Search Results (101)

Enhancing the solubility and processability of graphene remains a critical challenge, limiting its integration into advanced materials systems. In this work, poly(tert-butyl acrylate) (PtBA) and poly(N-isopropyl acrylamide) (PNIPAM) were grafted onto graphene via controlled atom transfer radical polymerization (ATRP) to create well-defined polymer–graphene hybrids with tunable interfacial properties. ATRP enabled the synthesis of PtBA and PNIPAM homopolymers with narrow molecular weight distributions and systematically varied chain lengths (4–18 kDa), allowing direct correlation between polymer architecture and material performance. Notably, the thermos-responsive behavior of PNIPAM was strongly dependent on chain length, highlighting the importance of controlled polymer design. Raman and FTIR spectroscopy confirmed successful grafting and chemical modification of the graphene surface. In addition, pilot studies demonstrate the ATRP synthesis of PtBA-b-PNIPAM block copolymers and their hydrolysis to PAA-b-PNIPAM, providing a platform for future development of multifunctional graphene interfaces. Overall, this study establishes a versatile and precisely controlled route for engineering polymer-grafted graphene with enhanced solubility and tunable functionality, enabling broader applications in smart materials and hybrid nanocomposites. Full article

The widespread occurrence of pharmaceutical contaminants in aquatic environments poses significant risks to ecosystems and public health, necessitating the development of efficient and sustainable treatment technologies. Herein, a visible-light (VL)–active zinc single-atom catalyst supported on biochar (SAZn@BC) was synthesized via pyrolysis and applied for the degradation of ibuprofen (IBP), sulfamethoxazole (SMX), trimethoprim (TMP), and carbamazepine (CBZ) in water. Structural characterization confirmed the presence of g-C₃N₄ domains, abundant oxygen-containing functional groups, and atomically dispersed Zn sites with a Zn–N₄ coordination environment. Under VL irradiation, SAZn@BC achieved degradation efficiencies of 43.9%, 64.4%, and 61.9% for IBP, SMX, and TMP, respectively, within 30 min, while CBZ exhibited limited removal. Mechanistic investigations combining quenching experiments, electrochemical analyses, and X-ray photoelectron spectroscopy revealed that superoxide and hydroperoxyl radicals were the dominant reactive oxygen species, with hydroxyl radicals and singlet oxygen contributing to a lesser extent. In addition, a nonradical pathway involving direct interfacial electron transfer between oxygen functional groups on the biochar support and pharmaceutical molecules played a critical role, mediated by single-atom Zn sites and enhanced under VL irradiation. These findings demonstrate that SAZn@BC enables synergistic radical and nonradical pathways for pharmaceutical degradation and represents a promising strategy for water treatment applications. Full article

Methionine residues in proteins and peptides are frequently oxidized by losing one electron. The presence of nearby amide groups is crucial for this process, enabling methionine to participate in long-range electron transfer. Hydroxyl radical (HO^•) plays an important role being generated in aerobic organisms by cellular metabolisms as well as by exogenous sources such as ionizing radiations. The reaction of HO^• with methionine mainly affords the one-electron oxidation of the thioether moiety through two consecutive steps (HO^• addition to the sulfur followed by HO⁻ elimination). We recently investigated the reaction of HO^• with model peptides mimicking methionine and its cysteine-methylated counterpart, i.e., CH₃C(O)NHCHXC(O)NHCH₃, where X = CH₂CH₂SCH₃ or CH₂SCH₃ at pH 7. The reaction mechanism varied depending on the distance between the sulfur atom and the peptide backbone, but, for a better understanding of various suggested equilibria, the analysis of the flux of protons is required. We extended the previous study to the present work at pH 4 using pulse radiolysis techniques with conductivity and optical detection of transient species, as well as analysis of final products by LC-MS and high-resolution MS/MS following γ-radiolysis. Comparing all the data provided a better understanding of how the presence of nearby amide groups influences the one-electron oxidation mechanism. Full article

The radical-mediated intramolecular translocation of cyano groups has been recognized as a useful tool for the site-selective functionalization of organic molecules. The process is believed to proceed through the addition of an in situ-generated carbon-centered radical to the nitrile triple bond, followed by the β-scission of the resulting cyclic iminyl radical intermediate to relocate the cyano group and produce a more stable carbon radical for further elaboration. Beginning in the early 1960s and continuing for the next forty years, the research in this particular area has seen a surge of growth during the past two decades with advancements in radical chemistry and photocatalysis. The present article attempts to conduct a comprehensive review of existing studies on this topic by covering the literature from 1961 to 2025. The procedures developed for the purpose are grouped and discussed in four sections according to the strategies used to generate the initial carbon radicals, which include (i) hydrogen-atom transfer (HAT), (ii) radical addition to the π system, (iii) halogen-atom transfer (XAT), and (iv) the homolytic fission of a C-C single bond. In each section, a specific emphasis will be placed on reaction conditions, substrate scopes, and mechanisms. Full article

