Superior Anodic Lithium Storage in Core–Shell Heterostructures Composed of Carbon Nanotubes and Schiff-Base Covalent Organic Frameworks

Covalent organic frameworks(COFs)after undergoing the superlithiation process promise high-capacity anodes while suffering from sluggish reaction kinetics and low electrochemical utilization of redox-active sites.Herein,integrating carbon nanotubes(CNTs)with imine-linked covalent organic frameworks(COFs)was rationally executed by in-situ Schiff-base condensation between 1,1′-biphenyl]-3,3′,5,5′-tetracarbaldehyde and 1,4-diaminobenzene in the presence of CNTs to produce core–shell heterostructured composites(CNT@COF).Accordingly,the redox-active shell of COF nanoparticles around one-dimensional conductive CNTs synergistically creates robust three-dimensional hybrid architectures with high specific surface area,thus promoting electron transport and affording abundant active functional groups accessible for electrochemical utilization throughout the whole electrode.Remarkably,upon the full activation with a superlithiation process,the as-fabricated CNT@COF anode achieves a specific capacity of 2324 mAh g^(−1),which is the highest specific capacity among organic electrode materials reported so far.Meanwhile,the superior rate capability and excellent cycling stability are also obtained.The redox reaction mechanisms for the COF moiety were further revealed by Fourier-transform infrared spectroscopy in conjunction with X-ray photoelectron spectroscopy,involving the reversible redox reactions between lithium ions and C=N groups and gradual electrochemical activation of the unsaturated C=C bonds within COFs.

Highly mass activity electrocatalysts with ultralow Pt loading on carbon black for hydrogen evolution reaction

Pt-based nanocatalysts offer excellent prospects for various industries.However,the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge.In this study,nanocatalysts with ultralow Pt content,excellent performance,and carbon black as support were prepared through in-situ synthesis.These~2-nm particles uniformly and stably dispersed on carbon black because of the strong s-p-d orbital hybridizations between carbon black and Pt,which suppressed the agglomeration of Pt ions.This unique structure is beneficial for the hydrogen evolution reaction.The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction,exhibiting a potential of 100 mV at 100 mA·cm^(-2),which is comparable to those of commercial Pt/C catalysts.Mass activity(1.61 A/mg)was four times that of a commercial Pt/C catalyst(0.37 A/mg).The ultralow Pt loading(6.84wt%)paves the way for the development of next-generation electrocatalysts.

Boosting Oxygen Evolution Reaction Performance on NiFe‑Based Catalysts Through d‑Orbital Hybridization

Anion-exchange membrane water electrolyzers(AEMWEs)for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based catalysts.By introducing a third metal into NiFe-based catalysts to construct asymmetrical M-NiFe units,the d-orbital and electronic structures can be adjusted,which is an important strategy to achieve sufficient oxygen evolution reaction(OER)performance in AEMWEs.Herein,the ternary NiFeM(M:La,Mo)catalysts featured with distinct M-NiFe units and varying d-orbitals are reported in this work.Experimental and theoretical calculation results reveal that the doping of La leads to optimized hybridization between d orbital in NiFeM and 2p in oxygen,resulting in enhanced adsorption strength of oxygen intermediates,and reduced rate-determining step energy barrier,which is responsible for the enhanced OER performance.More critically,the obtained NiFeLa catalyst only requires 1.58 V to reach 1 A cm^(−2) in an anion exchange membrane electrolyzer and demonstrates excellent long-term stability of up to 600 h.

手性三齿Schiff-base配体的合成及其催化的不对称Henry反应研究

以L-酪氨酸甲酯盐酸盐为原料,通过格氏反应合成了一种手性β-氨基醇;以水杨醛为原料,通过溴代反应合成了3,5-二溴水杨醛和5-溴水杨醛;将手性β-氨基醇和溴代水杨醛在乙醇中缩合,制备了两种手性三齿Schiff-base配体.产物的结构经IR,1 H NMR,13C NMR和MS表征确定.将配体应用于催化不对称Henry反应中,考察其在不同反应条件下的催化性能,在最优化的反应条件下,不同底物均获得了较好的催化效果,产率最高达95%,ee值最高达90%.

基于Schiff-base结构化合物载体的汞离子选择性电极的制备与表征

高产率合成了一种新的Schiff-base结构化合物，并将其表征为高选择性聚合物膜汞离子选择性电极载体。考察了不同增塑剂及离子交换剂对膜电极响应性能的影响，在最佳膜组分条件下测得该电极对汞离子的线性响应范围为1．0×10^-6-3．0×10^-4mol／L，响应斜率为（29．3±0．3）mV／dec，检出限为2．6×10^-7mol/L；该电极响应速率快（小于12s），可在较宽的pH范围内（pH2．8～5．6）使用，且其它常见碱金属、碱土金属以及过渡金属离子对该测试电极的干扰小；可准确检测自来水中汞离子的浓度。

The Rapid Synthesis of Schiff-Base without Solvent under Microwave Irradiation

A microwave-assisted preparation of a series of Schiff-base via efficient condensation of salicylaldehyde and aryl amines without solvent is described in high yield as well as environmental friendship reaction in organic synthesis.

