Zo_Hearne–化学通讯博客 - 新利手机客户端

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Copper A3 Coupling using a Switchable Homogeneous/Heterogeneous Catalyst

06 Nov 2018

A MOC,我这周学的，是一个金属有机笼子。我和妈妈很熟，财政部和暴民,但是主运行中心是一个新的。A MOM (metal-organic material) is a coordination-driven assembly constructed from metal nodes linked by organic ligands.MOM包括MOF（金属有机框架）和MOC（金属有机笼）。A MOF is an extended network with the potential for inner porosity,and a MOC is a discrete metal-ligand cluster.And that's just about as far down the nomenclature rabbit hole I'm willing to go.If you're keeping up you'll realise that I forgot one!A MOB is a crowd of graduate students competing for free coffee at the public seminar.

山东师范大学的Dong及其同事设计并制备了一种由铜（II）节点和三脚架配体构成的MOM催化剂，该配体由一个功能化为二酮的苯基轮组成。在氯仿中，这两种成分排列成含有两个三脚架配体和三个铜离子的分立MOC组件。The copper ions in the cluster are each coordinated to two diketone moieties (in a acetylacetonate-like fashion) in a quasi-square planar arrangement.

Synthesis of the tripodal ligand functionalised with diketone coordinating moieties.

材料的一个有趣特性是它可以在主运行中心形式之间切换，soluble in halogenated solvents,以及一种不溶性MOF，在加入1，4-二恶烷后聚集。1,4-Dioxane is both an anti-solvent and a ligand;coordination between copper and 1,4-dioxane binds the discrete MOC cages to each other,arranging them into the extended MOF structure.This behaviour can be exploited to prepare a practical catalyst that combines the benefits of both homogeneous and heterogeneous catalysis,namely that homogeneous catalysts are generally more efficient,有选择性且容易学习，but heterogeneous catalysis are easier to recover and recycle.What better way to solve this problem than with a catalyst that is homogeneous during the reaction conditions,但当涉及到产品分离时，是异构的吗？

Reversible metal-organic cage MOC(top left)-MOF(top right) metal-organic framework transition mediated by the addition of 1,4-dioxane.Coordination bonds between 1,4-dioxane shown (bottom image).

Reversible MOC(top left)-MOF(top right) transition mediated by the addition of 1,4-dioxane.Coordination bonds between 1,4-dioxane shown (bottom image).

作者使用了A³耦合反应，在催化反应中证明这一概念。A³reaction is a transition metal-catalysed,醛之间的多组分耦合反应，alkynes and amines.产品为丙炔胺，practical synthetic intermediates for the synthesis of nitrogen heterocycles.A³反应已被广泛研究，并能受到各种过渡金属催化剂的影响。Its versatility makes it a popular choice as a model catalytic reaction to demonstrate innovative ideas in catalytic design – as the authors have done here.

配位驱动组件在合成不同可溶性材料方面具有独特的潜力，作者用于新型催化设计。这种特殊的金属配体组合能否应用于其他铜催化反应，还有待观察。nevertheless the principle offers an innovative approach that augments the range of methods striving to bridge the gap between homogeneous and heterogeneous catalysis.

To find out more please read:

铜₃L₂金属有机笼³-耦合反应：可逆配位作用触发均相催化和非均相回收

陈功军，Chao-Qun Chen,薛天丽，马慧超和董玉斌。
Chem.公社。，2018,五十四，11550-11553
DOI：10.1039/C8CC7208F

关于作者

Zo_Hearne是蒙特利尔麦吉尔大学化学博士生，新利手机客户端加拿大，在李超教授的监督下。她来自堪培拉，澳大利亚，where she completed her undergraduate degree.她目前的研究重点是过渡金属催化，以实现新的转变，在实验室之外，她是一位热情的化学导师和科学传播者。新利手机客户端新利手机客户端

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MOFS，Zmofs和汽车

2018年9月5日

Mohamed Eddaoudi and co-workers at KAUST have synthesised a porous metal organic framework (MOF) constructed from carboxylic acid-functionalised imidazole linkers coordinated to yttrium and potassium cations.The researchers classified this material as a zeolite-like MOF (ZMOF) due to its topological resemblance to the naturally occurring zeolite mineral analcime.

