Archive for 2011

Copper sulfide nanotwins

In their recent CrystEngComm paper, Zhimao Yang and co-workers from Xi’an Jiaotong University in China, tell us about the cubic CuS cages they have synthesised. These cubic cages (see image below) form high-activity nanotwinned building blocks. The group also study the significance of these copper sulfide nanotwinned structures for enhancing the catalytic degradation of methylene blue (MB). Read more in the article below – free to access until the 2nd December.

Copper sulfide cages wholly exposed with nanotwinned building blocks
Shaodong Sun, Xiaoping Song, Chuncai Kong, Dongchu Deng and Zhimao Yang
CrystEngComm, 2012, DOI: 10.1039/C1CE06135F

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CrystEngComm Symposium: Pharmaceutical Polymorphism

CrystEngComm Symposium: Pharmaceutical Polymorphism
Many different aspects of polymorphism as it relates to pharmaceutical solids were discussed at the CrystEngComm Symposium: Pharmaceutical Poymorphism in The Chemistry Centre, Friday 4th November.
 
From modelling and control, through development and formulation to intellectual property aspects, all areas concerning the impact that polymorphism has on the development of pharmaceuticals were covered by the speakers. Dr Örn Almarsson (Alkermes Inc. USA) began the day with an overview of crystal polymorphism and pharmaceuticals, followed by Dr Graeme Day’s (University of Cambridge, UK) account of how computational methods are being developed to deal with complex molecular flexibility when predicting polymorphs and crystal structures. Professor Ivo Rietveld (Universite Paris Decartes, France) then closed the morning session with a review of using pressure-temperature diagrams to determine the stability hierarchy of a set of polymorphs.
 
Dr Ann Newman (Seventh Street Development Group, IN, USA) began the afternoon session with a discussion of the importance of solid form screening to drug development, while Dr Simon Black  (Astra Zeneca, UK) illustrated some of the issues around the discovery of a new polymorph with some interesting case studies.
 
Professor Jamshed Anwar (University of Bradford, UK) outlined the methodology for molecular simulation and its application to polymorph phase transitions, followed by Dr Z. Jane Li  (Boehringer Ingelheim, USA) who gave an overview of the impact that the necessary control of polymorph formation has on the development of pharmaceutical formulation.  Dr Avijit Kelkar (Dr Reddy’s Laboratories (UK) Limited, UK) then finished the Symposium by sharing his expertise in the area of patents and intellectual property.
 
Many thanks are due to CrystEngComm Editorial Board member, Dr Z. Jane Li, who provided the vision and concept behind the symposium, and without whom the event would not have been possible. Full details of the presentations (abstracts, biographies etc), take a look at the symposium programme which can be found on the symposium website.
 
CrystEngComm will publish a themed issue on ‘Crystal engineering and crystallography in the pharmaceutical industry’ in early 2012 with Guest Editors Dr Magali Hickey, Dr Örn Almarsson and Dr Matt Peterson. For more information, contact the Editorial Office.


 

 

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Interview: Nobel prizewinner Dan Shechtman

Dan Shechtman copyright Technion

Professor Dan Shechtman holds the Philips Tobias chair of Materials Science at Technion – Israel Institute of Technology. Prof. Shechtman was an NRC fellow at the aerospace Research Laboratories at Wright Patterson AFB, Ohio, where he studied for three years the microstructure and physical metallurgy of titanium aluminides. In 1975 he joined the department of materials engineering at Technion. In 1981-1983 he was on sabbatical at the Johns Hopkins University, where he studied rapidly solidified aluminum transition metal alloys (joint program with NBS). During this study he discovered the Icosahedral Phase which opened the new field of quasiperiodic crystals. In 1992-1994 he was on sabbatical at NIST, where he studied the effect of the defect structure of CVD diamond on its growth and properties. For the past 6 years he has also been a part time faculty member of Iowa State University. He recently won the Nobel Prize in Chemistry 2011 for his discovery of quasicrystals.

