Tumor hypoxia severely impedes the therapeutic efficacy of type II photodynamic therapy (PDT) depending on singlet oxygen (1O2) generation. To combat hypoxic tumors, herein, a new approach is devised ...to boost superoxide radical (O2•−) photogeneration for type I PDT. Heavy atoms are introduced onto aza‐BODIPY molecules (iodine substituted butoxy‐aza‐BODIPY, IBAB) to promote their intersystem‐crossing (ISC) ability. Meanwhile, methoxy‐poly(ethylene glycol)‐b‐poly(2‐(diisopropylamino) ethyl methacrylate) (mPEG‐PPDA) with enhanced electron‐donating efficiency is employed as a coating matrix to encapsulate IBAB, thereby obtaining amphiphilic aza‐BODIPY nanoplatforms (PPIAB NPs). Under irradiation, triplet‐state IBAB in PPIAB NPs is efficiently generated from singlet state favored by the elevated ISC ability. The electron‐rich environment provided by mPEG‐PPDA can donate triplet‐state IBAB with one electron to form charge‐separated‐state IBAB, which in turn transfers electron to O2 for O2•− production. Significantly, owing to recyclable O2 generated by disproportionation or Harber–Weiss/Fenton reaction, prominent O2•− is generated by PPIAB NPs even in a severe hypoxic environment (2% O2), enabling superior therapeutic efficacy (96.2% tumor‐inhibition rate) over NPs not following this strategy. Thus, the proof‐of‐concept design of ISC‐enhanced and electron‐rich polymer encapsulating PPIAB NPs illuminates the path to preparing O2•− photogenerator for hypoxic cancer treatment.
This study devises a new approach to boost O2•− photogeneration for type I photodynamic therapy (PDT). By improving the photosensitizers' intersystem‐crossing ability and coating polymers' electron‐donating ability, amphiphilic aza‐BODIPY nanoplatforms (PPIAB NPs) with O2•− photogeneration ability are obtained. PPIAB NPs can achieve remarkable PDT efficacy in hypoxia, illuminating the path to preparing O2•− photogenerators for cancer treatment in the future.
Aqueous Zn‐ion batteries are emerging as a promising candidate for large‐scale energy storage, while the short lifetime and poor reversibility of Zn anodes limit their further development. When ...attempting to enhance reversibility, most reported methods involve toxic and pollutive substances and decreased water content, which inevitably sacrificed safety level, rate performance, and environmentally benign characteristics. Herein, a series of low‐cost and “green” molecules are introduced into the aqueous (ZnCl2, ZnSO4) electrolytes, featured with cations coordination capability, which can significantly inhibit the hydration step of Zn2+ and delay the formation of the key by‐products (Zn5(OH)8Cl2·H2O, 3Zn(OH)3·ZnSO4·5H2O) in aqueous electrolytes via regulating the coordination status of Zn2+. In the optimized electrolyte system, a highly reversible Zn metal anode presents excellent electrochemical performance, featured with a long lifespan over 1185 h at 1 mA cm−2 and smooth deposition morphology. Furthermore, Zn–MnO2 batteries based on the electrolyte deliver high capacity retention of 82.9% after 200 cycles. These breakthroughs suggest that this method offers a versatile toolbox toward developing future advanced multivalent metal batteries for large‐scale energy storage.
The introduction of electron‐donating substituents can improve the electron‐donating capacity of ligands, a critical factor in the cation coordination process. In this way, the formation of Zn(OH2)62+, which is a key species that leads to the formation of by‐products through dehydrogenation, is well inhibited. This method can improve the efficiency of Zn metal plating/stripping in a water‐abundant electrolyte.
