Archive for September, 2013

The chemists’ enzyme

The title of this post was taken from the website of Barry Trost, one of the world’s leading scientists and author of an astonishing 924 papers. Describing his work, he states:

One major activity in designing new reactions and reagents involves the development of “chemists’ enzymes” – non-peptidic transition metal based catalysts that can perform chemo-, regio-, diastereo-, and especially enantioselective reactions.

Chemists have, for a long time, sought to reproduce the incredible feats of nature. Natural biology has evolved over many years to achieve the efficiency and reactivity that most lab-based chemists could only dream of. Nature achieves this by employing incredibly sophisticated enzymes which are, sadly, almost impossible to replicate by a synthetic chemist due to their complexity. An alternative idea is to use these enzymes as inspiration for new catalysts and try to focus on the general reasons why they work rather than trying to create direct copies.

Supramolecular catalysts for decarboxylative hydroformylation and aldehyde reduction.

Dr Bernhard Breit, Lisa Diab and Urs Gellrich at Albert-Ludwigs-Univertat in Germany have shown in a HOT ChemComm article that a highly selective catalyst can be created when combining a metal catalyst with a directing ligand to control the reaction. In this Communication, they report excellent results using  rhodium, the classic metal of choice for hydroformylation, and a functional group for recognition of the substrate. The net effect of these features combined is that the substrate is held in a specific way at the catalytic site. As a result, the reaction which follows can only occur in a specific way. This is similar to how enzymes control the chirality.

The concept behind this catalyst is one which could be applied to a great number of different reactions – no doubt we can look forward to reading about these in the near future.

Read this HOT ChemComm article today!

Tandem decarboxylative hydroformylation–hydrogenation reaction of α,β-unsaturated carboxylic acids toward aliphatic alcohols under mild conditions employing a supramolecular catalyst system
Lisa Diab, Urs Gellrich and Bernhard Breit
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC45547E, Communication

Ruaraidh McIntosh is a guest web-writer for ChemComm.  His research interests include supramolecular chemistry and catalysis.  When not working as a Research Fellow at Heriot-Watt University, Ruaraidh can usually be found in the kitchen where he has found a secondary application for his redoubtable skills in burning and profanity.

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The big bang theory (made safe) — Impact insensitive dinitromethanide salts

The improvement of high energy density materials (HEDM) is an ongoing challenge. These materials are widely used in propellants, explosives, and pyrotechnics, and researchers face the difficult task of optimising their explosive potential while ensuring their safety and ease of handling. Nitro-substituted methanide compounds are an important class of HEDM, but often suffer from thermal instability and impact sensitivity. This HOT ChemComm article addresses this challenge by highlighting the preparation and analysis of impact insensitive dinitromethanide salts.

Jean’ne Shreeve at the University of Idaho, working with Ling He at Sichuan University and co-workers at the US Naval Research Laboratory, proposed that by combining an oxygen-rich polynitromethanide anion (either a nitroform anion TNM, or a dinitromethanide anion DNM) with nitrogen-rich cations such as guanidinium, triazolium and tetrazolium anions, the resulting salt would exhibit high energetic properties as well as improved stability.

Using a range of guanidinium, triazolium and tetrazolium halides, the researchers prepared nine DNM salts and analysed their physicochemical properties. All of the salts displayed good thermal and detonation properties while being significantly less sensitive to impact than common explosives such as 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX).

Molecular structure and Packing diagram of DNM salt 3

Guanidinium–DNM salt 3, decomposing at 187 °C, displayed the best thermal stability among all other known DNM salts. X-ray crystallography revealed that this increased stability is due to its strongly hydrogen-bonded structure. Each guanidinium cation forms six hydrogen bonds with the NO2 groups of four surrounding anions, creating a planar, layered packing structure.

Insights such as these will allow researchers to design HEDM with better thermal stability and less impact sensitivity, controlling their energetic potential yet ensuring greater safety and utility.

For more, check out the ChemComm article in full:
Impact insensitive dinitromethanide salts
Ling He, Guo-Hong Tao, Damon A. Parrish, and Jean’ne M. Shreeve
Chem. Commun., 2013, Accepted Manuscript
DOI: 10.1039/C3CC46518G

Ruth E. Gilligan is a guest web-writer for ChemComm.  She has recently completed her PhD in the group of Prof. Matthew J. Gaunt at the University of Cambridge, focusing on the development and application of C–H functionalisation methodology.