What achievement are you most proud of?
The whole thing. I have opened a door to something new in crystallography, and many crystallographers came in through it, resulting in a paradigm shift. Many believed, many did not, and so it was a battle of minds for ten years.
In 1982, I was alone, and couldn’t explain my results. In 1984, I returned to Technion, where my colleague Ilan Blech was the first to believe in my findings, and helped by elucidating the structure and building a model to explain this phenomenon. We submitted this in 1984 to the Journal of Applied Physics, but it was rejected, and we finally managed to publish it in Metallurgical and Materials Transactions more than half a year later. In the meantime, John Cahn (my colleague at NIST) and the French crystallographer Denis Gratias became involved with the project, and we submitted a short paper to Physical Review Letters based on my original results from day one. In the period that followed, many scientists accepted quasicrystals, but there were still many people who rejected the idea, including the International Union of Crystallography (IUCr). They wanted single crystal X-ray diffraction results to definitively confirm the existence of quasicrystals.
Between 1984 and 1987 many attempts were made to grow crystals big enough for single crystal X-ray diffraction, and two groups in Japan and France achieved it. I presented these results at the 14th IUCr Congress in Perth, Australia, and the crystallographic community finally said ‘OK Danny, now you are talking!’ and they established a committee to redefine crystals. This was very meaningful, as it demonstrated that the community could be open to new discoveries.

What drove you to stand by your results, even though you knew many people would challenge them?
Most of the people in my close environment who knew didn’t believe and were very negative about my findings, and some were even negative towards me. Some of my colleagues at NIST, where I was on sabbatical, were more subjective. My host John Cahn told me: ‘Danny, this material is telling us something, and I challenge you to find out what it is.’

I am my own worst critic. I tried everything necessary in order to convince myself that I knew what it was not. No one had a better explanation. I remember the discovery date well, April 8 1982.

Electron diffraction played a fundamental role in the discovery of quasicrystals, and it is still a growing field. What are your thoughts on electron diffraction?
Electron diffraction is a wonderful tool, and nowdays it can be a wonderful crystallographic tool. Before electron diffraction was not as precise, but now using convergent beam electron diffraction we can determine with precision the structure of tiny crystals. Electron diffraction is the tool for discovery.

What projects are you working on at the moment?
I am looking at a range of materials, such as the B2 materials which are intermetallics. There are B2 materials which are very brittle, but we are working on some which are very ductile. We are now working mostly with Mg alloys for various applications, such as biodegradable and biocompatible implants and as antibacterial materials to fight bacterial infections.

What will be the next big breakthrough?
Nobody knows! Great discoveries are stumbled on. If you are clever enough you will work hard on a problem and elucidate the answer.

Do you have any advice for young scientists?
Be an expert in something, regardless of what it is. I was good at electron microscopy, but you can be good at X-ray diffraction, synthetic chemistry etc. Read everything, familiarise yourself with the instrumentation and methodology so that when you see something different, you will realise and know that it is different, rather than thinking it is an anomaly or an error.

Find out more about Dan Shechtman on his webpage at Technion Institute of Technology. You might also be interested in reading more in my recent blog on Professor Shechtman’s Nobel Prize.

Why not check out Chemistry World’s recent story on this year’s award too!

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HOT Article: Nano-bamboo shoots

In this CrystEngComm HOT Article, two kinds of micro/nano-sized single-crystalline cuprous oxide (Cu2O) crystals with novel porous cubic or hierarchical rod-like morphologies were successfully synthesized via a facile ethanol-assisted double-solvothermal method. It was found that the addition of ethanol in precursor solution is critical for the formation of hierarchical rod-like structures (nano-bamboo shoots). Their growth process and shape evolution together with their optical properties and field emission have also been reported.

Read more about nano-bamboo shoots for FREE until the 22nd November at:

Controllable synthesis of novel Cu2O micro/nano-crystals and their photoluminescence, photocatalytic and field emission properties
Hui Shi, Ke Yu, Fang Sun and Ziqiang Zhu
CrystEngComm, 2011, Advance Article

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HOT Article: New model for disorder in vaterite

Vaterite is one of the three crystalline polymorphs of calcium carbonate, and plays a significant role in biomineralisation, either as an intermediate formed from amorphous calcium carbonate prior to transformation to aragonite or calcite, or can be utilized by organisms in its own right.

Recently there have been several key advances in our understanding the formation of calcium carbonate, and owing to its great importance not only in biomineralization the lack of a proper understanding of the solid-state structure of vaterite is certainly a considerable deficit. Despite its significance, there has been considerable debate regarding the nature of the structure of this material. While vaterite is known to exhibit disorder, several ordered structures are used as models to understand its crystal chemistry. In this HOT Article, Demichelis et al. have used ab initio calculations to show that the two most widely used structural models are actually transition states, rather than being stable, and that the third proposed literature model is too high in energy to be viable. Several new distorted structures for vaterite are proposed that are very close in energy and able to interchange, thereby creating a mechanism to explain the observed disorder. The final nature of the disorder may ultimately depend on the kinetics of the transformation from a precursor phase, as postulated for the ikaite to vaterite conversion.

