Single atom doping induced charge-specific distribution of Cu1-TiO_(2)for selective aniline oxidation via a new mechanism

Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2))is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2)from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2)did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2)catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2)generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.

基于宽带隙小分子给体第三组分的三元有机光伏器件

三元策略是提升器件光电转换效率的重要途径.本文设计合成了基于苯并噻二唑并二噻吩桥联基团的宽带隙小分子给体DRDTBT,并将其作为有机太阳能电池中的第三组分.通过引入具有缺电子性质的苯并噻二唑并二噻吩单元,使DRDTBT获得了较低的最高占有轨道能级以及高的结晶性,将其作为第三组分引入基于PM6∶BTP-eC9的器件中时有效提升了器件的开路电压,活性层形貌也得到了更好的调节.得益于提升的开路电压和填充因子,三元器件取得了优于二元器件的光电转换效率,其开路电压为0.86 V,短路电流密度为26.99 mA/cm~2,填充因子为76.34%,最终取得了17.72%的高光电转换效率,证明将高结晶性缺电子单元引入小分子给体第三组分中是提升三元有机太阳能电池效率的有效途径.

新冠病毒SARS-CoV-2检测方法研究进展

自2019年新冠肺炎(COVID-19)出现以来,疫情已波及全球100多个国家,截至2020年5月8日,全球范围内已有累计确诊新冠肺炎病例3 767 744例,累计死亡病例259 593例。应对新冠肺炎疫情最有效的方式是快速检测、隔离、治疗,可见新冠病毒的快速、准确检测是遏制疫情蔓延的关键技术手段。首先介绍了新冠病毒SARS-CoV-2结构及与生物体的作用机理,之后详细总结了目前新冠病毒SARS-CoV-2检测方法进展,并对各种方法的优缺点进行比较,最后对检测方法存在的问题及可能改进之处进行了展望。

单粒子效应的激光模拟方法研究进展

单粒子效应是一种会引起器件状态改变的辐射效应现象,会对器件性能、状态造成重大影响,甚至可能造成器件无法正常工作。本文介绍了目前各种单粒子效应的研究方法,重点综述了脉冲激光模拟研究的进展,汇总了近些年来国内外的代表性研究机构以及相应的测试装置参数,同时对脉冲激光诱导产生单粒子效应的机理、研究测试方法和代表性前沿器件研究的成果进行了概括,最后对脉冲激光模拟单粒子效应的方法、器件的研究方向等进行展望。

Metal-Free C_(3)N_(4) with plentiful nitrogen vacancy and increased specific surface area for electrocatalytic nitrogen reduction

As a substitute for synthetic ammonia under mild condition, electrocatalytic nitrogen reduction reaction(NRR) provides a hopeful approach for the development of ammonia. Nevertheless, the current development of NRR electrocatalysts is far from enough and a systematic research is needed to gain a better improvement. This article presents that 2 D C_(3)N_(4)-NV with a large specific surface area and abundant nitrogen vacancies is prepared by a simple and feasible method, and used as a metal-free catalyst for electrocatalytic NRR. Experiment result and density functional theory(DFT) calculation reveal that nitrogen vacancies in 2 D C_(3)N_(4)-NV can act as an efficient active site for catalytic NRR, which is conducive to capturing and activating N_(2), lowering Gibbs free energy(DG) in reaction and inhibiting hydrogen evolution reaction(HER) at the same time. In addition, the larger specific surface area also makes more active site exposed, which is good for the contact between the electrolyte and the active site, thus enhancing its NRR activity. The electrocatalyst shows an excellent catalytic activity for NRR in 0.1 M HCl, including Faradaic efficiency of 10.96%, NH_(3) yields of 17.85 lg h^(-1) mg_(cat)^(-1)., and good stability(over 20 h).

