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Precious metal complexes remain ubiquitous in photoredox catalysis (PRC) despite concerted efforts to find more earth‐abundant catalysts and replacements based on 3d metals in particular. Most otherwise plausible 3d metal complexes are assumed to be unsuitable due to short‐lived excited states, which has led researchers to prioritize the pursuit of longer excited‐state lifetimes through careful molecular design. However, we report herein that the C−H arylation of pyrroles and related substrates (which are benchmark reactions for assessing the efficacy of photoredox catalysts) can be achieved using a simple and readily accessible octahedral bis(diiminopyridine) cobalt complex, [1‐Co](PF6)2. Notably, [1‐Co]2+ efficiently functionalizes both chloro‐ and bromoarene substrates despite the short excited‐state lifetime of the key photoexcited intermediate *[1‐Co]2+ (8 ps). We present herein the scope of this C−H arylation protocol and provide mechanistic insights derived from detailed spectroscopic and computational studies. These indicate that, despite its transient existence, reduction of *[1‐Co]2+ is facilitated via pre‐assembly with the NEt3 reductant, highlighting an alternative strategy for the future development of 3d metal‐catalyzed PRC. [ABSTRACT FROM AUTHOR]

Resveratrol (3,5,4′-trihydroxystilbene, RSV) is a natural stilbene synthetized as trans -isomer in plants exposed to oxidative stress. In order to understand the mechanism involved during photosensitized degradation of trans -resveratrol, steady-state and time-resolved experiments were performed and compared with quantum-chemical calculations using density functional theory (DFT). Pterin (Ptr), a well-known photosensitizer, under UV-A radiation induces the oxidation of several biomolecules mainly through electron-transfer mechanisms. On the one hand, it was observed that trans -RSV participates in an energy-transfer pathway with Ptr triplet excited state (3Ptr*) forming 3 trans -RSV*, which dissipates the energy by isomerization to cis -RSV. On the other hand, RSV neutral radical (trans -RSV(-H)•) was detected in laser flash photolysis experiments, evidencing an electron-transfer mechanism. The electron-transfer from 3Ptr* to trans -RSV is a barely feasible reaction, however, more favorable is the formation of trans -RSV(-H)• in a reaction between trans -RSV and Ptr radical cation (Ptr•+), which is produced during irradiation. The combination of experimental and theoretical approaches evidences the capability of trans -RSV to undergo energy-transfer (feasible by DFT calculations) and/or one-electron transfer pathways with 3Ptr*. These findings reveal the mechanisms involved in the interaction of trans -RSV and pterin excited states and provide information on the antioxidant action of resveratrol during photosensitized oxidation of biomolecules. [Display omitted] • Resveratrol is a natural polyphenol synthesized against oxidative stress in plants. • Pterin excited states with the ability to oxidize biomolecules are deactivated by resveratrol. • Energy transfer from trans -resveratrol to pterin triplet excited state is feasible. • Resveratrol acts as electron donor to pterin triplet excited state. [ABSTRACT FROM AUTHOR]

Hybrid TDDFT/MM approaches are very popular methods for describing electronic transitions of molecules in solution or embedded in more complex (bio)matrices. However, when combined with a polarisable force field some problems can appear depending on the type of environment response scheme that is used. In particular, specific a posteriori corrections are generally needed to accurately describe charge-transfer states implying a large reorganisation of the electron density in the excited state. Here, we present a possible strategy to solve this issue by introducing a ΔSCF formulation. As the ΔSCF strategy has the advantage of being intrinsically state specific, its coupling to a polarisable model is expected to be particularly suited to describe all cases where the standard, linear response, formulation of a polarisable TDDFT/MM approach is not sufficient. [ABSTRACT FROM AUTHOR]

The fabrication of a green, high activity and low-cost carbon-based catalyst capable of activating new oxidant (peroxymonosulfate, PMS) for contaminants abatement is needed. In this research, we prepared novel N-doped biochars via one-step pyrolysis of algal sludge without external nitrogen sources. The obtained ASBC800 possessed the largest specific surface area (SBET = 145.596 m2 g−1) and thus it displayed the best catalytic performance, as revealed by the effective elimination of sulfadiazine (SDZ, >95% within 70 min) with 0.2 g L−1 ASBC800 and 0.5 mM PMS. Both radical species (e.g., SO4•−, and •OH), and nonradical regime (1O2 and electron-transfer) contributed to SDZ oxidation, in which ASBC800 played essential roles in activating PMS, accumulating SDZ, and regulating electron shuttle from SDZ to ASBC800-PMS*. Overall, this work not only provides a novel strategy for the synthesis of N-rich and cost-effective biochar but also promotes the development and application of carbon-based functional materials in environmental remediation. [ABSTRACT FROM AUTHOR]

A one-step hydrothermal method for preparation of copper oxides with different valences using ascorbic acid as a reducing reagent was developed for environmental remediation. The results suggested that the notable degradation performance of CuO0 may be attributable to the abundant active sites, such as Cu or Cu–O, and was not significantly related to the Cu valence state. In contrast to direct degradation of pollutants by traditional superoxide radicals (O2•−), O2•− played an important role in the reduction of high-valence Cu ions (Cu(III)). In addition, a series of radical quenching, electron paramagnetic resonance (EPR), and electrochemical experiments validated the existence of direct electron transfer between methylene blue (MB) and PMS mediated by CuO0 and surface-bound radicals. The results suggested that the CuO0/PMS system may be less susceptible to diverse ions and natural organic matter other than dihydrogen phosphate anions. The mechanism of MB degradation under alkaline conditions was different from that under acidic conditions in that it was not reliant on radicals or charge transfer but direct oxidation by PMS. This study provides new insights into the heterogeneous processes involved in PMS activation by the copper oxides. Furthermore, this paper devotes to providing theoretical basis on pollutant removal via PMS activated by copper oxides and developing low-cost and high-efficiency catalysts. [ABSTRACT FROM AUTHOR]

