Optical recording materials utilizing the change in molecular arrangement

具有高密度的光学记录系统的目标现在集中在基于635 nm的GaInPAl激光二极管的系统上。该系统的记录密度比现有的780 nm系统高1.5倍，因此有望成为DVD的理想系统。我们的研究目的是探索或合成能够在635 nm附近切换吸收带的功能染料。在本研究中，对二萘嵌苯颜料以及非苯型化合物如8，8-二氰基七富烯进行了研究。在二萘嵌苯颜料中，我们发现了一种黑色的二萘嵌苯，它在无定形状态下显示出鲜艳的红色，但在结晶时变成黑色（在635 nm附近出现吸收带）。因此，电子结构的特点是广泛的晶体结构，偏振反射光谱以及MO计算的基础上。与此同时，我们测试了一些基于黑色苝的光盘，并确认了良好的记录特性。对于8，8-二氰基七富烯衍生物，我们新制备了各种衍生物，其中一种在从非晶态到结晶态的过程中显示出在635 nm附近的光开关。这种化合物在光学记录系统中也引起了人们的注意，但我们很快发现非晶相在环境大气中迅速结晶。因此，我们不得不放弃将这种材料用于光盘。然而，出乎意料地，发现本发明化合物表现出非线性光学特性，并且已经要求保护该申请的专利。

The target of the optical recording system with high density is now focused on systems based on a GaInPAl laser diode of 635 nm. This system achieves 1.5 times higher recording density in comparison with the present system of 780 nm and is therefore expected as an ideal system for DVD.The purpose of our investigation is to explore or synthesize functional dyestuffs that can switch the absorption band around 635 nm. In the present investigation, perylene pigments as well as non-benzenoid compounds such as 8,8-dicyanoheptafulvenes have been investigated. Among perylene pigments, we found a black perylene which exhibits a vivid red color in an amorphous state but turns black (appearance of the absorption band around 635 nm) when crystallized. The electronic structure has therefore been characterized extensively on the basis of the crystal structure, polarized reflection spectra as well as MO calculations. In parallel, we have tested a number of optical disks based on the black perylene and confirmed good recording characteristics. As for 8,8-dicyanoheptafulvene derivatives, we have newly prepared a variety of derivatives, one of which showed an optical switching around 635 nm on going from an amorphous state to the crystallized state. This compound has also attracted attention for optical recording systems, but we soon found that the amorphous phase crystallizes rapidly in the ambient atmosphere. For this reason, we were obliged to abandon the application of this material for optical disks. However, unexpectedly, the present compound was found to exhibit non-linear optical characteristics, and a patent for this application has been claimed.