材料的结构，圆柱形通道和孔径为3.8 x 6.2_的孔，作为分子筛的预期用途，研究表明，ZMOF可以根据链烷烃的分支程度对其进行分类。线性和单支链戊烷和丁烷被材料吸附不同的时间长度（线性异构体保留的时间长于其支链对应物），允许动力学分离，while the di-branched alkane 2,2,4-trimethylpentane was excluded entirely.The authors anticipate that this material could have practical applications in crude oil refining,to upgrade petroleum into more energy-efficient fuels with reduced emissions.

ZMOF类分子筛金属有机骨架晶体结构，具有方沸石（ANA）结构，显示孔道和孔径。

方沸石的Zmof晶体结构（ana) topology showing channels and pore aperture.

用于驱动内燃机的石油由低分子量的混合物组成。直链烷烃和支链烷烃。研究辛烷值（RON）是衡量石油性能的标准指标。指示燃油在发动机自燃（爆震）前能承受的压力。High compression engines,比常规发动机更节能，排放更少，require high RON fuels.

罗恩随支链烷烃比例的增加而增加，so can be improved by supplementing fuels with branched isomers obtained by catalytic isomerisation.这个过程产生了直链烷烃和支链烷烃的混合物，所以所需要的产物必须通过分馏分离出来，这是能源密集型的。This creates a dilemma: high RON fuels are more energy efficient,但他们的能源密集型生产降低了净效益。

The authors envisaged an energy-efficient strategy for increasing the RON of petroleum fuels: A low RON fuel is pumped into the engine,当它遇到由ZMOF基膜组成的分离室时。膜排除并重新定向二支链烷烃，which have a very high RON,to the internal combustion engine.低罗恩分数，由单支链和直链烷烃组成，通过ZMOF孔在下游进行进一步的重整过程。换句话说：低罗恩燃料进入，but high RON fuels are combusted.

图中显示了ZMOF材料如何根据烷烃的分支程度来分离烷烃，从而升级汽油。zeolite-like metal organic framework petroleum reforming

Scheme showing the RON of common small-chain alkanes and the use of ZMOF membranes in upgrading gasoline by separating alkanes based on their level of branching

In this work the authors show the potential of ZMOFs to maximise the energetic potential and reduce emissions of petroleum based fuels,同时也提供了一个更一般的策略，即使用定制的材料对化学相似分子进行节能分离。

To find out more please read:

Upgrading gasoline to high octane number using zeolite-like metal organic framework molecular sieve withana-topology

M.英法斯H.莫希登，Youssef Belmabkhout,普拉尚特M.Bhatt,阿列克山德·什库伦科，陈志杰，卡里姆·阿迪尔，Mohamed Eddaoudi.
Chem.公社。，2018,五十四，9414-9417年
DOI:10.1039/C8CC04824J

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大理石，Microreactions and Magic Tricks

2018年8月3日

反应容器是每种创新化学合成的固定变量，material or catalyst.It may be as simple as a round bottom flask or as complex as a single cell,as large as an industrial batch reactor or as small as a test tube.

冯玉军和同事们，at Sichuan University in China,研究一种不同的反应容器：水滴。液滴是“液态弹珠”，composed of microlitre volumes of water with fine hydrophobic particles covering their surface.液体弹珠可以用作反应容器来处理小体积的液体。avoiding the use of specialised microfluidics equipment.在这篇通讯中，作者指出二氧化碳可以引发含有多种试剂的液滴的聚结。为了进行微型化学。新利手机客户端This research could be useful for developing high-throughput assays for procedures that would benefit from remotely controlled induction such as very fast or hazardous reactions.

作者合成了一氧化碳₂-由聚苯乙烯和PDEA的混合物组成的反应性粒子：一种含叔胺辅助基团的甲基丙烯酸酯聚合物。The amine is vital to the properties of the polymer: when deprotonated the powder is hydrophobic,but exposure to carbon dioxide renders the polymer hydrophilic by transforming the amine into an ammonium bicarbonate salt.用一小块钴合成了液态大理石。₂-responsive polymer powder.其余的大理石都涂上了石松，a moss spore with hydrophobic properties that is not CO₂-responsive (trivia: the high fat content of lycopdoium makes it a great flash powder,used by magicians since the middle ages).