Sutin realized that the theories of electron-transfer reactions could be applied to reactions that involve a transfer between two different electronic surfaces such as the transitions between excited states or between different spin states.[[33] In 1974, Sutin turned his attention to applying the techniques he had developed for thermal electron-transfer reactions to excited state reactions of transition metals. Sutin and Marcus developed a deep friendship and a long-term collaboration.[[4]] Sutin quickly used Marcus' early theory of electron transfer reactions to interpret rates he was measuring for inorganic-metal complexes. Keywords: Obituary; electron-transfer; Solar Energy; Inorganic Photochemistry EN Obituary electron-transfer Solar Energy Inorganic Photochemistry 66 76 11 02/03/23 20230101 NES 230101 Norman Sutin, a distinguished inorganic chemist who studied electron and charge-transfer reactions, died on January 31, 2022, at the age of 93. 23 Sutin, N., and Creutz, C. Light Induced Electron Transfer Reactions of Metal Complexes. [Extracted from the article]

[Display omitted] • A simple heat treatment method was proposed to simultaneously introduce Sv and P doping. • The k obs value obtained by CuFe-NC-SP-2 was nearly 33 higher than that of CuFe-PBA. • CuFe-NC-SP-2/PMS system dominated by the electron transfer process (ETP) achieved 100 % removal of SDZ. • Synergistic effect of Sv (improved the adsorption energy of PMS) and P doping (accelerated the electron transport) enhanced the ETP. In this work, Prussian blue analogues (CuFe-PBA) derived copper-iron sulfides/N-doped porous carbon composite (CuFe-NC-SP- x) was prepared as an effective peroxymonosulfate (PMS) activator to degrade sulfadiazine (SDZ). A strategy that kills two birds with one stone was proposed to construct CuFe-NC-SP- x , i.e., S-etched CuFe-PBA (CuFe-PBA-S) was annealed with NaH 2 PO 2 in N 2 atmosphere to simultaneously introduce sulfur vacancy (Sv) and phosphorus doping. 40 μM SDZ was completely removed by CuFe-NC-SP-2/PMS in 20 min (0.2 g/L catalyst and 0.5 mM PMS). The k obs value obtained by CuFe-NC-SP-2 (0.48 min−1) was nearly 33 and 17 times higher than that of CuFe-PBA (0.014 min−1) and CuFe-PBA-S (0.028 min−1), respectively. Quenching tests, electron paramagnetic resonance (EPR) analysis indicated that PMS activation in the system involved radical pathway (26.1 % OH and 22.7 % SO 4 –) and non-radical pathway (17.8 % 1O 2 and 33.4 % electron transfer process). OH, SO 4 – and 1O 2 were mainly produced by S enhanced metal sites for PMS activation. The synergistic effect of Sv and P doping enabled the powerful electron transfer mechanism. Electrochemical tests and DFT calculations demonstrated that Sv existing in CuFe-NC-SP- x improved the electron donor ability and increased the adsorption energy toward PMS, and phosphorus doping accelerated the electron transport from SDZ to PMS. This work not only provides a novel strategy to synthesize a high effective PMS activator by introducing Sv and phosphorous doing in one step, but also manages to comprehensively understand the electron transfer activation mechanisms of PMS facilitated by Sv and phosphorous doping. [ABSTRACT FROM AUTHOR]

Interfacial charge-transfer between perovskite and charge-transport layers plays a key role in determining performance of perovskite solar cells. The conventional viewpoint emphases the necessity of favorable energy-level alignment of the two components. In recent reports, efficient electron-transfer is observed from perovskite to fullerene-based electron-transport layers even when there are unfavorable energy-level alignments, but the mechanism is still unclear. Here, using an ultrafast in situ two-photon photoelectron spectroscopy, real-time observations of electron-transfer processes at CsPbI 3 /C 60 interface in both temporal and energetic dimensions are reported. Due to strong electronic coupling, a large amount of interfacial hybrid states is generated at the interfaces, aiding fast photoinduced electron-transfer in ≈124 fs. This process is further verified by nonadiabatic molecular dynamics simulations and transient absorption experiments. The short timescale explains why electron-transfer can overcome unfavorable energy-level alignments, providing a guideline for device design., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Semi-biological photosynthesis combines synthetic photosensitizers with microbial catalysts to produce sustainable fuels and chemicals from CO2. However, the inefficient transfer of photoexcited electrons to microbes leads to limited CO2 utilization, restricting the catalytic performance of such biohybrid assemblies. Here, we introduce a biological engineering solution to address the inherently sluggish electron uptake mechanism of a methanogen, Methanosarcina barkeri (M. barkeri), by coculturing it with an electron transport specialist, Geobacter sulfurreducens KN400 (KN400), an adapted strain rich with multiheme c-type cytochromes (c-Cyts) and electrically conductive protein filaments (e-PFs) made of polymerized c-Cyts with enhanced capacity for extracellular electron transfer (EET). Integration of this M. barkeri-KN400 co-culture with a synthetic photosensitizer, carbon nitride, demonstrates that c-Cyts and e-PFs, emanating from live KN400, transport photoexcited electrons efficiently from the carbon nitride to M. barkeri for methanogenesis with remarkable long-term stability and selectivity. The demonstrated cooperative interaction between two microbes via direct interspecies electron transfer (DIET) and the photosensitizer to assemble a semi-biological photocatalyst introduces an ecosystem engineering strategy in photocatalysis to drive sustainable chemical synthesis., (© 2024 Wiley‐VCH GmbH.)

