Latest ArticlesHomogeneous C–H and C–X borylation via transition-metal-catalysis have undergone rapid development in the past decades and become one of the most practical methods for the synthesis of organoboron compounds. However, the catalysts employed in homogeneous catalysis are generally expensive, sensitive, and difficult to separate from the reaction mixture and reuse. With the rapid development of heterogeneous catalysis, heterogeneous C–H and C–X borylation have emerged as highly efficient and sustainable approaches towards the synthesis of organoboron compounds. This review aims to highlight the recent advances in the synthesis of organoboron compounds employing heterogeneous C–H and C–X borylation strategies. We endeavor to shed light on new perspectives and inspire further research and applications in this emerging area.
Proton exchange membrane water electrolysis (PEMWE) is a favorable technology for producing high-purity hydrogen under high current density using intermittent renewable energy. The performance of PEMWE is largely determined by the oxygen evolution reaction (OER), a sluggish four-electron reaction with a high reaction barrier. Nowadays, iridium (Ir)-based catalysts are the catalysts of choice for OER due to their excellent activity and durability in acidic solution. However, its high price and unsatisfactory electrochemical performance severely restrict the PEMWE’s practical application. In this review, we initiate by introducing the current OER reaction mechanisms, namely adsorbate evolution mechanism and lattice oxygen mechanism, with degradation mechanisms discussed. Optimized strategies in the preparation of advanced Ir-based catalysts are further introduced, with merits and potential problems also discussed. The parameters that determine the performance of PEMWE are then introduced, with unsolved issues and related outlooks summarized in the end.
Crystalized CeO2 structures were typically considered potential photocatalysts due to their great capacity to alter the active sites’ size and ability to absorb light. However, the controllable fabrication of well-defined hierarchical structures of CeO2 with high reactive facets is significant and challenging. Herein, a series of CeO2 supports including hierarchical flower-like (F-CeO2), ball-like (B-CeO2), cube-like (CCeO2), and rod-like CeO2(R-CeO2) supports were prepared by hydrothermal method (B-CeO2, R-CeO2 and CCeO2) or ice-bath method (F-CeO2) respectively. V atoms were selected as the active atoms and loaded on these supports. Their structure-activity relationship in photo-assisted thermal propane dehydrogenation (PTPDH) was investigated systematically. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption isotherms, and Fourier transform infrared spectrum. Results show that R-CeO2 support exhibits the biggest surface area thus achieving the best dispersion of VOx species. UV–vis spectrum and photoluminescence spectrum indicate that V/F-CeO2 has the best light adsorption property and V/R-CeO2 has the best carrier migration capacity. The activity tests demonstrate that the V/R-CeO2 has the largest net growth rate and the V/F-CeO2 has the biggest relative growth ratio. Furthermore, the non-thermal effect was confirmed by the kinetic method, which lowers the propane reaction orders, selectively promoting the first C–H bond activation. The light radiation TPSR experiment confirmed this point. DFT calculations show a good linear relationship between the energy barrier and the exchanged electron number. It inspires the design of high-reactive facets for boosting the intrinsic activity of the C–H bond in photo-assisted thermal chemical processes.
Triphenylamine (TPA) is the most promising donor fragment for the construction of long-wavelength thermally activated delayed fluorescence (TADF) emitters owing to its suitable dihedral angle that could enhance radiative decay to compete with the serious non-radiative decay. However, the moderate electron-donating capacity of TPA seriously limits the selection of acceptor for constructing long-wavelength TADF emitters with narrow bandgaps. To address this issue, in this work, the peripheral benzene of TPA was replaced with 1,4-benzodioxane and anisole to obtain two new electron-donating units N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-N-phenyl-2,3-dihydrobenzo[b][1,4]dioxin-6-amine (TPADBO, −5.02 eV) and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (TPAMO, −5.00 eV), which possess much shallower highest occupied molecule orbital (HOMO) energy levels than the prototype TPA (−5.33 eV). Based on TPA and the modified TPA donor fragments, three TADF emitters were designed and synthesized, namely Py-TPA, Py-TPADBO and Py-TPAMO, with the same acceptor fragment 12-(2,6-diisopropylphenyl)pyrido[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline (Py). Among them, Py-TPAMO exhibits the highest photoluminescence quantum yield of 78.4% and the smallest singlet-triplet energy gap, which is because the introduction of anisole does not cause significant molecule deformation for the excited Py-TPAMO. And Py-TPAMO-based OLEDs successfully realize a maximum external quantum efficiency of 25.5% with the emission peak at 605 nm. This work provides a series of candidate of donor fragments for the development of efficient long-wavelength TADF emitters.
Metal ions trigger Fenton/Fenton-like reactions, generating highly toxic hydroxyl radicals (•OH) for chemodynamic therapy (CDT), which is crucial in inducing lethal oxidative DNA damage and subsequent cell apoptosis. However, tumor cells can counteract this damage through repair pathways, particularly MutT homolog 1 (MTH1) protein attenuation of oxidative DNA damage. Suppression of MTH1 can enhance CDT efficacy, therefore, orderly integrating Fenton/Fenton-like agents with an MTH1 inhibitor is expected to significantly augment CDT effectiveness. Carrier-free CuTH@CD, self-assembled through the supramolecular orchestration of γ-cyclodextrin (γ-CD) with Cu2+ and the MTH1 inhibitor TH588, effectively overcoming tumor resistance by greatly amplifying oxidative damage capability. Without additional carriers and mediated by multiple supramolecular regulatory effects, CuTH@CD enables high drug loading content, stability, and uniform size distribution. Upon internalization by tumor cells, CuTH@CD invalidates repair pathways through Cu2+-mediated glutathione (GSH) depletion and TH588-mediated MTH1 inhibition. Meanwhile, both generated Cu+ ions and existing ones within the nanoassembly initiate a Fenton-like reaction, leading to the accumulation of •OH. This strategy enhances CDT efficiency with minimal side effects, improving oxidative damage potency and advancing self-delivery nanoplatforms for developing effective chemodynamic tumor therapies.
