Electron Transfer Reactions Research Articles

Organophotocatalytic or Electrophotocatalytic Reduction and Functionalization Reactions with a Thioxanthone-TfOH Complex Catalyst

AbstractThioxanthone has long been a prominent catalyst in the field of photocatalysis, owing to its high triplet energy and long triplet lifetime that render it suitable for energy transfer reactions. However, its low oxidation potential and short singlet lifetime have posed challenges when employing it for electron-transfer reactions. This account summarizes our efforts in developing a potent and long-lived thioxanthone-TfOH complex (9-HTXTF) catalyst, and its application in energy-demanding redox transformations such as organophotocatalytic or electrophotocatalytic reduction and functionalization reactions.1 Introduction2 Discovery and Properties of the Catalyst 9-HTXTF3 Organophotocatalysis4 Electrophotocatalysis5 Conclusion

Eosin Y derivatives for visible light-mediated free-radical polymerization: Applications in 3D-photoprinting and bacterial photodynamic inactivation

This study reports the design and the subsequent use of mono-allylated (EY-MA) and di-allylated (EY-DA) derivatives of eosin Y (EY) as highly efficient visible light-sensitive photosensitizers (PS) of bio-based H-donor molecules (cysteamine (Cys) or N-acetyl-L-cysteine (NAC)) and an electron donor (N-methyldiethanolamine, MDEA) for free-radical and thiol-acrylate polymerizations of a biobased monomer derived from soybean oil (SOA) upon exposure to visible light. High final acrylate conversions for SOA polymerization (up to 80 %) evidence the efficient photoinitiating properties of the eosin derivatives systems under irradiation with light emitting diodes (LEDs) centred at 405, 455 and 505 nm, and outperform those obtained with EY and other common photosensitizers such as camphorquinone or benzophenone. As described by fluorescence and phosphorescence analyses, laser flash photolysis (LFP) and electron paramagnetic resonance spin-trapping (EPR-ST) experiments, EY-MA and EY-DA can react via a proton/proton-coupled electron transfer reaction with Cys (or NAC) and MDEA respectively. The efficient singlet oxygen generation of the EY-MA-based materials upon exposure to visible light leads to excellent antibacterial properties, against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). A 3-log decrease of E. coli adhesion on the surface of the materials is observed and 100 % adhesion inhibition of S. aureus is also demonstrated. The co-polymerization of the eosin-derived PS with the polymer matrix ensures sustainable antibacterial properties against both bacteria strains upon visible light exposure as it prevents their leakage out of the polymer network. Finally, finely complex 3D structures are successfully obtained by a 3D-photoprinting technology with the investigated EY-MA-based formulation using LED@405 nm.

Elementary Reaction Steps That Precede or Follow a Unimolecular Reaction Step Can Obfuscate Interpretation of the Driving-Force Dependence to Its Rate Constant.

Assessing the validity of a driving-force-dependent kinetic theory for a unimolecular elementary reaction step is difficult when the observed reaction rate is strongly influenced by properties of the preceding or following elementary reaction step. A well-known example occurs for bimolecular reactions with weak orbital overlap, such as outer-sphere electron transfer, where bimolecular collisional encounters that precede a fast unimolecular electron-transfer step can limit the observed rate. A lesser-appreciated example occurs for bimolecular reactions with stronger orbital overlap, including many proton-transfer reactions, where equilibration of an endergonic unimolecular proton-transfer step results in a relatively small concentration of reaction products, thus slowing the rate of the following step such that it becomes rate limiting. Incomplete consideration of these points has led to discrepancies in interpretation of data from the literature. Our reanalysis of these data suggests that proton-transfer elementary reaction steps have a nonzero intrinsic free energy barrier, implying, in the parlance of Marcus theory, that there is non-negligible nuclear reorganization. Outcomes from our analyses are generalizable to inner-sphere electron-transfer reactions such as those involved in (photo)electrochemical fuel-forming reactions.

