PURPOSE: To obtain a photochromic material which has minimized reduction in the rate of conversion due to isomerization, can form an ultra-thin LB film, and is suitable used for an optical recording medium, by using a specified fulgide having a long-chain group introduced therein to provide steric hindrance.
CONSTITUTION: A photochromic material comprising a fulgide of formula I (wherein R is 5W31C alkyl). Photochromic material has been known as a material undergoing a reversible change in color, an example of which is fulgide. For example, a compound (colorless) of formula II is converted into a compound (red) of formula III when irradiated with an ultraviolet light of 337nm, which is returned to the compound of formula II when irradiated with a visible light of 473nm. However, the rate of conversion of a fulgide used to date through the main reaction is lowered due to a side reaction through which the fulgide is converted into a positional isomer showing no isomerism, and also it is difficult to form a thin film from said fulgide. A fulgide of formula I is provided, by the introduction of a long-chain R thereinto, with steric hindrance for control of the isomerization and also has both a hydrophilic group and a hydrophobic group. Therefore, this fulgide can form an ultra-thin film (LB film) suffering no deterioration of photochromic characteristics so that it can be suitably used for an optical recording medium.
HIBINO JUNICHI
ANDO EIJI
| JPS5331656A | 1978-03-25 |