| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Photochromic molecules attract much attention from both fundamental as well as practical points of view because of their potential for applications to optical devices such as optical memories and switches, Among the photochromic compounds, diarylethenes are regarded as the best candidate, because of the thermal stability of their both isomers and the fatigue resistant property. For the fabrication of thin photochrbmic films for the applications, various methods have been employed. Dispersing the photochromic molecules into polymer matrices is the most convenient method to prepare the photochromic films. Although increment of the dye concentration is strongly desired to enhance the photochromic efficiency, preparation of films containing high concentration of the dyes is not easy because segregation takes place to some, extent after long term storage. Bulk amorphous and crystalline photochromic films have been extensively studied for the purpose. We now propose a new method to form thin
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films by oxidation polymerization.
A diarylethene derivative 1,2-bis[2,4-dimethyl-5-(o-hydroxy-phenyl)-3-thienyl]-hexafluorocyclopentene (1a) was synthesized from commercially available 2,4-dibromo-3,5-dimethylthiophene. The isomer 1,2-bis[2,4-dimethyl-5-(m-hydroxyphenyl)-3-thienyl]-hexafiuorbcyclopentene (2a) was also synthesized by similar method. Upon UV light (280 nm) irradiation, the solution of la turned to red and absorption bands appeared at 545 and 347 nm attributable to the closed-ring isomer 1b, and the peak of 1a at 254 nm was suppressed. Upon visible light irradiation, the red color was bleached and regenerated the open-ring isomer la. The quantum yields of cyclization and cycloreversion of 1 were 0.19 (measured by 280 nm light irradiation) and 0.03 (measured by 492 nm light irradiation), respectively.
The diarylethene 1a was polymerized according to Hay's method The prepared polymer film p(1a) showed a reversible photochromic reaction by alternate irradiation with UV and visible light. X-ray diffraction measurement showed no peaks even after 1 year storage at room temperature. This indicates that the polymer film is in the amorphous phase. The new amorphous photochromic film will be applicable for wave-guide and novel recording media. Less
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