Constructing green and sustainable advanced oxidation processes (AOPs) for the degradation of organic contaminants is of great importance but still remains big challenge. In this work, an effective AOP (MnFe 2 O 4 -activated periodate, MnFe 2 O 4 /PI) was established and investigated for the oxidation of organic contaminants. To avoid the severe aggregation of MnFe 2 O 4 nanoparticles, a hybrid MnFe 2 O 4 -biochar catalyst (MnFe 2 O 4 -BC) was further synthesized by anchoring MnFe 2 O 4 nanoparticles on chemically inert biochar substrate. Intriguingly, MnFe 2 O 4 -BC/PI exhibited different selectivity towards organic contaminants compared with MnFe 2 O 4 /PI, revealing that biochar not only served as the substrate, but also directly participated into the oxidation process. Electron-transfer mechanism was comprehensively elucidated to be responsible for the abatement of pollutants in both MnFe 2 O 4 /PI and MnFe 2 O 4 -BC/PI. The surface oxygen vacancies (OVs) of MnFe 2 O 4 were identified as the active sites for the formation of high potential complexes MnFe 2 O 4 -PI*, which could directly and indirectly degrade the organic pollutants. For the hybrid MnFe 2 O 4 -BC catalyst, biochar played multiple roles: (i) substrate, (ii) provided massive adsorption sites, (iii) electron-transfer mediator. The differences in selectivity of MnFe 2 O 4 /PI and MnFe 2 O 4 -BC/PI were determined by the adsorption affinity between biochar substrate and organics. Overall, the findings of this study expand the knowledge on the selectivity of PI-triggered AOPs. [Display omitted] • Biochar altered the selectivity of MnFe 2 O 4 /PI towards different organic pollutants. • Organic contaminants were oxidized by the high potential complexes MnFe 2 O 4 -PI* • Oxygen vacancy in MnFe 2 O 4 was responsible for the formation of MnFe 2 O 4 -PI*. • Biochar served as the electron-mediator between organics and MnFe 2 O 4 -PI*. • Biochar adjusted the active sites of organics and led to the different selectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-dimensional coral-like gold nanorods are electrosynthesized on acupuncture needle. • The specific nanocavities for trimethoprim are constructed within the collaborative interface. • Acupuncture needle based microsensor is fabricated via green route of electrochemistry. • The microelectrode might furtherly integrate with Chinese medicine acupuncture in the future. Excessive amount of antibiotics have serious detrimental effects on the environment, making precise monitoring and removal increasingly crucial. Trimethoprim (TMP) is a typical kind of antibiotic. Herein, a novel microdetector was fabricated on the matrix of acupuncture needle (AN). The functional interface was constructed using a green electrosynthesis method, incorporating three-dimensional coral-like gold nanorods (3D-CAuNRs), polydopamine (pDA), polypyrole (pPY) and TMP molecules. Characterization was performed using electrochemistry, high-resolution SEM and elemental mapping techniques. Notably, nanocavities were formed through electropolymeric molecular imprinting, resulting in highly selective and sensitive detecting of TMP. This was attributed to the structure-complementary and configuration-suitable microenvironment, facilitating specific electron-transfer. The intrinsic properties of the microsensor were thoroughly investigated. Under optimized conditions, the sensor exhibited a wide linear range of 0.05 ∼ 50 µmol/L with a low limit detection of 0.017 µmol/L (S/N = 3) for TMP, along with high selectivity, reproducibility, and stability. Furthermore, the sensor demonstrated applicability for detecting TMP in environmental water, soil and cefalexin and trimethoprim capsules. [ABSTRACT FROM AUTHOR]

Our previous studies (Shields et al 2020 J. Phys. B: At. Mol. Opt. Phys. 53 125101; Shields et al 2020 Euro. Phys. J. D 74 191) have predicted that the atom-fullerene hybrid photoionization properties for X = Cl, Br and I endohedrally confined in C60 are different before and after an electron transfers from C60 to the halogen. It was further found as a rule that the ionization dynamics is insensitive to the C60 level the electron originates from to produce X âˆ'@ C 60 + . In the current study, we report an exception to this rule in F@C60. It is found that when the electron vacancy is situated in the C60 level that participates in the hybridization in Fâˆ'@ C 60 + , the mixing becomes dramatically large leading to strong modifications in the photoionization of the hybrid levels. This novel effect is fundamentally based on a level-crossing phenomenon driven by the electron transfer in F@C60. But when the vacancy is at any other pure level of C60, the level-invariance is retained showing weak hybridization. Even though this case of F@C60 is an exception in the halogen@C60 series, the phenomenon can be more general and can occur with compounds of other atoms caged in a variety of fullerenes. Possible experimental studies are suggested to benchmark the present results. [ABSTRACT FROM AUTHOR]

