Toxicity is a hazardous waste

Today I came across an opinion article in Chemistry World which highlights what I believe is a very important issue – chemists today are not being properly trained and prepared in reducing toxicity in their methods.

Now, this isn’t only an issue for the green chemists out there – as chemistry undergraduates and postgraduates we’re often completely unaware of how significant the toxicity of solvents, reagents and products are further down the development pipeline of a new material. We’re simply overjoyed if we manage to make the product we’ve been working on for months, and we’re thrilled if it exhibits the properties we’ve been hoping for, such as cancer killing activity. Never do we step back and consider the carcinogenic chloroform we carried out a work-up with, or the explosive starting materials which couldn’t possibly be used on an industrial scale.

And, why would we? I personally only remember the reduction of toxicity being mentioned in specific green/environmental chemistry modules I chose as an undergraduate, which often leads students to only considering these issues in this context. It’s a green chemistry issue, not one to think about in every day synthetic laboratory work, right? I have come across some of these issues in my PhD, as its industrially funded, so I have some appreciation of what solvents might not be desirable/scaleable, but this has only been mentioned in passing, and I’ve had no formal training in this area.

It’s a common problem throughout chemistry degrees/PhDs, which his highlighted throughout this article. Newly trained chemists give very little thought to the toxicity issues of their work and, crucially, it isn’t instilled in them by their professors or supervisors that they should be. Indeed, many supervisors are more interested in results which they can publish than whether or not their methodology would be commercially viable. However, when these students venture out of academia into the world of industry, this is something they’ll very much have to be aware of, and this knowledge would be extremely useful if taught beforehand.

Unless we want to hide in academia forever, it’s about time we opened our eyes to how our chemistry might affect the real world, and whether the work we’re carrying out would be remotely industrially viable. If we came together with engineers, process chemists and industrial chemists, we could all save ourselves valuable time, energy and resources by knowing what our final goals really are.

Of course, chemistry for the sake of chemistry is still something I advocate – we always need to learn more about the world around us – but, if we’re going to have a grand goal for our research, we need to take a step back and no our limits right from the beginning. Only then, will we reach a conclusion everyone can benefit from.

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One metal centre, three different M-N bonds!

Why have one type of metal-nitrogen bond when you can have three? Well, a team from Michigan State University have done just that! A fascinating nitrogen analogue of the Schrock and Clark “yl-ene-yne” complex, W(CBut)(CHBut)(CH2But)(dmpe),  has been published in Chemical Science today.

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The compound and Schrock’s carbon analogue were both analysed using a combination of Mayer bond orders and Natural Resonance Theory (see above), which were both in good agreement and showed triple, double and single bonds to all be present in each compound.

The new compound unsurprisingly gave interesting reaction products with different electrophiles. Indeed, reactions with methyl iodide and acetic anhydride occur at the imido nitrogen, which may be predictable since you might expect a more negative charge to be located there. However, pivaloyl chloride reacts at the nitrido nitrogen atom, giving a rare example of a transition metal nitrido complex containing a carboxyl group on the nitrogen. This outcome may be down to sterics, but it would be very interesting to see the scope of reactivity with this new complex and other electrophiles.

All in all, this is a pretty cool new compound, and I’m sure we’ll see lots of interesting chemistry coming from it.

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The Chemistry of Chocolate

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If you’ve got a sweet tooth, like me, you’ll be interested in this article published in Chemistry World this month outlining the chemistry behind perfectly tempered chocolate.

Tempering of chocolate involves the alteration of the crystal structure of the cocoa butter within chocolate to the highly desired V polymorph, and maintaining this high-gloss state means tempering must be carried out every time chocolate is heated and manipulated.

With cocoa butter being able to crystallise in 7 different polymorphs, the temperature of the chocolate must be carefully controlled and held between 27 and 35 degrees Celsius to achieve the desired effect. The process sounds simple, but is in fact terribly tricky.

Indeed, Matt Hartings, who teaches the chemistry of cooking classes at  American University, Washington DC, states that ‘Chocolate is one of the more demanding things chemically to work with.’

The changing crystal structures of cocoa butter explains why chocolate tends to go white over time, as the more stable polymorph VI is formed, which diffuse light and give the paler, less glossy colour. They can even explain how flavour can be changed, as smaller crystals release flavour more slowly into the mouth. It’s then down to the organic molecules within the chocolate to fully define what the flavour will be like.

