Synthesis of Thermally Irreversible Photochromic Compounds and Their Application for Optical Data Storage Media

光致变色化合物的特征是表现出两种不同的化学形式。用适当波长的光照射可引起从一种到另一种的可逆转变。无需处理的即时成像特性已导致考虑将其用于可重写的直接读后系统。对可逆光数据存储介质的要求如下。(1)档案存储能力。(2)低疲劳(可以多次循环而不会有任何显著的性能损失)。(3)对半导体激光波长的灵敏度。(4)非破坏性读出能力。本研究旨在开发满足上述要求的光致变色化合物。这是通过对具有杂环的二芳基乙烯进行化学修饰来实现的。为了获得在较长波长具有敏感性的化合物，具有各种杂环的对称的具有不同杂环的二芳基乙烯，如苯并噻吩烯、硒或吲哚…合成了更多的化合物。尽管二吲哚基马来酸酐使闭环式的最大吸收峰移至620 nm，但闭式式的热稳定性较差。为了得到具有较长波长吸收带的热稳定化合物，合成了不对称取代的非对称二芳基乙烯。一端带有吲哚环、另一端带有噻吩环的非对称顺丁烯二酸酐变得热稳定，在595 nm处观察到闭环型的最大吸收峰。通过在吲哚环的5个位置引入甲氧基和在噻吩环的5个位置引入氰基，进一步将吸收峰移动到680 nm。非对称化合物表现出抗疲劳性能。即使在1.1×10~(-4)个开环/闭环循环后，一端带有吲哚环、另一端带有苯并噻吩环的非对称顺丁烯二酸酐的闭环强度几乎保持不变。下一个要解决的问题是设计具有非破坏性读出能力的化合物。较少

Photochromic compounds are characterized by exhibiting two different chemical forms. A reversible transformation from one to the other is induced by irradiation with light of an appropriate wavelength. The instant image forming property without processing has led to the consideration of their use in rewritable direct read after systems. The requirements for the reversible optical data storage media are followings. (1) Archival storage capability. (2) Low fatigue (can be cycled many times without any significant loss of performance). (3) Sensitivity at diode laser wavelength. (4) Non-destructive read out capability. The present study aimed at development of photohromic compounds which fulfill the above requirements. This was carried out by chemical modification of diarylethenes with heterocyclic rings.In order to gain access to compounds which have sensitivity at longer wavelengths, symmetric diarylethenes with various heterocyclic rings, such as benzothiophene, selenophene, or indole r … More ing, were synthesized. Although diindolylmaleic anhydride shifted the absorption maximum of the closed-ring form to 620 nm, the closed-form was thermally unstable. In an attempt to get thermally stable compounds having the absorption bands at longer wavelengths, unsymmetrically substituted non-symmetric diarylethenes were synthesized. Non-symmetric maleic anhydride with indole ring on one end a thiophene ring on the other end became thermally stable and the absorption maximum of the closed-ring form was observed at 595 nm. The absorption maximum was further shifted to 680 nm by introducing a methoxy group at 5 position of the indole ring and a cyano group at 5 position of the thiophene ring. The non-symmetric compounds showed fatigue resistant property. The intensity of the closed-ring form of non-symmetric maleic anhydride with an indole ring on one end and a benzothiophene ring on the other end remained almost constant even after 1.1 x 10^4 ring-closure/ring-opening cycles. The next problem to be solved is to design compounds which have non-destructive read out capability. Less