charge transfer.

In-situ designed Bi metal @ defective Bi2O2SO4 to enhance photocatalytic NO removal via boosted directional interfacial charge transfer.

Identification of novel tetrabromobisphenol A byproducts in industrial chemicals and the environment near a manufacturing site: an overlooked source of novel pollutants.

To evaluate the migration, transformation, and fate of tetrabromobisphenol A (TBBPA) in the environment, the transformation/degradation (T/D) products of TBBPA and byproducts of industrial production should be distinguished. Herein, 7 reported T/D products (R1-R7) and 7 novel byproducts (N1-N7) of TBBPA were identified in industrial-grade TBBPA chemicals by using high-performance liquid chromatography coupled ion trap mass spectrometry and high-resolution mass spectrometry with a suspect screening strategy. The possible formation pathways of these byproducts were attributed to the bromination, debromination, methylation, demethylation, hydroxylation, substitution, and radical coupling reactions of bisphenol A (BPA), BPA impurities, and TBBPA. The detection frequencies of R1-R7 and N3 (80-100%) were higher than those of N1, N2, and N4-N7 (20-60%) in industrial-grade TBBPA chemicals, with contents extended to 2.29% and 0.0989%, respectively. In the soils and sediments near the TBBPA plants, R1-R4 and N1 were detected with the highest concentration of 1.56 × 102 ng g-1 dry weight, while in the river waters, only R1-R4 were detected with the highest concentration of 4.57 × 102 ng L-1. An in silico analysis indicated the potential toxicity of these compounds, including their hepatotoxicity and carcinogenicity. To accurately estimate the environmental effects of the T/D products of TBBPA, the contributions of byproducts in industrial-grade TBBPA chemicals should be considered separately.

Bacteria-Mediated Intracellular Radical Polymerizations.

Intracellular radical polymerizations allow for the direct bioorthogonal synthesis of various synthetic polymers within living cells, thereby providing a pathway to polymer-modified cells or the fermentative production of polymers. Here, we show that Escherichia coli cells can initiate the polymerization of various acrylamide, acrylic, and methacrylic monomers through an atom transfer radical reaction triggered by the activity of naturally occurring biomolecules within the bacterial cells. Intracellular radical polymerizations were confirmed by nuclear magnetic resonance spectroscopy, gel permeation chromatography of polymers extracted from the cells, and fluorescence labeling of the polymer directly inside the cells. The effect of polymerization on cell behavior and the response of the cells to polymerization was investigated through fluorescence microscopy and flow cytometry techniques, as well as metabolic and membrane integrity assays. The polymer synthesis and resulting products are cell-compatible, as indicated by the high viability of the polymerized cells. In cellulo synthesis of synthetic polymers containing fluorescent dyes was also achieved. These results not only enhance our understanding of the untapped potential of bacterial cells as living catalysts for polymer production but also reveal intracellular polymerization based on atom transfer radical polymerization initiators as a bioorthogonal tool for cell engineering and synthetic biology.

Stereoselective Synthesis of 1,2-cis-α-Glycosyl Thiols and Trehalose-Type α,α'-Thiodisaccharides by Cryo Thiol-Ene Photocoupling - Thio-Click Reaction in Frozen State.

α-Glycosyl thiols are key building blocks for the formation of stable thioglycoside mimetics of widespread and biologically relevant α-O-glycosides, which urges their efficient synthesis. Here, we demonstrate that the photoinitiated radical-mediated addition of thioacetic acid to 2-substituted glycals followed by selective S-deacetylation is a generally applicable and fully stereoselective method for the synthesis of 1,2-cis-α-glycosyl thiols. The low reactivity of thioacetic acid in the radical reaction was overcome by carrying out the reaction in AcOH at -80 °C, in frozen state, with UVA irradiation, achieving high yields irrespective of the sugar configurations. For effective irradiation and simultaneous effective cooling, a self-made spiral vessel reactor was used, which also enables large-scale synthesis. By subjecting 1,2-cis-α-1-thiosugars to a second thiol-ene coupling reaction with 2-substituted glycals, 34 trehalose-type symmetrical and unsymmetrical α,α'-thiodi- and oligosaccharides were obtained with full stereoselectivity. Moreover, the oxidation of α-1-thiosugars provided an easy access to α,α'-diglycosyl disulfides.

Advanced Oxidation Process: Tearting Organic Pollutant

Advanced Oxidation Process: Tearting Organic Pollutant

In-Cell Fast Photochemical Oxidation Interrogates the Native Structure of Integral Membrane Proteins.

Integral membrane proteins (IMPs) are pivotal for cellular functions but challenging to investigate. Here, we introduce IC-FPOMP (in-cell fast photochemical oxidation of MPs), a method enabling in situ footprinting of IMPs within live cells. IC-FPOMP generates reactive oxygen radicals from various precursors (TiO2 nanoparticles or H2O2) nearby the membrane. Leveraging a laser and a 96-well plate platform, we achieve high-throughput and rapid footprinting of IMPs. IC-FPOMP of two human IMPs (human glucose transporter-hGLUT1 and human gamma glutamyl carboxylase-hGGCX) were successful, providing footprinting of both the transmembrane and extramembrane regions. Comparative analysis of hGLUT1 in liposomes versus cells shows that the membrane impacts the transporter's conformation differently. In-cell drug screening targeting hGLUT1 reveals drug binding behavior in vivo. In summary, IC-FPOMP offers insights on IMP structure-function relationships in cell and facilitates drug discovery.