The article goes on to describe how water emulsions can be used instead of traditional chocolate fillings such as creams and butter to give a creamy sensation in the mouth without taking over the chocolate flavour and giving the chocolates fewer calories.

The chemistry of chocolate is more complex and more intricate than I’m sure many of us imagined, and I found it fascinating reading about the level of control and thought required to make high-quality chocolate.

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Spicing Up MOFs

This article on the Chemistry World website describes interesting new research into Metal Organic Frameworks (MOFs) made from bio-friendly curcumin – one of the ingredients of turmeric.

A MOF is a 3D framework constructed with metal centres joined together by an organic linker capable of binding to 2 or more metals, and their chemistry has really exploded in recent years, with them being peddled as solutions to a variety of the world’s main chemical problems, such as hydrogen storage and the capture of carbon dioxide. Indeed, we have a large MOF research group right here in Nottingham focusing on such applications. MOFs for these uses typically need to have high porosity and surface area, and measuring this is often an early indication of their performance.

However, many of the highest performing MOFs are constructed from expensive rare metals or petrochemical-derived ligands. This limits their eventual applications as, if they’re to compete industrially, they need to be cheap and sustainable. A team of researchers led by Guangshan Zhu from China may have overcome this in their construction of a MOF designed to deliver drugs.by using the naturally-occurring pigment curcumin, which has anti-cancer properties itself.

The group used biologically-friendly zinc as their metal centres, with curcumin ligating between them. The resulting framework was found to be highly porous, and initial studies have shown it is able to deliver ibuprofen into the body. What’s more, the MOF degrades under biological conditions to also deliver curcumin, which means both drugs can be delivered effectively using this framework.

This really is exciting news for both the MOF and science communities, as it could pave the way for a new method of drug delivery into the body which has real potential for the future.

You can find the original research article here on the Royal Society of Chemistry website.

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Cider Science

This interesting article from Chemistry World this week explores the chemistry behind the cider making process.

Many of us are aware of the basic science behind the fermentation process – turning sugar into alcohol – but do you know what chemicals are responsible for the various flavours and aromas in each different cider?

The article explains the whole process of cider production, which is unknown to many of us, and is a career path many chemists wouldn’t have even thought of. It’s actually quite complex, and even the exact variety of apple can have a massive effect on a cider by having different amounts of tannins and malic acid. Apple tannins vary between different apple varieties, with the degree of polymerisation of polyphenols affecting the bitterness of the cider.

There’s also some insight into the research being carried out into cider production, and the analysis being carried out by chemists not only to determine the composition of ciders, but to investigate the processes at work during their fermentation.

It really is quite a fascinating read, and I personally always enjoy finding out the chemical background of something apparently so simple in our every day lives.

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NMR – Atom by Atom

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This interesting post on the Chemistry World website describes a very exciting piece of research published in Science recently that describes a new technique which may allow us to ‘see’ individual spins of electrons and atoms in a molecule – possibly leading to atom-resolved NMR spectroscopy.

The technique utilises a a STM set up which is sensitive enough to detect the flipping of spins within atoms of the molecule being probed. They managed to use a radiofrequency wave, such as those used in NMR or EPR, to induce transitions between the two spin states of the nuclei being analysed, which alters the current in the STM and leads to a peak in the detection.

The team were able to probe a terbium sandwich complex, and were even able to monitor several hyperfine transitions due to couplings between the spins being observed.

The work is still in its early days, and more depth is definitely needed, but it’s interesting and exciting research which could not only lead to atom by atom resolution in magnetic spectroscopies, but also allow for manipulation of nuclear spins on the road to spintronics and quantum computing.

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Highlights from Dalton 2014

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As you know, this week I attended the Royal Society of Chemistry‘s Dalton 2014 conference held at the University of Warwick. It was three days of key note lectures, shorter presentations from young researchers, a poster session and lots of food and drink. Overall, it was a great experience – the science was not only interesting but relevant and novel, and Warwick looked after us very well. The the Dalton Division’s new president, Professor David Cole-Hamilton, welcomed us all very warmly, and his enthusiasm for the conference and the division came across immediately.

