Latest ArticlesAs hydrogen energy technologies gain momentum, the role of renewable energy in facilitating sustainable hydrogen production is becoming increasingly critical. As a hydrogen production method, water electrolysis has attracted much attention from researchers due to its operational simplicity, the high purity of the hydrogen generated, and its potential for achieving zero carbon emissions throughout the process. Numerous studies has been manipulated on platinum (Pt)-based catalysts, which exhibit superior performance in hydrogen evolution reactions. Within this category, Pt nanoclusters stand out due to their unique attributes, such as quantum size effects and unique coordination environments. These features enable them to outperform both Pt metal atoms and nanoparticles in hydrogen evolution reactions regarding activity and stability. Here, we primarily delve into the reaction mechanisms underlying Pt nanocluster-based hydrogen catalysts, with particular emphasis on the interactions between the metal catalysts and their associated support materials. We provide an exhaustive summary of the strategies employed in the synthesis, the structural analyses conducted, and the performance metrics observed for Pt nanocluster catalysts when paired with various supporting materials. In closing, we explore the future potential and challenges facing Pt nanocluster-based catalysts in the context of industrial water electrolysis, along with emerging avenues for their design and optimization.
Aryl ketones as photolabile protecting group (PPG) to modify purine imines is a novel nucleic acid protection strategy. Especially, photoprotection of N7-guanosine is the first reported photoprotected nucleoside that can affect the Hoogsteen recognition site of guanosine. However, the mechanism, which is pivotal to high efficiency of photorelease and applications of PPGs in biological and medical systems, is unclear. Here, a detailed deprotection mechanism of benzophenone protected guanosine (BP-Guo) at N7 position is reported. Upon irradiation, BP-Guo populates to singlet state, which generates 3[BP]-Guo via intersystem crossing process. Thereafter, triplet energy transfer competes with hydrogen atom transfer forming BP-3[Guo] and ketyl-Guo, respectively. Both species break CN bond to release guanosine. These results provide deeper insights into exploiting improved strategies for photo-protecting nucleic acids. In particular, the TTET pathway could trigger well-known cyclization reactions that brings about DNA mutagenic adducts. The latter should be avoided in developing improved strategies for photoprotecting nucleic acids.
Oxygen evolution reaction (OER) is one of the most important half-reactions related to metal-air batteries, fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to be particularly important for the OER. Knowing the reaction mechanism is fundamental to developing new catalysts and improving OER efficiency. In this work, phase transition and atomic reconstruction on CoO (111) plane were revealed through ex-situ diffraction methods and X-ray absorption spectroscopy. At the same time, the electronic state evolution of Co(Ⅱ)/Co(Ⅲ) during the OER process has also been concluded by analyzing the magnetic properties. This work shows that during the OER process, Co(Ⅲ) experiences surface electron rearrangement from IS (intermediate-spin state) to LS (low-spin state) and then returns to IS/HS (high-spin state) under high voltage region. This work provides a new view to reveal the reaction mechanism through the magnetic property and it can be extended to more magnetic 3d transition metals for future catalyst design.
The first total synthesis of marine sesquiterpene (hydro)quinone meroterpenoids dysideanones A and E–G (1 and 4–6) has been accomplished in an enantioselective and divergent way. The sesquiterpene fragment and the aromatic moiety were efficiently connected via a site-selective and diastereoselective intermolecular alkylation of Wieland–Miescher ketone derivative 9 and benzyl bromide 10. The core 6/6/6/6-fused backbone of dysideanones was efficiently constructed through an intramolecular radical cyclization reaction. Dysideanone G (6) was easily prepared on a gram-scale and dysideanones A, E, and F (1, 4, and 5) were divergently transformed from dysideanone G (6) in one or two steps
The cross-photodimerization often comes with the formation of undesired and competitive homo-photodimer as side products. Herein, we report a series of highly selective [4 + 4] cross-photodimerization between anthracene and 4a-azoniaanthracene derivatives within a cucurbit[10]uril (CB[10]) host in water. Heteroternary inclusion complexes were formed through encapsulation of donor (D1-D2, anthracene derivative) and acceptor (A1-A3, 4a-azoniaanthracene derivatives) pairs in CB[10]. In the presence of CB[10] (1.0 equiv.), the [4 + 4] cross-photodimerization between D1 and A1/A2/A3 efficiently gave a single racemic cross-photodimer. Furthermore, the cross-photodimerization between 9-substituted anthracene D2 and A1/A3 was catalyzed by CB[10] (0.1 equiv.) to quantitatively yield a cross-photodimer with high regioselectivity. Efficient formation of selective cross-photodimers could be attributed to the exclusive encapsulation of D-A hetero-guest pairs in CB[10] and the confinement effect of the CB[10] host cavity. Our study further proves host–guest complexation as a powerful strategy for cross-cycloaddition reactions with high efficiency.
