铜基N-杂环Pincer配合物的合成、表征以及对芳香化合物的催化研究

将Pincer形配体2,6-双(5-叔丁基-1H-吡唑-3-基)吡啶(H 2 L)与CuBr 2反应,合成一种新的配合物[H 2LCuBr 2](H 2L=2,6-双(5-叔丁基-1H-吡唑-3-基)吡啶),并进行元素分析、紫外-可见(UV-Vis)光谱、傅里叶变换红外光谱(FT IR)和热重分析等表征.在70℃条件下的乙腈溶液中,以过氧化氢为氧化剂,以H 2 LCuBr 2为催化剂,分别对芳族底物如异丙苯、苯乙烯、α-甲基苯乙烯和苯甲醇进行了氧化催化活性测试.实验证明该催化剂对苯甲醇、苯乙烯和α-甲基苯乙烯的氧化表现出良好的催化活性,主要产品分别为苯甲醛、苯甲醛和苯乙酮.苯甲醇在8 h内转化率为51.77%,选择性95.46%;苯乙烯在4 h内转化率为94.84%,选择性81.07%;α-甲基苯乙烯在4 h内转化率为99.80%,选择性97.91%.通过对苯甲醇氧化反应的质谱跟踪监测,提出了合理的催化反应机理.

Synthesis and reactivity of cobalt dinitrogen complex supported by nonsymmetrical pincer ligand

A nonsymmetrical PNN pincer ligand[6-(^(t)Bu_(2)PNH)C_(5)H_(4)N-2-(3-Mes)C_(3)H_(2)N_(2)]and its corresponding cobalt-N_(2)complex were synthesized and characterized.By the stoichiometric reaction of the PNN ligand lithium salt with CoCl_(2),the complex 3,(PNN)CoCl,was obtained.Then,reduction of 3 with NaBHEt3under a dinitrogen atmosphere yielded complex 5,(PNN)Co(Ⅰ)(η^(1)-N_(2)).Single-crystal X-ray analysis,IR spectrum,and DFT calculations revealed that the dinitrogen in 5 was only weakly reduced by the cobalt center.The reactions of 5 with carbon monoxide and 2,6-dimethylphenyl isocyanide gave carbonyl and isocyanide complexes 6 and 7 with the release of N_(2),respectively.Furthermore,these cobalt complexes,especially complex 5,demonstrated the capacity to convert dinitrogen to N(TMS)_(3)with moderate efficiency.

Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst system.This system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=20 °C,98.2%;Tp=-20 °C,】 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582 kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum alkyls.Dynamic investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.

Colorimetric recognition of melamine in milk using novel pincer zinc complex stabilized gold nanoparticles

A convenient colorimetric approach for visual detection of melamine in raw milk was realized by using gold nanoparticles(AuNPs)stabilized by an unsymmetrical terpyridyl zinc complex with a thymine fragment at one terminal and a quaternary ammonium salt at the other.Even without pre-addition of melamine or relative additives,obvious color change from red to blue was observed by naked eye in the presence of trace amount of melamine,which was attributed to the alternation of aggregation state of AuNPs caused by the selective binding between the thymine fragment and melamine via triple hydrogenbonding interactions.Remarkably,the detection limit for melamine was as low as 2.4 ppb,providing a highly sensitive and efficient approach for the visual detection of melamine.

Development of unique dianionic Ir(Ⅲ) CCC pincer complexes with a favourable spirocyclic NHC framework

A new type of dianionic Ir(Ⅲ) CCC pincer complexes(SNHC-Ir, 1a–1c) is successfully designed and synthesized by developing a one-step methodology, which involves an initial coordination of Ir(I) with the NHC and subsequent metallation of double sp2C–H bonds. This method is considerably useful over those reported by using strong coordination ligand or carbonic anion exchange,and would provide an alternative efficient template of organometallics synthesis. Experimental and density functional theory(DFT) calculation results indicate that the spirocyclic framework is a favourable factor for the facile formation and stabilization of these complexes. Primary investigation shows that chloride 1b can well catalyze homo and hetero addition of styrene derivatives and remote olefin isomerization, which represents the first catalytic application of the dianionic CCC pincer complexes.

Aromatic and olefinic C–H alkenylation by catalysis with spirocyclic NHC Ru(Ⅳ) pincer complex

Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.