Photochemistry of plateau lake-derived dissolved organic matter: Reactive species generation and effects on 17β-estradiol photodegradation

Naturally strong ultraviolet irradiation at high altitudes causes photobleaching of plateau lake DOM (P-DOM) and affects its photochemical activity. However, the photoreactivity of P-DOM has remained unclear under natural photobleaching condition. Here, six P-DOM samples isolated from plateau lakes in Yunnan Province, China as well as two reference DOM as comparisons were used to explore the photogeneration of reactive species (RS) and their effects on 17β-estradiol photodegradation. Compared with SRHA/SRFA, P-DOM has lower aromaticity, average molecular weight, and electron-donating capacity. The quantum yields of triplet state P-DOM (3P-DOM*), 1O2, and ∙OH produced in P-DOM solutions were greatly higher than those of reference DOM. The RS quantum yields had positive linear correlations with E2/E3 and SR, whereas were negatively linear correlated with SUVA25. Radical quenching experiments showed that 3P-DOM* was the prominent RS for 17β-estradiol photodegradation, and its contribution exceeded 70% for each of P-DOM. 3P-DOM*-mediated photodegradation was mainly attributed to the electron-transfer reactions with an average second-order rate constant of 4.62 × 109 M-1s-1, indicating the strong photoreactivity towards 17β-estradiol. These findings demonstrate that P-DOM is an efficient photosensitizer for RS production, among which 3P-DOM* may play an important role in enhanced photodegradation for organic micropollutants in plateau lake enriched with DOM.

Factors that Impact Photochemical Cage Escape Yields.

The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production to medicine and organic synthesis. These reactions are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) and a redox-active quencher to yield radical pairs that are intimately associated within a solvent cage. Many of these radicals undergo rapid thermodynamically favored "geminate" recombination and do not diffuse out of the solvent cage that surrounds them. Those that do escape the cage are useful reagents that may undergo subsequent reactions important to the above-mentioned applications. The cage escape process and the factors that determine the yields remain poorly understood despite decades of research motivated by their practical and fundamental importance. Herein, state-of-the-art research on light-induced electron transfer and cage escape that has appeared since the seminal 1972 review by J. P. Lorand entitled "The Cage Effect" is reviewed. This review also provides some background for those new to the field and discusses the cage escape process of both homolytic bond photodissociation and bimolecular light induced electron transfer reactions. The review concludes with some key goals and directions for future research that promise to elevate this very vibrant field to even greater heights.

Electronic inductive and resonance effects of substituents on concerted two-proton-coupled electron transfer between electrogenerated superoxide and hydroquinone derivatives in N,N-dimethylformamide

Improving energy conversion technologies is pivotal for reducing the effects of global warming. The use of electron transfer catalysts based on electron carriers found in organisms, such as redox biomimetic quinone systems, is a promising route for truly efficient energy conversion. Herein, we report the density functional theory (DFT)-based analysis of the reaction between electrogenerated superoxide radical anion (O2•−) and methyl- or chloro-substituted benzene-1,4-diol (hydroquinone) derivatives in N,N-dimethylformamide. We investigate the electrochemical scavenging of O2•− by hydroquinone derivatives involving two proton transfers (PTs) and one electron transfer (ET). We show that chloro and methyl substituents promote a proton-coupled electron transfer (PCET) reaction with the effect increasing with the number of substituent groups. Our DFT results demonstrate that the substituent effect promotes either of the PT or ET processes, along a sequential PCET pathway. The electrochemical and DFT analyses of the substituent effect indicate that the concerted two-proton-coupled electron transfer (2PCET) promoted by an increasing number of the substituents is a plausible pathway for the reaction between electrogenerated O2•− and hydroquinone derivatives. In addition, our findings show that the resonance effect is the main driving force for the promotion of 2PCET.

Confinement effect of FeMOFs glass enhances the proton coupled electron transfer reaction for the organic pollutants polymerization toward sustainable water purification

Polymerization-driven removal of pollutants in advanced oxidation processes (AOPs) offers a sustainable way for the simultaneous achievement of contamination abatement and resource recovery, supporting a low-carbon water purification approach. In this work, metal–organic frameworks (MOFs) glass complexes (g-ZIF-62@8) were used as a platform to enhance proton transfer through the confinement effect of nanopores, modulating proton coupled electron transfer (PCET) reaction to promote organic pollutant polymerization. The results show that the confinement effect of nanopores in ZIF-62 glass can significantly improve the proton and electron transfer behavior, the proton diffusion coefficient is increased by 4.9 times (2.91*10−3 to 1.43*10−2), the energy barrier of the PCET reaction can be reduced by 1.9 eV, and the reaction kinetic rate constant is increased from 0.0198 min−1 to 0.20118 min−1. Photogenerated holes and Fe(IV = O), as the main reactive oxygen species (ROS), undergo PCET reaction with Bisphenol A (BPA) to convert them into phenoxy radicals, which are then polymerized into macromolecular organic compounds. PCET with proton-electron synergy was identified as a key driver of pollutant polymerization. This enables low-carbon purification and organic carbon recovery in wastewater. Our work provides new insights into the application of confinement effects to enhance proton and electron behavior to regulate pollutant polymerization toward sustainable water purification.