Star polymers—macromolecules featuring multiple arms radiating from a central core—offer unique potential for biomedical applications due to their tunable architecture, multifunctionality and ability to incorporate stimuli-responsive and biocompatible components. In this study, functional star polymers with oligo (ethylene glycol) methyl ether methacrylate (OEOMA) arms and 2-(dimethylamino)ethyl methacrylate (DMAEMA) core units were synthesized via atom transfer radical polymerization (ATRP) using the “arm-first” strategy. The star polymers were used as nanoreactors for the in situ reduction of silver nitrate to form silver nanoparticles (AgNPs) without additional reducing agents. UV–Vis spectroscopy confirmed the formation of spherical AgNPs with absorption maxima around 430 nm, and transmission electron microscopy revealed uniform particle morphology. These hybrid nanomaterials (STR-AgNPs) were incorporated into polymethyl methacrylate (PMMA)-based bone cement to impart antibacterial properties. Mechanical testing showed that the compressive strength remained within acceptable limits, while antibacterial assays against E. coli demonstrated a significant inhibition of bacterial growth. These findings suggest that STR-AgNPs serve as promising candidates for infection-resistant bone implants, providing localized antibacterial effects while maintaining mechanical integrity and biocompatibility. Full article

CO₂-responsive polymers have emerged as a significant class of smart materials, distinguished by their ability to reversibly alter their properties upon exposure to CO₂. Due to CO₂’s abundant availability, low cost, non-toxicity, energy efficiency, and excellent biocompatibility, these polymers offer remarkable environmental and practical advantages. This review succinctly explores recent advancements in the synthesis, mechanisms, and applications of CO₂-responsive polymers, emphasizing the pivotal roles of specific acidic and basic functional groups such as carboxylic acids, phenolic groups, amines, amidines, guanidines, and imidazoles. Advanced polymerization techniques including free radical polymerization (FRP), atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), and nitroxide-mediated polymerization (NMP) are critically evaluated for their precision and flexibility in polymer design. Significant applications in smart separation, carbon capture, drug delivery, desalination, emulsions, tissue engineering, and sensing technologies are discussed comprehensively. Although substantial progress has been made, ongoing challenges include enhancing response speed, durability, sustainability, and economic viability. Future research is recommended to focus on innovative polymer structures, computational modeling, hybrid materials, and greener synthesis methods. This review aims to inspire continued exploration and practical utilization of CO₂-responsive polymers to address pressing environmental and technological needs. Full article

Global industrialization has intensified the emission of emerging contaminants (ECs), posing a serious threat to the environment and human health. Persulfate-based advanced oxidation processes (PS-AOPs) have become a research hotspot due to their efficient degradation capability and environmentally friendly features; carbon-based materials are ideal catalysts for activating persulfate (PS) due to their tunable electronic structure, abundant active sites, and low cost. This study summarizes the application of carbon-based materials (graphene, single-atom catalysts (SACs), etc.) in PS-AOPs, and provides insights into the degradation mechanisms of radicals (e.g., sulfate radical (SO₄^−·), hydroxyl radical (·OH)) and non-radicals (e.g., ¹O₂(singlet oxygen), electron transfer). The removal efficacy of carbon-based catalysts for antibiotics, phenols, and dyes was compared, and the key degradation pathways were elucidated. In addition, the activation of PS can be accelerated, and catalytic efficiency can be improved by synergizing with ancillary technologies (e.g., light, electricity). Despite the great potential of carbon-based catalysts, their large-scale application is limited by the complexity of the catalyst preparation process and the lack of selectivity for complex water qualities. Future studies can accelerate the practical application of PS-AOPs in wastewater treatment through the precise design of SACs and the construction of multi-mechanism synergistic activation systems. Full article

A novel efficient barium sulfate scale inhibitor was designed by examining important quantum parameters such as adsorption energy, solubility, steric hindrance parameter, and entanglement molecular weights. Through molecular simulation techniques, it was found that the carboxylic acid group of the scale inhibitor molecule could transfer an average of 0.07 e⁻ electrons to the barium sulfate surface. During molecular dynamics simulations, closer adsorption between oxygen atoms and barium ions in the scale inhibitor was observed, which resulted from van der Waals forces. Based on the simulation results at the molecular level, we successfully prepared this scale inhibitor by free radical polymerization and verified its high efficiency in our experiments: the scale inhibition efficiency was as high as 89.1% when used at a concentration of 160 mg/L under the conditions of pH = 7 and 70 °C. In addition, by SEM and XRD analyses, we further confirmed the consistency of the scale inhibition mechanism of the scale inhibitor with the molecular simulation results. Full article