Adsorption of Fe(OH) 3 colloids onto NiFeOH significantly enhances the OER activity, likely as a result of charge transfer from Ni2+ to Fe3+ that facilitates the adsorption of key oxygen intermediates. [Display omitted] Nickel iron hydroxides (NiFeOH) have been drawing enormous attention as effective catalysts for oxygen evolution reaction (OER), a key process in water splitting. Herein, we report that negatively charged iron(III) hydroxide colloidal particles, can significantly enhance the OER activity of NiFeOH in alkaline media. NiFeOH is grown on nickel foam in a supersaturated iron(III) salt solution, which also contains a high content of Fe(OH) 3 colloidal nanoparticles, forming free-standing NiFeOH@C x electrodes (with x being the Fe(OH) 3 concentration). The interface between NiFeOH and Fe(OH) 3 colloidal particles, as manifested by the unique volcano-like holes on the NiFeOH@C x surface, is likely the OER active sites. In comparison to Fe(OH) 3 -free NiFeOH, NiFeOH@C 1000 exhibits a 40-fold enhancement of the OER activity, confirming the significant effect of Fe(OH) 3 colloidal nanoparticles in boosting the OER activity, likely as a result of enhanced charge transfer from Ni2+ to Fe3+ that facilitates the adsorption of key reaction intermediates. Furthermore, by coupling the free-standing NiFeOH@C 1000 electrode with commercial Pt/C, full water splitting can occur and reach a current density of 10 mA cm−2 under a cell voltage of 1.51 V, which is lower than that (1.59 V) based on noble metal catalysts of RuO 2 + Pt/C. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are an ideal template to construct high-efficiency catalysts for oxygen reduction reaction (ORR) due to their predictable properties. However, the closely parallel-stacking manner and lacking intramolecular electron transfer ability of COFs limit atomic utilization efficiency and intrinsic activity. Herein, COFs are constructed with large interlayer distances and enhanced electronic transfer ability by side-chain functionalization. Long chains with electron-donating features not only enlarge interlayer distance, but also narrow the bandgap. The resulting DPPS-COF displays higher electrochemical surface areas to provide more exposed active sites, despite <1/10 surface areas. DPPS-COF exhibits excellent electrocatalytic ORR activity with half-wave potential of 0.85 V, which is 30 and 60 mV positive than those of Pt/C and DPP-COF, and is the record among the reported COFs. DPPS-COF is employed as cathode electrocatalyst for zinc-air battery with a maximum power density of 185.2 mW cm -2 , which is superior to Pt/C. Theoretical calculation further reveals that longer electronic-donating chains not only facilitate the formation of intermediate OOH* from O 2 , but also promote intermediates desorption , and thus leading to higher activity., (© 2024 Wiley‐VCH GmbH.)

[Display omitted] • Fe 0.14 Co 0.86 -P/CC is fabricated by hydrothermal plus phosphating treatment. • The catalyst exhibits excellent HER/OER performance in alkaline solution. • The bifunctional catalyst only needs 1.95/2.14 V to reach 500/1000 mA cm−2. • The synergy between FeP and CoP species dominates the excellent performance. The design and construction of highly efficient and durable non-noble metal bifunctional catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media is essential for developing the hydrogen economy. To achieve this goal, we have developed a bifunctional nanowire-structured FeP-CoP array catalyst on carbon cloth with uniform distribution through in-situ hydrothermal growth and phosphating treatment. The unique nanowire array structure and the strong electronic interaction between FeP and CoP species have been confirmed. Electrochemical studies have found that the designed Fe 0.14 Co 0.86 -P/CC catalyst appears excellent HER (130 mV@10 mA cm−2)/OER (270 mV@10 mA cm−2) activity and stability. Moreover, the bifunctional Fe 0.14 Co 0.86 -P/CC(+/−) catalyst is also used in simulated industrial water splitting system, where the pair catalyst requires about 1.95 and 2.14 V to reach 500 and 1000 mA cm−2, even superior to the control RuO 2 (+)||Pt/C(−) catalyst, showing good industrial application prospects. These excellent electrocatalytic properties are attributed to the synergy between FeP and CoP species as well as the unique microstructure, which can accelerate charge transfer, expose more active sites and enhance electrolyte diffusion and gas emissions. [ABSTRACT FROM AUTHOR]

Pterin (Ptr) is a model photosensitizer that acts mainly through type I mechanism and is able to photoinduce the one-electron oxidation of purine and pyrimidine nucleobases. However, under anaerobic conditions Ptr reacts with thymine (T) to form photoadducts (Ptr-T) but does not lead to the photodegradation of guanine (G), which is the nucleobase with the lowest ionization potential. Accordingly, G is thermodynamically able to reduce the radicals of the other nucleobases and has been described in this sense as the "hole sink" of the DNA double helix. Here we analyze by steady-state and time-resolved studies the effect of G in the anaerobic photosensitization of T by Ptr, using nucleotides and oligonucleotides of different sequences. We demonstrated that G is able to reduce T radicals but does not prevent the formation of Ptr-T adducts. Our results suggest that after the encounter between the excited Ptr and T, and completion of the electron transfer step, part of the radicals escape from the solvent cage, to further react with other species. However, a proportion of radicals do not escape and evolve to photoadducts before separation. We provide new evidence that contributes to understand the photosensitizing properties of Ptr in the absence of O 2 , the mechanism of formation of photoadducts in the DNA and the protective role of G towards the photodamage in other nucleobases. [Display omitted] • Thymine radicals are reduced by guanine generating guanine radicals. • dGMP acts as a sacrificial protector of dTMP. • Under anaerobic conditions, pterin reacts with thymine to form photoaddutcs. • Guanine does not prevent the formation of thymine-pterin adducts. [ABSTRACT FROM AUTHOR]

Synthetic methodologies involving the formation of carbon–carbon bonds from carbon–hydrogen bonds are of significant synthetic interest, both for efficiency in terms of atom economy and for their undeniable usefulness in late-stage functionalization approaches. Combining these aspects with being metal-free, the radical C–H intermolecular arylation procedures covered by this review represent both powerful and green methods for the synthesis of (hetero)biaryl systems. 1 Introduction 2 Arylation with Arenediazonium Salts and Related Derivatives 2.1 Ascorbic Acid as the Reductant 2.2 Hydrazines as Reductants 2.3 Gallic Acid as the Reductant 2.4. Polyanilines as Reductants 2.5 Chlorpromazine Hydrochloride as the Reductant 2.6 Phenalenyl-Based Radicals as Reductants 2.7 Electrolytic Reduction of Diazonium Salts 2.8 Visible-Light-Mediated Arylation 3 Arylation with Arylhydrazines: Generation of Aryl Radicals Using an Oxidant 4 Arylation with Diaryliodonium Salts 5 Arylation with Aryl Halides 6 Conclusions [ABSTRACT FROM AUTHOR]