A self-catalytic role of methanol in PNP-Ru pincer complex catalysed dehydrogenation

Extracting hydrogen from methanol is a safe and cost-efficient strategy for fuel supply. This process was realized recently at a mild condition with excellent efficiency by ruthenium pincer catalysts. Despite the experimental success, the associated mechanism remains under debate. With the aid of density functional theory(DFT) calculations, an updated and self-consistent mechanism which involves Me OH-catalysed dehydrogenation of ruthenium hydride intermediate and pre-protonation of the pincer ligand was present herein. This mechanism is kinetically favoured over the previously-proposed water- or formic- acid-participated ones and more consistent with the optimal experimental condition where strong base and neat methanol solvent are used.

Pincer Ru with a single stereogenic identity for highly efficient asymmetric transfer hydrogenation of ketones

The asymmetric reduction of carbonyl compounds by means of the Ru-chiral diphosphine-chiral diamine catalysts is widely useful in organic synthesis where high levels of enantioselectivities have been attributed to multiple ligand chiral elements as well as essential stereochemical matching synergies within them.Described here is the design and discovery of new pincer-type Ru-catalysts that feature only single stereogenic element within ligands,yet the such significantly simplified structure is demonstrated to be well competent for effecting asymmetric reductions as well as kinetic resolutions over a broad range of highly functionalized ketones/alcohols,including heteroaryl substituted substrates that were challenging by known catalyst systems.Alcohols were furnished not only in excellent enantioselectivities,but with turnover numbers(up to 100,000 TONs)that reach the highest levels known to date in asymmetric transfer hydrogenation of ketones.This work should help shed light on the intricate origin of enantioselection in these important processes,and further stimulate rational understanding as well as optimization of chiral catalysts towards efficiency and simplicity.

Structure and mechanical properties of pincers for freshwater lobster

The mineral phases and structure of pincer for the freshwater lobster were analyzed and observed by using X-ray diffraction and field-emission scanning electronic microscope with energy dispersive spectroscopy, and the mechanical properties of pincer were determined by using nano-indenter and micro-tribometer. The results showed that the pincers contained Ca, Mg, C, O, Na, etc. elements and there were many amorphous mineral phases in the lobster pincers. There were many concave hollows and convex domes with seta on the surface of pincer, and some spines were observed on the surface of seta, which exhibited non-smooth surface. The exoskeleton of pincer consisted of epicuticle, exocuticle and endocuticle, and the microstructure of exocuticle and endocuticle displayed the twisted plywood structure with chitin protein fibers. The mean hardness and elastic modulus on the surface of fresh pincers were 0.27 GPa and 5.28 GPa, respectively. With the increase in distance from the surface, the hardness and elastic modulus all decreased gradually. This indicated that the transition of hardness and elastic modulus occurred from exocuticle to endocuticle. When the heat treatment temperature was lower than 200°C, the values of hardness and elastic modulus fluctuated slightly, while they increased at the temperature beyond 200°C. As the pincers slid against Si3N4 balls in water and air, the friction coefficients in water were higher than those in air. The research could provide a bio-inspired basis for the structural design of composite materials and anti-friction surface.

Pincer iridium(Ⅲ)-catalyzed enantioselective C(sp3)-H functionalization via carbenoid C–H insertion of 3-diazooxindoles with 1,4-cyclohexadiene

The asymmetric carbenoid C–H insertion of 3-diazooxindoles into 1,4-cyclohexadiene has been accomplished in the presence of chiral bis(imidazoline) NCN pincer iridium(Ⅲ) complexes as the catalysts. With a catalyst loading of 0.5 mol%, the reactions proceeded smoothly at 0℃ to afford a variety of chiral 3-substituted oxindoles in good yields with moderate to excellent enantioselectivities(up to 99% ee). The protocol exhibits good functional group tolerance with respect to 3-diazooxindoles and is readily scaled up to 2 mmol scale without any loss in activity and enantioselectivity. Density functional theory(DFT)calculations have been performed to better understand the reaction mechanism and to explain the stereochemical outcome of the reactions.

