Department of Chemistry, School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan.
Photochem Photobiol Sci. 2018 Jul 11;17(7):946-953. doi: 10.1039/c8pp00205c.
Non-linear photoresponses against excitation light intensity are important for the development of attractive photofunctional materials exhibiting high spatial selective photoswitching that is not affected by weak background light. Biphotochromic systems composed of two fast photochromic units have the potential to show a stepwise two-photon absorption process in which the optical properties can be non-linearly controlled by changing the excitation light conditions. Herein, we designed and synthesized novel bisnaphthopyran derivatives containing fast photoswitchable naphthopyran units. The bisnaphthopyran derivatives show a stepwise two-photon-induced photochromic reaction upon UV light irradiation accompanied by a drastic color change due to a large change in the molecular structure between the one-photon product and the two-photon product. Consequently, the color of the bisnaphthopyran derivatives can be non-linearly controlled by changing the excitation intensity. This characteristic photochromic property of the biphotochromic system provides important insight into advanced photoresponsive materials.
非线性光响应与激发光强度有关，对于开发具有吸引力的光功能材料很重要，这些材料具有高空间选择性光开关，不受弱背景光的影响。由两个快速光致变色单元组成的双光致变色体系有可能表现出逐步的双光子吸收过程，通过改变激发光条件可以对其光学性质进行非线性控制。在此，我们设计并合成了含有快速光致变色萘并吡喃单元的新型双萘并吡喃衍生物。双萘并吡喃衍生物在紫外光照射下表现出逐步双光子诱导光致变色反应，由于单光子产物和双光子产物之间的分子结构发生了很大变化，因此颜色发生了明显变化。因此，通过改变激发强度可以对双萘并吡喃衍生物的颜色进行非线性控制。双光致变色体系的这一特征光致变色性能为先进的光响应材料提供了重要的见解。