In this research work, flower-like MnCo 2 O 4.5 was synthesized by introducing a short-chain surfactant as a surface-active agent. This structure was utilized as a precursor, and a gas atmosphere pyrolytic deep reduction strategy was employed to construct a sea urchin-like catalyst (DTR-V o -MCO) with abundant oxygen vacancies. A series of characterizations were conducted to reveal the catalyst's microstructure and crystal phase composition. DTR-V o -MCO achieved more than 90% degradation of OTC within 10 min, and the efficiency was 1.5 times that of V p -MCO. The substantial presence of oxygen defects on the DTR-V o -MCO surface expedited charge transfer processes, resulting in a remarkable enhancement of PMS activation efficiency. Electron paramagnetic resonance spectroscopy (EPR) and radical quenching experiments indicated that the contributions of radicals to oxytetracycline (OTC) degradation were in the order of 1O 2 > SO 4 •– > O 2 •– > •OH. 1O 2 and SO 4 •– played dominant roles in OTC degradation. The possible oxytetracycline degradation pathways were proposed based on LC-MS analysis. In summary, this work presents an efficient method for a highly oxygen-deficient catalyst, expanding the application of binary transition metal materials in environmental remediation. [Display omitted] • Urchin-like DTR-Vo-MCO was synthesized by pyrolysis deep reduction strategy. • DTR-Vo-MCO/PMS system demonstrated outstanding performance in OTC degradation. • The oxygen vacancy promoted the redox cycle of Mn2 + /Mn3 + /Mn4 + and Co2 + /Co3 +. • 1O2 and SO4•- are the dominant species responsible for OTC degradation. [ABSTRACT FROM AUTHOR]

Tyrosine is an amino acid related to crucial physiological events and its oxidation, that produce beneficial or detrimental effects on biological systems, has been extensively studied. Degradation of tyrosine often begins with the loss of an electron in an electron transfer reaction in the presence of a suitable electron acceptor. The reaction is facilitated by excited states of the acceptor in photosensitized processes. Several products of tyrosine oxidation have been described, the main ones being 3,4-dihydroxy- l -phenylalanine (commonly known as DOPA) and tyrosine dimers. Here, we report tyrosine recovery from tyrosyl radical, after one-electron oxidation, in the presence of DOPA. We propose that under high oxidative stress the oxidation of tyrosine may be controlled, in part, by one of its oxidation products. Also, we present strong evidence of antioxidant action of DOPA by preventing tyrosine dimerization, one of the most serious oxidative protein modifications, and the origin of structural modifications leading to the loss of protein functionality. [Display omitted] • DOPA acts as an electron donor to tyrosyl, preventing its further oxidation. • Tyr dimerization is prevented by the presence of DOPA. • DOPA is generated in the reaction between tyrosyl and superoxide anion. • Dopachrome is a secondary product of tyrosine photosensitized oxidation. • Superoxide anion recovers both tyrosine and DOPA after one-electron oxidation. [ABSTRACT FROM AUTHOR]

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Hydrogen is one of the most promising energy carriers to replace fossil fuels and electrolyzing water to produce hydrogen is a very effective method. However, designing highly active and stable non-precious metal hydrogen evolution electrocatalysts that can be used in universal pH is a huge challenge. Here, we have reported a simple strategy to develop a highly active and durable non-precious MoO2-Ni electrocatalyst for hydrogen evolution reaction (HER) in a wide pH range. The MoO2-Ni catalyst exhibits a superior electrocatalytic performance with low overpotentials of 46, 69, and 84 mV to reach -10 mA cm-2 in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M PBS electrolytes, respectively. At the same time, the catalyst also shows outstanding stability over a wide pH range. It is particularly noted that the catalytic performance of MoO2-Ni in alkaline solution is comparable to the highest performing catalysts reported. The outstanding HER performance is mainly attributed to the collective effect of the rational morphological design, electronic structure engineering, and strong interfacial coupling between MoO2 and Ni in heterojunctions. This work provides a viable method for the synthesis of inexpensive and efficient HER electrocatalysts for the use in wide pH ranges. [ABSTRACT FROM AUTHOR]

Copper(II) porphyrin-catalyzed coupling of alkyl tosylates and alkyl Grignard reagents afforded substituted alkanes. The role of the copper(II) porphyrin complex was examined using EPR and in-situ synchrotron-based X-ray absorption fine structure measurements. These studies suggested that neither Cu redox nor substitution via in-situ generated cuprate was involved in catalysis. The results supported a reaction mechanism involving single electron transfer from copper(II) porphyrin to tosylate to facilitate the nucleophilic addition of Grignard reagents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyridinic N promotes the adsorption of PDS on N-doped porous biochar NHBC-1. • Graphitic N and active defects are conducive to the electron transfer process. • The formed NHBC-PDS* complex exhibits a high oxidation potential of 0.91 V. • Selective oxidation of organic contaminants depends on their oxidation potential. For persulfate-based advanced oxidation process, the non-radical pathway is an important route due to the selective oxidation of pollutants and its strong tolerance to complex water bodies. However, the selective oxidation mechanism of organic pollutants needs further elaboration. Herein, we demonstrate a facile hydrothermal pretreatment and high-temperature carbonization route to synthesize the nitrogen-doped porous biochar (NHBC-1). Owing to the well-developed hierarchical porous structure, the created internal active defects, and tailored nitrogen dopants, the NHBC-1 catalyst exhibited excellent catalytic activity for peroxydisulfate (PDS) activation. The results show that pyridinic N facilitated the adsorption of PDS on NHBC-1 to form the highly active NHBC-PDS* complex. Meanwhile, graphitic N and the defective structures promoted the electron-transfer process, thus allowing the efficient catalytic performance of the NHBC/PDS system for phenol oxidation via an electron-transfer dominated pathway. In addition, the system exhibited versatile applicability for the remediation of various organic pollutants in different actual water matrices with wide pH adaptability and satisfactory mineralization efficiency. More importantly, the selective oxidation mechanism of organic contaminants was revealed. Specifically, only the pollutant with oxidation potential lower than that of the NHBC-PDS* complex (0.91 V) can be effectively eliminated. This study not only provides a facile route for the rational designing of a cost-affordable biochar catalyst for PDS activation, but also offers valuable insights into the understanding of selective oxidation of organic contaminants via an electron-transfer dominated pathway. [ABSTRACT FROM AUTHOR]

