Recently Professor Jean-Marie Lehn gave an interesting talk about his perspective of Chemistry.

He is a French chemist. He received the Nobel Prize together with Donald Cram and Charles Pedersen in 1987 for his work in Chemistry. In 1968, he achieved the synthesis of cage-like molecules, comprising a cavity inside which another molecule could be lodged. Organic chemistry enabled him to engineer cages with the desired shape, thus only allowing a certain type of molecule to lodge itself in the cage. This was the premise for an entire new field in chemistry, sensors. Such mechanisms also play a great role in molecular biology. (From Wiki http://en.wikipedia.org/wiki/Jean-Marie_Lehn)

Fig. 1 New molecule which he synthesized

I went to his talk because that he was not only talking about chemistry, he would talk about the principles of building molecular machines with well-defined structures. In his speech, he described a chemical system composed with many small reusable parts can undergo continuous composition, decomposition, recombination or reorganization to reach a design state by responding to temperature or magnetic field etc. Simply put, he painted a blueprint of a chemical system with parts which can self-evolve like something with life.

He told us that his inspiration comes from observing the phenomena in the life world. Nucleotides can self-organize themselves to form DNA, microtublins can form microtubules and can also be decomposed into parts and be reused later; virus can use simple proteins to form its walls. With this idea in mind, he showed us that by using Cu ions and some polymers a double helix or even triple helix could be formed by the self-organization. He also used the similar materials to form a regular 2D or3D rectangular grid. With these building blocking, in theory you can build many well-defined and functioning molecular structures with different geometry and different size. This offers a powerful alternative for Nano-fabrication and Nano-manipulation. Because you don’t need a super-tiny tool ( either laser or other chemical reactions) to curve materials into certain shapes. You can synthesize them in the first hand, instead.

These supermolecular structures are just like bricks: you can use bricks to build a functioning structure and then you can break it and build it into other shape again. With this idea in mind, he further develop it into a wonderful new idea: rather than design ONE molecule with certain functions; we can create millions of these suprmolecular structures and build a selection function to choose the right ONE which we need. Traditionally the molecule design is like make a key for a lock. You have to understand lots of information about the lock and make a right key for it. Now you wouldn’t bother. You simply create a mechanism to create millions of different keys ( they can be built from simple and repeatable parts), and let the lock be the selection to choose the right key. If the key fits the lock, it is OK; Otherwise the decomposition and recombination process will go on.

This really brings a revolution idea to the drug design process. Now the widely-used strategy is: after we find a target molecule for certain disease, we will use all known chemical molecules in the molecule library and screen them one by one to see which one can bind to the target molecule. Then these molecules are synthesized, tested on mice, then tested on human beings. The whole process is not efficient and cost lots of time. With this supermolecular structures, the target molecule can choose the right molecules to be the potential drugs. Also you don’t need a whole molecule library, you only need some reliable and reversible molecular building blocks to do this job.

Finally he mentioned a more challenging idea: adaptive evolution chemistry. Dynamic chemistry is no longer just about dynamic chemical reaction theories, not even motional chemistry which will address molecular motion and shape changes. It will finally become constitional dynamic chemistry, which will build theoretic foundations of modification of chemical entities and how to re-build them.

“This may be not new at all. There may be a chemical evolution well before the biological evolution. There must be a long way for simple inorganic molecules to form some basic units of life, some molecules can store energy, some can store information and some can self-copy themselves. One day, we may have Darwinian chemistry to address these problems.” He finished his speech with a smile.