Reactions – Ann Valentine

Ann Valentine is in the Department of Chemistry at Yale University, and works on how biology handles metal ions that are very sensitive to hydrolysis.

1. What made you want to be a chemist?

It was a “Goldilocks” decision…I loved basic science, but biology is too big (and also too complicated), and physics is too small (particle physics)… AND too big (astrophysics). Chemistry ‘the molecular scale’ was just right. Also, in my sophomore year of high school, my science club mentor, Ada Margaret Hutchison, let us have free rein in the lab for most of the year. I set a lot of things on fire. And I thought: sign me up for THIS!

2. If you weren’t a chemist and could do any other job, what would it be – and why?

I’d be a middle school science teacher. I love doing outreach programs with that age group – when kids aren’t too cool to get unabashedly excited about science. High school kids, on the other hand, terrify me. There have been exceptions, but they’re often too busy impressing each other to really get into science.

3. What are you working on now, and where do you hope it will lead?

In one of our projects I’m thinking about this afternoon, we’re working out some fundamental interactions of Ti(IV) with biomolecules that I hope will lead one day to a wide appreciation for a role for this metal ion in biology. Right now we all think of titanium as being mostly inert, but I find it hard to accept that biology would never have found a productive use for this incredibly abundant element for which humans have found many applications.

4. Which historical figure would you most like to have dinner with – and why?

I’d pick Ed Ricketts, a sort of renegade marine biologist who worked in Monterey, CA until the 1940s. He was a buddy of John Steinbeck and the inspiration for his character “Doc” in Cannery Row. Steinbeck wrote a tribute called About Ed Ricketts that’s now published with The Log from the Sea of Cortez, a book which describes their great adventure together. Reading that tribute makes me want to have a meal – or maybe a beer – with Ricketts. I imagine it would be scientifically enlightening but mostly really, really entertaining.

5. When was the last time you did an experiment in the lab – and what was it?

My most recent lab notebook entry is June 22, 2007. I was trying to troubleshoot the purification of a ferritin protein by getting in there and doing it all myself. The final gel is missing because I got distracted by some other demand on my time and left the gel in destain for a week. More often now, rather than trying to do anything myself, l spend a few hours alongside a grad student “helping” them with an experiment or an instrument they’re having trouble with – most often they figure it out themselves just to get me out of their way.

6. If exiled on a desert island, what one book and one music album would you take with you?

Wow, the urge is so strong to pick some highbrow thing that will make me sound smart and impressive. But I’ll be honest – the one book I re-read every few years is A Prayer for Owen Meany by John Irving. And an album I’d listen to anytime would be by Marc Cohn – let’s say his “Live 04-05” disc for a mix of older and newer.

7. Which chemist would you like to see interviewed on Reactions – and why?

Have you interviewed Harry Gray yet? He can always be counted on to be entertaining – I’ll bet he’d have great answers to your questions.

IUPAC ’09: Magical molecular machines

This afternoon’s session was one that leapt out of the (shoulder-destroying 2.4 kg) abstract book: Molecular Machines and Devices. Itamar Willner, Alan Rowan, Dirk Guldi, Lee Cronin and Harry Anderson. Some line-up! And all tucked away in a just-about-big-enough room in the depths of the conference venue.

Without wishing to summarise everything, I’m going to pick on the two talks I enjoyed most: Alan Rowan’s and Lee Cronin’s.

Alan Rowan covered his work trying to understand how long chain molecules thread through macrocycles – as an analogy to DNA polymerase. The macrocycle can be a catalyst that epoxidises double bonds, so being able to do it an controlled way would be very useful. Unlike the enzyme, it just hops about attacking double bonds almost at random. They’ve studied a non-catalytic macrocycle and found out all sorts about how the length of the chain and the size of the macrocycle affects things. I started to wonder if you could make a macrocycle with a variable aperture and control things that way – anyone got any ideas how to do that??

