含氮环烷烃选择性构建功能化芳烃研究进展

含氮杂环类化合物广泛存在于自然界,具有多种生物活性。近几年,使用含氮环烷烃作为原料合成含氮芳烃成为目前的一个研究热点,该方法无需导向基团,可选择性地一步实现C―C、C―N、C―S和C―Se键的构建和芳构化。本文整理了近年来有关该方法构建功能化喹啉和吲哚的文献报道,进行了系统的梳理和综述,并对该领域未来的发展作出展望。

一锅多组分反应选择性合成二芳基甲胺和三芳基甲烷——推荐一个有机化学综合实验

本文介绍了一个有机化学综合实验,实验以水杨醛、苯硼酸和芳胺为反应底物,通过芳胺上取代基控制亲核性选择性地制备二芳基甲胺和三芳基甲烷,并利用核磁共振氢谱(^(1)H NMR)和碳谱(^(13)C NMR)对产物结构进行表征。本实验与理论知识相结合,启发学生进行机理方面的思考,帮助他们开拓知识视野,更好地树立“绿色化学”理念和环保意识。

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

浅析项目性实践在化学学科教学环节的重要意义——以2019年暑期三下乡为例

项目性实践教学是中南民族大学本科日常教学的一种新型试探性的授课方式。本文介绍了组织学生团队参与2019年“追寻红色足迹∙情系圣地发展”全国大学生延安暑期社会实践专项活动,并分析了其在化学学科教学环节的意义。本次实践是一体化项目性实践教学的一次探索实施,进一步推动“理论、思考、动手”一体化项目性实践教学培养模式,将实践教学与课堂教学进行深度融合,让“理性思维”的工科同学更好地调动学习的积极性,发散思维,用不同的视角去看待问题。

Three-dimensional reconstruction of systematic histological sections:application to observations on palatal shelf elevation

Normal mammalian secondary palate development undergoes a series of processes,including palatal shelf(PS)growth,elevation,adhesion and fusion,and palatal bone formation.It has been estimated that more than 90%of isolated cleft palate is caused by defects associated with the elevation process.However,because of the rapidly completed elevation process,the entire process of elevation will never be easy to clarify.In this article,we present a novel method for three-dimensional(3D)reconstruction of thick tissue blocks from two-dimensional(2D)histological sections.We established multiplanar sections of the palate and tongue in coronal and sagittal directions,and further performed 3D reconstruction to observe the morphological interaction and connection between the two components prior to and during elevation.The method completes an imaging system for simultaneous morphological analysis of thick tissue samples using both synthetic and real data.The new method will provide a comprehensive picture of reorientation morphology and gene expression pattern during the palatal elevation process.

Metal organic framework‐ionic liquid hybrid catalysts for the selective electrochemical reduction of CO_(2) to CH4

The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current CO_(2) electrolyzers remain impractical on a large scale due to the low current densities and faradaic efficiencies(FE)on various electrocatalysts.In this study,hybrid HKUST‐1 metal‐organic framework‒fluorinated imidazolium‐based room temperature ionic liquid(RTIL)electrocatalysts are designed to selectively reduce CO_(2) to CH_(4).An impressive FE of 65.5%towards CH_(4) at-1.13 V is achieved for the HKUST‐1/[BMIM][PF_(6)]hybrid,with a stable FE greater than 50%maintained for at least 9 h in an H‐cell.The observed improvements are attributed to the increased local CO_(2) concentration and the improved CO_(2)‐to‐CH_(4) thermodynamics in the presence of the RTIL molecules adsorbed on the HKUST‐1‐derived Cu clusters.These findings offer a novel approach of immobilizing RTIL co‐catalysts within porous frameworks for CO_(2) electroreduction applications.

Tumor organoids for cancer research and personalized medicine

Organoids are three-dimensional culture systems generated from embryonic stem cells,induced pluripotent stem cells,and adult stem cells.They are capable of cell proliferation,differentiation,and self-renewal.Upon stimulation by signal factors and/or growth factors,organoids self-assemble to replicate the morphological and structural characteristics of the corresponding organs.They provide an extraordinary platform for investigating organ development and mimicking pathological processes.Organoid biobanks derived from a wide range of carcinomas have been established to represent different lesions or stages of clinical tumors.Importantly,genomic and transcriptomic analyses have confirmed maintenance of intra-and interpatient heterogeneities in organoids.Therefore,this technology has the potential to revolutionize drug screening and personalized medicine.In this review,we summarized the characteristics and applications of organoids in cancer research by the establishment of organoid biobanks directly from tumor organoids or from genetically modified non-cancerous organoids.We also analyzed the current state of organoid applications in drug screening and personalized medicine.

