An Arbitrarily Regulated Monomer Sequence in Multi-Block Copolymer Synthesis by Frustrated Lewis Pairs

Rapid access to sequence-controlled multi-block copolymers (multi-BCPs) remains as a challenging task in the polymer synthesis. Here we employ a Lewis pair (LP) composed of organophosphorus superbase and bulky organoaluminum to effectively copolymerize the mixture of methacrylate, cyclic acrylate, and two acrylates, into well-defined di-, tri-, tetra- and even a hepta-BCP in one-pot one-step manner. The combined livingness, dual-initiation and CSC feature of Lewis pair polymerization enable us to achieve not only a trihexaconta-BCP with the highest record in 8 steps by using four-component monomer mixture as building blocks, but also the arbitrarily-regulated monomer sequence in multi-BCP, simply by changing the composition and adding order of the monomer mixtures, thus demonstrating the powerful capability of our strategy in improving the efficiency and enriching the composition of multi-BCP synthesis.     

Acidic Media Impedes Tandem Catalysis Reaction Pathways in Electrochemical CO2 Reduction

Electrochemical CO₂ reduction (CO₂R) in acidic media with Cu-based catalysts tends to suffer from lowered selectivity towards multicarbon products. This could in principle be mitigated using tandem catalysis, whereby the *CO coverage on Cu is increased by introducing a CO generating catalyst (e.g. Ag) in close proximity. Although this has seen significant success in neutral/alkaline media, here we report that such a strategy becomes impeded in acidic electrolyte. This was investigated through the co-reduction of ¹³CO₂/¹²CO mixtures using a series of Cu and CuAg catalysts. These experiments provide strong evidence for the occurrence of tandem catalysis in neutral media and its curtailment under acidic conditions. Density functional theory simulations suggest that the presence of H₃O⁺ weakens the *CO binding energy of Cu, preventing effective utilization of tandem-supplied CO. Our findings also provide other unanticipated insights into the tandem catalysis reaction pathway and important design considerations for effective CO₂R in acidic media.     

Improving Low-temperature Performance and Stability of Na2Ti6O13 Anodes by the Ti−O Spring Effect through Nb-doping

Na₂Ti₆O₁₃ (NTO) with high safety has been regarded as a promising anode candidate for sodium-ion batteries. In the present study, integrated modification of migration channels broadening, charge density re-distribution, and oxygen vacancies regulation are realized in case of Nb-doping and have obtained significantly enhanced cycling performance with 92 % reversible capacity retained after 3000 cycles at 3000 mA g⁻¹. Moreover, unexpected low-temperature performance with a high discharge capacity of 143 mAh g⁻¹ at 100 mA g⁻¹ under −15 °C is also achieved in the full cell. Theoretical investigation suggests that Nb preferentially replaces Ti3 sites, which effectively improves structural stability and lowers the diffusion energy barrier. What's more important, both the in situ X-ray diffraction (XRD) and in situ Raman furtherly confirm the robust spring effect of the Ti−O bond, making special charge compensation mechanism and respective regulation strategy to conquer the sluggish transport kinetics and low conductivity, which plays a key role in promoting electrochemical performance.     

Biomarkers based on multiplatform comprehensive analysis: A systematic analysis of Geng-Nian-Shu in perimenopausal syndrome

Although Geng-Nian-Shu has been shown to be clinically effective in perimenopausal syndrome, its active components and mechanism have not yet been elucidated. To demonstrate the mechanism-based biomarkers of Geng-Nian-Shu in treating perimenopausal syndrome, a total of 135 chemical constituents including 52 prototype blood constituents were identified via high-performance liquid chromatography-quadrupole-time of flight/mass spectrometry. Then, network pharmacology showed significant enrichment for the PhosphoInositide-3 Kinase/Akt pathway, suggesting that it may be the main regulatory pathway for the Geng-Nian-Shu treatment of the perimenopausal syndrome. Subsequently, multivariate analysis was performed between the Geng-Nian-Shu sham-treated and Geng-Nian-Shu ovariectomy-treated groups and further screened out 18 prototype blood constituents by correlation analysis with plasma estrogen levels to identify potential biomarkers associated with Geng-Nian-Shu treat the ovariectomy-induced perimenopausal syndrome. Finally, the results of pharmacological experimental verification and Pearson correlation analysis indicated that catalpol, ligustilide, paeoniflorin, and gallic acid were selected as biomarkers of Geng-Nian-Shu which were strongly and positively correlated with PhosphoInositide-3 Kinase/Akt signaling pathway. In this study, based on high-performance liquid chromatography-quadrupole-time of flight/mass spectrometry combined with pharmacodynamics, network pharmacology, pharmacology, and other disciplines, we explored the effects and mechanisms of Geng-Nian-Shu in the treatment of perimenopausal syndrome at multiple levels. Using multiplatform technology to investigate the role of Geng-Nian-Shu represents a new strategy for the selection and verification of biomarkers of Geng-Nian-Shu and provides a basis for further development and utilization of Geng-Nian-Shu.     