A) Liquid marbles with white hydrophobic/hydrophilic CO2-responsive patches and pink (dyed) lycopodium powder.b）一分钟内二氧化碳暴露后两个液态弹珠聚结。C) Coalescence schematic

A) Liquid marbles with white CO₂-responsive patches and pink (dyed) lycopodium powder.B) & C) Photos and schematic of coalescence between two liquid marbles upon CO₂exposure

实现CO₂-induced 新利手机客户端chemistry,两个含有不同化学试剂的液态大理石与Co并排放置。₂-反应性粉末，位于两个大理石的界面。暴露于一氧化碳后₂the responsive powder becomes hydrophilic and disperses into the aqueous solution within the two marbles,causing them to coalesce and the reagents to react within a single vessel.作者用这种方法做了几个反应，所有这些都有明显的颜色变化以便快速分析：氧化还原（过硫酸盐和碘化物，permanganate and persulfate),complexation (starch and iodine),取代（溴水和苯酚）和化学发光（鲁米诺，peroxide and ferricyanide).

The authors show in this paper that innovations in 新利手机客户端chemistry needn't be limited to reactions themselves;the vessel we choose can broaden what is possible on a practical level.完全不切实际，遥控液体弹珠中的微反应听起来像是一个魔术，与覆盖其表面的石松闪粉共振。

To find out more please read:

CO₂-液态大理石中的触发微反应

Xinjie Luo,Hongyao Yin,李先娥，Xin Su,冯玉军。
Chem.公社。，2018,Advance Article
DOI:10.1039/C8CC1786克

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An enzymatic Rube Goldberg machine: a bioluminescent switch for the detection of uracil DNA-glycosylase

2018年7月6日

A team of researchers from Shandong Normal University in Jinan,中国开发了一种检测尿嘧啶DNA糖基化酶的高灵敏度无标签检测方法。a DNA repair enzyme that removes uracil from DNA molecules.Uracil is an RNA base,当尿嘧啶通过胞嘧啶脱氨基或DNA合成过程中的错误结合而出现在DNA中时，the error can have mutagenic consequences.

尿嘧啶DNA糖基化酶活性降低与许多疾病状态有关，包括人类免疫缺陷和布鲁姆综合征。an inherited disorder associated with an increased risk of cancer (among other symptoms).开发定量尿嘧啶DNA糖基化酶的敏感方法将有助于早期诊断此类疾病，并提高对DNA修复机制的理解。As a proof-of-concept,研究人员表明，这种方法可以定量分析希拉癌细胞裂解液中的酶。

他们的方法让我想起了Rube Goldberg机器，which achieve a task via a series of connected,mechanical steps.一个步骤的完成会触发另一个步骤的开始：例如一排多米诺骨牌掉落到大理石上，反过来，rolls down a track.在这项工作中，一种酶的作用返回另一种酶的首选底物产品。有轻微偏离的风险，one of the more spectacular examples of a Rube Goldberg machine is seen in the music video for OK GO's ‘this too shall pass',一个仓库大小的机器的单次拍摄，以滚动车为特色，摇摆钢琴，流水和滚球，all to perform the task of (spoiler alert) blasting the band members in the face with coloured paint.

该策略从尿嘧啶DNA糖基化酶的作用开始，通过一系列酶反应以生物发光信号结束。

作者的策略包括使用七种不同酶和三种核酸探针的一系列连续步骤。It begins with a double stranded DNA probe containing one rogue uracil base: the perfect bait for uracil-DNA glycosylase.The action of this enzyme and two others,in a process involving base excision,DNA骨架断裂和添加富含胸腺嘧啶的序列，产生大量的单链DNA分子，其尾部富含胸腺嘧啶。这些分子与富含腺嘌呤的RNA探针杂交生成RNA-DNA双链体。一种酶消化RNA部分，释放一磷酸腺苷单体，转化为三磷酸腺苷（ATP）。激活萤火虫荧光素酶所需的能量输入。荧光素酶催化荧光素氧化形成氧化荧光素，accompanied by a large bioluminescent signal.因此，尿嘧啶DNA糖基化酶的检测灵敏度比最先进的荧光和发光分析法高1-2个数量级。

与传统的rube goldberg机器不同，其特点是不必要的复杂性，在这种“酶促rube goldberg机器”中，每一步都有特定的用途，并用于放大最后一步的信号。这被称为“三环级联信号放大”，它使酶的高度敏感检测。

To find out more please read:

三环级联信号放大无标记高通量生物发光法检测癌细胞尿嘧啶DNA糖基化酶

张燕，Qing-nan Li,陈陈丽，陈杨章。
Chem.公社。，2018,五十四，6991-6994
DOI: 10.1039/c8cc03769h

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来看看变色水晶，坚持科学新利手机客户端

2018年5月31日

咪唑配体合成铜双金属配合物，以及经结晶和溶剂-客人交换形成的溶剂铬材料。The solvatochromic behaviour was quantified with visible-region diffuse reflectance spectra.

