"Dynamic" molecular recognition and chirality segregation utilizing concepts of molecular machines and molecular assemblies.

The need to measure the concentration of selected ions and small organic molecules in both in vivo and in vitro processes is continuously increasing beyond the borders of various research fields. This need has been fulfilled using "host-guest chemistry", or in general, by the use of "molecular recognition". The basic idea in these research fields was derived from the 1 : 1 host-guest interaction based on the "key-and-lock" concept. However, we have experienced that only with this classical concept, more precise, higher-order recognition faces serious difficulty. In this review article, I wish to explain that the introduction of two new concepts, i.e., the dynamic action of molecular systems and the amplification effect of molecular assemblies, overcame the limitation of the "key-and-lock" concept. In fact, we have found that even "complete" chirality segregation can be achieved under optimal conditions.