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Top 10 most accessed articles April–June 2013

The 10 most-accessed ChemComm articles between April and June 2013 were as follows:

Facile preparation and upconversion luminescence of graphene quantum dots
Jianhua Shen, Yihua Zhu, Cheng Chen, Xiaoling Yang and Chunzhong Li  
Chem. Commun., 2011,47, 2580-2582
DOI: 10.1039/C0CC04812G, Communication

Selective detection of NO2 and C2H5OH using a Co3O4-decorated ZnO nanowire network sensor
Chan Woong Na, Hyung-Sik Woo, Il-Doo Kim and Jong-Heun Lee  
Chem. Commun., 2011,47, 5148-5150
DOI: 10.1039/C0CC05256F, Communication

Exploration of the medical periodic table: towards new targets
Nicolas P. E. Barry and Peter J. Sadler  
Chem. Commun., 2013,49, 5106-5131
DOI: 10.1039/C3CC41143E, Feature Article
From themed collection Medicinal Inorganic Chemistry

Switchable viscosity triggered by CO2 using smart worm-like micelles
Xin Su, Michael F. Cunningham and Philip G. Jessop  
Chem. Commun., 2013,49, 2655-2657
DOI: 10.1039/C3CC37816K, Communication

Crystal facet engineering of semiconductor photocatalysts: motivations, advances and unique properties
Gang Liu, Jimmy C. Yu, Gao Qing (Max) Lu and Hui-Ming Cheng  
Chem. Commun., 2011,47, 6763-6783
DOI: 10.1039/C1CC10665A, Feature Article

Porous salts based on the pamoate ion
Helene Wahl, Delia A. Haynes and Tanya le Roex  
Chem. Commun., 2012,48, 1775-1777
DOI: 10.1039/C2CC14753J, Communication

Highly efficient catalytic hydrosilylation of carbon dioxide by an N-heterocyclic carbene copper catalyst
Liang Zhang, Jianhua Cheng and Zhaomin Hou  
Chem. Commun., 2013,49, 4782-4784
DOI: 10.1039/C3CC41838C, Communication

Graphene quantum dots: emergent nanolights for bioimaging, sensors, catalysis and photovoltaic devices
Jianhua Shen, Yihua Zhu, Xiaoling Yang and Chunzhong Li  
Chem. Commun., 2012,48, 3686-3699
DOI: 10.1039/C2CC00110A, Feature Article

The chemistry of pristine graphene
Laura Rodríguez-Pérez, M a Ángeles Herranz and Nazario Martín  
Chem. Commun., 2013,49, 3721-3735
DOI: 10.1039/C3CC38950B, Feature Article

Copper-catalyzed synthesis of trifluoromethyl-substituted isoxazolines
Yu-Tao He, Lian-Hua Li, Yan-Fang Yang, Yu-Qi Wang, Jian-Yi Luo, Xue-Yuan Liu and Yong-Min Liang  
Chem. Commun., 2013,49, 5687-5689
DOI: 10.1039/C3CC42588F, Communication

Take a look at the articles, then let us know your thoughts and comments below.

Fancy submitting your own work to ChemComm? You can submit online today, or email us with your ideas and suggestions.

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HOT ChemComm articles for September

Corrosion of self-propelled catalytic microengines
Guanjia Zhao, Bahareh Khezri, Samuel Sanchez, Oliver G. Schmidt, Richard D. Webster and Martin Pumera
Chem. Commun., 2013,49, 9125-9127
DOI: 10.1039/C3CC44998J, Communication

Free to access until 13th October


Tailoring the protein conformation to synthesize different-sized gold nanoclusters
Yong Yu, Zhentao Luo, Chia Sin Teo, Yen Nee Tan and Jianping Xie
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC46005C, Communication

Free to access until 13th October


Dihydrogen activation by a tungsten–alkylidyne complex: toward photoredox chromophores that deliver renewable reducing equivalents
Cesar A. Morales-Verdejo, Michael I. Newsom, Brian W. Cohen, Hunter B. Vibbert and Michael D. Hopkins
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC45606D, Communication