Variations in flavin redox states during extracellular electron transfer and electron conduction in Shewanella oneidensis

Flavin is one of the most prevalent redox molecules utilized by electroactive bacteria. Electroactive bacteria form a three-dimensional architecture with multiple cell assemblages on electrodes in bioelectrochemical systems. This provokes the importance of unveiling the redox chemistry of flavins during electron transfer not only at the bacteria/electrode interface but also inside cell assemblages. However, it has been difficult to directly compare the redox species contributing to each electron transfer reaction. In this study, to simultaneously detect the flavin redox species at the electrode surface and those in cell assemblages, we conducted bipotentiometric cyclic voltammetry on a colony of Shewanella oneidensis MR-1. The bipotentiometric data showed that flavin mononucleotide proceeds the redox cycle at − 0.43 V (vs. standard hydrogen electrode) in the MR-1 colony assignable to the semiquinone/hydroquinone redox cycle, which was supported by experiments with semiquinone scavenger and gene deletion mutants. Notably, the peak at − 0.43 V was not detected at the electrode surface, indicating that the flavin redox cycles and redox potentials involved in the electron transfer inside MR-1 assemblages differ from those at the MR-1/electrode interface. The measurement system presented herein offers a platform to clarify the redox reactions in cell assemblages as well as at the bacteria/electrode interface.

Plasma water treatment for PFAS: Study of degradation of perfluorinated substances and their byproducts by using cold atmospheric pressure plasma jet

This study evaluates the effectiveness of non-thermal plasma at atmospheric pressure (NTP APPJ) for treating PFAS - contaminated water in different matrices. Successful removal of several perfluoroalkyl carboxylic acids (PFCAs) (C6 to C4), perfluroalkane sulfonic acids (PFSAs) (C8 to C4) and perfluropolyethers (PFPEs) (GenX and ADONA) PFAS compounds was achieved in laboratory scale experiments. In the deionized water (DW), high removal efficiencies (> 90%) were observed for longer-chain PFAS, PFOS (99.89%), PFHxA (94.61%) and ADONA (94.83%), while shorter- chain compounds had lower removal rates. Real water samples (tap water and synthetic effluent) showed lower overall degradation percentages (8–50%) depending on compound and matrix. Short-chain PFAS displayed around 10% removal in tap water, while PFOS and GenX achieved 50% and 32% removal, respectively. Complex matrix effects influence degradation rates. Byproducts from the plasma treatment were investigated, revealing distinct degradation mechanisms for various PFAS compounds. For PFSAs and PFCAs, degradation involved electron transfer, bond breaking and subsequent reactions. Conversely, ADONA and GenX degradation initiated with ether-group cleavage, followed by additional transformation processes. Plasma-based technology shows potential for degradation of PFAS, especially for newer substitute compounds like ADONA and GenX. However, further research is needed to optimize plasma performance for complete mineralization of PFAS. This study also proposes a degradation mechanism for ADONA, marking a novel investigation into ether-group PFAS degradation with potential implications for further research and understanding toxicological implications.

Electrical Wiring of Malarial Parasite Intermediate Hematin on a Tailored N-Doped Carbon Nanomaterial Surface and Its Bioelectrocatalytic Hydrogen Peroxide Reduction and Sensing.

Hematin, an iron-containing porphyrin compound, plays a crucial role in various biological processes, including oxygen transport, storage, and functionality of the malarial parasite. Specifically, hematin-Fe interacts with the nitrogen atom of antimalarial drugs, forming an intermediate step crucial for their function. The electron transfer functionality of hematin in biological systems has been scarcely investigated. In this study, we developed a biomimicking electrical wiring of hematin-Fe with a model N-drug system, represented as {hematin-Fe---N-drug}. We achieved this by immobilizing hematin on a multiwalled carbon nanotube (MWCNT)/N-graphene quantum dot (N-GQD) modified electrode (MWCNT/N-GQD@Hemat). N-GQD serves as a model molecular drug system containing nitrogen atoms to mimic the {hematin-Fe---N-drug} interaction. The prepared bioelectrode exhibited a distinct redox peak at a measured potential (E1/2) of -0.410 V vs Ag/AgCl, accompanied by a surface excess value of 3.54 × 10-9 mol cm-2. This observation contrasts significantly with the weak or electroinactive electrochemical responses documented in literature-based hematin systems. We performed a comprehensive set of physicochemical and electrochemical characterizations on the MWCNT/N-GQD@Hemat system, employing techniques including FESEM, TEM, Raman spectroscopy, IR spectroscopy, and AFM. To evaluate the biomimetic electrode's electroactivity, we investigated the selective-mediated reduction of H2O2 as a model system. As an important aspect of our research, we demonstrated the use of scanning electrochemical microscopy to visualize the in situ electron transfer reaction of the biomimicking electrode. In an independent study, we showed enzyme-less electrocatalytic reduction and selective electrocatalytic sensing of H2O2 with a detection limit of 319 nM. We achieved this using a batch injection analysis-coupled disposable screen-printed electrode system in physiological solution.

