There is a big problem with carrying out chemical reactions in solution. The reacting molecules have to fight their way through the solvent molecules and on occasion collide with another reacting molecule. If the relative orientation of the two molecules isn’t correct, it’s just too bad. Off they go to another chance encounter.

This is not a very effective way to carry out chemical reactions. That’s why ribosomes used in the synthesis of proteins are so careful to have the t-RNA properly orient the incoming amino acids so that they react every time with the protein that is being assembled. It hasn’t taken chemists too long to recognize the ingenuity of the design of the ribosome. Julius Rebek and his fellow researchers at the Scripps Institute have used exactly the same idea. By creating a miniature reaction chamber (like two gloves) inside which only two different reacting molecules can fit, they have forced correct relative orientation of the molecules. Upon reaction, the product pushes open the chamber (there is a size increase), which is held together loosely with hydrogen bonds, and then exits the chamber. The efficiency is an order of magnitude better than would be observed without the helping hands of the mini-reaction vessel. With such a system, you have much greater productivity without the need for increased temperature. This is sort of like a three-dimensional catalyst (a volume orienting the molecules) rather than the normally used two-dimensional catalyst.

Figure 14.2

So in a chemical sense a small house can be very efficient and very productive. You have to hand it to those clever chemists in California!

References: Journal of the American Chemical Society, vol. 120, p. 7389.

New Scientist, December 5, 1998, p. 36.