Aggregation of Electrochemically Active Conjugated Organic Molecules and Its Impact on Aqueous Organic Redox Flow Batteries

Molecule aggregation in solution is acknowledged to be universal and can regulate the molecule's physiochemical properties, which however has been rarely investigated in electrochemistry. Herein, an electrochemical method is developed to quantitatively study the aggregation behavior of the target molecule methyl viologen dichloride. It is found that the oxidation state dicationic ions stay discrete, while the singly-reduced state monoradicals yield a concentration-dependent aggregation behavior. As a result, the molecule's energy level and its redox potential can be effectively regulated. This work does not only provide a method to investigate the molecular aggregation, but also demonstrates the feasibility to tune redox flow battery's performance by regulating the aggregation behavior.     

Regulation of Multiple Resonance Delayed Fluorescence via Through-Space Charge Transfer Excited State towards High-Efficiency and Stable Narrowband Electroluminescence

B- and N-embedded multiple resonance (MR) type thermally activated delayed fluorescence (TADF) emitters usually suffer from slow reverse intersystem crossing (RISC) process and aggregation-caused emission quenching. Here, we report the design of a sandwich structure by placing the B−N MR core between two electron-donating moieties, inducing through-space charge transfer (TSCT) states. The proper adjusting of the energy levels brings about a 10-fold higher RISC rate in comparison with the parent B−N molecule. In the meantime, a high photoluminescence quantum yield of 91 % and a good color purity were maintained. Organic light-emitting diodes based on the new MR emitter achieved a maximum external quantum efficiency of 31.7 % and small roll-offs at high brightness. High device efficiencies were also obtained for a wide range of doping concentrations of up to 20 wt % thanks to the steric shielding of the B−N core. A good operational stability with LT₉₅ of 85.2 h has also been revealed. The dual steric and electronic effects resulting from the introduction of a TSCT state offer an effective molecular design to address the critical challenges of MR-TADF emitters.     

负载型廉价金属催化剂在低温催化氧化甲醛中的应用

甲醛是室内常见的挥发性有机污染物之一,长期接触会严重危害人体健康。负载型廉价金属催化剂在甲醛去除和实际应用方面表现出优异性能,引起研究人员的广泛关注。本文阐述了低温条件下负载型廉价金属催化剂在甲醛热催化氧化、光催化氧化和等离子协同催化氧化方面的研究进展,介绍了甲醛低温催化的影响因素,并讨论了反应机理。反应条件、载体类型和制备方式是影响甲醛低温催化活性的重要因素。虽然负载型廉价金属催化剂在甲醛光催化氧化和热催化氧化方面均表现出良好性能,但仍须进一步探究提升其在可见光和室温下的催化活性。对于甲醛等离子协同催化氧化,降低反应过程所产生的副产物和能耗仍是研究重点。此外,本文还对负载型廉价金属催化剂在甲醛催化应用中的发展方向进行了展望。     

Direct synthesis of 3,5-diaryl-1,2,4-oxadiazoles using 1-(2-oxo-2-arylethyl)pyridin-1-iums with benzamidines

An efficient domino protocol for the synthesis of 1,2,4-oxadiazole derivatives from readily available 1-(2-oxo-2-arylethyl)pyridin-1-iums and amidine hydrochlorides was developed. In this practical approach, N-acyl amidine precursors were formed firstly via a simple nucleophilic substitution, without the purification of N-acylamidine intermediates, and the following intramolecularly dehydrative cyclization gave 1,2,4-oxadiazole derivatives in the presence of I₂/K₂CO₃/DMSO, which exhibited excellent functional group tolerance and proceeded under simple experimental conditions.     