Atom transfer radical addition (ATRA) reactions are essential transformations in organic synthetic chemistry that enable the atom-economic difunctionalization of abundant olefin feedstocks. In this way, a rich chemical space can be opened up by well-planned combinations of simple starting materials. To build an efficient photocatalytic transformation, the reactivity of trichloromethanesulfenyl chloride toward alkenes and alkynes was investigated under photocatalytic Cu(I) reaction conditions. In this study, we found that trichloromethanesulfenyl chloride can be added to a series of olefins (such as styrenes and electron-rich and -poor olefins) in the presence of 1 mol% [Cu(dmp)₂]BF₄ photocatalyst and blue LED irradiation, producing α-chloro trichloromethylthioethers in good yields. Experimental and theoretical (DFT) mechanistic studies are consistent with the proposed radical chain mechanism of transformation. This study may serve as a valuable reference for the development of new coupling reactions that are economical and highly efficient processes. Full article

The current paradigm of low-T combustion and autoignition of hydrocarbons is based on the sequential two-step oxygenation of fuel radicals. The key chain-branching occurs when the second oxygenation adduct (OOQOOH) is isomerized releasing an OH radical and a key ketohydroperoxide (KHP) intermediate. The subsequent homolytic dissociation of relatively weak O–O bonds in KHP generates two more radicals in the oxidation chain leading to ignition. Based on the recently introduced intramolecular “catalytic hydrogen atom transfer” mechanism (J. Phys. Chem. 2024, 128, 2169), abbreviated here as I-CHAT, we have identified a novel unimolecular decomposition channel for KHPs to form their classical isomers—enol hydroperoxides (EHP). The uncertainty in the contribution of enols is typically due to the high computed barriers for conventional (“direct”) keto–enol tautomerization. Remarkably, the I-CHAT dramatically reduces such barriers. The novel mechanism can be regarded as an intramolecular version of the intermolecular relay transfer of H-atoms mediated by an external molecule following the general classification of such processes (Catal. Rev.-Sci. Eng. 2014, 56, 403). Here, we present a detailed mechanistic and kinetic analysis of the I-CHAT-facilitated pathways applied to n-hexane, n-heptane, and n-pentane models as prototype molecules for gasoline, diesel, and hybrid rocket fuels. We particularly examined the formation kinetics and subsequent dissociation of the γ-enol-hydroperoxide isomer of the most abundant pentane-derived isomer γ-C5-KHP observed experimentally. To gain molecular-level insight into the I-CHAT catalysis, we have also explored the role of the internal catalyst moieties using truncated models. All applied models demonstrated a significant reduction in the isomerization barriers, primarily due to the decreased ring strain in transition states. In addition, the longer-range and sequential H-migration processes were also identified and illustrated via a combined double keto–enol conversion of heptane-2,6-diketo-4-hydroperoxide as a potential chain-branching model. To assess the possible impact of the I-CHAT channels on global fuel combustion characteristics, we performed a detailed kinetic analysis of the isomerization and decomposition of γ-C5-KHP comparing I-CHAT with key alternative reactions—direct dissociation and Korcek channels. Calculated rate parameters were implemented into a modified version of the n-pentane kinetic model developed earlier using RMG automated model generation tools (ACS Omega, 2023, 8, 4908). Simulations of ignition delay times revealed the significant effect of the new pathways, suggesting an important role of the I-CHAT pathways in the low-T combustion of large alkanes. Full article

As a promising polymer for the production of biomaterials and drug delivery systems, poly(lactic acid) (PLA) is characterized by its relative hydrophobicity, as well as its chemical and biological inertness. Here, we aimed to improve the biological properties of PLA-based materials via the covalent attachment of a hydrophilic biocompatible glycopolymer, namely poly(2-deoxy-N-methacrylamido-D-glucose) (PMAG) on their surface. PMAG is a water-soluble polymer that contains glucose units in its side chains, which are responsible for good biocompatibility and the ability to attach bioactive molecules. In the developed protocol, PMAG was synthesized by controlled radical polymerization in the presence of a reversible addition–fragmentation chain transfer (RAFT) agent, followed by the conversion of glycopolymer terminal dithiobenzoate functionality into a primary amino group (PMAG-NH₂). PLA-based films served as model aliphatic polyester materials for developing the surface biofunctionalization protocol. According to that, PMAG-NH₂ covalent immobilization was carried out after alkali treatment, allowing the generation of the surface-located carboxyl groups and their activation. The developed modification method provided a one-point attachment of hydrophilic PMAG to the hydrophobic PLA surface. PMAG samples, which differed by the degree of polymerization, and the variation of polymer concentration in the reaction medium were applied to investigate the modification efficacy and grafting density. The developed single-point polymer grafting approach provided the efficient functionalization with a grafting density in the range of 5–23 nmol/cm². The neat and modified polymer films were characterized by a number of methods, namely atomic force microscopy, thermogravimetric analysis, ellipsometry, and contact angle measurements. In addition, an ArgGlyAsp-containing peptide (RGD peptide) was conjugated to the PMAG macromolecules grafted on the surface of PLA films. It was shown that both surface modification with PMAG and with PMAG-RGD peptide enhanced the adhesion and growth of mesenchymal stem cells as compared to a neat PLA surface. Full article

