The Novel Selective Reduction of the C-C Triple Bond

A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.

Copper-Catalyzed C-C(O)C Bond Cleavage of Monoalkylated β-Diketone: Synthesis of α,β-Unsaturated Ketones

A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K3PO4) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .

Synthesis,Structure and Properties of a Novel Infinite Triple Helices Coordination Polymer{[Co(4,4'-bipyridine)(4,4'azobispyridine)_(2)(NCS)_(2)]·H_(2)O}_(n)

The novel complex{[Co(bipy)(azpy)_(2)(NCS)_(2)]·H_(2)O}n(where bipy=4,4′bipyridine,azpy=4,4′azobisp yridine)has been synthesized and characterized by elemental analyses,IR,UV,thermal analyses,and variable temperature magnetic susceptibility.The crystal(C_(32)H_(26)CoN_(12)OS_(2),Mr=717.70)belongs to the orthorhombic,space group Pnna,a=2.21312(16)nm,b=1.40403(10)nm,c=1.14237(8)nm,V=3.5497(4)nm^(3),Z=4,Dc=1.343g·cm^(-3),μ=0.645mm^(-1),F(000)=1476,and final R_(1)=0.0691,wR_(2)=0.1129 for 231 parameters and 1674 observed reflections[I>2.00σ(I)].The Co(Ⅱ)atom is,in a distorted octahedral geometry,coordinated by six nitrogen atoms from two bridging bipy,two monodentate azpy,and two thiocyanate groups.The bridging ligand bipy links Co(Ⅱ)atoms to form the infinite“rod"with terminal coordination azpy ligand acting as sidearms.Unprecedented three parallel interpenetrating two dimensional(4,4)networks and novel infinite triple helices are formed via hydrogen bonding interactions.CCDC:155588.

Structural and electronic effects boosting Ni-doped Mo_(2)C catalyst toward high-efficiency C-O/C-C bonds cleavage

The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.

A NOVEL SCISSION OF ALKYL-CARBONYL C-C BOND BY ALKYL p-HYDROXYPHENYL KETONES

Methyl, ethyl, n-propyl, and benzyl p-hydroxyphenyl ketones and 6-hydroxy-1-tetralone are shown under the condition of ethylene ketal formation to undergo alkyl-carbonyl C-C bondscission, but not with p-hydroxybenzophenone, p-hydroxyisobutyrophenone, and 5-hydroxy-1-indanone. It is suggested that the scissiou is preceded by an aldol condensation.

Further Report on A Novel Scission of Alkyl Carbonyl C-C Bond by Substituted 4-Hydroxyacetophenones

3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.

Recent Advances of Modern Protocol for C-C Bonds—The Suzuki Cross-Coupling

Over the past 20 years, small molecule solid phase synthesis has become a powerful tool in the discovery of novel molecular materials. In the development of organic chemistry, the carbon-carbon bond formation has always been one of the most useful and fundamental reaction. The current review summarizes recent developments in metal-catalyzed coupling reactions. The following method is discussed in detail—the cross-coupling of aryl halides with aryl boronic acids (the Suzuki coupling), and the others C-C bond formation reactions as the palladium-catalyzed reaction between an aryl and (or) alkyl halide and a vinyl functionality (the Heck reaction);and the palladium-catalyzed cross-coupling reaction of organostannyl reagents with a variety of organic electrophiles (the Stille reaction)—are mentioned.

The molecular orbital investigation of the metal triply bonded compounds M＿2X＿2（NMe＿2）＿4

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基于有限元模拟分析混凝土桥梁接缝性能

为分析混凝土桥梁接缝性能,运用理论知识借助有限元软件对单键齿胶接缝和三键齿胶接缝中的不同水平约束力以及不同胶层厚度对胶缝的抗剪性能影响进行模拟分析,同时分析单键齿胶接缝抗剪性能和环氧树脂弹性模量之间的关系,研究结果表明:其他条件保持不变的情况下,当水平约束力增大和当胶层厚度增大时,单键齿胶接缝对应的抗压强度和极限抗剪承载力都随之增大;在单齿胶接缝的胶层厚度相同的情况下,当水平约束力增大时,对应模型的主拉应力变小,单键齿胶接缝的最大承载能力提升;其他条件保持不变的情况下,当水平约束力增大和胶层厚度增大时,单键齿胶接缝对应的抗压强度和极限抗剪承载力都随之增大;在三键齿胶接缝中胶层厚度相同时,当水平约束力增加时,整个模型的所能承受的主拉应力减小;在三键齿胶接缝中水平约束力相同时,当胶层厚度增加后,整个模型的最大主拉应力变大;当一定范围内的环氧树脂弹性模量增加时,对应的单键齿胶接缝最大抗剪承载力也随之增加。

