Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany.
Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.
Chemistry. 2020 Dec 23;26(72):17361-17365. doi: 10.1002/chem.202004009. Epub 2020 Nov 23.
Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.
通过氧化还原过程可逆地切换有机分子的光吸收对于传感器、光捕获、智能材料和医学诊断等应用很有意义。本工作提出了一种具有高荧光量子产率的对称苯并噻二唑（BTD）衍生物，在溶液和晶体状态下均具有高荧光量子产率，并通过光谱电化学分析表明，在中性状态下，UV 吸收的可逆切换是可能的，从宽带 Vis/NIR 吸收到 1 价氧化态，再到尖锐的 Vis 吸收到 2 价氧化态。对于单电子氧化物种，电子顺磁共振光谱电化学证实了离域自由基的形成。此外，我们的结果表明，在 1 价和 2 价氧化过程中，醌型畸变逐渐增加，这可以作为基于 BTD 的氧化还原开关发展的主题。
