Molecular Brass

Victoria Richards writes about a hot ChemComm article for Chemistry World

Brass has been known to man since prehistoric times; now scientists in Germany have isolated the first molecular example of the copper–zinc alloy.

The chemistry of solid state alloys is well established, yet understanding why different alloys possess particular properties is a greater challenge. Using a bottom-up approach, scientists aim to build intermetallic materials from the smallest available components, and identify boundaries where molecular properties meet bulk material properties. Constructing molecular clusters which mimic such materials is a step in this direction, providing fundamental insights into the chemical bonding of the target materials.


Read the full article in Chemistry World»

Read the original journal article in ChemComm – it’s free to access until 13th August:
Molecular brass: Cu4Zn4, a ligand protected superatom cluster
Kerstin Freitag, Hung Banh, Christian Gemel, Rüdiger W. Seidel, Samia Kahlal, Jean-Yves Saillard and Roland A. Fischer  
Chem. Commun., 2014, Advance Article, DOI: 10.1039/C4CC03401E, Communication

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Announcing the ChemComm Emerging Investigator Issue 2015

We are delighted to announce the forthcoming 2015 ChemComm Emerging Investigators issue. This special issue, now in its fifth year, will showcase the high quality research being carried out by international researchers in the early stages of their independent careers. 

If you are interested in submitting to the issue please contact the ChemComm Editorial Office in the first instance. Please note that authors must not have featured in a previous ChemComm Emerging Investigators issue. The deadline for submission is 31 October 2014.

This annual issue is dedicated to profiling the very best research from scientists in the early stages of their independent careers from across the chemical sciences. We hope to feature principal investigators whose work has the potential to influence future directions in science or result in new and exciting developments.

Also of interest:

Browse the 2014 Emerging Investigators issue

Find out more about the ChemComm Emerging Investigator Lectureship – awarded annually to exceptional scientists in the early-stage of their independent career.

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Themed Issue on Metal-Mediated Transformations of Small Molecules

We would like to celebrate our themed ChemComm collection Metal-Mediated Transformations of Small Molecules with our authors and community.

Guest editors Louise A. Berben and Jason B. Love introduce this web collection showcasing outstanding contributions in the field of the design, development, and exploitation of metal mediated transformations of small molecules. The themed collection includes contributions from molecular inorganic chemists, biological chemists, electrochemists, and theoreticians who are working toward understanding and developing productive transformations of small molecules: dinitrogen, carbon dioxide, carbon monoxide, dihydrogen and dioxygen.

We invite you to submit your next communication article to ChemComm.

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Hot ChemComm articles for June

All of the referee-recommended articles below are free to access until 21st July: 

Coupled chemical oscillators and emergent system properties
Irving R. Epstein  
Chem. Commun., 2014, Advance Article
DOI: 10.1039/C4CC00290C, Feature Article
From themed collection Systems Chemistry


Well-defined “clickable” copolymers prepared via one-pot synthesis
Negar Ghasdian, Mark A. Ward and Theoni K. Georgiou  
Chem. Commun., 2014,50, 7114-7116
DOI: 10.1039/C4CC02660H, Communication


Template-free synthesis of beta zeolite membranes on porous α-Al2O3 supports
Yanting Tang, Xiufeng Liu, Shifeng Nai and Baoquan Zhang  
Chem. Commun., 2014, Advance Article
DOI: 10.1039/C4CC02101K, Communication


Synthesis of luminescent 3D microstructures formed by carbon quantum dots and their self-assembly properties
D. Mazzier, M. Favaro, S. Agnoli, S. Silvestrini, G. Granozzi, M. Maggini and A. Moretto  
Chem. Commun., 2014,50, 6592-6595
DOI: 10.1039/C4CC02496F, Communication


B(C6F5)3 promoted cyclisation of internal propargyl esters: structural characterisation of 1,3-dioxolium compounds
Max M. Hansmann, Rebecca L. Melen, Frank Rominger, A. Stephen K. Hashmi and Douglas W. Stephan 
Chem. Commun., 2014,50, 7243-7245
DOI: 10.1039/C4CC01370K, Communication