Long-lived photoinduced charge separation in adamantane-bridged donor-acceptor dyads: A case of adamantane bridge conferring orthogonal donor-acceptor orientation and restricted rotation

Design of compact donor-acceptor dyads that can exhibit charge separated (CS) state lifetimes extending to the microsecond time domain remains a major challenge even today. A simple but effective design strategy that can lead to long CS state lifetimes, in at least a few compact dyads, is still elusive. Herein we propose that use of adamantane (AD) as bridge can enhance CS state lifetimes in small molecule donor-acceptor dyads. This paper reports AD-bridged dyads, AN-AD-NB and PY-AD-NB, wherein the anthracene (or pyrene) donor and nitrobenzene acceptor are attached to bridgehead positions of AD. The singlet CS states generated upon irradiation were long-lived (lifetimes >1 μs) and decayed to the ground and local triplet states, simultaneously. Electron transfer reactions of the CS state with secondary donor and acceptor established that the CS state is sufficiently long-lived to participate in intermolecular reactions. X-ray crystal structure of the AN-AD-NB dyad reveals that the donor and acceptor are orthogonally oriented, which reduces the donor-acceptor interaction, and thereby the charge recombination rate, significantly. By analysing the X-ray structure, we predict that all adamantane-bridged compact dyads will have orthogonal donor-acceptor orientation and exhibit long-lived CS states. We also report studies with bisadamantyl-substituted dyads and the results confirmed that the local triplets are formed from the CS state through hyperfine interaction. Based on our work we propose that the hyperfine interaction, which is not expected to occur in compact dyads because of the short donor-acceptor separation, can indeed occur if the CS state is sufficiently long-lived.

A tetrahedral neptunium(V) complex.

Neptunium is an actinide element sourced from anthropogenic production, and, unlike naturally abundant uranium, its coordination chemistry is not well developed in all accessible oxidation states. High-valent neptunium generally requires stabilization from at least one metal-ligand multiple bond, and departing from this structural motif poses a considerable challenge. Here we report a tetrahedral molecular neptunium(V) complex ([Np5+(NPC)4][B(ArF5)4], 1-Np) (NPC = [NPtBu(pyrr)2]-; tBu = C(CH3)3; pyrr = pyrrolidinyl (N(C2H4)2); B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate). Single-crystal X-ray diffraction, solution-state spectroscopy and density functional theory studies of 1-Np and the product of its proton-coupled electron transfer (PCET) reaction, 2-Np, demonstrate the unique bonding that stabilizes this reactive ion and establishes the thermochemical and kinetic parameters of PCET in a condensed-phase transuranic complex. The isolation of this four-coordinate, neptunium(V) complex reveals a fundamental reaction pathway in transuranic chemistry.

High-energy and durable aqueous Zn batteries enabled by multi-electron transfer reactions

Aqueous Zn batteries (AZBs) have emerged as a highly promising technology for large-scale energy storage systems due to their eco-friendly, safe, and cost-effective characteristics. The current requirements for high-energy AZBs attract extensive attention to reasonably designed cathode materials with multi-electron transfer mechanisms. This review systematically overviews the development and challenges of typical cathode hosts capable of multiple electron transfer reactions for high-performance Zn batteries. Moreover, we also summarize how to trigger the multi-electron transfer chemistry of cathodes, including transition metal oxides, halogens, and organics, to further boost the energy storage capability of AZBs. Finally, perspectives on critical issues and future directions of the multi-electron transfer battery systems offer novel insights for advanced Zn batteries.