Lee Cronin’s talk had tons of videos – ranging from ‘cartoon’ simulations of the insides of the polyoxometalate (POM) cavity materials his group makes. As he said, they were a little big of a rollercoaster ride and I found myself wishing I was sitting further away from the screen at one point! But they did emphasise the cavernous space inside these things – ‘like a cathedral’, as Cronin said. The other videos were actual films (through a microscope) of the microtube growth from POM crystallites, as reported in our own issue 1 (free to read!). The ones where the growth could be controlled and played about with went down very well. He finished off with some some videos of ‘bags’ of these materials, acting almost like little reaction vessels – the colour change of a potassium permanganate solution was very striking.

The theme continued with the Plenary from Ben Feringa, with an amazing array of molecular machinery. I’ll leave you with some of his closing thoughts: Will we one day have nanomachines in our bloodstream, delivering drugs and tidying up our arteries? He doesn’t know, but was optimistic, because today’s chemist has a lot more available to him/her than nature did – we’re not limited to amino acids, for a start!

Neil

Neil Withers (Associate Editor, Nature Chemistry)

IUPAC ’09: Thinking big to save the world

The plenary lecture this morning was by Peter Bruce, from the University of St Andrews, over on the east coast of Scotland. His message was an appeal to chemists to open their minds in order to save the world from climate change. Free yourselves from thinking of the immediate applications, he said, and this challenge can be faced. “The chemistry to tackle this is still going to be fundamental chemistry,” he says. Chemists should forget the immediate technical challenges.

Stirring stuff. And he had some very good reasons for saying this. Bruce has spent many years looking at ion transport in polymer electrolytes, and along the way has invented a better way to probe the structure of these large crystalline polymers that are otherwise too large to get x-ray crystal structures of.

How can this help climate change? Well these fundamental chemistry advances have found their way into lithium batteries – the things that charge our laptops, mobile phones, as well as powering tiny implantable medical devices of the future.

Bruce is now looking at ways that might – eventually – make the charging and recharging process of batteries much much faster. This process involves lithium ions moving from one material to another. They travel one way when the battery is being used, and when it’s plugged in again to recharge, they hop back over from whence they came. As many of you will know, this can take hours.

Bruce’s work on solid crystalline polymer electrolytes could help. But to understand how these materials work their molecular-scale structure needs to be understood. The problem has been getting single crystals to do crystallography on. So Bruce developed a powder diffraction technique that worked a treat.

He’s also spent a lot of time investigating why and how these crystalline polymers can conduct. The reason is that ions in crystalline polymers hop, which is very different to the way floppy non-crystalline systems work, he says. The conductivities they show are way too low for industry, he says, but doesn’t much care. “Scientifically it opens up new avenues,” he said. And curiosity has led his group to investigate other metals in the same group of the periodic table as lithium.

Next is the challenge of making the energy density of the materials better. To try and get a ten-fold improvement in energy, Bruce has developed a lithium-air battery, where oxygen from air reacts to start the ion motion. It’s a neat idea, and you never know, it could work.

IUPAC ’09: Save the symbol!

Remember the latest addition to the periodic table, copernicium, element 112? Well the fall out from the name choice has begun.

The abbreviated symbol that discoverer Sigurd Hofmann chose was Cp. This hasn’t been confirmed by IUPAC yet, and this is the body that has the say in the end, but it seems appropriate that here at the IUPAC congress that the discussion over this shortened symbol should be aired.

The problem is that for many synthetic chemists Cp already means something – it is used as a shorthand form for the cyclopentadienyl ring, a 5 carbon and 5 hydrogen ring that is aromatic like benzene and often used as a ligand.

So some chemists are inevitably unhappy about the use of Cp for another purpose. One of these is Paul Chirik from Cornell University who in his talk about main group chemistry apparently said he wanted to start a campaign to have the abbreviation Kp, not Cp used for element 112. This, apparently is etymologically correct, because Copernicus was actually Polish and his name was spelled Mikolaj Koppernigk.

Chirik assures me he said this in jest and is by no means an expert in this area. But I wholeheartedly encourage this kind of campaign! Come on chemists, stand up for the rights of cyclopentadienyl ligands! Kp vs Cp – what do you think?