To investigate the impact of substitution patterns on the photophysical properties of pyrene derivatives, six novel pyrene derivatives A1-A6 were synthesised by directly coupling anthracene with ...pyrene units. The objective was to explore the influence of strong electron-donating groups and substitution patterns on their photophysical behaviour. Experimental and theoretical studies were conducted to analyse the photophysical properties of these compounds, revealing a clear dependence on the position of substitution within the pyrene core. Analysis of molecular orbitals revealed significant contributions from both pyrene and anthracene moieties, with deviations from typical electronic distributions attributed to the presence of electron-donating groups. The energy gap values remained consistent across derivatives, contrary to previous findings involving acceptor motif substitutions. Structural analyses indicated deviations from planarity with significant changes in angles upon excitation. The emission spectra of mono- and disubstituted pyrene derivatives predominantly exhibited a single broad maximum with slight shoulders in each solvent. However, the emission spectra of the tetrasubstituted compound (A6) displayed a vibrational structure with three maxima in all solvents, reminiscent of pyrene itself but red-shifted by approximately 30 nm. Furthermore, the central maximum for compound A6 was around 20 nm blue-shifted compared to the other compounds, although its shoulder at around 440 nm corresponded to a maximum observed in other pyrene derivatives. Typically, 1,3,6,8-tetrasubstituted pyrene derivatives, compared to their disubstituted analogues, exhibited red-shifted emission maxima associated with increased π-conjugation due to additional units on the pyrene core. A comprehensive analysis was performed on the absorption and emission spectra of the pyrene derivatives in solvents of various polarities and in the solid state. The fluorescence intensity was influenced by solvent polarity, with A6 showing limited sensitivity (similar quantum efficiency of approximately 45 % in all solvents). Moreover, the quantum yield decreases with the increasing number of anthracene substituents, being the lowest for tetrasubstituted A6. Bi-exponential decay and shorter lifetimes were observed for A1-A6 compared to known compounds, with quantum yields decreasing as solvent polarity increased. In the solid state, emission peaks shifted towards longer wavelengths, with A1 exhibiting the highest quantum yield attributed to steric hindrance. At low temperatures (77 K), emission spectra displayed redshifts, and longer lifetimes were observed. Spectrometric tests in THF/water mixtures indicated luminescence quenching at higher water fractions.
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•Influence of strong electron-donating substitutions on photophysical properties.•Unusual blue-shifted emission of tetrasubstituted pyrene compared to its analogues.•The significant impact of solvent polarity on fluorescence intensity and quantum yields for specific substitution patterns.•Substitution pattern has a strong influence on intermolecular interactions.
Organic solar cells based on semiconducting polymers and small molecules have attracted considerable attention in the last two decades. Moreover, the power conversion efficiencies for ...solution‐processed solar cells containing A–π–D–π–A‐type small molecules and fullerenes have reached 11%. However, the method for designing high‐performance, photovoltaic small molecules still remains unclear. In this review, recent studies on A–π–D–π–A electron‐donating small molecules for organic solar cells are introduced. Moreover, the relationships between molecular properties and device performances are summarized, from which inspiration for the future design of high performance organic solar cells may be obtained.
Over 100 electron‐donating, A–π–D–π–A‐type small molecules for solution‐processed organic solar cells are reviewed. The relationships between molecular properties and device performances are summarized and statistically analyzed, from which inspiration can be obtained for future design of electron‐donating small molecules and high‐performance, small‐molecule organic solar cells.
Introducing sulfur functionalities is reported as an efficacious route to regulate the electron distribution of single‐atomic Fe sites for improving the oxygen reduction reaction (ORR) activity, ...however, it remains controversial about the role of type of sulfur functionalities in enhancing the ORR activity. Herein, this study revisits the role of sulfur functionalities in regulating the electron distribution of single‐atomic Fe sites by the construction of single‐atomic Fe‐N4 sites with sulfur functionalities (FeSNC) using sulfur‐containing molecules with different molecular structures. X‐ray absorption spectroscopy and theoretical calculations confirm that thiophene S and oxidized S both possess the electron‐donating properties for regulating the electronic distribution of Fe‐N4 sites, which is beneficial to weaken the adsorption of the ORR intermediates. As expected, the optimal FeSNC has attractive ORR activity with half‐potential of 0.76 V in 0.5 m H2SO4 and 0.91 V in 0.1 m KOH along with remarkable Zn‐air battery performance. Moreover, the developed synthetic method has also been extended to construct B and P regulated FeNC catalysts.