Charge state-dependent catalytic activity of [Au25(SC12H25)18] nanoclusters for the two-electron reduction of dioxygen to hydrogen peroxide
Yizhong Lu, Yuanyuan Jiang, Xiaohui Gao and Wei Chen  
Chem. Commun., 2014, Advance Article
DOI: 10.1039/C4CC01841A, Communication

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Strutting Their Stuff – Enantiopure Struts in MOFs

Iain Larmour is a guest web writer for ChemSci. 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. In his spare time he enjoys reading, photography, art and inventing.

 

The introduction of chirality into Metal Organic Frameworks (MOFs) produces the possibility of them being used as solid supports for chiral chromatography. This chirality can be introduced through the use of pillar[5]arene struts where the pendant functional groups can be controlled to alter the overall properties. However, the incorporation of planar chirality into homochiral MOFs is a relatively unexplored phenomenon.

 

 

Homochiral MOFs which contain enantiopure active domains

 

In this Communication Fraser Stoddart, from Northwestern University, and his team report the production of homochiral MOFs which contain enantiopure pillar[5]arene active domains. This required the development of an efficient route to the large-scale production of racemic pillar[5]arene derivatives. However, to discover the secret you will have to read the ChemComm article – access is free* for a limited time only!

 

 

 

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

 

Enantiopure pillar[5]arene active domains within a homochiral metal-organic framework

Nathan L. Strutt, Huacheng Zhang and J. Fraser Stoddart

DOI: 10.1039/C4CC02559H


Interested in MOFs? Why not take a look our Chem Soc Rev MOFs Web collection – reviews are added to this collection as and when they are published.


*Access is free through a registered RSC account – click here to register

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Oren Scherman wins Cram Lehn Pedersen Prize 2014

Dr Eagling (left), Editor of ChemComm, presenting Dr Scherman (right) with the award

Congratulations to Dr Oren Scherman from the University of Cambridge, UK, winner of the 2014 Cram Lehn Pedersen Prize.

The annual prize, named in honour of the winners of the 1987 Nobel Prize in Chemistry, recognises significant, original and independent work by emerging investigators in supramolecular chemistry.

Scherman will receive a prize of £2000 and free registration for the 12th ISMSC meeting in Crystal City, Virginia. In addition to giving a lecture at ISMSC, a short lecture tour will be organised after the meeting in consultation with the Editor of Chemical Communications, the sponsor of the award.

“Dr. Sherman has advanced our thinking on supramolecular self-assembly of polymers in water. He has discovered new routes to use molecular recognition to synthesize hydrogels.” says Professor Roger Harrison, Associate Professor at Brigham Young University and Secretary of the ISMSC International Scientific Committee.  He adds, “his introduction of supramolecular handcuffing, where two molecules are brought together by supramolecular forces, gives scientists control to selectively make complex structures.”

Last year, the Cram Lehn Pedersen Prize was awarded to Professor Tomoki Ogoshi, from Kanazawa University in Japan.

Find out more about Dr Scherman’s research by reading his recent research in ChemComm:

Supramolecular colloidosomes: fabrication, characterisation and triggered release of cargo
Godwin Stephenson, Richard M. Parker, Yang Lan, Ziyi Yu, Oren A. Scherman and Chris Abell
DOI: 10.1039/C4CC01479K

Supramolecular polymeric peptide amphiphile vesicles for the encapsulation of basic fibroblast growth factor
Xian Jun Loh, Jesús del Barrio, Tung-Chun Lee and Oren A. Scherman
DOI: 10.1039/C3CC49074B

Check out the ChemComm web collection dedicated to Polymer Self-Assembly – articles are continuously being added to this collection.

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Separation by levitation

Michael Parkin writes about a hot ChemComm article for Chemistry World

 A team in the US has shown that enantiopure and racemic crystals can be separated by magnetic levitation.

