Of Molecular Machines and Merchants of Dreams

This year’s Nobel Prize in Chemistry is a testament to the romance of Science.

ByAnand Ranganathan
Of Molecular Machines and Merchants of Dreams
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This year’s Nobel Prize in Chemistry has been awarded to

Jean-Pierre Sauvage (University of Strasbourg, France), James Fraser Stoddart (Northwestern University, USA), and Bernard Lucas Feringa (University of Groningen, the Netherlands), for their pioneering work in constructing Molecular Machines.

Richly deserved, the award comes as a recognition of human ingenuity, and especially of those who inhabit the enthralling if esoteric world of Chemistry. From the time Friedrich August Kekulé dreamt up the structure of Benzene, as a snake catching its own tail, chemists have had this incurable itch to conjure up molecules that don’t exist, sometimes literally out of thin air. If you can dream it you can make it, said the father of modern organic chemistry Robert Burns Woodward, who got the Nobel Prize in 1965, and would have shared his second with Roald Hoffmann in 1981 for Woodward-Hoffmann Rules had he not passed away in 1979.

Indeed, Woodward enjoyed such a formidable reputation in synthesising impossibly difficult molecules – Chlorophyll, Vitamin B-12, Erythromycin, to name a few – that, during the Nobel Prize ceremony in 1965 – the year Richard Feynman also received the Nobel – when a light-hearted debate ensued as to who was greater – Woodward or Feynman, someone shouted from the audience, “Given ample time, Woodward can synthesise Feynman.”

Chemistry is fun; it is the closest science can come to being conducted satisfactorily in a run-down garage. Fumes, explosions, bubbling test-tubes, danger, colour – it has everything to excite and confound a curious mind. Things have moved on since the good old days of Science-for-Science-sake, what with funding cuts and Science-for-the-nation clarion calls by Prime Ministers and Presidents, but Chemists more than any other category of scientists have retained this heirloom. The three who received this year’s Nobel epitomise this, and among them the one who epitomises it most is James Fraser Stoddart.

This writer had the good fortune of spending a summer in the laboratories of Fraser Stoddart. The year was 1993. Fraser had moved recently from Sheffield to Birmingham and was already a mini-celebrity, having dreamt up a molecular shuttle and then gone ahead and synthesised it. Birmingham gave him an entire floor and a three-dozen strong workforce to dream further.

In the middle of my undergraduate degree at Cambridge, and nothing planned for the summer months, I wrote to him expecting a rebuff. Instead, the response came in the form of an invitation to “Come and have a look-around”. Those three months ended up providing some of the most memorable moments any impressionable sophomore could wish for.

Upon landing in his lab, when I asked him what my project was to be, Fraser smiled and said, “Think of something, I’ll provide the glassware.” It didn’t take long for a google-eyed undergrad to think of something, although looking back that ‘something’ yielded nothing in terms of a publication or a result that could be followed up. But the inspiration to “think of something” was everywhere in Fraser’s lab – Journal cover prints displaying his Esher-like molecular creations, mostly – and dumped on the coffee table in his sprawling office were Hofstadter’s Escher, Gödel, Bach and Drexler’s Nanosystems. The Barcelona Olympics had just got over and in celebration Fraser had dreamt up Olympiadane, a giant molecular machine with five interlocked rings. His lab was busy making it. Why? Well, to paraphrase Edmund Hillary, “Because it can be dreamt.” Two years of back-breaking work later, the Stoddart lab eventually succeeded in synthesising Olympiadane in 1994. It served absolutely no purpose at all, quite useless it was at eradicating poverty or educating the girl child. But it was beautiful to look at. Sometimes, that is enough. Back in the 60s, taken in by the excitement of the Space Race and the Apollo moon-landing, appeared a molecule called Apollane.

In 2003, Japanese chemists, inspired by a flower and a fragment of Buckminsterfullerene, synthesised Sumanene, the Sanskrit word for sunflower. Then there is a molecule called Bullvalene, not to mention Penguinone, Propellane, Lampane, and Basketane, that resemble a penguin, a propeller, a lamp, and a basket in that order. The magnificent book, Organic Chemistry: The Name Game, lists many such molecules along with delightful anecdotes surrounding their discovery and synthesis.

Chemists are anoraks. Shapes excite them, especially this notion of visual pleasure trumping functionality. What does Music do – does it cure a disease; is it a vaccine? When it comes down to it, Science is but Art. Was it to emphasise this understanding, or just an accident of literary flair, that the 1965 Nobel Prize Citation for RB Woodward read: “For his outstanding achievements in the art of organic synthesis”?

Is it Yakshini, the Hindu goddess guarding Kuber’s wealth, or is it the B-form of DNA?

Is it the mechanism of DNA replication or the first patent granted to a Zipper?

What do you want to look at today? What object of beauty shall provide you with that inspiration, that spark, that idea that might change the world?

In 1991, Fraser dreamt up something absurd. He had been tinkering with making interlocked chains, called Catenanes, and then suddenly, like Kekule I imagine, this idea, of passing molecular rings over a molecular rod, like bangles clinking around a hennaed forearm, must have struck him. A molecular shuttle. Devastatingly simple and yet profound in its implications. As Einstein said of Piaget’s discovery: It was an idea so simple only a genius could have thought of it.

Using negatively charged Hydroquinol moieties, “stations”, connected with a linker and flanked with molecular blockers so that the “bangles” wouldn’t slip off the arm, Fraser inserted positively charged bipyridine groups-containing bangles into the axle. The opposites were drawn to each other, as they do in real life, and the bangle came to rest over the station. When warmed up, the positively-charged bangle shuttled between the two negatively-charged stations, and when cooled, it rested over one of them. 0 and 1. Binary achieved through applying an external, controllable stimulus. There it was – a molecular machine.

The world of Molecular Machines, and in particular Molecular Shuttles, has come a long way since Fraser conjured the first one up in 1991. In a mind-boggling advancement, chemists in 2014 managed to incorporate a molecular shuttle inside a metal lattice. The implications for building a molecular computing machine are not lost on the Asimovs. There now exist molecular elevators, axles, rotors, gears, propellers, even computer chips.

One late night back in 1993, I gathered up enough courage to ask Fraser when and how he got the idea. He waved his hand and said, “Oh, it was nothing. Just a flash.” That flash has won him this year’s Nobel Prize.

In a seminal commentary in the journal Science, Robert Service once asked: Can Chemists Assemble a Future for Molecular Electronics? The question was loaded – Service had thrown the gauntlet at Chemists, not Biologists or Physicists or Engineers. Sauvage, Stoddart, and Feringa seem to be saying, “Yes, we can.”

The Nobel Committee agrees.

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