Electrochemical and Photochemical Cyclization and Cycloreversion of Diarylethenes and Diarylethene-Capped Sexithiophene Wires
Electrochemical and Photochemical Cyclization and Cycloreversion of Diarylethenes and Diarylethene-Capped Sexithiophene Wires
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DOI：
10.1021/nn102806z
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发表时间：
2011-02-01
期刊：
影响因子：
17.1
通讯作者：
Yoshizawa, Kazunari
中科院分区：
文献类型：
--
作者：
Staykov, Aleksandar;Areephong, Jetsuda;Yoshizawa, Kazunari
对二芳基乙烯和二芳基乙烯封端的六噻吩进行了理论和实验研究，旨在加深对电化学和光化学开环和闭环机制的理解。基于DFT和TDDFT的理论计算表明，前线轨道的空间分布和占据决定和控制了二芳基乙烯在光辐射和电化学氧化过程中的开环和闭环。优化的几何形状，势能面，和开环和闭环形式之间的活化能计算二芳基乙烯在中性基态，激发态，单和双阳离子状态。前线轨道的分析被用来理解二芳基乙烯的环化和环化反转，并预测和解释二芳基乙烯封端的六噻吩分子线的开关性质。TDDFT数据与实验测量的UV/维斯光谱进行了验证。用密度泛函理论计算了二芳基乙烯封端的六噻吩二价阳离子的开壳基态，并用EPR谱进行了验证，并用计算的单重三重态分裂解释了EPR谱峰的展宽.实验和理论的良好一致性允许的开关行为的二芳基乙烯在溶液中的理解，在金属断裂结，在金属表面上的单层，并作为复杂的有机分子线的一部分。
A combined theoretical and experimental study was performed on diarylethenes and diarylethene-capped sexithiophenes aiming at an Improved understanding of the electrochemical and photochemical ring-opening and ring-closing mechanisms. Theoretical calculations, based on DFT and TDDFT, suggested that the spatial distribution and the occupancy of the frontier orbitals determine and control the diarylethenes' ring-opening and ring-closing upon photoirradiation and electrochemical oxidation. Optimized geometries, potential energy surfaces, and activation energies between the open-ring and closed-ring forms were calculated for diarylethenes in the neutral ground state, excited states, and mono- and dicationic states. Analysis of the frontier orbitals was employed to understand the cyclization and cycloreversion of diarylethenes and to predict and explain the switching properties of diarylethene-capped sexithiophene molecular wires. The TDDFT data were verified with experimentally measured UV/vis spectra. The DFT calculations estimated open-shell ground states of diarylethene-capped sexithiophene dications, which were verified with EPR spectroscopy, and the broadening of the peaks in the EPR spectra were explained with the calculated singlet triplet splitting. The good agreement of experiment and theory allows for the understanding of switching behavior of diatylethenes In solutions, in metal break junctions, in monolayers on metal surfaces, and as a part of complex organic molecular wires.