A convenient heterogeneous continuous-flow procedure for the polarity reversal of aromatic α-diketones is presented. Propaedeutic batch experiments have been initially performed to select the optimal supported base capable to initiate the two electron-transfer process from the carbamoyl anion of the N,N-dimethylformamide (DMF) solvent to the α-diketone and generate the corresponding enediolate active species. After having identified the 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine on polystyrene (PS-BEMP) as the suitable base, packed-bed microreactors (pressure-resistant stainless-steel columns) have been fabricated and operated to accomplish the chemoselective synthesis of aroylated α-hydroxy ketones and 2-benzoyl-1,4-diones (benzoin- and Stetter-like products, respectively) with a good level of efficiency and with a long-term stability of the packing material (up to five days).

Spectrophotometric techniques has been applied for studying the kinetics and mechanistics between Ag+ and [IrCl 6 ]2− reaction in aqueous acidic solutions at a constant ionic strength of 1.0 moldm−3. The naked eyes observation showed that the brownish color of [IrCl 6 ]2− solution was rapidly vanishing with simultaneous appearance of a new dark-blue color on mixing solution of the oxidant with Ag+ ion electrolyte in either neutral or acidic media. The new color was persisted for a few seconds or minutes depending on the reaction conditions. Then, it began to fading out with time elapsing. This result means that the reaction occurs through two distinct stages. The spectral traces indicated the formation of binuclear intermediate complex at the initial fast stage [Ag+...ClIrCl 5 2−] (with the rate constants k 1 = 1.15 × 10−2 dm 3 mol−1 s−1; k − 1 = 7.35 × 10−5 s−1, formation constant (K) = 1.56 × 102 dm 3 mol−1 and pseudo first- order rate constant (k obs) = 1.31 × 10−4 s−1 at [IrCl 6 ]2− = 2.2 × 10−4, [H+] = 1.0 mol dm−3 and 30 °C. The initial rapid part was followed by a subsequent slow stage corresponding to the decomposition of the formed binuclear intermediate in the rate-determining step to give rise to the final oxidation products. The formation of such binuclear intermediate was found to be of acid-independent; nature; whereas its decomposition was dependent on the acid concentration with inverse fractional first-order in [H+]. This means that the binuclear decomposition is of acid-inhibition nature. In case of presence of a large excess of [Ag+] over that of [IrCl 6 ]2−, Ir(0) nanoparticles was formed as confirmed by the XRD-spectra and TEM morphology. The kinetic parameters for the formation constants and decomposition rate constants of the binuclear complex have been evaluated and a suitable reaction mechanism for the overall redox reaction is suggested and discussed. Unlabelled Image • A kinetic study of oxidation of silver (I) by [IrCl 6 ]2− in aqueous perchlorate solutions. • Formation of Ir(0) nanosize particles and characterized by XRD TEM. • The kinetic parameters of the binuclear complex have been evaluated. [ABSTRACT FROM AUTHOR]

Here we report recent studies of pH and polarity fluorescent molecular sensorics involving range of 4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives. Photophysical characteristics of the dyes were investigated in liquid solutions and in bulk materials, doped to sol-gel silicon dioxide (pure and with surface modifiers), polymethylmethacrylate (PMMA), polysulfone (PSU) and polyvinyl chloride (PVC) matrices. Investigated compounds were shown to be effective fluorescent probes for precise evaluation of H+ concentration in a broad range of input values (pH 2–12). Factors affecting accuracy of the measurements in solvents and matrices of a different nature are discussed. Finally, Catalan linear regression is introduced as a potential approach for discrimination of solvent polarity effects from acidity. Unlabelled Image • BODIPY dyes could be successfully utilized for pH and polarity measurements. • Sensory activity of the BODIPY dyes is determined by the donating atom environment. • Highest sensory callback was observed for Dibutylamino -phenyl- meso -BODIPY. • Formation of the hybrid materials is leading to pronounced changes in the sensory callback. [ABSTRACT FROM AUTHOR]

Abstract Emerging analytical technologies are being developed to provide advanced methods for monitoring 4-chlorophenol (4-CP) in the environment. Herein, a label-free, sensitive, and rapid photoelectrochemical (PEC) 4-CP detection system was constructed based on ternary composites of Ag nanoparticles, graphitic carbon nitride (GCN) and carbon spheres (CS) (Ag/GCN/CS). The proposed ternary composites were synthesized by a simple hydrothermal method. In this process, ascorbic acid (AA) played a crucial role in reducing Ag+ to metallic Ag, and provided a carbon source for CS. Due to synergistic promotion by the surface plasmon resonance (SPR) effect of Ag nanoparticles and electron-transfer behavior of CS, the ternary composites exhibited a broad visible light response and fast charge transfer, leading to a tremendously enhanced PEC response. Based on the promotion of the PEC response, a PEC sensor for 4-CP was designed by detecting the photocurrent signals of the PEC electrode after adding 4-CP to solution. Under optimal conditions, the PEC sensor exhibited a wide linear range for 4-CP from 16 to 1104 ng mL−1, with a limit of detection (LOD) of 5.33 ng mL−1. In particular, the present work may assistance in better understanding the synergistic effect between the SPR effect of Ag nanoparticles and electron-transfer properties of CS. The results can also be applied to other PEC and photocatalytic systems in conjunction with high-performance photoactive materials. Graphical abstract Unlabelled Image Highlights • Visible-light-active Ag/graphitic carbon nitride/carbon sphere composites were designed. • Efficient charge separation spatially resulted from ternary composites. • A highly efficient PEC sensor for 4-CP was constructed based on ternary composites. [ABSTRACT FROM AUTHOR]