电子辐照制备二维锑烯光限幅材料

块状材料锑粒通过液相剥离成功制备了锑烯纳米片。采用扫描电镜、紫外-可见吸收光谱和拉曼光谱对所制锑烯进行了表征,制备的锑烯纳米片展现出从紫外区到可见光区的宽谱吸收,并且展现出锑的拉曼特征峰,微观结构上展示出二维纳米片状的独特结构。利用Z-扫描技术对所制样品的三阶非线性光学性质测试发现,在脉冲宽度为4 ns、波长为532 nm的激光光源激发下,锑烯展示出饱和吸收的性质,其非线性吸收系数β为-7.86×10^-11m/W。通过对样品进行电子辐照,成功获取了具有光限幅性质的二维锑烯。辐照后的锑烯展示出反饱和吸收的性质,非线性吸收系数β为8.69×10-11m/W。

Design, preparation and pharmacodynamics of ICG-Fe(Ⅲ) based HCPT nanocrystals against cancer

The use of nanocrystal technology to manufacture drug delivery systems intended to enhance therapeutic efficacy has attracted the attention of the pharmaceutical industry.However,the clinical application of nanocrystal drugs for injection is restricted by Ostwald ripening and the large-scale use of stabilizers such as polysorbate and lecithin,which have potential toxicity risks including hemolysis and allergies.Here,we designed an amorphous nanocrystal drug complex(IHNC),which is stabilizer-free and composed of indocyanine green(ICG)framework loading with a chemotherapeutic agent of 10-hydroxycamptothecin(HCPT).Considering the possibility of industrial manufacturing,IHNC was simply prepared with the assistance of ferric ion(III)via supramolecular assembly strategy.The theoretical result of Materials Studio simulation indicated that the prepared ICG-Fe(III)framework showed a stable spherical structure with the appropriate cavity for encapsulating the two drugs of HCPT and ICG with equal mass ratio.The IHNC was stable at physiological pH,with excellent PTT/PDT efficacy,and in vivo probing characteristics.The nanoscale size and reductive stimuli-responsiveness can be conducive to drug accumulation into the tumor site and rapid unloading of cargo.Moreover,such combination therapy showed synergistic photo/chemotherapy effect against 4T1 breast cancer and its tumor inhibition rate even up to 79.4%.These findings demonstrated that the nanocrystal drug delivery strategy could avoid the use of stabilizers and provide a new strategy for drug delivery for combination therapy.

Reductive Deoxygenative Functionalization of Alcohols by First-Row Transition Metal Catalysis

Alcohols are among the most accessible functionalities.Catalytic deoxygenative functionalization of alcohols is highly synthetically appealing.While significant progress has been made on the reactions with nucleophiles,the reactions with electrophilic coupling partners remain a real challenge.This manuscript highlights the advance in this direction,which is mainly achieved by the first-row transition metals.The low-valent titanium catalyst has shown the unique reactivity to homolytically cleave the C—OH bonds.The formed carbon radicals could either undergo reduction to give protonation products or couple with carbon fragments to form C—C bonds.This chemistry is initially realized using a stoichiometric amount of titanium reagents and later extended to catalytic variants.Nickel features a variety of oxidation states ranging from Ni0 to NiIV,and both two-electron oxidative addition and single-electron process are involved in their activation of an electrophile.These properties enable nickel to catalyze reductive C—C coupling of alcohols with R–X electrophiles.The reaction is first reported on the reactions of allylic alcohols,then extended to benzylic alcohols and,very recently non-activated alcohols.Recent effort has resulted in many invaluable methodologies that highly improve the reaction efficiency for the construction of aliphatic C—C bonds.The use of cobalt and copper catalysts not only expands the substrate scope of these reactions but also shows the new reactivity and selectivity issues.

N-Aryl diketopyrrolopyrrole derivatives towards organic optical and electronic materials

Diketopyrrolopyrrole(DPP)and related derivatives have drawn great attention due to their applications in organic optical/electronic materials.Progress in these materials is associated with developments in the syntheses of the DPP family.Chemical modification of DPP at nitrogen atom,including N-alkylation and N-arylation,is an effective strategy to improve its physical and chemical properties,such as solubility,optical and semiconducting properties.However,N-arylation of DPPs remains challenging compared to the easily accessible N-alkylation.Herein,the synthesis of N-aryl DPP derivatives and correlatedπ-expanded DPPs are summarized,and their optical/electronic properties are introduced.The future perspectives of N-aryl DPP derivatives are also discussed.