Room-temperature phosphorescence (RTP) materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption, anti-counterfeiting, and sensing. However, most polymers exhibit a short RTP lifetime (<1 s) because of their unstable triplet excitons. Herein, a new strategy of polymer chain stabilized phosphorescence (PCSP), which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response, has been reported. The rigid polymer chains of poly(methyl mathacrylate) (PMMA) immobilize the emitter molecules through multiple interactions between them, giving rise to efficient RTP. Meanwhile, the loosely-packed amorphous polymer chains allow oxygen to diffuse inside, endowing the doped polymers with oxygen sensitivity. Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum, which was among the best performance of PMMA. Intriguingly, their RTP was rapidly quenched in the presence of oxygen. Furthermore, RTP microparticles with a diameter of 1.63 µm were synthesized using in situ dispersion polymerization technique. Finally, oxygen sensors for quick, visual, and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis. With distinctive advantages such as an ultralong lifetime, oxygen sensitivity, ease of fabrication, and cost-effectiveness, PCSP opens a new avenue to sensitive materials for oxygen detection.
A series of “half-sandwich” bis(imino)pyridyl iron complexes with a substituted 8-(p-X-phenyl)naphthylamine (X = OMe, Me, CF3) was designed and synthesized by combining weak π-π interaction with steric and electronic tunings. The weak noncovalent π-π interaction as well as the steric and electronic effects of bis(imino)pyridyl iron complexes were identified by experimental analyses and calculations. The roles of weak π-π interaction, steric bulk, and electronic tuning on the ethylene polymerization performance of bis(imino)pyridyl iron catalysts were studied in detail. The combination of π-π interaction with steric and electronic tunings can access to thermally stable bis(imino)pyridyl iron at 130 ℃.
Transition metal cobalt exhibits strong activation capabilities for alkanes, however, the instability of Co sites leads to sintering and coke deposition, resulting in rapid deactivation. Hierarchical zeolites, with their diverse pore structures and high surface areas, are used to effectively anchor metals and enhance coke tolerance. Herein, a post-treatment method using an alkaline solution was employed to synthesize meso-microporous zeolite supports, which were subsequently loaded with Co species for propane dehydrogenation catalyst. The results indicate that the application of NaOH, an inorganic base, produces supports with a larger mesopore volume and more abundant hydroxyl nests compared to TPAOH, an organic base. UV–vis, Raman, and XPS analyses reveal that Co in the 0.5Co/SN-1–0.05 catalyst is mainly in the form of tetrahedral Co2+, which effectively activates CH bonds. In contrast, the 0.5Co/S-1 catalyst contains mainly Co3O4 species. Co2+ supported on hierarchical zeolites shows better propane conversion (58.6%) and propylene selectivity (>96%) compared to pure silica zeolites. Coke characterization indicates that hierarchical zeolites accumulate more coke, but it is mostly in the form of easily removable disordered carbon. The mesopores in the microporous zeolite support help disperse the active Co metal and facilitate coke removal during dehydrogenation, effectively preventing deactivation from sintering and coke coverage.
Developing a high-efficiency catalyst with both superior low-temperature activity and good N2 selectivity is still challenging for the NH3 selective catalytic reduction (SCR) of NOx from mobile sources. Herein, we demonstrate the improved low-temperature activity and N2 selectivity by regulating the redox and acidic properties of MnCe oxides supported on etched ZSM-5 supports. The etched ZSM-5 enables the highly dispersed state of MnCeOx species and strong interaction between Mn and Ce species, which promotes the reduction of CeO2, facilitates electron transfer from Mn to Ce, and generates more Mn4+ and Ce3+ species. The strong redox capacity contributes to forming the reactive nitrate species and -NH2 species from oxidative dehydrogenation of NH3. Moreover, the adsorbed NH3 and -NH2 species are the reactive intermediates that promote the formation of N2. This work demonstrates an effective strategy to enhance the low-temperature activity and N2 selectivity of SCR catalysts, contributing to the NOx control for the low-temperature exhaust gas during the cold-start of diesel vehicles.
Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge. In this study, we present a three-step sequential energy transfer process, which was constructed through host-guest interactions between a piperazine derivative (PPE-BPI) with aggregation-induced emission (AIE) and cucurbit[7]uril (CB[7]) in water to serve as ideal energy donors. To achieve multi-step sequential energy transfer, we employ three distinct fluorescent dyes Eosin B (EsB), Sulforhodamine 101 (SR101), and Cyanine 5 (Cy5) as energy acceptors. The PPE-PBI-2CB[7]+EsB+SR101+Cy5 system demonstrates a highly efficient three-step sequential energy transfer mechanism, starting with PPE-PBI-2CB[7] and transferring energy successively to EsB, SR101, and finally to Cy5, with remarkable energy transfer efficiencies. More interestingly, with the progressive transfer of energy in the multi-step energy transfer system, the generation efficiency of superoxide anion radical (O2•–) increased gradually, which can be used as photocatalysts for selectively photooxidation of N-phenyltetrahydroisoquinoline in an aqueous medium with a high yield of 86% after irradiation for 18 h. This study offers a valuable investigation into the simulation of multi-step energy transfer processes and transformations in the natural world, paving the way for further research in the field.
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