The single‐atomic Fe‐N4 sites with sulfur functionalities are fabricated by a small‐molecule decorated self‐sacrificial template approach, which are demonstrated theoretically and experimentally to weaken the adsorption of the oxygen reduction reaction (ORR) intermediates by regulating the electronic distribution of Fe‐N4 sites due to the electron‐donating properties of sulfur functionalities of thiophene S and oxidized S, thereby promoting the ORR kinetics.
An ultrathin cobalt–manganese (Co‐Mn) nanosheet, consisting of amorphous Co(OH)x layers and ultrasmall Mn3O4 nanocrystals, is designed as an efficient co‐catalyst on an α‐Fe2O3 film for ...photoelectrochemical (PEC) water oxidation. The uniformly distributed Co‐Mn nanosheets lead to a remarkable 2.6‐fold enhancement on the photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and an impressive cathodic shift (≈200 mV) of onset potential compared with bare α‐Fe2O3 film. Furthermore, the decorated photoanode exhibits a prominent resistance against photocorrosion with excellent stability for over 10 h. Detailed mechanism investigation manifests that incorporation of Mn sites in the nanosheets could create electron donation to Co sites and facilitate the activation of the OH group, which drastically increases the catalytic activities for water oxidation. These findings provide valuable guidance for designing high‐performance co‐catalysts for PEC applications and open new avenues toward controlled fabrication of mixed metallic composites.
An ultrathin cobalt–manganese (Co‐Mn) nanosheet is designed as an efficient co‐catalyst on an α‐Fe2O3 film for photoelectrochemical water oxidation. Incorporation of Mn sites in the nanosheets could create electron donation to Co sites and facilitate the generation of key intermediates, which drastically increases the catalytic activities for oxygen evolution reaction.
Biochar has shown a unique electrochemical property being involved in various redox reactions in soil and water. In this study, the electron donating capacities (EDCs) of biochar pyrolyzed at ...200–800 °C from pine wood, barley grass and wheat straw were investigated by using the mediated electrochemical oxidation method. The EDC values for all biochar were in the range of 0.18–1.83 mmol e− (g biochar)−1, showing the increase as the temperature increased from 200 °C to 400 °C, the decrease from 400 °C to 650 °C, and then increase from 650 °C until to 800 °C. At low and intermediate temperatures of 200–650 °C, the EDCs were mainly attributed to the phenolic hydroxyl groups, while the conjugated π-electron system associated with aromatic structure dominated the EDCs of biochar at the high temperatures of over 650 °C. The barley grass- and wheat straw-derived biochar had higher EDCs than the pine wood-derived biochar, resulting from the higher phenolic hydroxyl groups in the former samples than the latter one. In conclusion, the reductive property of biochar was mainly attributed to both phenolic hydroxy group and conjugated π-electron system associated with aromatic structure, depending on the pyrolytic temperature and feedstock source. The results will help us to obtain a complete view on the role of biochar in biogeochemical redox reactions and consider developing biochar with controlled redox properties for specific environmental applications such as electron shuttle and catalyst material.
•Quantification of the relationship between EDCs and phenolic groups and conjugate π-electron system were reported.•At low and intermediate temperatures, the EDCs were mainly attributed to the phenolic groups.•At high temperatures, the conjugated π-electron system associated with aromatic structure dominated the EDCs of biochar.•Developing biochar with controlled redox properties was proposed for specific environmental applications.
In this work, six thermodynamic parameters of 10 anionic hydrides XH− ascorbic acid (iAscH−), alcohol anions, imine anion, activated olefin anions and diene anions and their intermediates in hydride ...transfer process were researched. The hydride‐donating, hydrogen‐atom‐donating and election‐donating abilities of XH−, and the electron‐accepting abilities of X were also discussed. Two physical parameters of free radical XH⋅, homolytic Gibbs free energy to release hydrogen atom ΔGoHD(XH⋅), heterolytic Gibbs free energy to release proton ΔGoPD(XH⋅), were determined to evaluate the antioxidant ability and acidity of intermediate XH⋅ in thermodynamics. The structure‐activity relationship of XH−, XH⋅ and X were carefully discussed. It's easy to find that the hydride‐donating abilities of XH− are stronger than their neutral compounds XH2; except for iAscH−; the hydride‐donating abilities of XH− are stronger than their hydrogen‐atom‐donating abilities; the hydrogen‐atom‐donating abilities of XH− are weaker than their intermediate radicals XH⋅; the unsaturated compounds X are easier to accept electrons than the anionic hydrides XH− to donate electrons. This paper plays an important role in determining the mechanism of anionic hydride to release hydride ion and provides a new idea for the design and synthesis of more active hydride, hydrogen and electron donors.