Nickel-catalyzed cross-electrophile C–Ge coupling of benzyl pivalates and chlorogermanes

The C–Ge cross-coupling offers a promising approach for the precise synthesis of organogermanes. However, the current methods are primarily effective in the germylation of organo(pseudo)halides. This work demonstrates the possibility of transferring low-cost and easily available ester groups into organogermanes through the cleavage of stable C–O bonds. Primary,secondary, and even tertiary benzylic pivalates were coupled well with chlorogermanes. The reactions proceed under mild conditions. The scalability of this reaction and derivatization of the formed benzylgermanes are demonstrated.

Intermolecular coupling enhanced thermopower in single-molecule diketopyrrolopyrrole junctions

Sorting out organic molecules with high thermopower is essential for understanding molecular thermoelectrics.The intermolecular coupling offers a unique chance to enhance the thermopower by tuning the bandgap structure of molecular devices,but the investigation of intermolecular coupling in bulk materials remains challenging.Herein,we investigated the thermopower of diketopyrrolopyrrole(DPP)cored single-molecule junctions with different coupling strengths by varying the packing density of the self-assembled monolayers(SAM)using a customized scanning tunneling microscope break junction(STM-BJ)technique.We found that the thermopower of DPP molecules could be enhanced up to one order of magnitude with increasing packing density,suggesting that the thermopower increases with larger neighboring intermolecular interactions.The combined density functional theory(DFT)calculations revealed that the closely-packed configuration brings stronger intermolecular coupling and then reduces the highest occupied molecular orbital(HOMO)-lowest unoccupied molecular orbital(LUMO)gap,leading to an enhanced thermopower.Our findings offer a new strategy for developing organic thermoelectric devices with high thermopower.

Azulene-based organic functional molecules for optoelectronics

Design and synthesis of new organic functional materials with improved performance or novel properties are of great importance in the field of optoelectronics.Azulene,as a non-alternant aromatic hydrocarbon,has attracted rising attention in the last few years.Different from most common aromatic hydrocarbons,azulene has unique characteristics,including large dipole moment,small gap between the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO）.However,the design and synthesis of azulene-based functional materials are still facing several challenges.This review focuses on the recent development of organic functional materials employing azulene unit.The synthesis of various functionalized azulene derivatives is summarized and their applications in optoelectronics are discussed,with particular attention to the fields including nonlinear optics（NLO）,organic field-effect transistors（OFETs）,solar cells,and molecular devices.

Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes

The construction of secondary alkylsilanes is a challenging subject in the synthetic community.The cross-coupling provides a practical solution to address this problem,but it typically relies on organometallic species.Herein,we report an Mn-mediated reductive C(sp^(3))-Si coupling to synthesize these compounds from alkyl and silyl electrophiles.This approach avoids the requirement for activation of Si-Cl by transition metals and thus allows for the coupling of various common chlorosilanes.The reaction proceeds under mild conditions and shows good functional group compatibility.The method offers access toα-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.

Covalent carbene modification of 2D black phosphorus

Black phosphorus(BP)has attracted an ever-growing interest due to its unique anisotropic two-dimensional structure,impressive photoelectronic properties and attractive application potential.However,the tools for bandgap engineering and passivation via covalent modification of BP nanosheets remain limited to diazonium salt and nucleophilic addition methods,so that developing new modification strategies for BP nanosheets is crucial to explore its physical and chemical properties and enrich the toolbox for functionalization.Herein,we report the covalent modification of liquid-phase exfoliated BP nanosheets based on a rational analysis of BP structure.The modification of BP is achieved via carbene,a highly reactive organic mediate.The carbene modification improves the solubility and stability of BP nanosheets.Detailed microscopic and spectroscopic characterizations including infrared spectra,Raman spectra,X-ray photoelectron spectra,SEM and TEM were conducted to provide insights for the reaction.The proof of the existence of covalent bonds between BP nanosheets and organic moieties confirms the successful modification.Moreover,theoretical calculations were conducted to unveil the reaction mechanism of the two different types of bonds and the chemical property of two-dimensional BP.