Free to access until 13th October


A chemical genomics approach to identification of interactions between bioactive molecules and alternative reading frame proteins
Paul C. Taylor, Andrew J. Clark, Andrew Marsh, Donald R. J. Singer and Suzanne J. Dilly
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC44647F, Communication

Free to access until 13th October


Identification of bridged CO2 binding in a Prussian blue analogue using neutron powder diffraction
Stephen H. Ogilvie, Samuel G. Duyker, Peter D. Southon, Vanessa K. Peterson and Cameron J. Kepert
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC46019C, Communication

Free to access until 13th October


Reversible photo-controllable gels based on bisthienylethene-doped lecithin micelles
Jiaqi Zhang, Jiayu Jin, Lei Zou and He Tian
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC45805A, Communication

Free to access until 13th October


Oxidant-Resistant Imaging and Ratiometric Luminescence Detection by Selective Oxidation of Silver Nanodots
Junhua Yu, Sungmoon Choi, Soonyoung Park and Kwahun Lee
Chem. Commun., 2013, Accepted Manuscript
DOI: 10.1039/C3CC45601C, Communication

Free to access until 13th October


The liquid phase epitaxy method for the construction of oriented ZIF-8 thin films with controlled growth on functionalized surfaces
Mohamed Eddaoudi and Osama Shekhah
Chem. Commun., 2013, Accepted Manuscript
DOI: 10.1039/C3CC45343J, Communication

Free to access until 13th October

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Mind the gap – Enhancing intercalation of luminescent aggregates

Particular molecules, which are not luminescent in solution, can luminesce intensely upon molecular aggregation; this is known as aggregation-induced emission (AIE). AIE luminogens are used widely as efficient electroluminescent materials, sensitive chemosensors, and as bioprobes. The main cause of the AIE effect is the restriction of intramolecular rotation. Therefore it can be promoted by introducing the molecules into inorganic materials with a rigid skeleton such as α-zirconium phosphate layers.

Jihong Yu and colleagues from Jilin University in China have published a method describing the intercalation of a quaternary tetraphenylethene (TPEN) cation, an AIE chromophore, into α-zirconium phosphate. At first glance, this does not seem to be too difficult a task– after all, the TPEN has two permanent positive charges on either end suitable to interact with the negatively charged phosphate layers. But, in this case, size does matter. The chromophore is almost three times larger than the distance between phosphate layers, more than a tight fit!

Stretching the layers of α-zirconium phosphate by preintercalation of butylamine before introduction of the chromophore

To overcome this problem, Yu and colleagues carried out a preintercalation step with butylamine before performing a cation exchange step to place the TPEN chromophore within the phosphate layers. Ultimately, they stretched the layer before putting the final molecule inside, just like you would stretch a pair of shoes in an effort to make them fit before placing your sensitive feet inside.

The intercalated product was found to be highly emissive in the blue region of the electromagnetic spectrum and was readily internalized by cells. The system also showed good biocompatibility, suggesting that it would make an excellent base for fluorescent labels in future biomedical imaging applications.

To read the details, check out the HOT Chem Comm article in full:

AIE cation functionalized layered zirconium phosphate nanoplatelets: ion-exchange intercalation and cell imaging

Dongdong Li, Chuanlong Miao, Xiaodan Wang, Xianghui Yu, Jihong Yu and Ruren Xu
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC45041D

Iain Larmour is a guest web writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading, photography and art.

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A new, functionally tolerant route to organo-aluminium reagents

Paul Knochel and colleagues at the Ludwig Maximilians University in Munich have reported a new general synthesis of aryl and heteroaryl aluminium reagents.  The route described allows a larger range of functional groups to be incorporated, compared with the more usual approach of inserting Al into aryl halide bonds directly.  The synthetic methodology uses di-isobutyl aluminium chloride and n-BuLi at -78C in an exchange reaction with a functionalised aryl or heteroaryl halide.

General scheme for preparation and derivitisation of aryl aluminium reagents

The synthesis of a group of derivatives is described, via the reaction of the aluminium reagents with a variety of electrophiles.  Typical cross coupling reactions using palladium catalysis, as well as copper-catalysed Michael additions, allylation and acylations are reported, involving a rich variety of incorporated functional groups. Importantly, further derivitisation of the organo-aluminium reagents includes no further transmetalation steps.

