Topology is a very important way of classifying the connectivity of framework materials but ToposPro, the standard software for topological analysis can be quite intimidating. I am no mathematical topologist or ToposPro expert, but here is a short guide for how to take a CIF and analyse the topology of its simplified net. Much more information is available from the ToposPro website and manual. If you would rather one of the experts deteremines the topology of your structure for you, the ToposPro team will now do this for you.

Figure: An aphid sketched by George Bowlder Buckton in ‘A monograph of the Membracidæ’. Image digitised by the University of Illinois Urbana Champaign, available via the Biodiversity Heritage Library.

Most people’s idea of chemistry is of lab-coated scientists mixing liquids, making explosions, causing fires, and growing crystals. Though this stereotype—like most—is based on reality, a key part of any chemistry project is sitting down and reading the ‘literature’: the research papers written by scientists who have worked in the field before you. This is, as all researchers know, often quite a mixed experience: once you have located relevant papers and breached the thicket of customised journal websites, the task of reading begins. You have to wade through the many articles that do not quite cover the topics you had thought, struggle past lengthy screeds that emphasise precisely the least interesting part of their work, and have your hopes dashed as you discover your inspired new compound has been already been synthesised. Sometimes though, these searches can be an absolute pleasure. This is particularly true of older articles. There is a particular thrill in realising the paper you are reading is not only telling you about the topic in which you are interested, but the world as it was fifty, or even a hundred years ago. For example, imagine what it would be like to be G. S. Zhdanov, determining the structure of zinc cyanide in 1941,¹ just before the launch of Operation Barbarossa. No matter how exciting the topic of these old papers, they often leave questions completely unanswered: not for any scientific neglect, but because the technical capabilities to solve the problems at hand were simply not available. If you’re reading a chemistry paper written before World War I, for example, the authors will not know the structures of their samples because X-ray crystallography had not been invented. The combined technology of over a century of research can make the answers to these historical questions unambiguously straightforward. My current favourite historical author, George Bowdler Buckton, wrote probably the oldest paper I have consulted in earnest, which was published in 1855. 1855 is, by the standards of chemistry, practically prehistoric: Mendeleev’s periodic table wasn’t presented until fourteen years later, in 1869. As a result, there are some distinctive period features: the mass of nitrogen used is two times too big, and as a result the he described a complicated ‘sulpocyanide’ molecule (C₂NS₂^2–) rather than the simpler thiocyanate (NCS^–). Though the paper is disadvantaged by being 163 years old, it is otherwise a very careful piece of research. It is thorough in ways we’d never imagine exploring today: ‘[in] common with all the soluble salts to be described, [the compound] has an exceedingly nauseous taste’(!). The writing is also of a style and standard not commonly found in modern science. One product is poetically described as ‘a remarkably beautiful substance, thrown down in the form of innumerable golden plates’. Despite their beauty, most of the compounds in this paper have never subsequently been investigated, let alone had their structures determined (watch this space). George Bowlder Buckton is a figure of interest in his own right. He identifies himself as a Fellow of the Linnean Society, and indeed, many of his most lasting contributions are to be found in plant science, rather than chemistry. His most well known contribution to chemistry is being the first person to successfully synthesise dimethyl mercury.² In retrospect this is a substantial achievement, as dimethyl mercury is one of the more infamously toxic compounds; a few drops can kill, and your death can take many months. A quick read of Buckton’s original papers reassures me that he did not try to carry out his usual full taste characterisation of dimethyl mercury, though we can perhaps deduce this from the fact he had a subsequent career as a biologist. George Bowdler Buckton had a number of notable relatives, and those of you of the more literary persuasion may have had a twinge of recognition on seeing his middle name. George was named for his uncle, Thomas Bowdler, who is primarily famous for publishing, with his sister Harriet, a nineteenth century edition of Shakespeare in which ’those words and expressions are omitted which cannot with propriety be read aloud in a Family’. This attempt to moderate Shakespeare’s work is usually considered a ridiculous endeavour: Ophelia’s suicide became a drowning accident, and the character of Doll Tearsheet was removed from Henry IV, Part 2 entirely because she is a prostitute. In short, Thomas and Harriet ‘bowdlerized’ the language. Some near contemporaries of the Bowdlers argued that their efforts in making Shakespeare accessible outweighed the errors in excision. The Victorian poet Swinburne said of Thomas that ‘no man ever did better service to Shakespeare than the man who made it possible to put him into the hands of intelligent and imaginative children’.³ George Bowdler Buckton may not have put chemistry into the hands of children (luckily), but his story illustrates some of the manifold and exciting ways that scientific literature connects us to the past.⁴