IUPAC ’09: Chemistry in the main (group)

So since Monday I’ve been hopping between a few different symposia, starting with Functional Metal Complexes and Ligand Design, a meaty bit of Main Group Chemistry and finishing off with a little Degradable Polymers for Biomedical Applications. And of course the Plenaries ranging from the H + H2 reaction (a truly excellent talk from Dick Zare) to dendrimers/graphene ribbons (and a lot else besides from Klaus Müllen) to protein misfolding (well put across for chemists by Christopher Dobson). [It’s nice to see the increasing numbers of atoms involved in those three talks – which is certainly not to say complexity based on some the calculations/experiments Zare carefully didn’t go into too much detail on!]

Phew! What’s caught my eye then?

Probably the first session in the Main Group symposium. Rab Mulvey’s keynote gave a good overview of his work adding metals to organic compounds that don’t normally like to be metallated – and with metals that don’t normally like to be added. Metals outside of Group 1 are a bit shy of being added, but if there’s a Group 1 metal there to hold their hand, it can be done. It’s illustrated well in this Angewandte Chemie cover with the punning subtitle “Check M(etall)ate”. I think this needs explaining! Thankfully, he did: the queen (Na, Li) is normally the most powerful piece on the board (best at metallating), but this time it’s the lowly knight (Cr, Mn, Fe) that is holding the king (benzene or similar) in check, with the queen (Na, Li) covering (synergically bonding). Great analogy!

I also enjoyed Mikael Håkansson’s talk. He started with a quotation from McMurry’s Organic Chemistry that you can’t generate optical activity from non-optically active starting materials. Wrong! Håkansson showed some examples of chiral Grignard intermediates that are racemic in solution, but only one form crystallises. Induce crystallisation and you’ve got something chiral from achiral starting materials. If you then do a reaction in a solvent that promotes the reactions while hindering racemisation, you can go on to make other chiral compounds. I talked to him during the coffee break and he said he’s hoping other people take the idea forward, because at the moment the compounds he’s made aren’t too useful. Watch this space.

And finally…beware inorganic chemistry journal editors with the same ‘hairstyles’ (or rather, lack of) – an author of a Perspective in the next issue got confused by my similarity to Jamie Humphrey, editor of the RSC’s Dalton Transactions. What do you think? Separated at birth [scroll down]?

Jamie HumNeil

Neil Withers (Associated Editor, Nature Chemistry)

IUPAC ’09: posters and pink wine

Disaster struck at the poster session tonight. I thought that the session organisers had decided to extend the reach of refreshments provided to include rose wine (a summer drink) and I gladly took a glass full of the pink stuff. To my horror I discovered it was cranberry juice. Tsk.

Luckily, to calm my nerves I had the pleasure of talking to Charlotte Mallet a PhD student from the University of Angers, France. She explained to me that she was trying to take biomass – cellulosic waste from agricultural processes – and make electronic devices.

So far she has managed to make oligomers based on furans, derived from the fructose molecules she gets from the biomass. From this she can make an organic plastic and from that a transistor. The properties of this device aren’t quite good enough for industry, Mallet says, because they have low mobility, which means they can’t carry electrons very well. But she is working hard to improve this and hopes to have a news device by September.

I’m not sure how seriously this proposition will be taken in attempts to save the world from burning fossil fuels, but perhaps every little helps.

IUPAC ’09: Carbon capture conundrums

Back in my youth, when deciding what subjects to study at school and university I wanted to make sure that I would come out versed in something that would be of use to the wider world, perhaps even do some good. I chose chemistry. It’s clear from conferences like this that many chemists are interested in the subject for similar reasons.

Climate change is a big topic that chemists are tackling. This morning’s session on carbon capture and storage being a good example.

This is a technology intended to clean up coal-powered power stations by scrubbing out carbon dioxide from flue gas, and compressing it to be stored elsewhere – anywhere but into the atmosphere.