Read more for FREE until the 22nd November at:

A new structural model for disorder in vaterite from first-principles calculations
Raffaella Demichelis, Paolo Raiteri, Julian D. Gale and Roberto Dovesi
CrystEngComm, 2011, Advance Article

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Hot Article: Polar polymorph with potential

In their recent CrystEngComm Hot Article, Xutang Tao and colleagues report the successful growth of bulk α-BaTe-Mo2O9 polar single crystals using a top-seeded solution growth method. The search for new polar materials is of current interest owing to their potentially important functional properties including piezoelectricity, pyroelectricity, ferroelectricity and secondharmonic generation activity.Indeed these large crystals offer a promising candidate for optical devices such as light modulators, colour filters, wave plates and
optical axis gratings.
Find out more about this polar polymorph by reading the article – free to access until 24 November 2011.

Bulk crystal growth and characterization of a new polar polymorph of BaTeMo2O9: α-BaTeMo2O9
Junjie Zhang, Zhonghan Zhang, Youxuan Sun, Chengqian Zhang and Xutang Tao
CrystEngComm, 2011, DOI: 10.1039/C1CE05922J

 

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Hot Article: Making IMP-15

Scientists from Imperial College London, UK have made a novel hexacarboxylate organo-silicon molecule and used it in the construction of IMP-15–a Metal Organic Framework (MOF) material with pcu topology which is isoreticular to MOF-5 but with half the metal loading. Read more about IMP-15 in their recent Hot Communication in CrystEngComm:

An organosilicon hexacarboxylic acid and its use in the construction of a novel metal organic framework isoreticular to MOF-5
Robert P. Davies, Paul D. Lickiss, Karen Robertson and Andrew J. P. White
CrystEngComm, 2012, DOI: 10.1039/C1CE06091K

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Hot Article: Erratic aspirin crystallisation

In their recent CrystEngComm Hot Article, Katarzyna Solanko and Andrew Bond, from the University of Southern Denmark, looked at solution crystallisations of 5-X-aspirin (X = ¼ Cl, Br) to investigate if the polymorphism was affected by the presence of analgous aspirin anhydride species. The group show that small changes in temperature when the compound is being made can lead to erratic and apparently irreproducible crystallisation results, especially if the impurities remain undetected.

Read the article itself for FREE, until mid-November, to find out more.

Influence of impurities on the crystallisation of 5-X-aspirin and 5-X-aspirin anhydride polymorphs (X = Cl, Br, Me)
Katarzyna A. Solanko and Andrew D. Bond.
CrystEngComm, 2011, DOI: 10.1039/C1CE06065A

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Gautam Desiraju reveals his favourite space group!

Professor Gautam Desiraju was born in Madras, India, and received his B.Sc. at the University of Bombay, India, in 1972. He was awarded his Ph.D. from the University of Illinois at Urbana-Champaign, USA, in 1976. After two years at Eastman Kodak Company, Rochester, New York, USA, he joined the faculty at the University of Hyderabad, India. He left the University of Hyderabad in 2009 and is currently at the Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore. He was recently was elected President of the International Union of Crystallography (IUCr) during the IUCr General Assembly in Madrid, Spain for the triennium 2011-2014.
 
Prof. Desiraju was one of the founder members of the CrystEngComm Editorial Board and has also served on the Editorial Advisory Board of ChemComm. His 1989 book on crystal engineering and 1995 review in Angewandte Chemie on supramolecular synthons redefined several aspects of the subject of crystal engineering, and in particular led to an emphasis on the study of hydrogen bonds and other intermolecular interactions.  
 
Why did you want to become a scientist?
I always liked chemistry, I was fascinated by it. During my first lab experiment in chemistry I remember thinking I didn’t want to do anything else. I was very lucky that I had the opportunity to do what I liked.

What projects are you working on at the moment?
So many projects that I have lost count! Currently I have at least 10-15 projects underway in my group. We are very excited about nanoindentation, which is a new technique that allows us to experimentally compare the interaction strengths and monitor anisotropy of molecular crystals. This requires a very good student as it is a very laborious process – you need to know the faces of the crystal really well.

What do you think will be the next big breakthrough in your field?
If I knew what it was, I would be doing it! The beauty of scientific research is that you never know. If you could predict the next breakthrough, everyone would have gotten there!