The isolation of pure enantiomers is of particular importance in the pharmaceutical industry, where one enantiomer is typically responsible for the therapeutic effects of a drug, while the other may be inactive or even toxic. One alternative to the often used solution-based separation techniques such as high-performance liquid chromatography (HPLC) is to purify the desired enantiomer from a mixture of crystals of enantiomerically pure and racemic compound.


 
Read the original journal article in ChemComm – it’s free to access until 30th July:
Separation and enrichment of enantiopure from racemic compounds using magnetic levitation
Xiaochuan Yang, Shin Yee Wong, David K. Bwambok, Manza B. J. Atkinson, Xi Zhang, George M. Whitesides and Allan S. Myerson  
Chem. Commun., 2014,50, 7548-7551, DOI: 10.1039/C4CC02604G, Communication
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Goldilock’s Conundrum

Which Rotaxane Macrocycle is Just Right?

A rotaxane is a mechanically-interlocked molecule that consists of one or more rings trapped on a linear unit, the thread, by two bulky constituents, the stoppers. Remarkably, the ring components are not covalently attached to the dumbell component, rather a mechanical bond is present that intrinsically links the components of the molecule and prevents their dissociation without the cleavage of one, or more, covalent bonds. The synthesis of these interlocked molecules is of much interest to chemists today as a means of not only synthetically mimicking molecular geometries found in nature, but also, and perhaps more interestingly, as a means of exploiting the emergent properties imparted as a result of the mechanical bond for function as catalysts, motors and sensors, to name but a few examples.

The synthesis of rotaxanes is analogous to Goldilock’s quest to find the perfect bowl of porridge or the bed that is just right – finding the correctly-sized macrocycle to thread a rotaxane dumbbell is also a game of too big, too small or just right. Historically speaking, many of the rotaxanes reported thus far achieve “just right” by providing a steric bulk to the dethreading of the two components by simply increasing the size of the rotaxane stoppers. This is a valid approach, however it would also be advantageous in terms of synthetic ease and the possibility of introducing diversity to the rotaxane library if we could move away from big macrocycles and the necessary bulky stoppers, to smaller stoppers that allow for much smaller macrocycles.

But – how small is too small? Sometimes a macrocycle is just not big enough. Steve Moratti and James Crowley of the University of Otago, and coincidentally where i began my foray into chemistry, have set out to study just this – what is the smallest macrocycle that can be incorporated into a [2]rotaxane synthesized using the highly efficient Cu(I)-catalyzed Huigsen 1,3-dipolar cycloaddition active metal template approach developed by the Leigh group( JACS, DOI:10.1021/JA056903F).

To date, the smallest macrocycle that has been utilized in the synthesis of such rotaxanes is a 26-membered ring that generates [2]rotaxanes in high yields (DOI; 10.002/ANIE.201100415). Moratti and Crowley took this exploration a step further and studied the possibility of rotaxanation using even smaller 22- and 24-membered rings. One of the biggest advantages of moving towards smaller rotaxanes is the greater ability with which they can be functionalized over their larger analogues. Smaller macrocycles and less chemically-complicated stopper groups can be functionalized much more readily, as demonstrated in this work by the incorporation of a free hydroxymethyl group into the macrocycle and the use of unfunctionalized phenyl groups in the stopper components.

This study determined that the limit for rotaxanation was the larger of the two rings, with a [2]rotaxane forming in 70% yield –  read the article in full for free* to find out more!

CuAAC “click” active-template synthesis of functionalised [2]rotaxanes using small exo-substituted macrocycles: how small is too small?
Asif Noor, Warrick K. C. Lo, Stephen C. Moratti and James D. Crowley
DOI: 10.1039/C4CC03077J

You may also like to have a look at this Feature Article by Edward Neal and Stephen Goldup* from Queen Mary University, which reviews some of the less discussed consequences of mechanical bonding for the chemical behaviour of rotaxanes, and their application in synthesis

*Access is free through a registered RSC account – click here to register

About the web writer

Anthea Blackburn is a guest web writer for Chemical Science. Anthea is a graduate student hailing from New Zealand, studying at Northwestern University in the US under the tutelage of Prof. Fraser Stoddart (a Scot), where she is exploiting supramolecular chemistry to develop multidimensional systems and study the emergent properties that arise in these superstructures. When time and money allow, she is ambitiously attempting to visit all 50 US states before graduation.

