Rate-Tunable Stepwise Two-Photon-Gated Photoresponsive Systems Employing a Synergetic Interaction between Transient Biradical Units,Journal of the American Chemical Society

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Rate-Tunable Stepwise Two-Photon-Gated Photoresponsive Systems Employing a Synergetic Interaction between Transient Biradical Units
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-03-17 , DOI: 10.1021/jacs.6b13322
Katsuya Mutoh ₁ , Yoichi Kobayashi ₁ , Takuya Yamane ₁ , Takahiro Ikezawa ₁ , Jiro Abe ₁

Affiliation

The cooperative interaction between photons and molecules, recently termed as the "photosynergetic" effect, is crucial to develop advanced photofunctional materials beyond a one-photon reaction of a single chromophore. The two-photon absorption is one of the attractive processes for the efficient utilization of photons. Especially, the nonlinear response of the two-photon absorption process is of interest not only to realize temporal and spatial control of reactions but also to develop the rewritable optical memory media and smart optical devices responding to the intensity of light. The stepwise two-photon-induced photochromism, which involves a short-lived transient species as an intermediate state, is one of the advanced photoresponsive compounds. The key feature of the stepwise two-photon-induced photochromism is an effective electronic interaction between the photogenerated transient chromophores. Here, we designed bis(phenoxyl-imidazolyl radical complex) (bisPIC) derivatives, which are composed of a couple of photochromic units and absorb two photons in a stepwise manner. The stepwise photochromic properties were investigated in detail by using double pulse laser flash photolysis and time-resolved Fourier transform infrared (TR-FTIR) spectroscopy. The one-photon reaction leads to the generation of a short-lived biradical species, which absorbs an additional photon and generates two electronically coupled biradical units, resulting in the formation of the long-lived quinoid species. The short-lived biradical species and the long-lived quinoid species of each bisPIC derivatives show the significantly different absorption spectra and rates of the thermal back reactions. These results indicate the colors and the lifetimes of the transient species can be systematically changed by switching the wavelength and intensity of the excitation light. The development of an excitation light threshold system based on the fast-switchable photochromic compounds will give important insights not only for the development of functional photoresponsive materials but also for the fundamental research using the cooperative excitation and interaction between photochromophores.

中文翻译：

采用瞬态双基单元之间协同相互作用的速率可调步进双光子门控光响应系统

光子和分子之间的协同相互作用，最近被称为“光协同”效应，对于开发超越单个发色团的单光子反应的先进光功能材料至关重要。双光子吸收是有效利用光子的有吸引力的过程之一。特别是，双光子吸收过程的非线性响应不仅有利于实现反应的时间和空间控制，而且有利于开发响应光强的可重写光存储介质和智能光学器件。逐步双光子诱导的光致变色是一种先进的光响应化合物，它涉及一种短寿命的瞬态物质作为中间状态。逐步双光子诱导光致变色的关键特征是光生瞬态发色团之间的有效电子相互作用。在这里，我们设计了双（苯氧基-咪唑基自由基复合物）（bisPIC）衍生物，它们由一对光致变色单元组成，并以逐步的方式吸收两个光子。通过使用双脉冲激光闪光光解和时间分辨傅里叶变换红外（TR-FTIR）光谱详细研究了逐步光致变色性能。单光子反应导致产生短寿命的双自由基物种，该物种吸收额外的光子并产生两个电子耦合的双自由基单元，从而形成长寿命的醌型物种。每种 bisPIC 衍生物的短寿命双自由基物质和长寿命醌类物质显示出显着不同的吸收光谱和热逆反应速率。这些结果表明，通过切换激发光的波长和强度，可以系统地改变瞬态物质的颜色和寿命。基于可快速切换的光致变色化合物的激发光阈值系统的开发不仅将为功能性光响应材料的开发提供重要的见解，而且将为使用光致发色团之间的协同激发和相互作用进行基础研究。这些结果表明，通过切换激发光的波长和强度，可以系统地改变瞬态物质的颜色和寿命。基于可快速切换的光致变色化合物的激发光阈值系统的开发将为功能性光响应材料的开发以及使用光致发色团之间的协同激发和相互作用的基础研究提供重要的见解。这些结果表明，通过切换激发光的波长和强度，可以系统地改变瞬态物质的颜色和寿命。基于可快速切换的光致变色化合物的激发光阈值系统的开发将为功能性光响应材料的开发以及使用光致发色团之间的协同激发和相互作用的基础研究提供重要的见解。

更新日期：2017-03-17

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