The key note lectures over the 3 days covered all of the 4 sections which had come together for the conference – coordination chemistry and organometallics, main group chemistry, inorganic reaction mechanisms and bioinorganic chemistry. This gave every delegate the chance to experience something outside their immediate area of interest.

Highlighted Speakers:

Richard Layfield – University of Manchester – Reactive Metal-Carbon Bonds in Three-Coordinate Iron NHC Complexes – Winner of the Sir Edward Frankland Fellowship

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If you haven’t heard of NHCs, or N-heterocyclic carbenes, where have you been for the last few years? They’ve been coming up in all areas of inorganic chemistry, and have been used to stabilise all manner of interesting and reactive compounds. Dr Richard Layfield has been working on three-coordinate iron complexes featuring bulky NHC ligands which have been proving to have interesting structures and reactivity. I heard Richard give a talk a year ago at the Coordination Chemistry Discussion Group Meeting last July at Imperial College London, and he is still a great speaker, who conveys real enthusiasm for his work. I suggest anyone interested in this area takes a look at his research webpage for for information.

Rebecca Melen – University of Toronto – Activation of Alkynes with B(C6F5)3: Intramolecular Cyclisation Reactions and Rearrangements – Winner of the Dalton Young Researcher Award

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Rebecca is another researcher I’ve heard speak before, and here she was explaining her work which led to her receiving the Dalton Young Researcher award. Being a main group chemist myself, I take a great deal of personal interest in Rebecca’s work, particularly in the area of frustrated Lewis pairs. I was impressed by the remarkable volume of work she has carried out, and found her to be an engaging and interesting speaker. She explained her research into various main group-catalysed processes, which proved to be very efficient, and could lead to the replacement of transition metal catalysts in some reactions. Having already amassed a number of publications and having received a string of awards through her academic life, Rebecca is definitely a young researcher to keep an eye on!

Kit Cummins – MIT – Group 15 Element Triple Bonds and Reactive Intermediates

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This was one of the highlights for me! Professor Christopher Cummins is an excellent speaker, and his research group at MIT carry out some very interesting work utilising low-coordinate transition metal compounds to activate various important small molecules, such as N2, and to provide accessible routes to new small molecules, such as the P2 and PN. I myself remember during my undergraduate studies learning about his molybdenum-amido compound which was able to split dinitrogen, which was a remarkable discovery. Kit has continued this work into the activation of heavier group 15 molecules, with very interesting results so far. His work was fascinating, and he was an excellent speaker, providing a great deal of knowledge and detail to support his discoveries. If you’re interested in low-coordinate coordination compounds and their reactivity, I strongly suggest looking into his work. You can find his webpage here.

 

Other than the key note lectures, there was a plethora of shorter presentations given by PhD students and post-doctoral researchers. These were split into four parallel sessions each day, for each of the 4 interest groups which were attending. I admit I mostly went to the Main Group presentations, which proved to be interesting, engaging and to contain very high-quality science. For such a small interest group, there’s a great deal of variety and good work coming out of it, and I found myself furiously scribbling down notes throughout.

I particularly enjoyed Dr Ewan Clark, from the University of Manchester, talking about his work on frustrated Lewis Pairs, Owen Metters, from the University of Bristol, talking about the use of amine-boronium cations to synthesise polyaminoboranes, Dr Benjamin Day, from the University of Manchester, talking about the selective functionalisation of pentadienylsilanes, Rebecca Musgrave, from the University of Bristol, talking about silicon-bridges ferrocenophanes and Dr Sophia Solomon, from the University of Cambridge, talking about mesityl-phosphonium salts. However, all of the presentations were very good, and I was very pleased with the standard of talks throughout the conference.

On the first evening there was a poster session consisting of over 150 excellent posters, which gathered considerable interest from students and academics alike. I myself presented a poster on radical BODIPY anions and other main group analogues, which I thought was a bit of a different area that hadn’t been talked about elsewhere at the conference. The session was great for allowing researchers to network and learn about what other work was being carried out within the Dalton Division. Hopefully, this will pave the way for new collaborations and the sharing of information for the benefit of the progression of this area of chemistry. The posters were mostly of a very high quality, and it was encouraging to see so many PhD students getting both their names and research known in the inorganic chemistry community.

 

Overall, I thoroughly enjoyed my time at Dalton 2014, and I am greatly looking forward to the next one in two years!

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