Biomimetic Hydrogenation Catalyzed by a Manganese Model of [Fe]‐Hydrogenase

[Fe]‐hydrogenase is an efficient biological hydrogenation catalyst. Despite intense research, Fe complexes mimicking the active site of [Fe]‐hydrogenase have not achieved turnovers in hydrogenation reactions. Herein, we describe the design and development of a manganese(I) mimic of [Fe]‐hydrogenase. This complex exhibits the highest activity and broadest scope in catalytic hydrogenation among known mimics. Thanks to its biomimetic nature, the complex exhibits unique activity in the hydrogenation of compounds analogous to methenyl‐H₄MPT⁺, the natural substrate of [Fe]‐hydrogenase. This activity enables asymmetric relay hydrogenation of benzoxazinones and benzoxazines, involving the hydrogenation of a chiral hydride transfer agent using our catalyst coupled to Lewis acid‐catalyzed hydride transfer from this agent to the substrates.     

1,3‐Difunctionalizations of [1.1.1]Propellane via 1,2‐Metallate Rearrangements of Boronate Complexes

1,3‐Disubstituted bicyclo[1.1.1]pentanes (BCPs) are valuable bioisosteres of para‐substituted aromatic rings. The most direct route to these structures is via multicomponent ring‐opening reactions of [1.1.1]propellane. However, challenges associated with these transformations mean that difunctionalized BCPs are more commonly prepared by multistep reaction sequences with BCP‐halide intermediates. Herein, we report three‐ and four‐component 1,3‐difunctionalizations of [1.1.1]propellane with organometallic reagents, organoboronic esters, and a variety of electrophiles. This process is achieved by trapping intermediate BCP‐metal species with boronic esters to form boronate complexes, which are versatile intermediates whose electrophile‐induced 1,2‐metallate rearrangement chemistry enables a broad range of C?C bond‐forming reactions.     

Palladium‐Catalyzed Asymmetric [8+2] Dipolar Cycloadditions of Vinyl Carbamates and Photogenerated Ketenes

Higher‐order cycloadditions, particularly [8+2] cycloadditions, are a straightforward and efficient strategy for constructing significant medium‐sized architectures. Typically, configuration‐restrained conjugated systems are utilized as 8π‐components for higher‐order concerted cycloadditions. However, for this reason, 10‐membered monocyclic skeletons have never been constructed via catalytic asymmetric [8+2] cycloaddition with high peri‐ and stereoselectivity. Here, we accomplished an enantioselective [8+2] dipolar cycloaddition via the merger of visible‐light activation and asymmetric palladium catalysis. This protocol provides a new route to 10‐membered monocyclic architectures bearing chiral quaternary stereocenters with high chemo‐, peri‐, and enantioselectivity. The success of this strategy relied on the facile in situ generation of Pd‐containing 1,8‐dipoles and their enantioselective trapping by ketene dipolarophiles, which were formed in situ via a photo‐Wolff rearrangement.     

A Photochemical/Thermal Switch Based on 4,4′-Bis(benzimidazolio)stilbene: Synthesis and Supramolecular Properties.

Stilbene derivatives are well-recognised substructures of molecular switches based on photochemically and/or thermally induced (E)/(Z) isomerisation. We combined a stilbene motif with two benzimidazolium arms to prepare new sorts of supramolecular building blocks and examined their binding properties towards cucurbit[n]urils (n=7, 8) and cyclodextrins (β-CD, γ-CD) in water. Based on the ¹H NMR data and molecular dynamics simulations, we found that two distinct complexes with different stoichiometry, i. e., guest@β-CD and guest@β-CD₂, coexist in equilibrium in a water solution of the (Z)-stilbene-based guests. We also demonstrated that the bis(benzimidazolio)stilbene guests can be transformed from the (E) into the (Z) form via UV irradiation and back via thermal treatment in DMSO.     

A Simple and Strong Electron‐Deficient 5,6‐Dicyano[2,1,3]benzothiadiazole‐Cored Donor‐Acceptor‐Donor Compound for Efficient Near Infrared Thermally Activated Delayed Fluorescence

Despite the success of thermally activated delayed fluorescent (TADF) materials in steering the next generation of organic light‐emitting diodes (OLEDs), effective near infrared (NIR) TADF emitters are still very rare. Here, we present a simple and extremely high electron‐deficient compound, 5,6‐dicyano[2,1,3]benzothiadiazole (CNBz), as a strong electron‐accepting unit to develop a sufficiently strong donor‐acceptor (D?A) interaction for NIR emission. End‐capping with the electron‐donating triphenylamine (TPA) unit created an effective D?A?D type system, giving rise to an efficient NIR TADF emissive molecule (λ_em=750 nm) with a very small ΔE_ST of 0.06 eV. The electroluminescent device using this NIR TADF emitter exhibited an excellent performance with a high maximum radiance of 10020 mW Sr^?1 m^?2, a maximum EQE of 6.57% and a peak wavelength of 712 nm.     

[100]LiF单晶在60 GPa以内冲击加载下的高压屈服强度特性

获取光学窗口自身的高压强度特性是开展材料高压高应变率冲击响应行为精密测量和数据反演的重要基础。利用平板撞击和双屈服面法,通过冲击-卸载、冲击-再加载原位粒子速度剖面精细测量和数据反演,获得了约60 GPa范围内[100]LiF屈服强度特性随冲击压力的变化规律。结果表明:在实验压力范围内,[100]LiF的屈服强度随加载压力的提高而显著提高,压力硬化效应显著;同时,LiF在冲击加载下的屈服强度高于磁驱准等熵加载结果,应变率硬化效应强于热软化效应。采用Huang-Asay模型确定了可描述冲击加载[100]LiF强度特性的本构模型参数,为LiF在强度、相变、层断裂等加窗测量实验中的深入应用和数据准确解读提供了重要支撑。     

柱心为A53的SD型拟本原置换群的次轨道

 分析了SD型拟本原置换群的作用,确定了柱心为A₅³的SD型拟本原置换群G的次轨道的个数及其长度,从而确定了所有G弧传递图的度数.     

面向重用的三维CAD模型检索算法

针对现有CAD领域的检索算法对模型的局部细节特征描述不足的现状,提出了一种基于最大公共子图的三维CAD模型检索算法,通过提取CAD模型的B-Rep信息,将模型用属性邻接图来表示.根据如果2个CAD模型存在相似的特征或局部结构,CAD模型所对应的属性邻接图应存在公共子图的原理,通过检测属性邻接图中的公共子图,得到了2个与CAD相似的局部细节特征,并利用这2个相似的局部细节特征对CAD模型进行了相似性评价.实验表明,该方法能够实现三维CAD模型检索,且检索的效率能够满足工程检索的要求,因此可以实现CAD模型设计和制造知识的重用.     

k连通图在边点割原子与点割上的可去边

图的可收缩边与可去边是研究连通图的构造和使用归纳法证明连通图的一些性质的有力工具.利用边点割断片的性质给出某些k连通图中在特定子图上可去边的分布情况,得到了最小度至少为(3(k-1)/2)或围长至少为4的k连通图(k≥4)中由边点割原子与点割所导出的子图的每一条边都是可去边.     

一种基于DAG图的异构可重构任务划分方法

为了实现高性能低功耗的计算,以任务划分为研究对象,提出了异构可重构计算的基本概念和形式化描述方法,给出了基于异构计算任务和异构可重构体系结构相结合的异构可重构两种任务划分方法:节点内部可重组及网络可重建的任务划分及算法,最后验证了其任务划分方法的有效性.