Synthesis and Characterization of Planar Five-Ring-Fused Dithiophene-dione

A series of new organic semiconductors based on s-indaceno[1,2-b：5,6-b＇]dithiophene-4,9-dione was success fully synthesized and characterized. The electron withdrawing carbonyl group lowers the LUMO energy levels, leading to increased electronegativities, which is beneficial for high photo-stability in air. The n-alkyl substituted compounds, lc and ld, crystallize with the rigid coplanar systems packed into slipped face-to-face n-stacks. Inter- estingly, lc and ld also show liquid crystalline behaviors, which give highly ordered molecular packing over large area.

Nickel-Catalyzed Cross-Electrophile Vinyl–Vinyl Coupling:An Approach to Structurally Versatile Dienylboronates

Cross C–C bond formation of two vinyl electrophiles is a long-standing challenge in synthetic chemistry.Herein,we report a nickel-catalyzed reductive vinyl–vinyl coupling between vinyl triflates and boron-substituted vinyl bromides.This new protocol offers facile access to dienylboronates with high structural complexity and molecular diversity.The reaction proceeds with a broad substrate scope under very mild conditions.The synthetic utility of the method is highlighted by its gram-scale reaction,modification of complex molecules,and diverse transformation of the products.

Fluoro-substituted DPP-bisthiophene conjugated polymer with azides in the side chains as ambipolar semiconductor and photoresist

Photoresists are essential for the fabrication of flexible electronics through all-photolithographic processes.Single component semiconducting photoresist exhibits both semiconducting and photo-patterning properties,and as a result,the device fabrication process can be simplified.However,the design of semiconducting polymeric photoresist with ambipolar semiconducting property remains challenging.In this paper,we report a single component semiconducting photoresist(PFDPPF4T-N_(3))by incorporating azide groups and noncovalent conformation locks into the side alkyl chains and conjugated backbones of a diketopyrrolopyrrole-based conjugated polymer,respectively.The results reveal that PFDPP4FT-N_(3) exhibits ambipolar semiconducting property with hole and electron mobilities up to 1.12 and 1.17 cm^(2) V^(−1) s^(−1),respectively.Moreover,field effect transistors with the individual photo-patterned thin films of PFDPP4FT-N_(3) also show ambipolar semiconducting behavior with hole and electron mobilities up to 0.66 and 0.80 cm^(2) V^(−1) s^(−1),respectively.These results offer a simple yet effective design strategy for high-performance single component semiconducting photoresists,which hold great potential for flexible electronics processed by all-photolithography.

High performance nonvolatile organic field-effect transistor memory devices based on pyrene diimide derivative

Developing high-quality electret layer is important for the fabrication of highperformance nonvolatile organic field effect transistor memory devices(OFETNVMs).In this work,three representative aromatic diimide frameworks are employed for comparative studies as n-type doping materials for the electret layers in OFET-NVMs,which are naphthalene diimide(NDI),perylene diimide(PDI),and pyrene diimide(PyDI).When blended with polystyrene(PS)to prepare the electret layers,all the memory devices containing aromatic diimide dopants exhibited significantly improved performances compared with the undoped counterparts,indicating that low-lying LUMO energy levels of these dopants are beneficial for charge injection.All the devices with n-type dopants exhibited long retention times(more than 104 s)and good switching reliability in more than 400 continuous write-read-erase-read cycles.Among them,the PyDI-based memory device exhibited superior performance compared with other aromatic diimides,which achieved a memory window of 34.0 V,a trapping charge density of 1.98×1012 cm−2 along with an on/off ratio higher than 104.This work indicates that PyDI framework could be a new platform for the future design of n-type dopant for high-performance nonvolatile organic field-effect transistor memory devices.

Introduction to the Special Issue of π-Functional Molecules ＆ Polymers

π-Functional materials refer to small molecules and polymers that contain conjugated structures and exhibit interesting electronic and optical properties and may have potential applications.Early applicationsπ-conjugated organic systems can be dated back to eighteen century when organic molecules containing aromatic unites were used as dyes and pigments.