在我本科期间的第一门无机化学课程中，新利手机客户端我们的教授开始上课的时候把一些矿物样品传来传去，向我们保证，如果我们追求金属化学，我们每天都可以用漂亮的彩色晶体。新利手机客户端当时，colour seemed like such a trite detail amongst the complexity of the subject.Why would you choose a field of study based on something so simple?Well,在博士学位被淡黄色的油占据之后，I think I get it now.

南非Stellenbosch大学的Nikolayenko和Barbour为我们带来了色彩！作者合成了有机金属铜配合物，which crystallise to form porous single crystals that drastically change colour upon absorption of various solvents.作者用X射线晶体学研究了溶剂变色机理。EPR,紫外可见光谱和干膜厚度计算。Solvatochromic materials are not just made to look pretty;它们有可能被用作敏感物质，用于检测溶剂蒸汽的选择性和可回收传感器，在工业过程风险管理中具有有用的应用，chemical threat detection and environmental monitoring.

The researchers synthesised a series of complexes comprised of a bidentate ligand with 2-methylimidazolyl groups coordinated to copper(II) ions.复合物在晶体中堆积形成通道，能够捕获溶剂分子以得到不同颜色的晶体：含有二甲基亚砜和四氢呋喃的晶体是绿色的（λ_最大值= 574 nm and 540 nm,respectively),含乙腈的为红色（λ_最大值=624牛米）and crystals trapping acetone,ether and pentane are yellow (λ_最大值= 588),橙色（λ_最大值= 598 nm) and red/brown (λ_最大值= 592 nm),分别。

The authors revealed a correlation between the size of the solvent guest,铜配合物的配位几何学，and the ligand field splitting.Small guests such as acetonitrile minimally perturb the metallocyclic framework,保留菱形配体场几何（大δ_xyof g values in the EPR spectrum),小配体d-轨道分裂和红移光谱。像THF这样的大客人有相反的效果，给出接近四方（小δ）的配位体场几何图形_xy）大配体场d-轨道分裂和蓝移光谱。

By delving into the complexity beneath a seemingly simple phenomenon,Nikolayenko,Barbour and their co-workers have shown using a series of single-crystal complexes that there is nothing simple about colour (and nothing trite about detail).

To find out more please read:

超分子溶剂色谱：从结晶学的机械洞察，spectroscopy,and theory

Varvara I.Nikolayenko,丽莎M。范怀克，Orde Q.Munro,伦纳德J。Barbour.
Chem.公社。，2018,Advance Article
DOI: 10.1039/c8cc02197j

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Ruthenium Currency for a Hydrogen Fuel Economy

2018年5月2日

A group of researchers at the Chinese Academy of 新利手机客户端Sciences and Southwest University want us to kick the fossil fuels habit.他们的研究来自中国，a country using roughly one quarter of the world's yearly energy consumption,而化石燃料的有限性对能源供应安全构成了非常现实的威胁。Leading in energy use,China also leads the world in electricity production from renewable sources and investment in clean energy projects.

氢被认为是化石燃料的可行替代品，因为它富含能源，比汽油或乙醇高39 kWh/kg（汽油：13 kWh/kg，乙醇：8.2 kWh/kg）燃烧时只放出水蒸气。然而，hydrogen is often obtained from fossil fuels,and it will only be a practical option for the world's future energy needs if it can be produced from a renewable source.

准备RU₂P/reduced graphene oxide catalyst

为此，分水提供了一种解决方案。In a water electrolysis cell,阴极产生氢气via氢演化反应2h⁺+2e^–-> h₂）and molecular oxygen is produced at the anode (2H₂O –> O₂+4h⁺+4e^–）It is ideal in theory,但是，要使水分裂成为可能，就需要高能效，and this relies on the development of catalytic electrodes to minimize overpotentials required to drive the reaction.Currently,最先进的电催化剂使用铂，which is expensive and rare.Furthermore,platinum catalysts are most efficient in an acidic electrolyte and proceed 2-3 times slower in alkaline solutions.另一方面，在碱性环境中，最好的氧进化催化剂表现更好。Using an alkaline electrolyte has overall advantages as it is less corrosive,thus increasing the stability and lifetime of the electrolytic cell.