CeO2修饰Ni3S2纳米片用于高效电催化析氧

电化学水分解制氢作为重要的生产氢能的新能源技术,包括氢气析出反应(HER)和氧气析出反应(OER).然而,OER进行的是多步电子转移过程,动力学过程缓慢且过电位高,严重制约了电解水制氢的发展.因此开发低成本、高效稳定的非贵金属催化剂替代贵金属催化剂(RuO2,IrO2)来降低过电位,减少能源消耗十分必要.Ni₃S₂由于其高导电性、高活性、低成本等优点,具有作为贵金属催化剂替代品的广阔应用前景,但其OER性能仍需进一步提高.对已有的有效OER催化剂进行表界面调控是提高催化剂性能的一种有效策略.CeO₂中的Ce3+和Ce4+价态之间可以灵活过渡,使其具有良好的电子/离子导电性、可逆的表面氧离子交换和较高的储氧能力.CeO₂的多价性使其有机会与其它基质产生强烈的电子相互作用,良好的电子/离子导电性和较高的储氧能力是提高催化剂析氧活性的有利因素.因此,用CeO₂对Ni₃S₂进行修饰是提高其析氧活性的有效途径.基于此,本文运用水热和电沉积相结合的方法将CeO₂修饰到Ni₃S₂纳米片上,制备得到生长于泡沫镍上的Ni₃S₂-CeO₂纳米片阵列(Ni₃S₂-CeO₂/NF),并运用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)等手段进行了表征,以三电极系统测试了其电催化析氧性能及稳定性,并通过密度泛函理论计算进行了验证.XRD结果表明,复合材料中确实存在Ni₃S₂和CeO₂.通过SEM发现,泡沫镍基底上均匀分布着Ni₃S₂纳米片阵列;电沉积CeO₂后,Ni₃S₂-CeO₂仍保持其纳米片特性,但表面变得粗糙.Ni₃S₂-CeO₂的TEM结果也证实了纳米片结构的形成,高分辨率TEM图像清晰的显示出Ni₃S₂和CeO₂之间具有明显的界面.XPS结果表明,Ni₃S₂-CeO₂的Ni 2p的结合能与Ni₃S₂相比出现负位移.与纯CeO₂的Ce 3d谱图相比,Ni₃S₂-CeO₂杂化体系中Ce4+的比例明显增加,表明Ce的价态发生了重排,部分电子转移给了Ni元素.这些结果均说明Ni₃S₂与CeO₂之间存在着较强的电子相互作用.相应的电催化测试结果显示,在1.0 M KOH中,当电流密度达到20 mA cm^–2时,Ni₃S₂/NF需提供356 mV的过电位,Ni₃S₂-CeO₂/NF只需264 mV的过电位,仅次于RuO2/NF.而且,Ni₃S₂-CeO₂/NF在中性条件下也显示出了较理想的析氧活性.Ni₃S₂-CeO₂/NF的Tafel斜率明显低于CeO₂/NF和Ni₃S₂/NF,表明其具有良好的OER反应动力学.循环伏安法和计时电位法结果均表明,Ni₃S₂-CeO₂/NF具有良好的电化学稳定性.电化学阻抗谱测试结果表明,与Ni₃S₂/NF和CeO₂/NF相比,Ni₃S₂-CeO₂/NF明显具有更小的半圆直径,说明其电荷转移阻抗更小,进一步表明CeO₂的修饰有助于催化过程中电子的快速转移.在非法拉第区域的循环伏安扫描曲线以及拟合扫描速度对电容电流曲线结果显示,Ni₃S₂-CeO₂/NF的最大电容值大于CeO₂/NF和Ni₃S₂/NF,表明其暴露了更多的活性位点,具有更大的电化学活性表面积;而且,Ni₃S₂-CeO₂/NF在400和500 mV时的电催化析氧转换频率明显高于Ni₃S₂/NF和CeO₂/NF,进一步说明Ni₃S₂-CeO₂/NF具有更高的本征催化活性.密度泛函理论计算表明,由于^*OH,^*O和^*OOH与Ni₃S₂-CeO₂中的Ni和Ce原子相互作用的存在,使得反应中间产物与Ni₃S₂-CeO₂之间的结合强度较纯Ni₃S₂或CeO₂强,使其显示出了更高的OER性能.在经过24 h连续电解后,SEM和TEM结果均表明,Ni₃S₂-CeO₂/NF材料仍保持了其纳米片形貌.稳定性测试后的XPS结果表明,Ni 2p对应的峰强度降低,而与氧化镍物种对应的峰强度增强;S元素在Ni₃S₂-CeO₂表面的信号强度明显降低.根据文献报道,在强烈的氧化环境下,过渡金属硫化物会部分转化为氧化物或氢氧化物,这通常被认为是OER过程的实际催化物种.     

Anti-Inflammatory Activity and Mechanism of Isookanin,Isolated by Bioassay-Guided Fractionation from Bidens pilosa L.

Bidens pilosa L. (Asteraceae) has been used historically in traditional Asian medicine and is known to have a variety of biological effects. However, the specific active compounds responsible for the individual pharmacological effects of Bidens pilosa L. (B. pilosa) extract have not yet been made clear. This study aimed to investigate the anti-inflammatory phytochemicals obtained from B. pilosa. We isolated a flavonoids-type phytochemical, isookanin, from B. pilosa through bioassay-guided fractionation based on its capacity to inhibit inflammation. Some of isookanin’s biological properties have been reported; however, the anti-inflammatory mechanism of isookanin has not yet been studied. In the present study, we evaluated the anti-inflammatory activities of isookanin using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We have shown that isookanin reduces the production of proinflammatory mediators (nitric oxide, prostaglandin E₂) by inhibiting the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Isookanin also inhibited the expression of activator protein 1 (AP-1) and downregulated the LPS-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun NH₂-terminal kinase (JNK) in the MAPK signaling pathway. Additionally, isookanin inhibited proinflammatory cytokines (tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1β (IL-1β)) in LPS-induced THP-1 cells. These results demonstrate that isookanin could be a potential therapeutic candidate for inflammatory disease.