I was very pleased to be asked to write the introduction for Scientific American’s feature timed to coincide with this year’s Lindau Nobel Laureate Meeting — the 63rd incarnation of the meeting, and this one dedicated to chemistry. The feature (it’s here, but you’ll need to be a subscriber to read it) begins with my introduction and is followed by excerpts from 11 chemistry-related articles — written by Nobel Laureates — published in Scientific American over the years. I was told that the purpose of my essay was to introduce readers to topics covered by the excerpts, and I was encouraged to reflect on the history of chemistry and to seek out patterns or themes in the work being described.
The excerpts I was sent at the start of the process were taken from articles by Curie, Svedberg, Libby, Kendrew, Gilbert, Cech, Urey, Crutzen, Natta, MacDiarmid and Zewail (and a few others that did not make the cut). I was also given a copy of the introduction that was written for last year’s physics-focused Lindau-meeting feature, but it was hard to know where to start… Sum up the history of chemistry — and trends in research — in just 1,000-or-so words, and do it for SciAm’s audience; not the readers that I typically write for. The feedback on my first draft wasn’t too bad, but I was asked to include more current research in the piece, and a couple of iterations followed in which even more detail about contemporary chemistry was added.
The published piece can be found using the link at the start of this post, but I was curious how similar it ended up being to my first (unedited) draft sent to the SciAm editors. So, I decided to run both essays through a document comparison service (I used DOC Cop) and was somewhat surprised when it turned out that there was only an 8% correlation between the two pieces! The edits were fairly extensive, but I didn’t realise they were that extensive. Anyway, that being the case, I don’t feel too bad posting my original draft here on the blog — especially considering how different it is to what was actually published. Thanks to Gav and Vikki for feedback on the essay before I submitted it to SciAm.
The whole process was an interesting experience; I regularly rewrite/restructure News & Views articles and other content for Nature Chemistry without really stopping to consider what the authors will think about me — on occasion — taking their lovingly crafted sentences and paragraphs and editing them to within an inch of their lives. I’ve now seen it from the other side, so I hope I have a better appreciation of the editor–author relationship… I’m still very much an editor at heart though!
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A brief history of (Nobel) chemistry
Most definitions of chemistry are somewhat generic statements referring to the study of matter — its composition, structure, interactions and capacity for change. More specifically, however, chemists are typically concerned with the properties of matter at the level of atoms and molecules. As with other natural sciences, chemistry aims to increase our understanding of the world around us — from why a small molecule made up of just a few atoms can have profound implications for the Earth’s atmosphere to how a protein built from thousands of atoms can make strands of DNA in our cells.
It might come as somewhat of a surprise, therefore, that it was only at the beginning of the 20th century that the previously abstract notions of atoms and molecules were finally put on a solid experimental footing. Writing in the pages of Scientific American in 1913, Theodore Svedberg described how Ernest Rutherford’s work on alpha particles (the nucleus of the helium atom) and studies of colloidal particles suspended in liquid established the existence of atoms and molecules beyond reasonable doubt. Svedberg noted that the ability to count atoms (and determine their mass as a result) should even satisfy the skeptics.
Even though their physical reality was now accepted, it was not possible to see molecules directly because the vast majority of them have dimensions that are much smaller than the wavelength of visible light. Nevertheless, the development of X-ray crystallography in the early part of the 20th century enabled scientists to produce pictures of the three-dimensional arrangement of atoms in simple organic molecules and inorganic materials. The technique was improved and refined as the century wore on and more complex targets were identified, including molecules with biological relevance.
A pioneer of this field was Dorothy Crowfoot Hodgkin, who received the 1964 Nobel Prize in Chemistry for using X-ray crystallography to determine the structure of compounds such as penicillin and vitamin B12. When it comes to biomolecules, however, these two examples are still very small — a molecule of vitamin B12 is built from fewer than 200 atoms, whereas most protein molecules are made up of thousands. The first protein to have its structure worked out by X-ray crystallography was myoglobin, a relatively small oxygen-binding protein found in mammals. Describing the discovery in the pages of Scientific American in 1961, John C. Kendrew likened the experience of seeing the first ever three-dimensional picture of a protein to that of the first European explorers catching sight of the Americas. Kendrew shared the 1962 Nobel Prize in Chemistry with Max F. Perutz, who unravelled the structure of the related protein, hemoglobin, with the same technique.