Density Functional Theory Study on La Complex with Schiff-base as Building Block

Quantum density functional theory （DFT） results are reported for the building block [LaL^1（NO3）] of La complex [LaL^1（NO3）]NO3·5H2O （L^1 = （CH3）2CHCH2CH（NCHC4H3O）COO^-）. The structure was optimized and the calculation results show that the lanthanum ion is coordinated by one nitrogen atom and three oxygen atoms of L^1 and two oxygen atoms of nitrate ion. The bond length of La-N is 0.2637 nm and the average length of La-O is 0.2526 nm, which are consistent with the literatures. In addition, the stabilities, electronic structural characteristics and IR spectra of the complex have been analyzed, which describe the coordination of lanthanum ion with other atoms in detail.

Synthesis,Crystal Structure and Electrochemical Property of the Ferrocenyl Schiff-base (E)-N’(Ferrocene Ethylidene)Picolino Hydrazide

A novel Schiff-base compound based on ferrocene C18H17OFeN3 （1） has been synthesized and characterized by X-ray diffraction. The title compound crystallizes in monoclinic, space group P21/c with a = 19.2343（17）, b = 10.5084（9）, c = 7.9373（7） A, β = 97.7740°, Z = 4, V = 1589.6（2） A^3, Dc = 1.451 g/cm^3, μ（MoKα） = 0.956 mm^-1, F（000） = 720, the final R = 0.0343 and wR = 0.0973 for 2759 observed reflections （I 〉 2σ（I））. Electrochemical measurements exhibit that compound 1 undergoes a reversible one-electron redox process.

Two 3-D Neutral Zn(Ⅱ)-MOFs Generated from the Asymmetric Schiff-base Ligand

Two new Zn（Ⅱ）-MOFs were synthesized based on an asymmetric Schiff-base ligand LH, which is obtained by the condensation of 5-formyl-8-hydroxyquinoline and 3-pyridinecar- boxylic acid hydrazide. In different mixed solvents, we get two new isomorphism compounds, [Zn（L）2]＇CaHsO2-2MeOH （1） and [Zn（L）2]＇CH2CIz＇2MeOH （2）. Compounds 1 and 2 have been characterized by single-crystal X-ray diffraction, elemental analysis and IR. Compound 1 crystallizes in monoclinic, space group P2/c, with a - 13.856（4）, b = 14.156（4）, c = 9.620（3）А, β = 110.167（5）°, V = 1771.3（9） /k3, Dc = 1.500 g/cm3, C3sH3sNsOsZn, Mr = 800.13, F（000） = 832, p（MoKa） = 0.761 mm-1, Z = 2, the final R = 0.0596 and wR = 0.1221 for 2112 observed reflections （I 〉 2σ（0）. Compound 2 belongs to monoclinic, space group P21/c, with a = 13.575（3）, b = 14.130（3）, c = 9.485（2） A, β = 107.908（3）°, V= 1731.2（6） A3, Dc = 1.529 g/cm3, CasH32C12NsO6Zn, Mr = 796.96, F（000） = 820, g（MoKa） = 0.926 mm-1, Z = 2, the final R -- 0.0527 and wR = 0.1395 for 2501 observed reflections （I 〉 2σ-（/））. The Zn（II） centers in both 1 and 2 display a distorted octahedral coordination geometry. The octahedral Zn（lI） nodes and L linkages build up 2-D nets consisting of parallelogram-like grids in the ab plane. The neighboring nets stack through hydrogen bonds to generate 3-D rhombic channels. In 1, the 1,4-dioxane and MeOH guests alternatively arrange in the channels and effectively take up the free space; while in 2, the CH2CI/guests are arranged in the channels. In addition, the encapsulated MeOH molecules are bonded to the framework by hydrogen bonds.

Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin （BSA）, which afforded BSA binding Schiff-base metal complexes （BSA-SalGluM, M=Cu, Co, Ni, Zn）. The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

Synthesis, Crystal Structure and Characterization of a New Mononuclear Zn(Ⅱ) Complex from Schiff-base Ligand

A new mononuclear [Zn（H-1L）2] （L = 1H-indole-3-ethylene-salicylaldimine） was synthesized through the reaction of Zn（Ac）2, salicylaldehyde and tryptamine in hot ethanol solution and characterized by X-ray crystal structure analysis. The crystal belongs to monoclinic, space group P21/n with a = 15.014（2）, b = 10.857（1）, c = 17.489（1）A,β = 95.49（1）°, V = 2837.8（5） A^3, Z = 4, Dc = 1.386 g/cm^3, μ = 0.904 mm-1, F（000） = 1232, the final R = 0.0463 and wR = 0.0890 for 4990 independent reflections. In the complex, the Zn2＋ ion presents a distorted N2O2 tetrahedral coordination involving two H-1L ligands.