There are a number of problems that chemists are looking at. Today kicked off with a talk by Gary Rochelle from the University of Texas at Austin. He took us through the major considerations that are needed for the solvent that is used to collect the carbon dioxide from the gas. The standard at the moment is something called MEA, monoethanolamine. Rochelle’s fundamental physical chemistry calculations on this and other candidate solvents showed that there isn’t a simple one-size-fits-all solvent. The considerations are: capacity of the solvent to hold carbon dioxide; how much the solvent degrades when heated; how fast the reaction is; how much heat it requires.

Some of these properties are better in different solvent, he says, which are again different in different plants. Another good candidate solvent looks to be piperazine.

Then we heard from Trevor Drage from Nottingham University, UK, about using solids not liquid solvents to strip out the carbon dioxide. His systems are a long way from being scaleable but show promise. On paper, he said, solid sorbets could reduce energy loading in the systems by 30 – 50%. These systems are amine polymers loaded onto porous silica-based materials, or basic nitrogen in an activated carbon matrix.

One area that is often overlooked, says Drage is the regeneration of these sorbents and how the carbon dioxide is removed so they can be reused.

Matthew Hunt is from Doosan Babcock, a Scottish-based company

spending a lot of effort in scaling up CCS technology, with demonstration plants in Canada. This is just a 4 tonne plant so far, which is no real use for a power plant which will need to porcess 850 tonnes of carbon dioxide a day, he said. But according to Hunt, the company is on track to full-scale post-combustion carbon dioxide removal by 2014.

Of course, the impetus for these small demonstration scale plants needs to come from government, and the feeling in certain quarters of this meeting at least, was that not enough push, and not enough decisiveness is being shown to make the technology viable.

My hope is that in 2014 we are not still at the stage where academics working in small groups are showing results of small scale CCS projects and saying that scale up is needed urgently.

IUPAC ’09: Livin’ La Vida Loca

If you happen to swing by the Nature stand at the IUPAC congress exhibition, you’ll have a rare treat. In the booth opposite is the stand for the next IUPAC congress, which will be in Puerto Rico in two year’s time. 2011 is also going to be the International Year of Chemistry.

The stand there has on a loop a video of Puerto Rico’s most famous (?) export Ricky Martin, as well as Marc Anthony (J. Lo’s husband). This really is a rare treat in a chemistry conference, let me tell you.

Another treat is bumping into the congress chairman over a glass of wine at the poster session. Paul O’Brien from Manchester University seemed to be feeling the pressure of constant dinner engagements over the week. He said the whole experience made him nervous. From where I was standing listening to the gentle murmur of happy chemists I would say that any nerves were unfounded.

IUPAC ’09: Patenting bacteria

Chemists love to talk about the details of a synthetic reaction: swapping this carbon atom for that one, changing the angle between sulfur atoms by 2 degrees and so on. So during this morning’s talk by Daniel Rabinovich from the University of North Carolina at Chapel Hill, I was happy to listen to him talking about tinkering with ligands to try and recreate the chemical environment that a copper atom finds itself in the small protein methanobactin thinking no more of it other than “chemists like to try and do this kind of thing”.

Methanobactins are a small part of the large bacteria called methanotrophic bacteria that use methane to make their own carbon and energy. At their heart is a copper binding compound, which has fairly unusual chemical groups called thiones around it. As far as I could tell, the interest was in the synthetic challenge in recreating these unusual chemical group around the copper atom.

I mean, if chemists want to try and mimic nature’s functions they tend to go after big things, like photosystem II, or a huge protein structure.

But I was wrong. It turns out that a patent was granted (to other scientists unrelated to this work) on the small copper-based protein methanobactin because it is a potent antibacterial agent against S. aureus, although this is a delicate protein that will be hard to recreate in its natural form.

Whilst trying to recreate the chemical geometry of the copper atom in this small delicate protein, Rabinovich actually found a way to make a synthetic version of an antibacterial, and that is what he’s working on now.

Rabinovich has a better chance of making large amounts of the stuff. His work was all based on known procedures – albeit some obscure ones.