Directly Knitted Ruthenium Pincer Complexes with Enhanced Activity as Recyclable Single-Site Catalysts for Hydrogenation of CO_(2)to Methanol

Considering the importance of the valorization of CO_(2),a number of phosphine-containing ruthenium pincer complexes have been successfully heterogenized using a“direct knitting”strategy without any premodification.The resulting porous organometallic polymers(POMPs)with high specific-surface areas,hierarchical pores,and uniformly dispersed Ru single-sites exhibited outstanding catalytic activity toward the N-formylation of diverse amines with CO_(2).Besides excellent turnover number(TON,5×10^(5))and turnover frequency(TOF,5592 h-1),the obtained formamides were readily hydrogenated to methanol with the same catalyst.Consequently,an amine-assisted direct hydrogenation system of CO_(2)to methanol was established by POMPs with higher activity and TON(1.46×10^(4))than their molecular precursors,shedding light on the direct valorization of CO_(2)and carbon neutral recycling.

C-H Bond Activation of Bisimines by Palladium(Ⅱ) and Platinum(Ⅱ). Synthesis,Characterization of Bis( imino) aryl-palladium(Ⅱ) Pincer Complexes and Their Application in Carbon-Carbon Cross Coupling Reactions

The reactions of a variety of 4,6-dimethyl-1,3-bis(imino)benzenes 2a-g derived from 4,6-dimethylisophthalaldehyde and anilines or benzylamine with palladium(II)acetate in anhydrous acetic acid under nitrogen were investigated.Experiment results demonstrate that cyclopalladations in such condition are applicable not only to the present system under study but also to the 5-substituted bis(imino)benzenes 6,7.The molecular structure of 3b was further confirmed by X-Ray single-crystal diffraction.3b Crystallizes in orthorhombic,space group P2(1)2(1)2(1)with a=0.734 53(8),b=1.683 8(3),c=1.691 7(2)nm,α=β=γ=90°.Treatment of 2b with K2PtCl4in anhydrous acetic acid affords the corresponding NCN-platinum pincer.Carbon-carbon cross coupling reactions catalyzed with 3b were investigated.These palladium complexes have been proved to be high effective catalysts for Suzuki coupling reaction.

PN^(3)P-钳型镍硝酸根配合物的合成及光反应性质

PN^(P-)钳型镍硝酸根配合物2可通过其前体镍氯化物1与硝酸银复分解反应制备,产率高达95%;配合物2的结构通过核磁、红外、HRMS、X-射线单晶衍射等表征进行了确认,其中硝酸根以η^(1)-ONO_(2)的方式与金属镍配位。配合物2具有优异的光反应性质,通过控制光照时间,可分别转化为钳型镍硝基配合物3、氧原子分子内转移的硝基配合物4和配体磷完全氧化的镍双硝酸根配合物5。它们的结构均通过核磁和单晶表征证实,配合物3的结构还通过对比1与亚硝酸银反应生成产物的核磁数据进行了验证。

吲哚基NCN钳型钛族金属配合物的合成及其催化苯乙烯聚合反应

以吲哚为骨架,在吲哚的1位、3位引入2条边臂基团得到了1,3-双取代吲哚基化合物,用丁基锂去质子后与MCl_(4)(M=Ti、Zr、Hf)反应,得到一系列NCN钳型钛、锆、铪金属配合物(3-Ti、3-Zr、3-Hf)。该系列配合物通过核磁、元素分析及单晶X射线衍射进行了表征。单晶结构显示,金属中心除与3个氯原子配位外,还与配体以κ^(3)_(NCN)的形式配位,形成六配位的八面体构型。考察了该类型配合物在不同助催化体系条件下催化苯乙烯聚合反应的性能。实验发现:在室温下,助催化剂为AlEt_(2)Cl/(Ph_(3)C)[B(C_(6)F_(5))_(4)],甲苯为溶剂,单体与催化剂在浓度比300∶1的条件下,不同金属中心配合物都能以高转化率得到聚苯乙烯,其中铪配合物的催化活性最高。催化所得的聚苯乙烯经表征发现均为无规结构,数均分子量为4 000~8 000。