A Novel Copper(Ⅱ)Complex Based on 4-Amino-1,2,4-triazole Schiff-base:Synthesis,Crystal Structure,Spectral Characterization,and Hirshfeld Surface Analysis

A novel copper complex Cu2（L）4（1, HL = 2-ethoxy-6-（[1,2,4]triazol-4-yliminomethyl）-phenol） has been synthesized and characterized by IR, single-crystal X-ray diffraction, and elemental analysis（CHN）. The single crystal belongs to the triclinic system, space group P1 with a = 10.0991（10）, b = 10.5280（12）, c = 10.5777（11） A, α = 97.230（9）, β = 90.640（8）, γ = 92.412（9）°, Mr = 1052.05, V = 1114.6（2） A3, Z = 1, Dc = 1.567 g/cm3, F（000） = 542, μ = 1.029 mm–1, R = 0.0562 and w R = 0.1562. The fluorescence and electrochemiluminescence（ECL） of 1and HL ligand were studied. The luminescence properties of 1 can be attributed to the ligand-metal charge transfer.

Reaction视频中用户弹幕信息交互行为的情感反应生成机理研究

深入挖掘Reaction视频中弹幕信息交互行为的情感反应机理有助于理解用户弹幕创作背后的情感生成原因及情感变化过程。本文基于情感反应模型,利用定向内容分析法对哔哩哔哩网站中11个热门视频的弹幕信息资源、视频内容以及reactor反应情况展开编码研究,构建了Reaction视频中用户弹幕信息交互行为的情感反应生成机理模型。研究发现,Reaction视频弹幕信息交互行为中的情感反应生成机理总体上遵循“信息刺激-情感反应”的路径,信息刺激有时会独立唤醒情绪或特定情感态度,有时也会通过唤醒特定情感态度进而影响情绪或内化情感态度的生成。该模型有助于提升情感反应理论在计算机协助交流中的情境化探索,也将为社交媒体中用户与信息交互提供优化建议。

Asymmetric Cyclopropanation Catalyzed by Four Stereoisomers of a Copper-(Schiff-base) Complex with Double Chiral Centers

Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiomeric excess of up to 91.8%. A mechanism that predicts the observed results accurately was proposed.

Mass Spectral Behavior of Some Indole Schiff-Base Derivatives

Twenty-two indole Schiff-base derivatives were synthesized. Two special ways of cleavage were discussed in the formation of the specific fragment ions in the mass spectra(MS).

Lanthanum heterocyclic Schiff-base complex initiated ring-opening polymerization of ε-caprolactone

Lanthanum complex supported by the heterocyclic Schiff-base ligand of N-(2-pyridyl)-3,5-di-tert-butyl-salicylaldimine was prepared and employed for the ring-opening polymerization(ROP)ofε-caprolactone(ε-CL).The polymers obtained with this initiator showed a unimodal molecular weight distribution implied that only one active species was present.Mechanism study revealed that the polymerization proceeds via acyl-oxygen bond cleavage.

Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

Exciting lattice oxygen of nickel–iron bi-metal alkoxide for efficient electrochemical oxygen evolution reaction

High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.

Schiff-base polymer derived FeCo-N-doped porous carbon flowers as bifunctional oxygen electrocatalyst for long-life rechargeable zinc-air batteries

Rational design and exploration of low-cost and robust bifunctional oxygen electrocatalysts are vitally important for developing high-performance zinc-air batteries(ZABs).Herein,we reported a facile yet cost-efficient approach to construct a bifunctional oxygen reduction reaction(ORR)/oxygen evolution reaction(OER)electrocatalyst composed of N-doped porous carbon nanosheet flowers decorated with Fe Co nanoparticles(Fe Co/N-CF).Rational design of this catalyst is achieved by designing Schiff-base polymer with unique molecular structure via hydrogen bonding of cyanuramide and terephthalaldehyde polycondensate in the presence of metal cations.It exhibits excellent activity and stability for electrocatalysis of ORR/OER,enabling ZAB with a high peak power density of 172 m W cm^(-2)and a large specific capacity of 811 m A h g^(-1)Znat large current.The rechargeable ZAB demonstrates excellent durability for 1000 h with slight voltage decay,far outperforming a couple of precious Pt/Ir-based catalysts.Density functional theory(DFT)calculations reveal that high activity of bimetallic Fe Co stems from enhanced O_(2)and OH-adsorption and accelerated O_(2)dissociation by OAO bond activation.