3D printing is widely predicted to be the future of manufacturing, by groups as varied as the excitable fringes of Silicon Valley and the accelerationist left. They believe that everyone will have a 3D printer in their home, just like everyone has (had?) a ‘2D’ printer, and these printers are going to produce the quotidian objects of our lives. Just as a printer allows you to produce a piece of paper with whatever words or pictures you desire, your desktop 3D printer will produce any arbitrary physical object.


At this time of year my thoughts begin to turn to food, as of course do many other people’s. As a chemist however, I can’t help but think about food from a scientific perspective. One of the most interesting trends, to my mind at least, is the way that food science has come into the public’s consciousness through the high-end cuisine of ‘molecular gastronomy’ — even if, like cooking science doyen Harold McGee, I find the name a little daft . I thus really enjoyed the Netflix series “Chef’s Table”, both as a collection of character portraits and as a showcase for really astonishing food. As someone who is unlikely to eat at any of the featured restaurants and thus get a chance to sample the foods for real, I enjoyed the chance to see the creativity of the cooking that is available.

This is a short and personal introduction to my research interests. I have tried to keep it non-technical and as brief as possible. I will be also posting some additional short articles explaining the key concepts in more detail as I go. Hopefully even with pictures!

I am a materials chemist. Materials chemistry, like all fields of research, does not have a firm dictionary definition. What I mean by a materials chemist, then, is a chemist who tries to make and understand chemicals that do things: that is, materials with interesting and unusual properties.

This is a short article which was published in Oxford’s student popular science magazine, Bang!. See it in its illustrated glory here (page 21).

Explosives

Ask the average ten-year-old what chemists do, and “make explosions” would probably be the first answer. As explosions tend to be inconvenient if you are concerned about the structural integrity of your working environment, most chemists try to avoid them. But what is an explosion?

Simply put, it’s the very rapid expansion or release of gas. Any kind of rapid expansion can cause an explosion, whether from a chemical explosive, the intense heat of a nuclear weapon or from steam, e.g. microwaving an unpierced potato for too long. Explosives, though, are by far the useful way to generate an explosion no matter if you want to fire a gun, demolish a building, or mine. The power of explosives, for example one gram of RDX, a modern explosive, produces 24000 times its own volume in gas, is down to their chemical structure.

This is a short post based on a J Chem Ed article, describing a remarkable hydrocarbon in permanent flux. Figure: The structural formula of bullvalene - every single carbon atom in the structure will interchange with every other atom at room temperature.

Bullvalene

A glance at a line drawing of a molecule might give the impression that molecules are sedate entities, calming drifting through the microscopic world. Molecules are in reality very lively, perpetually vibrating, tumbling and bouncing off each other. Despite all this motion, bonds in molecules remain intact, as the energy needed to break them is so much larger than the energy of a molecule at room temperature.

This is a short article which was published in Oxford’s student popular science magazine, Bang!. See it in its illustrated glory here (page 20).

Things expand when heated and contract when compressed. Obvious – but not always true. In the past fifteen years researchers have produced some striking examples of counterintuitive materials that contract on heating (negative thermal expansion, NTE) or expand in one direction when uniformly compressed (negative linear compressibility NLC).