基于仿生学的梭子蟹蟹钳收拢装置设计

为解决梭子蟹捕捞后的抱团问题,需将蟹钳进行单个捆绑,而蟹钳收拢是实现蟹钳捆绑的关键环节。研究设计了一种基于仿生学的梭子蟹蟹钳收拢装置。该装置的设计灵感汲取自梭子蟹蟹钳的自然运动方式,通过对蟹钳的生理结构进行细致分析,深入理解其活动特点,据此设计出一种蟹钳仿生收拢装置。实验结果表明,该装置对10只不同体质量的梭子蟹进行收拢测试,成功收拢了8只,对体积为133 mm^(3)、体质量130 g以上的梭子蟹,收拢效果较好。该装置为有效解决梭子蟹蟹钳捆绑问题提供了一个初步而有效的方案。

髋关节撞击综合征

髋关节撞击综合征是一种常见的、可引起慢性髋关节疼痛及髋关节屈曲和内收受限的疾病,是髋关节骨性关节炎常见的病因。根据不同的解剖异常可分为Cam凸轮碰撞和Pincer钳形碰撞两型。髋关节X线正位片可观察到股骨头颈之间的凹陷度不足,表现为股骨头突起部向外侧伸延、头与颈间的凹陷减少或消失。CT及MRI能发现不明显的股骨头颈交界处及髋臼的解剖异常。而显示关节盂缘病变和邻近软骨病变及软骨下囊性变和滑膜疝,MRI较X线平片及CT更准确。主要就髋关节撞击综合征的临床、分型及影像学表现予以综述。

修井作业井口无人操作起下油管装置

基于现有修井机的动力和提升条件,研制出一种井口无人操作起下油管装置,主要包括油管自动悬吊系统、液压钳自动上卸扣系统和远程液压控制系统。各部分的操作指令集中到修井机的控制台上,由司机手远程操控完成油管的抓放、扶正、对中、悬持、上卸扣、锁定和起下,实现了1名司机手和1名场地工即可完成起下油管作业,不仅降低了工人劳动强度,而且保证了工人起下油管时远离井口危险区域免受伤害。该装置结构简单,体积小,性能稳定,不占用井口人工操作空间,不影响人工井控抢险,不妨碍井口人员逃生,不增加搬家车辆和运行成本,施工速度可控且与人工操作水平相当,受到现场工人的欢迎。

远程控制液压油管钳自动上卸扣装置设计

在油气田修井作业起下管柱过程中,需要工人站在井口反复操控液压油管钳上卸扣,不但劳动强度大,而且时刻面临磕碰夹挤、高空落物、有害井液飞溅等多种危险与危害。为了解决这一问题,依托现有修井机的液压、电气动力和提升条件,结合开口型液压油管钳结构特点,综合运用电控及液压驱动技术研制出一种液压油管钳自动上卸扣装置,其控制指令集中到一个十字主令操作盘上,修井机司机推拉操作手柄即可远程控制液压油管钳自动就位、上卸扣和对缺口,从而使作业工人从脏苦累险的工作条件中得以解放出来。

经皮鱼嘴钳固定治疗胫骨平台骨折

目的：分析微创技术治疗胫骨平台骨折的疗效。方法：胫骨平台骨折83例，男59例，女24例；年龄18～58岁，平均37岁。交通事故伤36例，坠落伤21例，砸伤10例，摔伤16例。外翻应力伤31例，内翻应力伤9例，垂直压迫或合并旋转应力伤43例。按Schatzker分类：Ⅰ型15例，Ⅱ型26例，Ⅳ型17例，Ⅴ型25例。均行经皮撬拨复位、鱼嘴钳固定治疗。结果：随访81例，时间2～7年，骨折均于3个月内愈合，膝关节完全伸直，屈膝平均127°（95°～145°）。参照Rasmussen胫骨髁部骨折膝关节功能进行评分：优49例，良27例，可4例，差1例。结论：经皮鱼嘴钳固定手术创伤小，固定可靠，能早期进行功能锻炼，避免二次手术取内固定物，是治疗胫骨平台骨折的有效方法。

液压静力沉桩机钳口调心结构的研究

对夹桩及压桩时钳口及桩的受力以及危险截面的位置进行力学分析 ,并在对现场情况进行细致观察的基础上 ,结合现场实践和理论研究设计了准球头式钳口调心结构。理论分析和实践证明 ,准球头式双层调心结构实现了钳口内表面与桩表面的良好贴合 ,具有造价低 ,结构简单 ,夹桩安全 。