How do you think Crystal Engineering will develop in the next couple of years?
There is no doubt that crystal engineering has spread far and wide. Unlike other areas in crystallography, it has attracted lots of people and interest, even though it is hard. Big ideas in chemistry are sustained when there is commercial application because this brings in money to attract research. Crystal engineering is very lucky as areas like metal-organic frameworks and pharmaceuticals are very big and have lots of money, and so there is lots of interest. The commercial applications and the challenge are an irresistible temptation. No subject addressed by the both the RSC and ACS can be small.

According to the evolutionary model it is the survival of the fittest, and so the not so good areas of science will die out because of the lack of support. These are not good times for science, and we do need to worry about it. However, the future is very bright for crystal engineering, as the pharmaceutical industry sustains the organic research, and the chemical industry sustains the metal-organic framework research.

What is the most rewarding aspect of your work?
Just the fun of doing it! Scientists like me are very lucky as we work with young people all the time, which keeps both the scientist and the young person active. Other careers such as medicine, police, etc. are not so happy because they are not exposed to young people as much, but we are fortunate enough to see the ‘innocence of life’ all the time.

What is the secret to a successful research group?
This really depends on the personality of the research advisor, because they are the central person in the group. As the manager it is their role to get the best output possible out of the team depending on how they motivate the people around them. It is a very fine balance between happiness and productivity. There should be an abundance of both in every research group.

What achievement are you most proud of?
Pride is a bad word. All scientists like to do their own thing. Serious scientists would do this irrespective of anything. It is best when you do it for yourself and it interests your peers. For my plenary at the IUCr Congress in Madrid I specifically kept the material to be recent, and even though there was a large lecture hall full of people at 9am on the last day of the conference, I could have easily have given that talk to myself, as it gives me the greatest happiness to explore my work.

What advice would you give to a young scientist?
Go have fun in the lab. Be bold and do what you like to. Let go of inhibition and remember that your training is only a platform so you don’t do nonsense. Research is highly individual, and you have to do your own thing. Think like this from the very beginning.

What would you do if you weren’t a scientist?
I would have studied history or sociology.

What is your favourite space group and why?
P21/c  with Z’=1 (not 0.5 + 0.5), because this is the norm, and merits no further consideration. Anything else needs a chemical explanation, as this condition requires no chemistry. What is not P21/c with Z’=1 is crystal engineering/me.

What was your first crystal structure?
It was horrible! I did my PhD in the US in 1975, and we had to hand-centre the reflections before data collection! It was hard work and lots of effort to turn arcs on this enormous machine. The structure was in Pbca with a c-axis of 44Å and very close spots. I was baptised by fire! You never forget the first!
 
 Find out more about Gautam Desiraju on his webpage at the Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore
 
Read some of Gautam’s exciting research in the following articles:
 
Shape and size mimicry in the design of ternary molecular solids: towards a robust strategy for crystal engineering
S. Tothadi, A. Mukherjee and Gautam R. Desiraju
Chem. Commun., 2011, Advance Article
DOI: 10.1039/C1CC14567C
 
Drug-drug co-crystals: Temperature-dependent proton mobility in the molecular complex of isoniazid with 4-aminosalicylic acid
Pawel Grobelny, Arijit Mukherjee and Gautam R. Desiraju
CrystEngComm, 2011, 13, 4358-4364
From themed issue Dynamic behaviour and reactivity in crystalline solids
 
Nature and strength of C–H···O interactions involving formyl hydrogen atoms: computational and experimental studies of small aldehydes
Tejender S. Thakur, Michael T. Kirchner, Dieter Bläser, Roland Boese and Gautam R. Desiraju
Phys. Chem. Chem. Phys., 2011, 13, 14076-14091
From themed issue Weak hydrogen bonds – strong effects?

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HOT Article: Role of anions in coordination polymer structure

In this HOT Article, two new phenyl-bridged pseudopeptidic ligands have been prepared and structurally characterised. The nature of the ligands’ substituents play an important role in the nature of the solid state structure yielding either hydrogen bonded linked sheets of molecules or infinite hydrogen bonded networks. To investigate this further, these ligands were reacted with a range of zinc(II) salts with the aim of synthesising coordination polymers and networks; the role of anions in determining the final structure was explored.

Read more for FREE about the role of anions in coordination polymer structure until the 9th December 2011 at:

Zinc(II) coordination polymers with pseudopeptidic ligands
Vicente Martí-Centelles, D. Krishna Kumar, Andrew J. P. White, Santiago V. Luis and Ramon Vilar
CrystEngComm, 2011, Advance Article
DOI: 10.1039/C1CE05872J

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