Modification of a photochromic 3-aryl-3-(α-naphthalene)-3H-naphtho[2,1-b]pyran system with a fast fading speed in solution and in a rigid polymer matrix
作者:Shulie Han、Yi Chen
DOI:10.1039/c1jm10139k
日期:——
We have demonstrated that 3-aryl-3-(α-naphthalene)-3H-naphtho[2,1-b]pyrans photochromic system shows large optical density at photosteady state at ambient temperature. In this paper, we describe a strategy for modifying this photochromic system with a fast fading speed in both solution and in a rigid polymer matrix. It is found that the nature and position of the substituted groups attached to the aryl moiety at the 3-position play a key role in determining the fading speed of 3-aryl-3-(α-naphthalene)-3H-naphtho[2,1-b]pyrans at ambient temperature. The fading speed of colored forms increase significantly when the electron-donating groups are attached to the para-position of aryl moieties at the 3-position. Further investigations find that (1) a strong electron-donating group is better than a weak electron-donating group for a fast fading speed, (2) an electron-donating group attached to the para-position of the naphthalene ring is better than one attached to the para-position of a benzene ring, and (3) with electron-donating groups at both para-positions of the naphthalene and benzene rings, the fading speed is dramatically increased in both solution and in the rigid polymer matrix.
我们已经证明,3-芳基-3-(δ-萘)-3H-萘并[2,1-b]吡喃光致变色系统在环境温度下的光稳定状态下显示出很大的光密度。本文介绍了一种在溶液和刚性聚合物基体中改变这种光致变色系统快速消退速度的策略。研究发现,3-芳基-3-(δ-萘)-3H-萘并[2,1-b]吡喃在常温下的褪色速度主要取决于芳基 3-(δ-萘)-3H-萘并[2,1-b]吡喃 3 位上所附取代基团的性质和位置。在芳基的 3 位对位上连接电子捐赠基团时,有色形式的褪色速度会明显加快。进一步的研究发现:(1) 强电子供能基团比弱电子供能基团更有利于快速褪色;(2) 连接在萘环对位上的电子供能基团比连接在苯环对位上的电子供能基团更有利于快速褪色;(3) 在萘环和苯环的对位上都有电子供能基团时,溶液和刚性聚合物基体中的褪色速度都会显著提高。