Yonekawa Izumi, Mutoh Katsuya, Kobayashi Yoichi, Abe Jiro
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 Mar 14;17(3):290-301. doi: 10.1039/c7pp00420f.
The development of two-photon induced photochromic compounds is important for advanced photoresponsive materials. The utilization of the long-lived transient states or species for two-photon absorption is one of the efficient strategies to realize the advanced photochemical behavior beyond a one-photon photochemical reaction. We have synthesized bi-photochromic compounds composed of two photochromic phenoxyl-imidazolyl radical complex units. The biphotochromic compounds generate two biradical units when the two photochromic units absorb photons with a stepwise manner. The interaction between the two biradicals through the central bridging phenyl ring is the key feature to control the stepwise photochromic reaction. Here, we introduced aromatic spacers in order to modulate the distance and the dihedral angle between the biradical units. The color and the rate of the thermal back reaction of the stepwise photochromism can be regulated by the control of the central bridging part. These results give important insights to develop desirable advanced photoresponsive compounds.
双光子诱导光致变色化合物的发展对于先进的光响应材料至关重要。利用长寿命瞬态态或物种进行双光子吸收是实现超越单光子光化学反应的先进光化学行为的有效策略之一。我们合成了由两个光致变色苯氧基-咪唑基自由基络合物单元组成的双光致变色化合物。当两个光致变色单元逐步吸收光子时，双光致变色化合物会产生两个双自由基单元。两个双自由基通过中心桥连苯环的相互作用是控制逐步光致变色反应的关键特征。在此，我们引入芳族间隔基以调节双自由基单元之间的距离和二面角。通过控制中心桥连部分，可以调节逐步光致变色的颜色和热逆反应速率。这些结果为开发理想的先进光响应化合物提供了重要的见解。
