| Research Abstract |
Complexation of macrocyclic cyclophane compounds with guest molecules in water has always attracted a major interest since it can mimic the molecular recognition which is a basic process in biological systems. Although modified cyclodextrins have been extensively investigated in terms of inclusion, recognition, and catalysis in aqueous media, versatility of their structure is limited. On the contrary water-soluble calixarenes and cyclophanes have a great advantage of molecular design. On the other hand it has been reported that the chemical compounds known as endocrine disrupters could have an unexpected influence on human beings. Thus, novel cyclophans consisting of fluorene, naphthalene, anthracene or pyrene component which could exhibit a binding ability against some kinds of endocrine disrupters have been proposed. We have shown the facile synthetic methods of such macrocyclic cyclophanes containing fluorene, naphthalene, anthracene or pyrene component. In order to recognize the en
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docrine disrupters weak intermolecular interactions such as CH-π interaction, π-π interaction, hydrogen bondings and so on could be very important. We have clarified the conformational properties of these cyclophanes, indicating that the ring inversion is highly dependent on their molecular structures, especially the inner substituents and the length of the bridging part. Hydrogen bondings also play a decisive role on the conformation. Some cyclophanes exhibit a very interesting properties by switching an intramolecular hydrogen bonding to an intermolecular one. During this process crystal structure changes. In the cyclophanes having the fluorene component fluorescence energy transfer is observed, depending the rigidity of the molecule and the orientation of two aromatic components. The cyclophanes consisting of anthracene or pyrene unit exhibit a unique CH-π interaction between the amino group and the aromatic unit, which has an influence on the conformation. Now we are developing the desired system using the knowledge of weak interactions obtained here. Less
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