Molecules, candy and microwaves

The New Chemistry
January 5, 2001

Allen Hill rediscovers an undergraduate interest in organic chemistry and decides that the new superconductors may turn out to be useful.

What is in a name? Some have said that one should forgo the term chemistry and speak of "molecular science", just as metallurgists now deal in "materials science" and geologists in "earth science". Perhaps chemistry should now be called molecular science, and biochemistry biomolecular science? Subjects have changed their names before, either to avoid confusion - and what United Kingdom chemist has not been irritated by being confused with a high-street shopkeeper? It could be that the term "nuclear magnetic resonance imaging" was changed to placate the public in their mistaken fear of the term nuclear. How many universities have gained more applicants for the course entitled environmental science, rather than environmental chemistry?

The New Chemistry complements the beautifully produced celebration of the success of chemistry, The Age of the Molecule , published in 2000 by the Royal Society of Chemistry and also edited by Nina Hall. As the prime minister said in his introduction to that book: "Advances in chemistry contribute directly to our everyday lives - to the medicines we take, the food we eat, the clothes we wear, the environment we live in. I hope (this book) will help us inspire a genuine interest in chemistry, and in science generally among young people." Provided official support is there, I am sure that chemists will respond to this challenge.

When Peter Day and I edited a book 30 years ago, we were troubled by the different standards adopted by those who contributed. Hall must have had similar problems, as each chapter is pitched at a different level, employing illustrations in different styles. Nevertheless, I was fascinated by a number of the articles. I even found myself reading the organic chemistry articles with interest, something I have rarely done since graduation.

"New roads to molecular complexity" by K. C. Nicolaou, E. W. Yue and T. Oshima is replete with structures and describes the methods of synthesis adopted. I was amazed at the skill, energy and perseverance (or masochism) of the authors. Many people who are uninformed think or claim that the most toxic substances are artificial. This is far from true. For example, a compound called maitotoxin is produced by a marine micro-organism called a dinoflagellate: 1mg of this substance can kill 50 million mice. The substances produced by, or contained in, living species are rarely without effect on other creatures. Many of these such as the penicillins have been used as pharmaceuticals.

P. P. Edwards asks "What is a metal?" He provides an exemplary description of how the question arose, the attempts that have been made to seek an answer, the present state of our knowledge and the new challenges made to our understanding by systems such as the high-temperature superconductors. His illustrations liven up the article, and are beautifully produced and printed.

Other chapters are more challenging, but if one responds to the challenge they are eventually rewarding. However, the penultimate chapter by G. Dewie, D. Kondepudi and I. Prigogine on "Chemistry far from equilibrium: thermodynamics, order and chaos", is difficult to grasp and left me dissatisfied, either with myself or with the exposition or both. It must be tough to describe such an intransigent subject with such a limited space but, at times, I got rather frustrated by glimpsing the meaning of some aspects of irreversible thermodynamics, only for the mist to come down again.

R. J. P. Williams considers "The inorganic chemistry of life", a subject to which he has made the most valuable contribution of all living scientists. Most readers will know of the need for elements such as and zinc among all living creatures, but the need for selenium, required to combat oxidative stress, and a component of a key enzyme in the blood, will give some reassurance to those who see it in high-street chemists.

Many readers will be surprised by a passage in parentheses at the very end of the article where Williams says that "the major reason for leaving DNA to one side is that it is only representative of the living system in the coded form. It is not active except in relationship to regulation. Understanding life is dependent upon the insight we have into systems not individual molecules." This statement sweeps away the reason often given for the work of biomolecular scientists and genetic engineers. It is not unusual for Williams to include a sting in the tail of his articles. If the author had known the book would be so well produced, he might have chosen to make his figures more aesthetically pleasing.

Supramolecular chemistry, as described by J. M. Lehn and P. Ball in a beautiful article (in its style and its illustrations) provides an excellent demonstration of the stimulus that biology has provided to molecular scientists. The elegant molecules and systems have found many uses in sensors, catalysts and liquid crystals. I hope the authors are correct when they say that "the fundamental building block of nanotechnology will be not the atom but the molecule", though the reasons they give are not completely convincing.

"The search for new elements" by G. T. Seaborg and W. D. Loveland is a fitting memorial to the first author (who died recently). It recounts 60 years of effort and skill in the synthesis of the transuranic elements.

Interestingly, the authors stress how, in attempting to treat the electronic properties of these elements, it is necessary to use the fully relativist treatment of Dirac. I had an argument with a colleague about whether undergraduates should be introduced to the relativistically correct treatment. As the authors point out, one cannot explain that prime example of "old" chemistry (or indeed alchemy) - the colour of gold - without having recourse to the relativistically correct treatment.

It was necessary to relay the rigour of theoretical treatments that have been applied to molecular problems. With the advent of modern computers, the subject has advanced enormously. It is a pity that the author of the relevant chapter has not found space for many of the striking results obtained.

T. Shono describes the use of electrochemistry for various synthetic purposes. I knew of P. Baizer's striking work describing an electrochemical method used in the synthesis of an intermediate in the production of nylon, but other methods were surprising.

D. P. M. Mingos and D. R. Baghurst provide an entertaining description of the use of microwaves in synthesis. I learnt here that the use of microwaves in cooking started with one M. M. Spencer, who discovered, by leaning next to an open waveguide (a source of microwaves) that the candy in his pocket had melted. Similarly, the use of ultrasound, described by P. D. Lickless, is quite informative: anyone who has witnessed the data provided by an ultrasound scan in hospital will have been impressed by the living detail provided.

It is hard to imagine an area of modern life that is not dependent on, or influenced by, the myriad advances in information technology. Few realise the immense contribution of materials and molecular science to this subject, in particular the search for a replacement for silicon as the major component of present-day chips. "Advanced materials" by P. Calvert and "Molecular electronics" by B. Munn go some way towards describing the excitement of this subject, though whether organic compounds will make a lasting impression is hard to say.

Do the studies of the lead-acid battery and developments over the past 20 years qualify as new chemistry? In "Electrochemical and photo-electrochemical energy conversion", A. Hamnett and P. Christiansen describe fuel cells that, although they have been known for more than a century, are now coming into their own; some believe they will make a major contribution to automotive power.

It is said that the powers-that-be in Brussels consider there are two areas of scientific research to be supported in the near future: post-genomics research and nanotechnology. The former is not referred to at all in this book: the latter is, though only just.

What cannot be doubted is that chemists will play their part in both these research fields, particularly nanotechnology. If this book serves to make non-chemists more receptive to their efforts, it will have served its purpose well.

H. Allen O. Hill is professor of bioinorganic chemistry, University of Oxford.

The New Chemistry

Editor - Nina Hall
ISBN - 0 521 45224 4
Publisher - Cambridge University Press
Price - £30.00
Pages - 493

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