作者们开发了她的催化剂，using ruthenium,在碱性和酸性条件下，过电位和电流密度均优于铂/碳。

DFT calculation to probe the hydrogen adsorption energies on the active catalytic surface of the Ru₂P催化剂。a) and b) front and side views of the calculated Ru₂P/reduced graphene oxide surface.c) free energy diagram for the HER with different catalysts.

电催化剂由小的，uniform Ru₂p纳米颗粒（~2-4纳米）均匀分布在还原石墨烯氧化物薄片上。The activity of the prepared catalyst (1.0 mg cm^-2）因为她是在酸性介质（0.5 m h）中测量的₂所以₄) and the overpotential to achieve a current density of -10 mA cm^-2was -22 mV,superior to Pt/C (-27 mV).在碱性环境（1.0 m氢氧化钾）下，催化剂的性能得到提高。过电位为-13 mV（比pt/c低29 mV）。High Faradaic efficiencies of more than 98% were measured in both acidic and alkaline solutions.Additionally,analysis was undertaken to further understand how the structure and composition of the catalyst influences its activity.Double layer capacitance measurements gave clues about the catalyst surface,同时利用理论DFT计算研究了H-吸附能。

There is no way to avoid the reality that ruthenium is also a rare and costly metal,因此，我们可能无法掌握解决能源困境的关键。然而，of real value are the insights gained from probing the structure function relationship of this highly active catalyst,which may guide the synthesis of rationally-designed catalysts using inexpensive and abundant materials.

To find out more please read:

超小型RU₂石墨烯上的P纳米粒子：酸性和碱性介质中一种高效的析氢反应电催化剂

Tingting Liu,Shuo Wang,Qiuju Zhang,Liang Chen,胡伟华，Chang Ming Li.
Chem.Commun.,2018,五十四，第3343-3346页
DOI:10.1039/c8cc01166d

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彩色荧光染料马来酰亚胺的合成

2018年4月18日

A group of researchers based at universities spanning the UK,中国和西班牙合成了多种荧光马来酰亚胺染料库，旨在建立结构-功能关系。将取代基效应与这些分子的光学性质联系起来。这项工作不仅对建立对荧光机理的基本认识很重要，但为了发展知识，可以用来指导合成有机荧光团，这需要特殊的光学性能。

有机荧光分子被用作许多领域的工具，如法医学，genetic analysis,DNA sequencing and biotechnology.马来酰亚胺通常用作蛋白质的荧光标记。as they can couple with the thiol groups of cysteine residues.They are suited to this purpose as they are stable,easily functionalised,give strong emissions and do not perturb the protein structure to a large extent.

分子吸收紫外线或可见光后发出荧光，把电子从基态轨道提升到高能轨道，产生单重激发态。Relaxation to the ground state occurs rapidly (~ 10 ns) with concomitant emission of a photon – this is what we observe as ‘fluorescence'.发射的光子的波长几乎总是比吸收的光长，a phenomenon known as the ‘Stokes shift'.

Structures of selected amino-halo-maleimides and alkoxy-halo-maleimides synthesised for the study

手握三种二卤马来酰亚胺前体（cl，Br and I) the researchers assembled a library of amino-halo-maleimides,氨基烷氧基马来酰亚胺，氨基硫代马来酰亚胺。They varied the R groups bound to the N,O和S杂原子包括脂肪族，苯基和苄基实例。

The optical properties of the amino-halo-maleimides in diethyl ether were examined and the emission wavelengths were measured to be 461-487 nm,giving green-blue fluorescence.荧光量子产生，测量发射光子与吸收光子的数量，并指示发射亮度，随着卤化物的电负性降低（cl:37%，br:30%，I: 8%).与溶液中的许多荧光分子一样，这些化合物也表现出了溶剂的折衷性：当溶剂的极性改变了光学性质。在原溶剂（甲醇和水）中，荧光量子产率降低到1%以下，发射波长增加73-109纳米。另一方面，在非极性溶剂（环己烷）中，荧光量子产率增加，高达56%的氯类似物。

a）含氨基（2A-C）和烷氧基（3A，3b）取代基。b）所选氨基和烷氧基马来酰亚胺的量子产率。c) The solvafluorochromism effect for three aminomaleimides (2a-c) in increasingly non-polar solvents.