Competition between C-C and C-H Activation in Reactions of Neutral Nickel Atom with Cycloalkanes （n = 3-7）

A theoretical investigation of the reaction mechanisms for C-H and C-C bond activation processes in the reaction of Ni with cycloalkanes C,,H2. （n = 3-7） is carried out. For the Ni ＋ CnH2, （n = 3, 4） reactions, the major and minor reaction channels involve C-C and C-H bond activations, respectively, whereas Ni atom prefers the attacking of C-H bond over the C-C bond in CnH2n （n = 5=7）. The results are in good agreement with the experimental study. In all cases, intermediates and transition states along the reaction paths of interest are characterized, It is found that both the C-H and C-C bond activation processes are proposed to proceed in a one-step manner via one transition state. The overall C-H and C-C bond activation processes are exothermic and involve low energy barriers, thus transition metal atom Ni is a good mediator for the activity of cycloalkanes CnH2n （n = 3 -7）.

Single Covalent Bonding Structure in Fullerenes, Carbon Nanotubes and Closed Nanotubes

The present paper deals with carbon in highly organized solids like graphene and its three-dimensional derivatives: fullerenes, carbon nanotubes and capped carbon nanotubes. It proposes an alternative to the typical bonding pattern exposed in literature. This novel bonding pattern involves alternating positively and negatively charged carbon atoms around hexagonal rings, then a few uncharged and partially bonded atoms close to the pentagon rings. The article focuses on fullerenes inscribed into a regular icosahedron, then addressing the most common fullerenes like C60. Carbon atoms are found to have predominantly three single bonds and less often two separated single bonds. The same pattern explains equally well carbon nanotubes and closed-tip nanotubes, of which C70 is a special case.

Catalytic transformation of cellulose and its derived carbohydrates into chemicals involving C–C bond cleavage

The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through C-O bond activation. There also ex- ist considerable studies on the catalytic cleavage of C-C bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of C-C bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce Q -Cs polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of C-C bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of C-C bonds can be achieved in biomass.

3D打印超级“拉曼码”用于多维信息加密及防伪研究

发展兼具防伪和溯源功能的信息化材料,以实现“一物一码”将是打击假冒伪劣商品的重要手段。本文拟对多维空间内具备特异信号的叁键拉曼散射光谱进行可控编码,构建超容量的“拉曼码”并作为新型的信息化材料用于防伪及信息加密研究。在课题组前期叁键拉曼标签制备基础上,进一步筛选和制备出六种既含乙烯基又可在聚合中保护叁键特征基团的小分子单体,随后通过乳液聚合方式制备出高灵敏、高光谱分辨、叁键拉曼散射在1800~2800 cm^(-1)区间可调谐且具备多色特性的聚合物拉曼标签;叁键拉曼标签为墨水着色剂与可光交联的水性树脂材料共混,制备出了可光固化3D打印的“拉曼墨水”,进一步利用3D打印技术实现了“拉曼墨水”在多种包装基材上多维度且特异性的图形、文字等信息打印,进而叁键聚合物标签可在打印的限域空间内进行可控排布,从而获得了一系列的多维结构码,即超级拉曼码。利用超快拉曼成像技术可对超级拉曼码(图文信息)进行解码,图文中光谱信息的差异性编码将对多类型、多样化商品的防伪及溯源有指导意义。

NHC-Boryl Radical Catalysis for Cycloisomerization With C–C Triple Bond Reorganization

Our present study unveils a new and efficient N-heterocyclic carbene(NHC)-boryl radical-catalyzed cycloisomerization of N-(2-ethynylaryl)arylamides.This catalytic process is triggered by the addition of an NHC-boryl radical to the alkynyl moiety,followed by a radical cascade comprising of an intramolecular cyclization,successive 1,5-and 1,2-aryl migrations,and the reorganization of a C–C triple bond.