Other techniques (such as nuclear magnetic resonance spectroscopy) can now be used to determine the three-dimensional structures of proteins and other biomolecules, but most are still solved using X-ray crystallography. Two of the last four Nobel Prizes in Chemistry (2009 and 2012) have been based, in part, on X-ray structural studies of collections of biological macromolecules, namely G protein coupled receptors and the ribosome. Although it is possible to determine the function of a biomolecule without knowing its structure, a three-dimensional picture of its atomic makeup might provide clues to how it works on a molecular level. This information can then be used to rationally design synthetic molecules — drugs — to modulate the activity of that particular biological target.
The exquisitely complex biochemistry of living systems has developed over billions of years and it is an intriguing question to consider its origins. A 1952 Scientific American article written by Harold Urey ponders the question of how the Earth came to be formed and speculates as to the composition of its atmosphere. In that same year, Urey and his student Stanley L. Miller performed what is now regarded as the classic chemical origins-of-life experiment. Simple chemical compounds (methane, ammonia, hydrogen and water), which they believed were likely major components of the Earth’s early atmosphere, were circulated inside a sealed glass apparatus and exposed to an electrical discharge intended to simulate lightning. After the experiment had been running continuously for one week, they found that some amino acids — the building blocks from which proteins are made — had been formed. Although the similarity of conditions used in the Miller–Urey experiment to those present on early Earth have since been called into question, interest in the possible chemical origins of life remains high and it is an active area of chemical research today.
Although the chemical composition of the atmosphere on the early Earth may offer some tantalizing clues to answer the fundamental question of how life began, atmospheric chemistry hit the headlines for very different reasons towards the end of the 20th century. The study of chemical reactions in the atmosphere, including those between ozone and the now infamous man-made chlorofluorocarbons (CFCs), left no doubt that human activity had contributed to the depletion of the ozone layer. For their work on this topic, Paul J. Crutzen, Mario J. Molina and F. Sherwood Rowland shared the 1995 Nobel Prize in Chemistry. The article by Crutzen and Thomas E. Graedel that appeared in Scientific American in 1989 pulls no punches when it comes to the potentially disastrous consequences of anthropogenic atmospheric change and recognizes, even then, that only a global effort between scientists, governments and the population at large can truly tackle such environmental issues.
One unique aspect of chemistry that extends its reach beyond the natural world is its ability to produce substances artificially in the laboratory through chemical synthesis. This concept was expressed succinctly in 1860 by the French chemist Marcellin Berthelot who wrote, ‘la chimie crée son objet’, which translates as ‘chemistry creates its object’. During the last century, synthetic chemistry became increasingly sophisticated and has enabled us to make useful materials and medicines that are either present in only small quantities in nature, or do not occur naturally at all.
Materials that have had a huge impact on our everyday lives are synthetic polymers — large molecules made up from repeating units of small building blocks (monomers) that are typically linked together in chains (that are sometimes cross-linked further into three-dimensional networks). Their trademarked names do not always betray their polymeric nature, but will probably be quite familiar: Nylon, Teflon, Styrofoam and Kevlar, for example. The properties of a polymer are influenced by the structure of the monomer unit and, in some cases, by the way in which they are connected to one another. In recognition of their development of catalysts that can control the orientation of monomers as they are added to a growing polymer chain, Giulio Natta and Karl W. Ziegler were awarded the Nobel Prize in Chemistry in 1963. Commercial plastics made using Ziegler–Natta (and related) catalysts are still produced on a massive scale today.
Writing in Scientific American in 1988, Alan G. MacDiarmid and Richard B. Kaner describe what they refer to as the next generation of plastics — polymers than can conduct electricity. Noting that many would have dismissed this idea as ludicrous just a few decades before, they described how some polymers could be turned into conductors by doping them with other chemicals. Despite the technological implications not being clear at the time, conducting polymers have gone on to find application in organic light-emitting diodes (OLEDs) and organic solar cells. In 2000, MacDiarmid shared the Nobel Prize in Chemistry with Alan J. Heeger and Hideki Shirakawa for discovering and developing conducting polymers.
Chemistry is a diverse subject, and tackles problems that range from how atoms and small molecules can have a huge impact on the global environment to how complex molecular machines regulate the biochemical processes that sustain life. And chemistry can create artificial substances of its own that can open up new fields of study. With such a broad remit, it is hard to make guesses about what the future breakthroughs will be that may warrant recognition with a Nobel Prize. Nevertheless, they will undoubtedly offer new insights into how the world around us works or offer exciting new materials that could change our lives in significant ways.