Of note are the reactivities of electron-rich furan and thiophene bromides functionalised with ester groups, which also could remain intact during the reaction with di-isobutylaluminium chloride and butyl-lithium at -78C, yielding the desired reagents that were further derivatised, as in other examples.

N-heterocycles such as 3-bromo-quinoline also received attention, yielding the aluminium reagent in 73% yield, and smoothly converting in a palladium catalysed cross coupling reaction with 4-iodobenzonitrile.  Full NMR data for the products of the reactions described is given in the supplementary information.

In general, this Communication describes a considerable step forward in the field of organo-aluminium reagents for organic synthesis, and no doubt will be of interest to synthetic chemists in many fields.

Read this HOT ChemComm article today!

Generation of Functionalised Aryl and Heteroaryl Aluminium Reagents by Halogen/Lithium Exchange
Thomas Klatt, Klaus Groll and Paul Knochel
Chem. Commun., 2013,49, 6953-6955
DOI: 10.1039/C3CC43356K, Communication

Kevin Murnaghan is a guest web-writer for Chemical Communications. He is currently a Research Chemist in the Adhesive Technologies Business Sector of Henkel AG & Co. KGaA, based in Düsseldorf, Germany. His research interests focus primarily on enabling chemistries and technologies for next generation adhesives and surface treatments. Any views expressed here are his personal ones and not those of Henkel AG & Co. KGaA.

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All-in-one 3D printing

Imagine printing anything from electronic devices to artificial bones using the same 3D printer. Now, scientists have developed a universal approach for printing materials with easy-to-modify surfaces to eliminate the need for multiple 3D printers.

3D printing is a potentially powerful manufacturing tool. However, numerous printing technologies have had to be developed as several 3D printers with single-purpose inks are often needed for different uses, increasing fabrication costs. Finding one all-purpose ink or 3D printing process has proven elusive and nearly impossible, until now.

Xiaolong Wang at the Chinese Academy of Sciences in Lanzhou and co-workers in Jun Yang’s group at the University of Western Ontario in Canada have developed a versatile 3D printing technique where a bromine-containing acrylate is added to a 3D printing resin. The acrylate acts as an initiator to allow polymer brushes to grow on the printed surface.

A 3D printed cubic lattice repels a water droplet (left) while a hollow sieve ball traps water without leaks (right)

Read the full article in Chemistry World»

Read the original journal article in ChemComm:
i3DP, a robust 3D printing approach enabling genetic post-printing surface modification
Xiaolong Wang, Xiaobing Cai, Qiuquan Guo, Tengyuan Zhang, Brad Kobe and Jun Yang
Chem. Commun., 2013, Advance Article, DOI: 10.1039/C3CC45817B

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Discoloured detection of sarin

UN inspectors seeking evidence of a chemical weapons attack in Syria have now left the country. As the world awaits their official findings, scientists in France and the Czech Republic report a new complex that could be used to develop simpler and more sensitive detection devices for the nerve agent, sarin.

Sarin’s use as a deadly weapon include a terrorist attack on Tokoyo’s subway in 1995 and an attack by Iraqi government forces on the town of Halabja in Southern Kurdistan in 1988. It is highly toxic, affecting muscle function, and at high doses it causes death by asphyxiation.

Current detection methods are expensive and have low selectivity, or require complex equipment that is not portable. Sensors based on chemicals that visually respond to sarin would be very simple for untrained first responders to use at the site of an attack. Now, Alexandre Carella and colleagues at the French Laboratory of Innovation for New Energy Technologies and Nanomaterials and the University of Defence in the Czech Republic have designed a bipyridine ligand that changes colour on contact with sarin.

Read the full article in Chemistry World»

Read the original journal article in ChemComm:
Chromogenic detection of Sarin by discolouring decomplexation of a metal coordination complex
Lucie Ordronneau, Alexandre Carella, Miroslav Pohanka and Jean-Pierre Simonato  
Chem. Commun., 2013, Advance Article, DOI: 10.1039/C3CC45029E

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