Thermodynamic energies of oxygen centred, nitrogen centred and carbon centred 10 anionic hydrides to release hydrides, hydrogen atom and electron on six elementary steps were researched. The structure‐activity relationship of XH−, XH⋅ and X were carefully discussed.
•Pb–MBHA had stronger collecting ability and pH adaptability than Pb–BHA.•The Pb–MBHA has stronger chemical adsorption ability for oxygen atoms on scheelite surface.•The foaming ability and foam ...stability of Pb–MBHA were stronger than those of Pb–BHA in solution.•The electron donating group improves the flotation efficiency of Pb–BHA.
Lead complexes of benzohydroxamic acid (Pb–BHA) are metal-organic complex collectors having excellent selectivity. However, the flotation efficiency of Pb–BHA needs improvement. In this research, we report the introduction of an electron-donating group into the BHA ligand to improve the performance of Pb–BHA in mineral flotation; p-methyl-benzohydroxamic acid (MBHA) was synthesized and used as a new ligand to form the Pb–MBHA complex. The flotation behavior of Pb–MBHA in scheelite flotation was investigated using micro-flotation experiments. The adsorption mechanism of collectors at the solid–liquid interface was investigated via solution chemistry analysis, Fourier-transform infrared spectroscopy (FTIR), zeta potential, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Froth stability tests were used to study the adsorption behavior of the collectors at the gas–liquid interface. Pb–MBHA had stronger collecting ability and pH adaptability than Pb–BHA. The Pb(MBHA)+, Pb(MBHA)2, and Pb(OH)MBHA were the main species of Pb–MBHA in solution. For oxygen atoms on the scheelite surface, Pb–MBHA has stronger chemical adsorption ability than Pb–BHA, and its adsorption made the scheelite surface more hydrophobic. The foaming ability and foam stability of Pb–MBHA were stronger than those of Pb–BHA in solution, and stable foam was more likely to form at the gas–liquid interface.
•S-ZVI exhibited superior activity for PAA activation and micropollutants removal.•Enhancement of the electron donating ability of ZVI by sulfidation was the key.•HO• was the main contributor ...responsible for micropollutants degradation.•Simple strategy for extending the applicability of S-ZVI/PAA is proposed.•Fe(III) slowed Fe° consumption and elevated electron utilization of S-ZVI.
In this study, mechanically sulfidated microscale zero valent iron (S-ZVI) was found to effectively activate the peracetic acid (PAA) with a result of almost complete degradation of six micropollutants within 10 min under neutral conditions, and > 95% sulfamethoxazole (SMX) removal after six cycles. Reactive oxidized species (ROS) including HO•, carbon-centered radicals, and Fe(IV) were generated in the S-ZVI/PAA system, while HO• was the main contributor towards micropollutants degradation. This study clearly revealed that enhancement of the electron donating ability of ZVI by the formed conductive iron sulfides was crucial for promoted Fe(II) generation and subsequent PAA activation over several cycles, rather than the ability of sulfides to reduce Fe(III) for Fe(II) regeneration as reported previously. Interestingly, it's discovered that co-existence of Fe(III) would dramatically improve the contaminants removal efficiency of the S-ZVI/PAA system; transform the surfaced Fe(II) dominated ROS generation process to aqueous Fe(II) one; enhance the tolerance of the proposed system to water matrix. The promoting effect of predosed Fe(III) on PAA activation by S-ZVI should be mainly associated with: the greater ability of Fe(III) than H2O to accept electron from Fe0 for obtaining more active sites; slower Fe0 consumption and solid sulfur species release for elevated electron utilization efficiency and PAA activation. Considering the convenient and cost-effective access of Fe(III), the decrease of acute toxicity of treated SMX, excellent stability and good removal of various micropollutants fully demonstrate the superiority of S-ZVI/PAA system for practical application.
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