a）含氨基（2A-C）和烷氧基（3A，3b）取代基。b）所选氨基和烷氧基马来酰亚胺的量子产率。c）三种马来酰亚胺（2a-c）在不同溶剂中的溶剂氟罗氏妥协效应。

与它们的氨基取代对应物相比，烷氧基卤代马来酰亚胺的量子产率较低（降低20-25%），指出胺基取代基的电子给予能力的提高对荧光强度有重要影响。Furthermore,烷氧基卤代马来酰亚胺（458-465nm）的发射波长略有下降，使其发出蓝色荧光。Amino-thio-maleimides,with greater electron-donating capacity than both the amino and alkoxy analogues,have increased emission wavelengths (526-564 nm),因此发出黄色荧光。

This study is a worthwhile read for anyone who uses fluorescent molecules in their work,那些希望更多地了解荧光的实际原理的人，以及那些喜欢形成自己假设的好奇的人。

To find out more please read:

Rational design of substituted maleimide dyes with tunable fluorescence and solvafluorochromism

谢玉杰，乔纳森T。丈夫，米奎尔激流苏卡拉特，杨欢，刘伟生，Rachel K.O'Reilly.
Chem.Commun.,2018,五十四，3339至3342
DOI：10.1039/C8CC00772A

作者简介：

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三重激活扭结恶唑啉的合成

2018年4月4日

A group of researchers based in Valencia,西班牙，开发了一种合成恶唑啉的对映和非对映选择性方法，使用银和有机催化剂的组合，它与经典的英国鸡尾酒只有一个程度的分离（要得到这种混合物，你可能需要继续阅读）。This method complements the current literature by employing unactivated ketone substrates to prepare products with two adjacent chiral centres,one of which is quaternary.

恶唑啉是一个多功能的官能团，found in synthetic precursors and functional molecules and materials.它们是许多天然产物的常见结构特征，在药物化学中，它们作为其他功能组的生物同系物被纳入合成药物候选物中。新利手机客户端such as thiazoles and imidazoles.Oxazolines can also be used to prepare poly(2-alkyl/aryl-oxazoline) polymers,which have utility in biomedical fields to prepare hydrogels,nanoparticles for drug delivery and imaging,and polymer-protein conjugates.In an organic synthesis laboratory oxazolines are encountered as ligands in asymmetric catalysis,such as the bis(oxazoline) ‘BOX' family of compounds.

Synthesis of oxazolines from ketones and isocyanaoacetate esters via a formal [3+2] cycloaddition reaction.

研究人员优化了与苯乙酮和 叔丁醇-异氰乙酸丁酯，发现了 ₂O (2.5 mol%) and a dihydroquinine squaramide organocatalyst (5 mol%) promoted the reaction to obtain a quantitative yield of the cis-oxazoline (80:20 cis/trans）24小时内，对映体过量（99/93%E.E.）。研究人员测试了反应范围，发现苯乙酮衍生物被抽电子和给电子基团取代（没有 ₂，氯，Br我）给了 cis-恶唑啉产品的可靠产量（60–99%），正常到良好的非对映选择性（56:44–95:5 cis/ trans）以及优良的对映选择性（91–99%e.e.）。其他测试实例包括环己酮，2-acetylthiophene,脱氧安息香和丙酮以及带有甲基组合的脂肪族酮，isopropyl and cyclopropyl groups (63-99% yield,45:55 – 98:2 cis/ trans，56 – 98% e.e.).

Diagram showing the triple activation of substrates using a dihydroquinine squaramide organocatalyst combined with a silver lewis acid.

The dihydroquinine squaramide organocatalyst used is a composite structure comprising a rigid cyclobutendione ‘squaramide' and a reduced quinine analogue.前者与羰基衍生物形成强烈的氢键，后者在催化剂上具有手性，并具有Br nsted的基本双核嘧啶部分。Quinine is an alkaloid isolated from the cinchona plant,而抗疟疾的补品中也有同样的成分，最好用杜松子酒冲掉。反应通过银配位进入异氰酸酯的末端碳，通过奎尼定碱加速α质子脱质子化并形成亲核的烯酸盐。The electrophilicity of the ketone is enhanced by the formation of two hydrogen bonds with the N-H bonds of the squaramide,shaping a doubly activated system which rapidly undergoes a formal [3+2] cycloaddition to give the products.