Systemic administration of the anti-rheumatic drug methotrexate (MTX) for a long period of time may lead to therapeutic tolerance, various adverse effects, and potential harm to the immune system. Therapeutic nano-delivery carriers constructed based on biologically active phenols provide a promising approach to enhance the therapeutic effect of anti-rheumatic drugs. Caffeic acid, a natural compound with anti-inflammatory properties, holds significant potential in the treatment of diverse inflammatory conditions. In this paper, we first constructed a nano-delivery platform for MTX using caffeic acid-based polyphenol polymer Ph-CaA-OH (PCOH), and investigated the treatment of rheumatoid arthritis (RA) at low drug administration doses (2.5 mg/kg). PCOH nanoparticles (NPs) could inhibit lipopolysaccharidesstimulated macrophage inducible nitric oxide synthase (iNOS) expression and pro-inflammatory differentiation in vitro. In vivo imaging revealed the rapid accumulation and sustained presence of PCOH NPs at inflamed joints in collagen induced-arthritis (CIA) mice. Therapeutic evaluation of CIA mice demonstrated that MTX@PCOH NPs were superior to free MTX in reducing the progression of RA and decreasing the expression of multiple pro-inflammatory cytokines without significant toxic effects. By enhancing drug aggregation at inflammatory joints and capitalizing on the synergistic effects of active carriers, MTX@PCOH NPs effectively minimized the required drug dosage and mitigated toxic side effects in RA treatment. The application of PCOH NPs to RA treatment provides a new strategy for the development of safer and more effective anti-RA nanomedicines.
Diabetic liver injury is a widespread complication of diabetes and carries a high risk to liver function. Therefore, early diagnosis of diabetic liver injury is of great significance for providing quality of life for diabetic patients. Most of the activated dual-modal probes are usually activated by single factor stimulation, which greatly reduces the diagnostic accuracy of liver injury. Here, a novel cysteine (Cys)/homocysteine (Hcy) and viscosity-enhanced dual-modal probe DAL was developed for the first time to monitor diabetic liver injury and its repair process. In the presence of Cys/Hcy, the near-infrared fluorescence (NIRF) and photoacoustic (PA) signals of the probe DAL were activated, with further signal enhancement in high viscosity environments. This Cys/Hcy and viscosity cascade probe exhibits heightened sensitivity and enhanced anti-interference capabilities, contributing to the advancement of liver injury diagnosis accuracy. In addition, the probe DAL shows exceptional mitochondrial targeting ability, enabling sensitive monitoring of Cys/Hcy and viscosity alterations within mitochondria. Based on NIRF/PA dual-modal imaging technology, the probe was successfully used for the first time in a mouse diabetic liver injury model to evaluate the extent of liver damage and the repair process by tracking the levels of Cys/Hcy and viscosity. Therefore, the two-factor activated dual-modal probe developed in this study provides a powerful instrument for accurate diagnosis and efficacy evaluation of complications related to diabetes.
Density functional theory (DFT) was performed to systematically study the adsorption and dissociation of N2 on Ir(100) and Ir(110) surfaces. By analyzing the properties, including adsorption energies, reaction barriers, and optimal adsorption sites, the hollow (H) sites were finally identified as favorable dissociation sites for N2. The dissociation barriers of N2 are 0.87 eV on Ir(100) and 1.12 eV on Ir(110), which can be overcome at around 348 and 448 K, respectively. Therefore, Ir(100) is screened as a promising catalyst for N2 dissociation compared to Ir(110). This can be attributed to the significantly higher adsorption energy of N2 on the H site of Ir(100) (−0.48 eV) compared to that on Ir(110) (−0.22 eV), leading to different dissociation mechanisms on Ir(100) and Ir(110). Ir(100) can dissociate N2 directly on H site and Ir(110) should firstly capture N2 via bridge site and further transfer the adsorbed N2 to the H site, which will dramatically deteriorate the reactivity of N2 dissociation. In addition, the following protonation processes of dissociated *N atoms are all exothermal at 348 K on Ir(100), indicating that the ammonia synthesis can occur spontaneously as the temperature higher than 348 K. These results have provided a reasonable materials design scheme for subsequent ammonia synthesis.
The cyclic guanosine monophosphate-adenosine monophosphate synthase and the stimulator of interferon genes (cGAS-STING) has emerged as a promising target for cancer immunotherapy. However, the development of natural STING agonists is impeded by several challenges, including limited biostability, poor pharmacokinetics, and inefficient cytosolic delivery. Herein, we meticulously designed a double-layer polyethylenimine (PEI) modified nanoscale covalent organic polymer (CPGP) for efficient delivery of 2′3′ cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), a natural STING agonist. The double-layer PEI structured CPGP enhanced both the loading capacity and stability of cGAMP. Furthermore, CPGP improved the intracellular delivery efficiency and amplified the activation of STING pathway for the secretion of type-Ⅰ interferon and pro-inflammatory cytokines. In contrast, single-layered nanoparticles failed to permit stable loading and intracellular delivery of cGAMP for immune response. The nano-STING agonist also mitigated the immunosuppressive tumor microenvironment (TME) by reducing regulatory T cells and polarizing M2 macrophages to the M1 phenotype, thereby creating an immune-supportive TME to enhance adaptive immune responses. The combination of CPGP and immune checkpoint blockers showed synergistic effect, further enhancing the inhibition effect on tumor growth. This double-layer PEI modified CPGP may offer a generalizable platform for other natural dinucleotide STING agonists to overcome the cascade delivery barriers, augmenting immune activation for tumor immunotherapy.
By introduction of hydrogen peroxide into the reaction system of ZrOCl2·8H2O and K14[As2W19O67(H2O)], a novel polyoxometalate K8Na19.5H0.5[Zr2(O2)2(β-AsVW10O38)]4·68H2O (1) has been successfully obtained via one-pot method and systematically characterized by IR, XPS, solid UV spectra, PXRD pattern, and TGA analysis. The analysis of X-ray crystallography exhibits that compound 1 crystallizes in the triclinic space group P-1 and presents a novel square-shaped Zr-substituted tetrameric polyoxometalate. The catalytic oxidation of sulfides by 1 are carried out, which demonstrate that 1 exhibits a good performance for the catalytic oxidation of sulfides to sulfones with high conversion (100%) and high selectivity (100%).
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