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A pentiptycene-derived molecular brake: Photochemical Ea→Z and electrochemical Za→E switching of an enone module

机译:五百萜衍生的分子制动器:光化学EA→Z和电化学ZA→E切换eNONE模块

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摘要

The synthesis and brakelike performance of a new molecular system (1) consisting of a pentiptycene rotor and a 2-methyleneindanone brake are reported. The rotation kinetics of the rotor was probed by both variableerature 1H and 13C NMR spectroscopy and DFT calculations, and the switching between the brake-on and brake-off states was conducted by a combination of photochemical and electrochemical isomerization. Because of the greater steric hindrance between the rotor and the brake units in the Z form ((Z)-1) than in the E form ((E)-1), rotation of the rotor is slowed down 500-fold at room temperature (298 K) on going from (E)-1 to (Z)-1, corresponding to the brake-off and brake-on states, respectively. The (E)-1a→(Z)-1 photoisomerization in acetonitrile is efficient and reaches an (E)-1/(Z)-1 ratio of 11:89 in the photostationary state upon excitation at 290 nm, attributable to a much larger isomerization quantum efficiency for (E)-1 versus (Z)-1. An efficient (Z)-1a→(E)-1 isomerization (96%) was also achieved by electrochemical treatment through the radical anionic intermediates. Consequently, the reversibility of the E-Z switching of 1 is as high as 85%. The repeated E-Z switching of 1 with alternating photochemical and electrochemical treatments is also demonstrated.
机译:报道了由五庚啶转子和2-亚甲基茚环酮制动器组成的新分子系统(1)的合成和Brakelike性能。转子的旋转动力学通过可变的1H和13C NMR光谱和DFT计算探测,并且通过光化学和电化学异构化的组合进行制动器接通和制动偏离状态之间的切换。由于转子和Z形式((Z)-1)中的制动单元之间的空间脉冲越大,而不是E形式((e)-1),转子的旋转在室温下减慢500倍(298 K)分别从(e)-1至(z)-1,分别对应于制动和制动和制动状态。乙腈中的(e)-1A→(Z)-1光象分子化是有效的,在激发状态下在290nm的激发时达到(e)-1 /(z)-1比率,归因于(e)-1与(z)-1的更大的异构化量子效率。通过电化学处理通过自由基阴离子中间体,还通过电化学处理来实现高效(Z)-1A→(e)-1异构化(96%)。因此,E-Z开关1的可逆性高达85%。还证明了具有交替光化学和电化学处理的重复的E-Z开关。

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