• N-doped biochar catalyst shows high activity and stability for peroxymonosulfate (PMS) activation. • The biochar/PMS system has remarkable resistance for background ions and natural organic matter. • Offering new insights into the electron-transfer mechanism involved in carbon/PMS system. Carbon-catalyzed persulfate activation processes are promising techniques for oxidizing aqueous organic pollutants, while high-performance and low-cost carbocatalysts are urgently needed. To address this issue, nitrogen-doped biochar catalyst from alkaline lignin was developed to activate peroxymonosulfate (PMS) for acetaminophen (APAP) degradation. The optimized N-doped biochar achieved a complete removal of 50 ppm APAP within 15 min under the conditions of 0.1 g/L catalyst and 0.5 mM oxidant across a wide pH range of 4–10. Notably, the optimized N-doped biochar exhibits remarkable stability, retaining 75% APAP removal after four cycles. Moreover, a comprehensive investigation, including quenching tests, electron paramagnetic resonance measurements, and electrochemical analyses, elucidated the electron-transfer mechanism involved in the nonradical N-doped biochar/PMS system. Surprisingly, the results indicated that the primary species responsible for APAP oxidation was an activated state of N-doped biochar with electron deficiency generated from the interactions between the catalyst and PMS. This work not only provides cost-effective and high-performance biochar catalyst for selectively removing APAP from actual water body, but also sheds new light on the electron-transfer mechanism involved in nonradical carbon/PMS systems. [ABSTRACT FROM AUTHOR]

Kinetic and structural investigations of the flavohemoglobin-type NO dioxygenase have suggested critical roles for transient Fe(III)O 2 complex formation and O 2 -forced movements affecting hydride transfer to the FAD cofactor and electron-transfer to the Fe(III)O 2 complex. Stark-effect theory together with structural models and dipole and internal electrostatic field determinations provided a semi-quantitative spectroscopic method for investigating the proposed Fe(III)O 2 complex and O 2 -forced movements. Deoxygenation of the enzyme causes Stark effects on the ferric heme Soret and charge-transfer bands revealing the Fe(III)O 2 complex. Deoxygenation also elicits Stark effects on the FAD that expose forces and motions that create a more restricted NADH access to FAD for hydride transfer and switch electron-transfer off. Glucose also forces the enzyme toward an off state. Amino acid substitutions at the B10, E7, E11, G8, D5, and F7 positions influence the Stark effects of O 2 on resting heme spin states and FAD consistent with the proposed roles of the side chains in the enzyme mechanism. Deoxygenation of ferric myoglobin and hemoglobin A also induces Stark effects on the hemes suggesting a common 'oxy-met' state. The ferric myoglobin and hemoglobin heme spectra are also glucose-responsive. A conserved glucose or glucose-6-phosphate binding site is found bridging the BC-corner and G-helix in flavohemoglobin and myoglobin suggesting novel allosteric effector roles for glucose or glucose-6-phosphate in the NO dioxygenase and O 2 storage functions. The results support the proposed roles of a ferric O 2 intermediate and protein motions in regulating electron-transfer during NO dioxygenase turnover. [Display omitted] • O 2 binds Fe(III) heme in flavohemoglobin as detected by Stark-effect spectroscopy. • O 2 also forces motion of the CD loop, FAD and electron-transfer switch. • Glucose binding opposes the O 2 -driven motions in flavohemoglobin. • O 2 binds Fe(III) heme in myoglobin and hemoglobin. • Glucose or glucose-6-phosphate bind myoglobin and presumably other globins. [ABSTRACT FROM AUTHOR]

The steric and electronic effects of 4-substitution in various 4-aryl substituted 5-carboethoxy-2-oxo-1,2,3,4-tetrahydropyridines were investigated by exposing them to the UV-light in the presence or absence of the TiO2 anatase-nanoparticles. The results clearly indicate the effective presence of the photo-catalyst and also the electron-donating effect of 4-aryl substitution on drastic decreasing of the irradiation time. The experimental results concerning the electronic nature of 4-substitution were supported by the DFT computational studies and cyclic voltammetric measurements. [ABSTRACT FROM AUTHOR]

Electron transfer in solid is crucial to switchable magnetic, electrical, optical and mechanical properties. However, it is a formidable challenge to control electron-transfer behaviors via manipulation of crystalline phases, especially through dynamic crystalline transformation. Herein, three crystalline phases of an {Fe2Co2} compound were obtained via enhancement of intermolecular π···π interactions inducing successive single-crystal-to-single-crystal transformations, from solvated 1·2CH3OH·4H2O, to desolvated 1 and its polymorph 1a accompanying electron transfer. 1·2CH3OH·4H2O showed thermally induced reversible intermetallic electron transfer in mother liquor. No electron-transfer behavior was observed in 1. 1a showed reversible intermetallic electron transfer upon thermal treatment or alternative irradiation with 808- and 532-nm lasers at cryogenic temperatures. The electron-transfer behaviors significantly change the magnetic and optical properties, providing a strategy to realize different electron-transfer behaviors and switchable functions via π···π interactions manipulated dynamic crystalline transformation. [ABSTRACT FROM AUTHOR]