乍一看，这似乎是一个简单而直接的转变，但实际上，作者成功地优化了对两个手性中心具有立体控制的非活化底物的反应。one of which is quaternary.Furthermore,该反应使用两种催化剂通过三种活化方式进行反应的组合。

To find out more please read:

非活化酮和异氰乙酸酯协同银/有机催化合成手性恶唑啉

Pablo Martínez-Pardo,冈萨洛·布雷，M.Carmen Muñoz,José R.Pedro,Amparo Sanz-Marco and Carlos Vila.
Chem.共同体.,2018,五十四，2862–2865年
DOI：10.1039/C8CC0856F

关于作者：

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纳米级工业革命

2018年3月27日

“小型可移动机器的可能性是什么？它们可能有用，也可能不有用，but they surely would be fun to make".In December 1959 Richard Feynman addressed the annual meeting of the American Physical Society at Caltech with a talk entitled ‘There's Plenty of Room at the Bottom',呼吁科学界开始小心谨慎，like ‘entire 24 volumes of the Encyclopaedia Britannica on the head of a pin' kind of small.许多人引用这节课的话是，当纳米机器的概念第一次进入科学领域时——谈到微型汽车，注射分子“外科医生”和机器，把原子放在一起，合成任何可以想象的分子。The lecture reads like the description of the futuristic setting in ‘Back to the Future',在我们根本缺乏使其成为现实的工具的时候对可能性的探索。

就像“回到未来”，早在移动银行技术出现之前，video calling and personal drones,Richard Feynman's plea for scientists to prepare molecular-scale machines has also become a reality,and for their successes in this field Jean-Pierre Sauvage,Sir Fraser Stoddart and Ben Feringa were jointly awarded the Nobel Prize in 新利手机客户端Chemistry in 2016.

伦敦和新加坡的一组研究人员写了一篇专题文章，介绍了这一领域的基础工作和最先进的例子。纳米机器是纳米尺度上的单分子或分子组件（本综述定义了1-100纳米范围），能够在应用外部能源时执行“有用的工作”。为了提取功（通常以受控机械运动的形式），分子机器被设计成在远离平衡状态的热力学状态下工作，由能量输入维持，with movement occurring as the system relaxes towards equilibrium.At the synthetic level,molecules are designed with components which have restricted translational and rotational movements with respect to each other,控制这些运动的能力是获得所需功能的关键。

A catalytically active rotaxane synthesised by Nolte and co-workers acts as a tiny epoxidising machine,沿着聚丁二烯聚合物移动

The catalytically active rotaxane synthesised by Nolte and co-workers acts as a tiny epoxidising machine,沿着聚丁二烯聚合物移动

纳米机械合成的最早进展之一是Jean-Pierre Sauvage的研究小组，实现了链烷的模板合成；具有两个相互连锁的环状分子的结构，就像链条中的两个链环。It was subsequently shown that a catenane motor could be prepared,一个环以可控方式相对于另一个环旋转。Fraser Stoddart further contributed to the field with ‘rotaxanes',由一个环穿在轴上组成的复合分子。基于Rotaxanes的纳米机器已经开发出来，包括开关，shuttles and ‘molecular elevators'.Nolte及其同事在2003年合成的催化活性的轮烷的一个最先进的例子展示了纳米机器革新有机合成的潜力。罗塔烷由镁结合卟啉构成，which threads onto a polybutadiene polymer (300 kDa,98%cis) and catalyses the epoxidation of the double bonds (turnover number: 140,cis/trans聚环氧化物的比例：1:4）。

Ben Feringa's electric nano-car,一种单分子，有四个能穿过铜表面的氟橡胶“轮子”。

In 2011 Ben Feringa and co-workers synthesized the worlds tiniest electric car using the same design principles they had used to create a spinning motor in 1999.The car is a single molecule with the ability to propel itself across a crystalline copper surface upon activation by a voltage pulse,with 10 pulses moving the car 6 nm across the surface.汽车本身是由一个中心的二yne支柱连接在两端的咔唑“车轴”。Each axle is bound through alkenes to two fluorene ‘wheels'.The key design elements are the alkenes and two chiral methyl substituents on each axle which forces each wheel to twist out of the plane.对于单轮旋转：电子激励trans–cisisomerisation of the alkene causing a quarter turn of the wheel such that it sits adjacent to the methyl group.下一步，a vibrational excitation induces helical inversion,allowing the wheel to push past the methyl group another quarter turn.另一个异构化和螺旋反转完成了一个完整的旋转。Research achievements like these demonstrate mechanical work on the nanoscale,通过同步运动在宏观尺度上实现运动。

这些例子代表了在专题文章评论中讨论的那些例子中的一小部分，which not only spans the current scope of molecular-scale machines,但回顾了指导它们发展的设计原则以及纳米机器在未来科学研究中所代表的可能性。

To find out more please read:

用于先进纳米机械的人工分子和纳米结构

伊丽莎白·埃利斯，苏雷什·穆尔西，翁一、赵秀莲、李东春。
Chem.公社。，2018,Advance Article
DOI: 10.1039/c7cc09133h

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用于研究和合成独特N-杂环卡宾的有机金属工具箱

2018年3月05

氮杂环卡宾（NHCS）是一个有趣的例子，化学好奇心变得司空见惯。NHCs are stable singlet carbenes located within an N-heterocycle,其中碳中心有一个SP²hybridised pair of electrons.As early as 1835 chemists were thinking about carbenes,with Dumas' optimistic (if unsuccessful) attempt to synthesise the methylene carbene by dehydrating methanol.For many years the intentional study of carbenes was considered too demanding because of their instability,所以他们仍然相对默默无闻。一些具有开创性的论文改变了这种先入为主的观念；特别地，Wanzlick在1968年的一份报告中报告了第一种使用汞的NHC金属配合物的合成，以及Ardunego在1991年首次合成了一种稳定且可分离的NHC。

在过去的三十年中，对NHC的研究和兴趣的加强可能是由这些开创性的报告引起的，but it continues because of the success of NHCs in catalysis: both as strongly σ-donating metal ligands and nucleophilic organocatalysts.NHC最有价值的特性之一是能够通过改变杂环和N键取代基来调整它们的立体和电子性质。Accordingly,对NHC反应性的研究和功能化NHC方法的发展对该领域的持续创新至关重要。

斯特拉斯克莱德大学的Marina Uzelac博士和Eva Hevia博士，苏格兰，综述了金属化氮杂环卡宾的有机金属方法。The work summarises metallation of all three components of the NHC: the carbenic carbon,the heterocyclic backbone and the N-bound substituents.

岩化杂岩（1）synthesised by treatment of the N-heterocyclic carbene NHC with nBuLi,可以在C4位置被一些主要的基团元素转化，得到各种双金属复合物（2）。这些配合物可以选择性地猝灭生成具有非常规区域化学（3）的NHC配合物。新利手机客户端

岩化杂岩（一）可以在C4位置通过一些主要的基团元素进行转化，得到各种双金属复合物。（2）These complexes can be selectively quenched to generate NHC complexes with unconventional regio新利手机客户端chemistry (3）

To exemplify the breadth of research discussed;从2,6-二异丙基苯基（DIPP）取代的咪唑-2-亚基开始，NHC的反应性可以通过初始添加碱金属（如锂）来解锁。钠或钾（见图）。Metallation at the C4 position occurs by deprotonation of the vinyl protons in the NHC backbone,while a second metal coordinates to the carbene electron pair at the C2 position.从这个物种（一）可以用极性较低的金属（如锌）转化C4位置，aluminium,gallium,boron or iron to furnish a bi-metallic NHC (2）有趣的是，向该物种添加亲电甲基或质子源只会使C2位置骤冷，generating a suite of unconventional complexes (3）卡宾电子对位于C4碳上。

Lithiation of NHC complexes: a) deprotonation of the backbone of NHC-borane complex;b）NHC锌配合物与提供锌酸锂的烷基锂共络合；c）异常卡宾络合物的脱除。

Reactivity of main-group NHC complexes towards lithiation.

进一步的研究调查了不同的试剂对区域选择性和金属化程度的影响，金属化NHC如何激活小分子，如二氧化碳，导致N-dipp取代基金属化的条件，以及各种双金属试剂处理NHC后的产物和形态。

In addition to expanding the knowledge of NHC reactivity,本综述中总结的工作为寻求为合成和催化中的独特应用定制NHC的研究人员提供了参考和启示。

To find out more please read:

氮杂环碳烯区域选择性碳氢金属化的极性有机金属策略

Marina Uzelac和Eva Hevia。
Chem.公社。，2018,Advance Article
DOI：10.1039/C8CC0049B

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化学通讯博客

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Copper A3 Coupling using a Switchable Homogeneous/Heterogeneous Catalyst

MOFS，Zmofs和汽车

大理石，Microreactions and Magic Tricks

An enzymatic Rube Goldberg machine: a bioluminescent switch for the detection of uracil DNA-glycosylase

来看看变色水晶，坚持科学新利手机客户端

Ruthenium Currency for a Hydrogen Fuel Economy

彩色荧光染料马来酰亚胺的合成

三重激活扭结恶唑啉的合成

纳米级工业革命

用于研究和合成独特N-杂环卡宾的有机金属工具箱

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