低热零点漂移的高温绝压压力传感器

传统的高温绝压压力传感器一般采用硅和玻璃进行阳极键合来制备绝压腔。由于高温环境下硅片和硼硅玻璃的热膨胀系数不匹配,从而产生较高的热零点漂移。文中提出了一种低热零点漂移的压力传感器设计方案,由硅-玻璃-硅的三层结构代替普通的双层阳极键合结构,并给出了热力学仿真模型。分析表明:改变传感器硅与玻璃的结构比例,实现应力匹配可以有效减小热应力。对芯片进行了高温实验测试,发现传感器的热零点漂移变化率减小了50%。

拉曼光谱编码技术及其应用研究进展

光谱编码指的是将有限的光谱信号输出进行组合,从而得到更多光谱信号输出的手段,满足了高通量的生物检测和成像及高容量信息存储等需求。通常用于光谱编码的信号输出包括荧光光谱、拉曼光谱和反射光谱等。其中,拉曼光谱由于带宽窄、不易重叠,尤其是生物静默区的三键拉曼谱带尖锐、特异,无背景干扰,在光谱编码领域潜力巨大。本文综述了拉曼光谱编码技术的类型和编码方法,同时还介绍了拉曼光谱编码在生物医学检测、成像及信息安全等领域的应用。

Synthesis and Properties of Reversible Disulfide Bond-based Self-healing Polyurethane with Triple Shape Memory Properties

A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone)(PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG), and 4,4,-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (^1H-NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal properties, selfhealing properties, triple-shape memory effect, and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments, and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 50℃(with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. As-prepared polyurethane is expected to have potential applications in multi-shape coatings, films, and step-by-step deploying structures.

Endeavors on the development of efficient and sustainable supported metal catalysts for chemical synthesis on solid-liquid interfaces

Supported metal catalysts,particularly for precious metals,have gained increasing attention in green synthetic chemistry.They can make metal-catalyzed organic synthesis more sustainable and economical due to easy separation of product with less metal residue,as well as reusability of the high-cost catalysts.Although great effort has been spent,the precise catalytic mechanism of supported metal-catalyzed reactions has not been clearly elucidated and the development of efficient and stable recyclable catalysts remains challenging.This highlight reveals a“molecular fence”metal stabilization strategy and discloses the metal evolution in Pd-catalyzed C-C bond formation reactions using Nheterocyclic carbene(NHC)-functionalized hypercrosslinked polymer support,wherein the polymeric skeleton isolates or confines the metal species involved in the catalytic reactions,and NHC captures free low-valent metal species in solution and stabilizes them on the support via strong metal-support coordination interaction.This strategy creates a novel route for the development of supported metal catalysts with high stability and provides insights into the reaction mechanism of heterogeneous catalysis.

Recyclable Cu/g-C_(3)N_(4)nanometric semiconductor catalyzed N-formylation of amines via photocatalytic aerobic oxidative C-C bond cleavage of aldehydes under visible-light irradiation

Due to its difficulty and complexity,the cleavage and subsequent functionalization of the C(sp^(3))-C(sp^(3))single bond has received less attention than the C-C bond formation reactions that have been extensively studied.Herein,by utilizing Cu/g-C_(3)N_(4)nanometric semiconductor as a recyclable photocatalyst,an aerobic oxidative C-C bond cleavage of aldehydes was developed with the promotion of amines under visible light irradiation.Based on the reaction,phenylacetaldehyde was selected as a highly efficient formylation reagent for amines.Under blue light irradiation,good to excellent yields of formamides were achieved for various amines in 1 atm oxygen atmosphere at room temperature.This methodology offers a practical,neutral and gentle alternative to the preparation of formamides.

Generation,bonding and reactivity of transient zinc-substituted silylenes

The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(S-T)(singlet-triplet energy gap)or even the ground-state triplets.However,such compounds are highly unstable,and only two transient alkali metal-substituted silylenes M(^(t)Bu_(3)Si)Si:(M=Li,K)were generated by photoextrusion of the alkali metal-substituted silacyclopropenes and merely studied by spectroscopic method(EPR)at low temperature(14 to 50 K).Herein,we report the generation of transient zinc-substituted silylenes from zinc silacyclopropanyl complexes under very mild and convenient conditions.The generated transient zinc-substituted silylenes are highly reactive and undergo intermolecular cycloaddition with alkenes for the synthesis of zinc-substituted Si-heterocyclic compounds.If there is no substrate,the zinc-substituted silylenes attack the C-C bonds of the β-diketiminato ligands and break the C-C bonds.DFT studies further highlight the silylene nature of the zinc-substituted silylene and a very small ΔE_(S-T)(4.4 kcal/mol).