Development of Novel Photoresponsive Systems Using an Excimer State

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We have Shown through the present project that 1,n-bis(3-(1-pyrenyl)propyl-carboxy)-oxaalkanes (DP3n: n= 3 to 6), linear oligooxyethylenes with pyrenyl groups at both ends, captured and transported metal ions more effectively when they were irradiated. Two terminal pyrenyl groups link together to form an excimer when irradiated with uv light, and this structure is analogous to that of crown ethers. Thus, we refer to them as "photo-induced crown ether compounds" (PIC's). It is the first work to use an excimer to fix a conformation of a molecule. In the present work, we proved the concept of PIC by using 8 compounds such as DP3n and 7 metal ions having different sizes, and examined the relationship between the sizes of PIC's and the metal ions captured by them. We employed a quartz cell (1cm × 2.5cm × 7cm high) with a partition to determine the amount of metal ions transported by PIC molecules in the presence and absence of uv light, after a method for measuring transportation yield of metal ions by crown ethers. Consequently, DP35 and DP34 transported the greatest amount. of CaィイD12+ィエD1 and CdィイD12+ィエD1, respectively. We assume that DP3n molecules do not start with capturing metal ions after forming an excimer, but rather they have some interaction with ions before being excited, because some specific interactions were observed through ィイD11ィエD1H-NMR measurements when CaィイD12+ィエD1 and CdィイD12+ィエD1 were added into the solution of DP35 and DP34. The intramolecular excimer formation between the pyrenyl end groups is considered to make PIC's bind metal ions very tightly when irradiated. Finally the novel concept of a photo-induced crown ether compound is successfully established to be correct and useful for developing the photo-responsible system.