Development of Highly Fluorescent Materials Containing Pyrazine Ring

近年来，荧光化合物有望作为平板显示材料，使用电致发光器件，尽管已经实现了一些其他应用。在用吡嗪类化合物研究液晶和朗缪尔-布洛吉特薄膜的过程中，我们注意到吡嗪类化合物表现出很强的荧光。在本研究中，我们合成了许多吡嗪类化合物，以开发出高荧光的材料。主要研究结果如下：1.研究了三种合成吡嗪类化合物的方法。(1)锂化甲基吡嗪与羰基化合物反应，然后脱水得到烯基吡嗪衍生物。(2)叠氮甲基芳基酮与三苯基膦反应生成2，5-二芳基吡嗪。(3)乙二醛或溴甲基酮与邻苯二胺反应生成喹恶胺类化合物。在2，5-二芳基吡嗪的情况下，给电子基，如对甲氧基苯基或呋喃基团，增强了荧光。大的pi-电子体系，如萘基，对荧光的增强也有一定的影响。但是，呋喃类化合物在溶液中并不稳定，在几天内就会分解。在喹恶啉衍生物的情况下，被甲氧基苯基、2，3-二甲氧基苯基或N，N-二甲基苯基取代可增强化合物的荧光。虽然这些化合物的荧光强度不如2，5-二芳基吡嗪，但它们非常稳定。在本研究中，我们可以证明该基团的取代具有电子供体效应和共轭效应，增强了荧光。在这些结果的基础上，我们现在正计划制备更稳定的具有强荧光的吡嗪衍生物。

Recently, fluorescent compounds are expected as the material for flat display, using electro-luminescence device, althogh some other applications have been realized. In the course of our reserch on liquid crystal and Langmuier-Blodgett film using pyrazine derivatives, we noticed that pyrazine derivatives show strong fluorescence. In this investigation, we synsthesize many pyrazine derivatives to develope highly fluorescnet material. Important results are as follow ;1. Three methds fot the synthesis of pyrazine derivatives were investigted. (1) Reaction of lithiated mechylpyrazine with carbonyl compounds followed by dehydration was revealed to give alkenyl pyrazine derivatives. (2) Azidomethylaryl ketones gave 2,5-diarylpyrazine by the reaction with triphenylphosphine. (3) Reactions of glyoxals or bromomethyl ketones with o-phenylenediamine gave quinoxalilne derivatives.2. In the case of 2,5-diarylpyrazines, electron-donating groups, such as p-methoxyphenyl or furyl group, ebhanced the fluorescence. Conjugative effects of large pi-electron system, such as naphthyl group, was also edffective for the enhancement of fluorescence. However, the furyl derivative in solution was not stable as to decompose in a few days.3. In the case of quinoxaline derivatives, substitution by methoxyphenyl, 2,3-dimetoxyphenyl, or N,N-dimethyphenyl group cenhanced fluorescence of the compound. Although, the fluorescence of these compounds were not strong as 2,5-diarylpyrazine, they were shown to be very stable.In this investigation, we could demonstrate that substitution by the group, having electron-donating effect and conjugative effect, enhances the fluorescence. On the basis of these results, we are now planning to prepare more stable pyrazine derivattives showing strong fluorescence.