Transient spectroscopic insights into nitroindole’s T1 state: Elucidating its intermediates and unique photochemical properties

Indoles are notable for their distinct photophysical and photochemical properties, making them useful indicators in biological systems and promising candidates for a variety of pharmaceutical applications. While some indoles exhibit room temperature phosphorescence, such a phenomenon has not been observed in nitroindoles. Typically, adding of a nitro group into aromatic compounds promotes ultrafast intersystem crossing and increases the formation quantum yield of the lowest excited triplet (T1). Therefore, understanding the reactivity of nitroindoles′ T1 states is imperative. This study investigated the physical properties and chemical reactivities of the T1 state of 6-nitroindole (3HN-6NO2) in both polar aprotic and protic solvents, using transient absorption spectroscopy. Our results demonstrate the basicity and acidity of 3HN-6NO2, emphasizing its potential for protonation and dissociation in mildly acidic and basic conditions, respectively. Furthermore, 3HN-6NO2 has a high oxidizing capacity, participating in electron transfer reactions and proton-coupled electron transfer to produce radicals. Interestingly, in protic solvents like alcohols, 3HN-6NO2 dissociates at the –NH group and forms N-H…O hydrogen-bonded complexes with the nitro group. By identifying transient absorption spectra of intermediates and quantifying kinetic reaction rate constants, we illuminate the unique properties of the T1 state nitroindoles, enriching our understanding of their photophysical and photochemical behaviors. The results of this study have significant implications for their potential application in both biological systems and materials science.

Enzyme mimicking activity of the Ru(pic)3 complex in the oxidation NADH coenzymes: kinetic and mechanistic studies

Mimicking the enzymatic oxidation of NADH and obtaining mechanistic insight into the electron transfer reaction pertinent to the redox inter-conversion of NADH/NAD+ couple is a long-term challenge in biological and energy-related chemistry. The kinetics and mechanism of the oxidation of NADH by [RuIII(pic)3] (pic– = picolinate anion) has been studied spectrophotometrically and kinetically in aqueous solution at pH 7.0 (MES buffer). The reaction was followed over time at 466 nm (metal to ligand charge transfer band of [RuII(pic)3]–). The rate of NADH oxidation was found to be first-order with respect to Ru(III)-complex concentration. The values of the observed rate constant (k obs) increased linearly with increase in the concentration of NADH. The rate of the reaction was independent of the ionic strength of the reacting solution. Activation parameters (ΔH≠ = 56 ± 1 kJ mol−1 and ΔS≠ = −65 ± 3 J.deg−1 mol−1) were determined from the temperature dependence studies (15-35 °C) of the reaction. Kinetic data and activation parameters are interpreted in terms of a mechanism involving outer-sphere electron transfer.

Synthesis, Characterization and Reactivity Studies of Cobalt(III) Porphyrin‐Iodosylarene Adduct and Cobalt(III) Porphyrin π‐Cation Radical Species

AbstractBiomimetic metalloporphyrin complexes have been employed in a number of catalytic oxidation reactions by utilizing terminal oxidants such as iodosylarenes (ArIO). Although high‐valent metal‐oxo species have been considered as the reactive intermediates, their precursors, metal‐iodosylarene adduct species, also exhibit intriguing oxidation capability under certain conditions. However, late transition metal porphyrin‐oxidant adduct species have not been explored in oxidation reactions yet. Herein, we report the synthesis, characterization and reactivity studies of cobalt(III) porphyrin‐ArIO adduct complexes. These adduct species exhibit moderate oxidation capability in electron transfer reactions. More interestingly, addition of Brønsted acid or Lewis acid facilitated the O−I bond cleavage, resulted in the formation of cobalt(III) porphyrin π‐cation radical species, which is much more reactive than the corresponding adduct species in electron transfer reactions. Kinetic studies and theoretical calculations demonstrate that the O−I bond cleavage is triggered in the presence of acid, affording the porphyrin ligand oxidation while the formation of high‐valent cobalt‐oxo species is prohibited due to the “oxo‐wall” for late transition metals. This study provides a novel model of a late transition metal‐iodosylarene adduct species as an active oxidant in oxidation reactions, while in the cases of iron and manganese complexes, high‐valent metal‐oxo species are generated.

Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound-I Analogue.

