Design & Synthesis Of Photochromic Compounds With High Optical Density

Organic photochromic materials have attracted much interest for their extensive application prospects in both science and daily life. Among them, naphthopyran is one of the most promising candidates due to their outstanding properties such as high photocolourability and remarkable fatigue resistance. Despite of their many important applications, the more particularly advantageous known applications is ophthalmic lens for the purpose of screening light radiation as a function of its intensity.Although we have got fuchsia and blue spirooxazin photochromic materials, we still need red ones to obtain ophthalmic lens with neutral color, while this arose much difficulty, hi order to obtain red materials, we must design molecules with their open forms absorbing blue light with wavelength of ~ 450 nm under the sunlight or ultraviolet radiation. Thus, the open forms should have suitable conjugation length to avoid bathochromic shift. From the view of quantum chemistry, electron cloud density should be distributed symmetrically if the conjugate resists. As spirooxazins could not meet these requirements, herein, we choose naphthopyran derivatives, for their good optical response, fade speeds, intensity and anti-fatigue as well, as target molecules. However, their photocolourability and fatigue resistance must be improved for the practical application in ophthalmic lens field. For the purpose of getting red naphthopyran photochromic materials with good fatigue resistance as well as deep optical density, which should have large extinction coefficients withperfect conjugation degree, we designed and synthesized the following four compounds: 3,3-diphenyl-3H-naphtho[2,1-b]pyran, 3-(4' -methylphenyl)-3-phenyl-3H-naphtho[[2,1-b]pyran,3-phenyl-3-(3-chloro-benzothiophen-2-yl)-3H-naphtho[2,1 -b]-pyran,3-(4'-methylphenyl)-3-(3'-chloro-benzothiophen-2'-yl)-3H-naphtho[2,1-b] -pyran. And their photochromic properties had been investigated, the results indicated that all of them have good photochromic and anti-fatigue properties. Especially that 3-(4'-methylphenyl)-3-(3'-chloro-benzothiophen-2'-yl)-3H-naphtho[2,1-b]pyran had particularly photochromic properties, such as high colourability (in their open form, in the visible region), and its open form exhibits jacinth color.Furthermore, we first adopted microwave technique to improve the synthesis of the spirooxazins compounds, and got two kinds of spirooxazins compounds with better yields.