Quasi-Grotthuss mechanism in a nonporous sulphate

The transportation of the proton,the smallest ion in nature,is rudimentary in chemical and biological reactions[1,2],such as photosynthesis[3],enzyme catalysis[4],and Brensted acid/base reactions[5],and currently even imperative in some devices,namely proton exchange membrane fuel cells(PEMFCs)[6,7].The processes of these elementary reactions,like proton transfer,appear to be astonishingly analogous.

Trifold Frequency Multiplier by using Triode for the Feedback System of BEPC Ⅱ

In BEPC Ⅱ(Upgrade of Beijing Electron-Position Collider),multi-bunches and high current operation mode is usually used.Due to the influence of high frequency cavity structure or resistance impedance,the beam will be unstable.If the beam is unstable,the luminosity and brightness of the accelerator will be decreased.In order to improve the beam current and brightness of accelerator and the collider luminosity,the beam feedback system is needed to suppress the instability.The trifold frequency multiplier by using triode is simple to operate,and it has good performance.In the experiments,the 500MHz signal was passed through the Triode Frequency Multiplier to get the 1.5GHz signal,and its output amplitude stability is 1.7mV,and its synchronization stability is 3.46ps compared with the 500MHz input signal.

Catalysis stability enhancement of Fe/Co dual-atom site via phosphorus coordination for proton exchange membrane fuel cell

Non-precious metal catalysts(NPMCs)are promising low-cost alternatives of Pt/C for oxygen reduction reaction(ORR),which however suffer from serious stability challenge in the devices of proton-exchange-membrane fuel cells(PEMFC).Different from the traditional strategies of increasing the degree of graphitization of carbon substrates and using less Fenton-reactive metals,we prove here that proper regulation of coordination anions is also an effective way to improve the stability of NPMC.N/P cocoordinated Fe-Co dual-atomic-sites are constructed on ZIF-8 derived carbon support using a molecular precursor of C_(34)H_(28)Cl_(2)CoFeP_(2)and a“precursor-preselected”method.A composition of FeCoN_(5)P1 is infered for the dual-atom active site by microscopy and spectroscopy analysis.By comparing with N-coordinated references,we investigate the effect of P-coodination on the ORR catalysis of Fe-Co dual-atom catalysts in PEMFC.The metals in FeCoN_(5)P1 have the lower formation energy than those in the solo N-coordinated active sites of FeCoN6 and FeN_(4),and exhibits a much better fuel cell stability.This anion approach provides a new way to improve the stability of dual-atom catalysts.

Organic frameworks confined Cu single atoms and nanoclusters for tandem electrocatalytic CO_(2) reduction to methane

The electrochemical reduction reaction of carbon dioxide(CO_(2)RR)is considered to be an effective way to realize carbon neutrality.As a type of intensively studied materials,covalent organic frameworks(COFs)with a tunable pore structure and various functional groups are promising catalysts for CO_(2)RR.Herein,COF synthesized by 2,6‐diaminoanthraquinone and 2,4,6‐triformylphloroglucinol is employed to assist the synthesis of electrocatalysts from Cu single atoms(SAs)to nanoclusters by controlling the electrodeposition.A tandem catalyst for CO_(2)‐to‐CH4 conversion is thus achieved by the Cu nanoclusters dispersed among the isolated Cu SAs in the COF network.It is proposed that CO_(2) is first reduced to CO over the atomically isolated Cu SAs,followed by diffusion onto the neighboring Cu nanoclusters for further reduction into CH4.In addition,mechanistic analysis suggests that the coordinated K^(+)ions on the COF network promote the activation of CO_(2) and the adsorption of reaction intermediates,thus realizing the suppressed hydrogen evolution reaction and selective production of CH4.This study presents a new insight of COFs for the confined synthesis of a tunable SA to nanocluster electrocatalysts,disclosing the great potential of COFs in electrocatalysis.

