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Direct Observation of the Ultrafast Evolution of Open-Shell Biradical in Photochromic Radical Dimer
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-04-28 , DOI: 10.1021/jacs.7b01598
Yoichi Kobayashi 1 , Hajime Okajima 1 , Hikaru Sotome 2 , Takeshi Yanai 3 , Katsuya Mutoh 1 , Yusuke Yoneda 2 , Yasuteru Shigeta 4 , Akira Sakamoto 1 , Hiroshi Miyasaka 2 , Jiro Abe 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-04-28 , DOI: 10.1021/jacs.7b01598
Yoichi Kobayashi 1 , Hajime Okajima 1 , Hikaru Sotome 2 , Takeshi Yanai 3 , Katsuya Mutoh 1 , Yusuke Yoneda 2 , Yasuteru Shigeta 4 , Akira Sakamoto 1 , Hiroshi Miyasaka 2 , Jiro Abe 1
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Delocalized biradicals have been extensively studied because of fundamental interests to singlet biradicals and several potential applications such as to two-photon absorption materials. However, many of the biradical studies only focus on the static properties of the rigid molecular structures. It is expected that the biradical properties of the delocalized biradicals are sensitive to the subtle changes of the molecular structures and their local environments. Therefore, the studies of the dynamic properties of the system will give further insight into stable radical chemistry. In this study, we directly probe the ultrafast dynamics of the delocalized biradical of a photochromic radical dimer, pentaarylbiimidazole (PABI), by time-resolved visible and infrared spectroscopies and quantum chemical calculations with the extended multistate complete active space second-order perturbation theory (XMS-CASPT2). While the photogenerated transient species was considered to be a single species of the biradical, the present ultrafast spectroscopic study revealed the existence of two transient isomers differing in the contributions of biradical character. The origin of the two metastable isomers is most probably due to the substantial van der Waals interaction between the phenyl rings substituted at the imidazole rings. Unraveling the temporal evolution of the biradical contribution will stimulate to explore novel delocalized biradicals and to develop biradical-based photofunctional materials utilizing the dynamic properties.
中文翻译:
直接观察光致变色自由基二聚体中开壳双自由基的超快演化
由于对单线态双自由基和双光子吸收材料等几种潜在应用的基本兴趣,离域双自由基已被广泛研究。然而,许多双自由基研究只关注刚性分子结构的静态特性。预计离域双自由基的双自由基性质对分子结构及其局部环境的细微变化很敏感。因此,对系统动态特性的研究将进一步深入了解稳定的自由基化学。在这项研究中,我们直接探测了光致变色自由基二聚体五芳基联咪唑(PABI)的离域双自由基的超快动力学,通过时间分辨可见光和红外光谱以及扩展多态完全活性空间二阶微扰理论 (XMS-CASPT2) 的量子化学计算。虽然光生瞬态物种被认为是双自由基的单一物种,但目前的超快光谱研究揭示了存在两种对双自由基特征的贡献不同的瞬态异构体。两种亚稳态异构体的起源很可能是由于在咪唑环上取代的苯环之间存在大量范德华相互作用。解开双自由基贡献的时间演变将刺激探索新的离域双自由基并利用动态特性开发基于双自由基的光功能材料。
更新日期:2017-04-28
中文翻译:
![](https://scdn.x-mol.com/jcss/images/paperTranslation.png)
直接观察光致变色自由基二聚体中开壳双自由基的超快演化
由于对单线态双自由基和双光子吸收材料等几种潜在应用的基本兴趣,离域双自由基已被广泛研究。然而,许多双自由基研究只关注刚性分子结构的静态特性。预计离域双自由基的双自由基性质对分子结构及其局部环境的细微变化很敏感。因此,对系统动态特性的研究将进一步深入了解稳定的自由基化学。在这项研究中,我们直接探测了光致变色自由基二聚体五芳基联咪唑(PABI)的离域双自由基的超快动力学,通过时间分辨可见光和红外光谱以及扩展多态完全活性空间二阶微扰理论 (XMS-CASPT2) 的量子化学计算。虽然光生瞬态物种被认为是双自由基的单一物种,但目前的超快光谱研究揭示了存在两种对双自由基特征的贡献不同的瞬态异构体。两种亚稳态异构体的起源很可能是由于在咪唑环上取代的苯环之间存在大量范德华相互作用。解开双自由基贡献的时间演变将刺激探索新的离域双自由基并利用动态特性开发基于双自由基的光功能材料。