In this study, the DFT/M062X/PCM method was applied to investigate thermodynamic and kinetic aspects of reactions involved in possible mechanisms of antioxidant activity of caffeic acid against HOO^● radicals in aqueous medium at different pH values. Kinetic parameters of the reactions involved in HAT (Hydrogen Atom Transfer), RAF (Radical Adduct Formation), and SET (Single Electron Transfer) mechanisms, including reaction energy barriers and bimolecular rate constants, were determined, and identification and characterization of stationary points along the reaction pathways within HAT and RAF mechanisms were performed. Inspection of geometrical parameters and spin densities of the radical products formed within HAT and RAF mechanisms revealed that they are stabilized by hydrogen bonding interactions and the odd electron originated through the reaction with the HOO^● radical is spread over the entire molecule, resulting in significant radical stabilization. Thermodynamic and kinetic data collected in this study indicated that increasing pH of the medium boosts the antioxidant activity of caffeic acid by reducing the energy required to generate radicals within the RAF and/or HAT mechanism and, at extremely high pH, where the trianionic form of caffeic acid is a dominant species, by the occurrence of an additional fast, diffusion-limited electron-related channel. Full article

During gliotoxin biosynthesis in fungi, the cytochrome P450 GliF enzyme catalyzes an unusual C–N ring-closure step while also an aromatic ring is hydroxylated in the same reaction cycle, which may have relevance to drug synthesis reactions in biotechnology. However, as the details of the reaction mechanism are still controversial, no applications have been developed yet. To resolve the mechanism of gliotoxin biosynthesis and gain insight into the steps leading to ring-closure, we ran a combination of molecular dynamics and density functional theory calculations on the structure and reactivity of P450 GliF and tested a range of possible reaction mechanisms, pathways and models. The calculations show that, rather than hydrogen atom transfer from the substrate to Compound I, an initial proton transfer transition state is followed by a fast electron transfer en route to the radical intermediate, and hence a non-synchronous hydrogen atom abstraction takes place. The radical intermediate then reacts by OH rebound to the aromatic ring to form a biradical in the substrate that, through ring-closure between the radical centers, gives gliotoxin products. Interestingly, the structure and energetics of the reaction mechanisms appear little affected by the addition of polar groups to the model and hence we predict that the reaction can be catalyzed by other P450 isozymes that also bind the same substrate. Alternative pathways, such as a pathway starting with an electrophilic attack on the arene to form an epoxide, are high in energy and are ruled out. Full article

Synthetic radicals have intrinsic power for cascading and multifunctional reactions to construct diverse molecular scaffolds. In the previous review series, we covered 1,2-difunctionalizations, remote 1,3-, 1,4-, 1,5-, 1,6-, and 1,7-difunctionalizations, addition followed by cyclization reactions, and cycloaddition-initiated difunctionalizations. Presented in this paper are radical addition-initiated trifunctionalization reactions of alkenes, alkynes, and their derivatives. After the initial radical addition, there are different pathways, such as group or hydrogen atom transfer, cyclization, and radical coupling, to complete the second and third functionalizations. Full article

Functional polymers play an important role in various biomedical applications. From many choices, poly(2-isopropenyl-2-oxazoline) (PIPOx) represents a promising reactive polymer with great potential in various biomedical applications. PIPOx, with pendant reactive 2-oxazoline groups, can be readily prepared in a controllable manner via several controlled/living polymerization methods, such as living anionic polymerization, atom transfer radical polymerization (ATRP), reversible addition–fragmentation transfer (RAFT) or rare earth metal-mediated group transfer polymerization. The reactivity of pendant 2-oxazoline allows selective reactions with thiol and carboxylic group-containing compounds without the presence of any catalyst. Moreover, PIPOx has been demonstrated to be a non-cytotoxic polymer with immunomodulative properties. Post-polymerization functionalization of PIPOx has been used for the preparation of thermosensitive or cationic polymers, drug conjugates, hydrogels, brush-like materials, and polymer coatings available for drug and gene delivery, tissue engineering, blood-like materials, antimicrobial materials, and many others. This mini-review covers new achievements in PIPOx synthesis, reactivity, and use in biomedical applications. Full article