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Reviewing the synthesis of marine sponge metabolites

by webwriter Kate Montgomery, who is currently doing a PhD in drug delivery using polymer based nanoparticles, her project is a collaboration between Imperial College London and CSIRO in Melbourne. When she is not making extremely sticky polymers in the lab, Kate enjoys reading, running (very slowly) and deep sea diving.

This ChemComm Feature Article by Chuo Chen’s group, based at the Southwestern Medical Center, University of Texas focuses on biosynthesis and total synthesis of cyclic pyrrole-imidazole dimers. Pyrrole-imidazole alkaloids are secondary metabolites which are found exclusively in marine sponges. They have very unique structures and attractive biological properties. Part of what makes these molecules so interesting is the fact that they contain many functional groups and are highly populated with nitrogen atoms. Pyrrole-imidazole alkaloids often have polycyclic skeletons which make them ideal platforms to work on in the development of new synthetic ideas and methodologies.

AgeliferinMany pyrrole-imidazole alkaloids have been tested and determined to have promising biological properties such as anticancer, antimicrobial, antiviral or immunosuppressive activities. Although this is the case, much work still needs to be carried out to determine the full biological profile of pyrrole-imidazole alkaloids.

Another aspect of pyrrole-imidazole alkaloids which still contains unknowns is the biosynthetic pathway; a range of biosynthetic pathways have been suggested but the complete route has not yet been fully determined. It is agreed that the main stages of the biosynthesis are catalysed by cyclases and oxidases but the exact enzymes have not been identified. A number of interesting hypotheses are highlighted and discussed in this review including work from Faulkner and Clardy who isolated the first dimeric pyrrole-imidazole alkaloid, sceptrin, in 1981.

As well as summarising different biosynthetic routes to these intriguing compounds the authors also discuss synthetic strategies. Numerous groups have successfully synthesised different pyrrole-imidazole dimers and highlights of this section include Baran’s work synthesising a number of different dimers and Chen’s own work which involves developing a biomimetic approach for the synthesis of ageliferins. Chen’s synthesis contains an oxidative radical cyclisation as the key step to give the ageliferin core skeleton. The group have successfully synthesised a range of ageliferins using this adaptable approach.

To download the full article for free* click the link below:

Dimeric pyrrole-imidazole alkaloids: synthetic approaches and biosynthetic hypotheses
Xiao Wang, Zhiqiang Ma, Xiaolei Wang, Saptarshi De, Yuyong Ma and Chuo Chen
DOI: 10.1039/c4cc02290d

*Access is free until the 12.07.14 through a registered RSC account – click here to register

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Dual warhead kills and disarms bacteria

Carla Pegoraro writes about a hot ChemComm article for Chemistry World

A compound that kills bacteria and cleaves their DNA to prevent them passing on drug-resistant genes has been designed by researchers in India.

The increasing ineffectiveness of antibiotics and the absence of suitable new ones are problems long recognised by the medical community. Bacteria can mutate and adapt to become resistant so the stock of effective antibiotics is diminishing. In a recent report, the UK’s Chief Medical Officer stated that increasingly resistant microbes represent a global threat that in the next 20 years could see many more deaths associated with what were routine and safe surgeries.


Read the full article in Chemistry World»

Read the original journal article in ChemComm – it’s free to download until 11th July:
A prospective antibacterial for drug-resistant pathogens: a dual warhead amphiphile designed to track interactions and kill pathogenic bacteria by membrane damage and cellular DNA cleavage
Durairaj Thiyagarajan, Sudeep Goswami, Chirantan Kar, Gopal Das and Aiyagari Ramesh
Chem. Commun., 2014, Advance Article, DOI: 10.1039/C4CC02354D, Communication

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