Heterogeneous Fenton-like catalysts of tetranitro iron phthalocyanine@Fe3O4@fly ash composites for fast decomposition of environmental contaminants

Abstract Using fly ash (FA) solid wastes as economical carriers to construct Fenton-like catalytic composites with additional functions is more practical than the use of a single catalyst. Understanding the structure and properties of catalysts and carriers is vital to improve performance. Tetranitro iron phthalocyanine (TNFePc) is a highly active molecular catalyst, whose immobilization and Fenton-like heterogeneous catalysis remain unclear. In this study, magnetically recyclable composites of TNFePc@Fe3O4@FA were successfully fabricated. Further, Fe3O4 nanocrystals decorated on FA surfaces could be used as special functional layer for composite recycling and simultaneous in situ TNFePc synthesis. Peroxides of H2O2, KHSO5, and tert-butyl hydrogen could be effectively activated by composites and transformed into highly reactive radicals. Moreover, molecular oxygen could be activated as well. Model pollutants, methylene blue and oxytetracycline, could be synergistically degraded by the radical oxidation of superoxide, hydroxyl, alkoxy, and sulfate radicals and non-radical oxidation of high-valent iron-oxo species of TNPcFeIV=O. To the best of our knowledge, this is the first design of FA-based composites with dual function, Fenton-like heterogeneous catalysis and magnetic recyclability, for environmental decontamination. Graphical abstract

Fiber PROES: Phase resolved optical emission spectroscopy via optical fibers for knowledge-based plasma process development and monitoring.

High-frequency technological low-temperature plasmas play a key role in various industrial processes of high societal relevance, such as semiconductor manufacturing and gas conversion. Due to their complexity, the fundamentals of their operation are typically not understood and process development is done empirically. The continuous increase in process requirements with respect to precision and reproducibility, however, necessitates knowledge-based approaches toward process development and monitoring. Diagnostic techniques used for this should be non-invasive, have short measuring times, and have low equipment costs. A valuable tool to understand plasma processes is to measure the spatio-temporally resolved dynamics of energetic electrons with phase resolved optical emission spectroscopy (PROES), as these electrons generate the plasma through ionization and reactive radicals through dissociation of the neutral gas. However, PROES is typically performed based on expensive intensified charge-coupled device (ICCD) cameras, is slow, and requires large windows for optical access to the plasma, which do not exist in commercial reactors. To overcome these limitations, we present a modified version of this diagnostic, Fiber PROES, which is based on an optical fiber in combination with a photo-multiplier tube operated in a photon-counting mode. Compared to classical PROES, only a small fiber access port is required, which is typically available in commercial plasma reactors, the costs are strongly reduced, and the measurement speed is increased. We demonstrate that Fiber PROES yields similar results compared to classical ICCD-camera-based PROES by comparing measurements taken in geometrically symmetric capacitively coupled radio frequency plasma based on both PROES variants.

Kinetic studies of the rich interaction of cannabinoids with oxygen-centered radicals and excited carbonyl compounds.

Kinetic studies of the rich interaction of cannabinoids with oxygen-centered radicals and excited carbonyl compounds.

MXene-loaded multifunctional nanoparticles with on-demand controlled antimicrobial and antioxidant capacity for multi-modal treating bacterial prostatitis.

MXene-loaded multifunctional nanoparticles with on-demand controlled antimicrobial and antioxidant capacity for multi-modal treating bacterial prostatitis.

Synthesis of novel chalcone/lipoic acid derivatives and cross-linked chitosan for preparation of multi-functional packaging film.

Synthesis of novel chalcone/lipoic acid derivatives and cross-linked chitosan for preparation of multi-functional packaging film.

A review on the reaction mechanism of heavy oil catalytic aquathermolysis: Carbocationic reactions or free radical reactions?

A review on the reaction mechanism of heavy oil catalytic aquathermolysis: Carbocationic reactions or free radical reactions?

Multi-element Compound-Specific Stable Isotope Analysis (2H, 13C, 15N, 33/34S) to characterize the mechanism of sulfate and hydroxyl radical reaction and photolysis of benzothiazole

Multi-element Compound-Specific Stable Isotope Analysis (2H, 13C, 15N, 33/34S) to characterize the mechanism of sulfate and hydroxyl radical reaction and photolysis of benzothiazole

Wet scrubbing coupled with advanced oxidation process for removal of chlorobenzene: A study of performance and mechanisms.

Wet scrubbing coupled with advanced oxidation process for removal of chlorobenzene: A study of performance and mechanisms.

Development of single-chamber deposition equipment for organic/inorganic nanohybrid composite material

Development of single-chamber deposition equipment for organic/inorganic nanohybrid composite material