In this research a class of graphene modified electrodes based on self-assembled monolayer assisted binding of partially oxidized graphene on gold was achieved. The electrodes show two features: (1) the tunable electron-transfer mediation ability which is controlled by the oxidation degree of the graphene, and (2) the ability of in-situ electrochemical disassembly. The tunable electron-transfer mediation ability was investigated by interpreting the cyclic voltammogram recorded with the classic redox couple, potassium ferricyanide/ferrocyanide. The ability of in-situ electrochemical disassembly was investigated by cyclic voltammetry and electrochemical impedance spectroscopy in the case of enzyme adsorption. It was found that the “on” and “off” conditions of the partially oxidized graphene correspond to the assembly and disassembly of the mercaptosuccinic acid self-assembled monolayer respectively, endowing the electrodes with the ability of in-situ electrochemical disassembly. In addition, the experimental results on glucose sensing illustrate the potential applications of the graphene modified electrodes. [ABSTRACT FROM AUTHOR]

Fe VI O 4 2− (Fe VI ) is a promising oxidant/disinfectant and coagulant in treating water. Fe V O 4 3− (Fe V ) and Fe IV O 4 4− (Fe IV ) are intermediates in oxidations performed by Fe VI and are highly effective in degrading recalcitrant contaminants. The performance of each ferrate requires a comprehensive understanding of the mechanism. This paper presents the use of density functional theory (DFT) to understand the oxidation of cyanide by Fe VI , Fe V , and Fe IV . The sequence of steps in the oxidation process is the same for all three species. The electrostatic attraction of the positive H and C on HCN for two of the negative oxygen atoms on the ferrate is followed by the formation of a C-O bond with cleavage of an Fe-O bond. Subsequently, the formation of an H-O bond occurs with cleavage of the H-C bond, resulting in the formation of an NCO – ferrate complex. However, the energetics are different, with C-O bond formation being the rate determining step for Fe VI while for Fe V and Fe IV it is the transfer of the H from C to O. Energy calculations describe the order of reactivity of ferrates with HCN as Fe V > Fe IV > Fe VI , which agrees well with experimental results. [ABSTRACT FROM AUTHOR]

Singlet exciton fission, i.e., the splitting of a singlet exciton into two triplet excitons in molecular materials, is interesting due to its potential applications in organic photovoltaic devices. Traditionally, singlet fission can be explained by using an electron-transfer model in which twice concerted electron-transfer processes lead to the state conversion. In order to test this model, a highly efficient fission material, i.e., rubrene was mixed into other host materials which could be considered as spacers to separate doped rubrene molecules. Energy differences between LUMO levels of rubrene and host molecules constituted tunneling barriers for intermolecular electron-transfer between rubrene. Transient fluorescence spectroscopy was used to investigate the barrier effects in five series – two with varying barrier widths and three with varying barrier heights. The experimental results demonstrated that the transition rate of singlet fission exponentially decreased with the increasing distance between rubrene and the dynamics of fission process was apparently barrier-dependent. These findings could be regarded as clear confirmations of electron-transfer model for intermolecular singlet fission, and are of great importance for clarifying the true mechanism of singlet fission process. [ABSTRACT FROM AUTHOR]

Two coordination structures (Co-N 4 or Co-N 3) of cobalt single-atom catalysts (Co-SACs) were prepared by using the chitosan as starting precursor to evaluate the modulated coordination microenvironment of Co-SACs for organics degradation. The degradation performances for carbamazepine (CBZ) as well as the radical/nonradical pathways in Co-N 4 /PMS and Co-N 3 /PMS systems was evaluated. Results showed that more radicals could be produced by the Co-N 3 catalyst via stronger PMS adsorption as well as the subsequent peroxide bond cleavage of PMS. In addition, a lower energy gap between the CBZ and Co-N 3 /PMS complex was endowed for the Co-N 3 coordination to boost stronger electron-transfer process for CBZ. As a result, both radical and electron-transfer process was boosted by the coordinated Co-N 3 sites than those of Co-N 4 coordination. This work provides a new insight on the versatile catalytic pathways with modulated coordination microenvironment of carbon-based SACs for high-efficiency PMS activation. [Display omitted] • Two coordination structures (Co-N 4 or Co-N 3) of Co-SACs were prepared. • More radicals could be produced by the Co-N 3 catalyst via stronger PMS adsorption. • Lower gap between CBZ and Co-N 3C1/PMS complex was endowed • Both radical and electron-transfer oxidation was boosted by the coordinated Co-N 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic SBC 800 was fabricated via "One-step" pyrolysis process. • Magnetic SBC 800 effectively activates PMS for NOR elimination. • Magnetic SBC 800 can be magnetically separated from the treated water. • 1O 2 as well as electron-transfer regime dominated the NOR degradation. • Nonradicals-dominated oxidation process exhibits strong anti-interference. As an undesirable by-product of the wastewater treatment plants (WWTPs), sewage sludge (SS) caused considerable stress on the normal operation of WWTPs, because of its expensive disposal costs. On the other hand, exploiting resource utilization of the residual SS seems to be an attractive approach to resolve this problem. In this study, SS was thermally converted into biochar catalysts (SBC) under oxygen-limiting conditions. By using peroxymonosulfate (PMS) as the chemical oxidant, norfloxacin (NOR) could be effectively removed and the reaction was significantly accelerated after the addition of SBC. Specifically, over 90% of NOR was eliminated by the SBC 800 /PMS process within 70 min. As evidenced by the comprehensive mechanistic investigations, 1O 2 as well as electron-transfer regime primarily participated in the NOR degradation process, while radical species played minor roles. More importantly, the endogenous iron substances endowed SBC with magnetic properties, making the efficient separation of SBC from water available. Eventually, the possible intermediates were tentatively identified by liquid chromatography-mass spectrometry and the corresponding degradation pathways were proposed. Overall, this research developed a novel method to achieve the remediation of NOR-contaminated water and elimination of the potential risks of SS simultaneously. [ABSTRACT FROM AUTHOR]

Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor–acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor–acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor–acceptor graphene-based hybrids, will be discussed.