通过简单的亲核取代反应合成以三嗪为核心的苝二酰亚胺类高效非富勒烯受体

贵金属催化剂被广泛用于合成高效的光伏材料.但是,昂贵的催化剂很难去除,而残留的催化剂有损于光伏性能.本工作不使用贵金属催化剂,通过简单的亲核取代反应合成了新型、高效的非富勒烯受体(NFAs).这一受体被命名为NAQ-3,获得了高达8.91%的能量转换效率(PCE).据我们所知,这是通过简单亲核取代反应或无贵金属催化制备的NFAs所报道的最高PCE值.此外,我们合成了一个四臂的NF A作为该合成方法的扩展应用示例,其核心为联三嗪,命名为NAQ-4.通过比较NAQ-3和NAQ-4的吸收光谱和能级结构、分析基于NAQ-3和NAQ-4的有机太阳能电池的光伏性能、激子解离过程和电荷复合机制,研究了该类NFAs的结构-性能关系.本论文报道了一个通过简单的亲核取代反应合成高效NFAs的成功范例.

Boron-, Sulfur- and Nitrogen-Doped Tridecacyclic Aromatic Emitters with Multiple Resonance Effect for Narrowband Red Emission

Two novel boron(B),sulfur(S),nitrogen(N)-doped polycyclic aromatic hydrocarbon multiple resonance emitters(DBNS and DBNS-tBu)are designed and synthesized for narrowband red emission by embedding two pairs of S and N atoms and two B atoms in para-positions of central benzene rings within a tridecacyclic aromatic skeleton to form donor-π-donor(D-π-D)and acceptor-π-acceptor(A-π-A)structures,which not only exhibit emission maximum at 641 nm with small full width at half maximum of 39 nm,but also combine high photoluminescent quantum efficiency(85%)and rapid reverse intersystem crossing(kRISC=2.2×10^(5) s^(−1)).

Efcient soluble PTCBI‑type non‑fullerene acceptor materials for organic solar cells

Single perylene diimide(PDI)used as a non-fullerene acceptor(NFA)in organic solar cells(OSCs)is enticing because of its low cost and excellent stability.To improve the photovoltaic performance,it is vital to narrow the bandgap and regulate the stacking behavior.To address this challenge,we synthesize soluble perylenetetracarboxylic bisbenzimidazole(PTCBI)molecules with a bulky side chain at the bay region,by replacing the widely used“swallow tail”type alkyl chains at the imide position of PDI molecules with a planar benzimidazole structure.Compared with PDI molecules,PTCBI molecules exhibit red-shifted UV–vis absorption spectra with larger extinction coefcient,and one magnitude higher electron mobility.Finally,OSCs based on one soluble PTCBI-type NFA,namely MAS-7,exhibit a champion power conversion efciency(PCE)of 4.34%,which is signifcantly higher than that of the corresponding PDI-based OSCs and is the highest PCE of PTCBI-based OSCs reported.These results highlight the potential of soluble PTCBI derivatives as NFAs in OSCs.

Structural basis of Semliki Forest virus entry using the very-low-density lipoprotein receptor

Alphaviruses are a group of important viruses that cause significant diseases in humans.Among them,Semliki Forest vi-rus(SFV)not only causes symptoms such as joint pain but also infects neuron cells and induces encephalitis in rodents.Recently,the very-low-density lipoprotein receptor(VLDLR)was identified as the cellular receptor for SFV entry.In this study,we present the cryo-electron microscopy structure of SFV bound to human VLDLR.VLDLR targets E1-DIII region of SFV using its membrane-distal LDLR class A(LA)repeats.Structural and functional analyses emphasize the synergistic role of multiple VLDLR repeats in the SFV entry.Remarkably,VLDLR’s binding mode to SFV closely mirrors that of minor group human rhinoviruses but differs significantly from other alphaviruses’interactions with receptors in the canyon re-gion of the E protein.We also assessed SFV binding to VLDLR or apolipoprotein E receptor 2(ApoER2)proteins in horses and mosquitoes and revealed their use of multiple but different LA repeats for binding.Our findings illuminate SFV’s cross-species infectivity,offering insights into potential antiviral strategies against alphavirus infections.