ロタキサン型色素の創製と 効率的合成法の開拓

Organic fluorescent dyes are widely used in fields ranging from materials science to bio- science. On the other hand, these dyes often exhibit low solubilities in water and photo-stabilities, which sometimes cause difficulties in their practical use. To solve these problems, we have developed rotaxane-type fluorescence dyes, in which polycyclic aromatic hydrocarbons are irreversibly encapsulated with cyclodextrins. For example, the [3]rotaxanes encapsulating only one pyrene core show not only enough water-solubility and photo-durability but also high emission efficiency in various solvents and even in solid state because the fluorescent core is shielded from the external environment. The [4]rotaxanes encapsulating two pyrene or perylene cores emitted excimer-emission-based circular polarized luminescence with large dissymmetry factors. Furthermore, we succeeded in synthesizing [5]rotaxanes with various emission colors ranging from blue to red by adopting a cooperative capture strategy using cucurbit[6]uril in high yields. The obtained [5]rotaxane-type fluorescent dyes show desirable photo-physical and chemical properties in a manner much like the above [3] and [4]rotaxane-type dyes.