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Molecular recognition is the "...specific recognition of (and interaction with) one molecule by another"1. Two types of artificial molecules that exhibit molecular recognition will be presented here: Crown ethers, and Julius Rebek's self-replicating molecules. Crown ethers demonstrate specificity for shape as well as size and charge. Rebek's self-replicating molecules may model natural synthesis and replication. (1). |
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A crown ether is a cyclic, organic molecule containing ether groups. Simple crown ethers contain 9-18 carbon atoms. The lone pairs on the oxygen atoms are available to non-covalently bond metal ions. Crown ethers bond specifically, and may distinguish between a potassium and Sodium or Silver ions . The cavity of the crown ether is specific for shape, as well as charge and size. Azacrowns, are examples of more complex crown ethers, with nitrogen atoms participating in non-covalent interaction. (1) . |
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Julius Rebek presents evidence for the synthesis of molecules that can self-replicate from component parts. A molecule made of two complementary parts serves as a template for replication. Specific binding of components (via hydrogen bonds) positions components to form a peptide bond. The strain of the system is relieved by the breaking of the relatively weak hydrogen bonds, and the newly synthesized molecule is released.(1) |
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| REFERENCES:
1.Ball, P., Designing the Molecular World: Chemistry at the Frontier. Princeton university press, 1994. p145-185. |
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| For Further Reading
Lipkin,R., Darwin in Vitro: the quest to make synthetic molecules, Science News, vol.146,1994, p.362-363. Rebek, J., Synthetic self-replicating molecules, Scientific American, July 1994, p.48-55. Rebek research program web site http://www.scripps.edu/rebek/research/research.html Ronald N. Warrenera, Richard A. Russellb, and Shudong Wanga, Crown Ether Isobenzofurans: Key Reagents in Supramolecular Chemistry Studies. http://www.cqu.edu.au/research/cma/ShudongWang |
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