The nature of the axial ligand in high-valent iron-oxo heme enzyme intermediates and related synthetic catalysts is a critical structural element for controlling proton-coupled electron-transfer (PCET) reactivity of these species. Herein, we describe the generation and characterization of three new 6-coordinate, iron(IV)-oxo porphyrinoid-π-cation-radical complexes and report their PCET reactivity together with a previously published 5-coordinate analogue, FeIV(O)(TBP8Cz+•) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato3-) (2) (Cho, K. A high-valent iron-oxo corrolazine activates C-H bonds via hydrogen-atom transfer. J. Am. Chem. Soc. 2012, 134, 7392-7399). The new complexes FeIV(O)(TBP8Cz+•)(L) (L = 1-methyl imidazole (1-MeIm) (4a), 4-dimethylaminopyridine (DMAP) (4b), cyanide (CN-)(4c)) can be generated from either oxidation of the ferric precursors or by addition of L to the Compound-I (Cpd-I) analogue at low temperatures. These complexes were characterized by UV-vis, electron paramagnetic resonance (EPR), and Mössbauer spectroscopies, and cryospray ionization mass spectrometry (CSI-MS). Kinetic studies using 4-OMe-TEMPOH as a test substrate indicate that coordination of a sixth axial ligand dramatically lowers the PCET reactivity of the Cpd-I analogue (rates up to 7000 times slower). Extensive density functional theory (DFT) calculations together with the experimental data show that the trend in reactivity with the axial ligands does not correlate with the thermodynamic driving force for these reactions or the calculated strengths of the O-H bonds being formed in the FeIV(O-H) products, pointing to non-Bell-Evans-Polanyi behavior. However, the PCET reactivity does follow a trend with the bracketed reduction potential of Cpd-I analogues and calculated electron affinities. The combined data suggest a concerted mechanism (a concerted proton electron transfer (CPET)) and an asynchronous movement of the electron/proton pair in the transition state.

Intermolecular Proton-Coupled Electron Transfer Reactivity from a Persistent Charge-Transfer State for Reductive Photoelectrocatalysis.

Interest in applying proton-coupled electron transfer (PCET) reagents in reductive electro- and photocatalysis requires strategies that mitigate the competing hydrogen evolution reaction. Photoexcitation of a PCET donor to a charge-separated state (CSS) can produce a powerful H-atom donor capable of being electrochemically recycled at a comparatively anodic potential corresponding to its ground state. However, the challenge is designing a mediator with a sufficiently long-lived excited state for bimolecular reactivity. Here, we describe a powerful ferrocene-derived photoelectrochemical PCET mediator exhibiting an unusually long-lived CSS (τ ∼ 0.9 μs). In addition to detailed photophysical studies, proof-of-concept stoichiometric and catalytic proton-coupled reductive transformations are presented, which illustrate the promise of this approach.

Temperature fluctuation in soil alters the nanoplastic sensitivity in wheat

Despite the wide acknowledgment that plastic pollution and global warming have become serious agricultural concerns, their combined impact on crop growth remains poorly understood. Given the unabated megatrend, a simulated soil warming (SWT, +4 °C) microcosm experiment was carried out to provide a better understanding of the effects of temperature fluctuations on wheat seedlings exposed to nanoplastics (NPs, 1 g L−1 61.71 ± 0.31 nm polystyrene). It was documented that SWT induced oxidative stress in wheat seedlings grown in NPs-contaminated soil, with an 85.56 % increase in root activity, while decreasing plant height, fresh weight, and leaf area by 8.72 %, 47.68 %, and 15.04 % respectively. The SWT also resulted in reduced photosynthetic electron-transfer reaction and Calvin-Benson cycle in NPs-treated plants. Under NPs, SWT stimulated the tricarboxylic acid (TCA) metabolism and bio-oxidation process. The decrease in photosynthesis and the increase in respiration resulted in an 11.94 % decrease in net photosynthetic rate (Pn). These results indicated the complicated interplay between climate change and nanoplastic pollution in crop growth and underscored the potential risk of nanoplastic pollution on crop production in the future climate.

Facilitating Electron Transfer by Resizing Cyclocarbon Acceptor from C18 to C16.

Recent advances in synthetic methods, combined with tip-induced on-surface chemistry, have enabled the formation of numerous cyclocarbon molecules. Here, we investigate computationally the experimentally studied C16 and C18 molecules as well as their van der Waals (vdW) complexes with several typical donor and acceptor molecules. Our results demonstrate a remarkable electron-withdrawing ability of cyclocarbon molecules. The vdW complexes of C16 and C18 exhibit a thermodynamically favorable photoinduced electron transfer (ET) from the donor partner to the cyclocarbons that occurs on a picosecond time scale. The lower reorganization energy of C16 compared to C18 leads to a significant acceleration of the ET reactions.