Luminescent heteronuclear Au(I)5Ag(I)8 complexes of [1,2,3-C6(C6H4R-4)3]3- (R = H, CH3, But) by cyclotrimerization of arylacetylides

Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states.     

A donor–acceptor complex enables the synthesis of E-olefins from alcohols,amines and carboxylic acids

Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor–acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.

A visible-light-induced defunctionalization strategy for the synthesis of olefins by using easily available alcohols, amines and carboxylic acids as starting materials is demonstrated.     

Ring-opening reactions of arylvinylidenecyclopropanes with diaryl diselenide upon heating: formation of 1,2-diarylselenocyclopentene derivatives

Arylvinylidenecyclopropanes undergo a novel reaction upon heating at 150 °C with diaryl diselenide to give the corresponding 1,2-diarylselenocyclopentene derivatives in good to high yields within 1.5 h. The further transformation of 1,2-diarylselenocyclopentene derivatives has been disclosed.     

激光诱导击穿光谱(LIBS)法微损快速检测党参中Pb

中药材重金属元素快速检测对污染监控及人们健康具有重要意义。激光诱导击穿光谱技术(Laser Induced Breakdown Spectroscopy, LIBS)属于一种快速检测方法,研磨压片等预处理方法相对样品消解已有所简化,但破坏了样品的物理性质,且不能满足中药材大宗品种、大批量检测需求。若进一步简化样品预处理,将更加凸显LIBS快速检测的优势。本文建立了激光诱导击穿光谱技术(LIBS)快速微损检测中药材样品重金属元素定标方法。线性相关系数R2为0.7764,建立的微损定标曲线线性可用于切片党参LIBS快速检测,对待测党参切片样品检测平均相对误差为3.74%,与电感耦合等离子体质谱法(ICP-MS)对比,相关系数R2为0.7957,验证了LIBS技术微损检测的可行性。制备的党参参考定标样品可多次重复用于待测样定标和仪器标定等。实验对待测党参样品仅进行切片处理,避免了研磨、压片等预处理,更加充分地体现LIBS快速检测的优势,为LIBS技术应用于中药材重金属元素快检等领域提供了一种新方法。     

无机元素与计量学模型结合的半夏产地溯源研究

目的:建立不同产地半夏无机元素的分析方法和溯源体系,为半夏药材的质量控制和道地性评价提供技术支持。方法:采用电感耦合等离子体质谱法(ICP-MS)和电感耦合等离子体原子发射光谱法(ICP-AES)对我国6个主产区72份半夏样品中K、Ca、Na、Mg、Al等37种无机元素的含量进行测定,并采用方差分析、主成分分析、因子分析等计量学方法进行统计与评价。通过对比BP-神经网络算法、K-最近邻算法、最小二乘支持向量机等多种模式识别方法,探索适合半夏产地溯源的最佳模型。结果:不同产地半夏中无机元素的构成各具特征,各无机元素含量在产地间差异显著(P＜0.05),其中La、Pb、As、Na、Bi、Hg、Sn、Cd、Ag 9种元素在不同产区间的差异最为明显;3D-plots图显示不同产地半夏样品分布相对集中,具备产地分类的可行性;KNN分类模型(曼哈顿距离)是半夏产地溯源的最佳方法,测试集的正确率达到100%。结论:无机元素分析技术结合适当的计量学模型可以实现半夏的产地溯源。     

A general electron donor–acceptor complex for photoactivation of arenes via thianthrenation

General photoactivation of electron donor–acceptor (EDA) complexes between arylsulfonium salts and 1,4-diazabicyclo[2.2.2]octane with visible light or natural sunlight was discovered. This practical and efficient mode enables the production of aryl radicals under mild conditions, providing an unrealized opportunity for two-step para-selective C–H functionalization of complex arenes. The novel mode for generating aryl radicals via an EDA complex was well supported by UV-vis absorbance measurements, nuclear magnetic resonance titration experiments, and density functional theory (DFT) calculations. The method was applied to the regio- and stereo-selective arylation of various N-heterocycles under mild conditions, yielding an assembly of challengingly linked heteroaryl–(hetero)aryl products. Remarkably, the meaningful couplings of bioactive molecules with structurally complex drugs or agricultural pharmaceuticals were achieved to display favorable in vitro antitumor activities, which will be of great value in academia or industry.

General photoactivation of EDA complexes between arylsulfonium salts and 1,4-diazabicyclo[2.2.2]octane was discovered. This practical mode enables the generation of aryl radicals for C–H functionalization of arenes.     

Towards the rational design of Pt-based alloy catalysts for the low-temperature water-gas shift reaction: from extended surfaces to single atom alloys

The rational design of Pt-based catalysts for the low-temperature water-gas-shift (LT-WGS) reaction is an active research field because of its important role played in the fuel cell-based hydrogen economy, especially in mobile applications. Previous theoretical analyses have suggested that Pt alloys, leading to a weaker CO binding affinity than the Pt metal, could help alleviate CO poisoning and thus should be promising catalysts of the LT-WGS reaction. However, experimental research along this line was rather ineffective in the past decade. In the present work, we employed the state-of-the-art kinetic Monte Carlo (KMC) simulations to examine the influences of the electronic effect by introducing sub-surface alloys and/or core–shell structures, and the synergetic effect by introducing single atom alloys on the catalytic performance of Pt-alloy catalysts. Our KMC simulations have highlighted the importance of the OH binding affinity on the catalyst surfaces to reduce the barrier of water dissociation as the rate determining step, instead of the CO binding affinity as has been emphasized before in conventional mean-field kinetic models. Along this new direction of catalyst design, we found that Pt–Ru synergetic effects can significantly increase the activity of the Pt metal, leading to Ru_1–3@Pt alloys with a tetrahedron site of one surface-three subsurface Ru atoms on the Pt host, showing a turnover frequency of about five orders of magnitude higher than the Pt metal.

KMC simulations show that decreasing the barrier of H₂O decomposition is more beneficial than decreasing the CO binding affinity in LT-WGS, while the latter was overemphasized by MF-MKM. Here Ru_1–3@Pt alloy is proposed as a promising catalyst.     

Sending-or-Not-Sending Twin-Field Quantum Key Distribution with a Passive Decoy-State Method

Twin-field quantum key distribution (TF-QKD) has attracted considerable attention because it can exceed the basic rate-distance limit without quantum repeaters. Its variant protocol, sending or not-sending quantum key distribution (SNS-QKD), not only fixes the security vulnerability of TF-QKD, but also can tolerate large misalignment errors. However, the current SNS-QKD protocol is based on the active decoy-state method, which may lead to side channel information leakage when multiple light intensities are modulated in practice. In this work, we propose a passive decoy-state SNS-QKD protocol to further enhance the security of SNS-QKD. Numerical simulation results show that the protocol not only improves the security in source, but also retains the advantages of tolerating large misalignment errors. Therefore, it may provide further guidance for the practical application of SNS-QKD.     

An Image Compression Encryption Algorithm Based on Chaos and ZUC Stream Cipher

In order to improve the transmission efficiency and security of image encryption, we combined a ZUC stream cipher and chaotic compressed sensing to perform image encryption. The parallel compressed sensing method is adopted to ensure the encryption and decryption efficiency. The ZUC stream cipher is used to sample the one-dimensional chaotic map to reduce the correlation between elements and improve the randomness of the chaotic sequence. The compressed sensing measurement matrix is constructed by using the sampled chaotic sequence to improve the image restoration effect. In order to reduce the block effect after the parallel compressed sensing operation, we also propose a method of a random block of images. Simulation analysis shows that the algorithm demonstrated better encryption and compression performance.