Photoinduced Charge Separation and Charge Recombination of Oligothiophene−Viologen Dyads in Polar Solvent
Photoinduced Charge Separation and Charge Recombination of Oligothiophene−Viologen Dyads in Polar Solvent
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DOI：
10.1021/jp048364r
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发表时间：
2004-11
影响因子：
2.9
通讯作者：
Y. Araki;Hongxia Luo;Takumi Nakamura;M. Fujitsuka;O. Ito;Hiroki Kanato;‡‖ and Yoshio Aso;T. Otsubo
中科院分区：
文献类型：
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作者：
Y. Araki;Hongxia Luo;Takumi Nakamura;M. Fujitsuka;O. Ito;Hiroki Kanato;‡‖ and Yoshio Aso;T. Otsubo
利用CH3CN中的时间分辨荧光光谱和瞬态吸收光谱，研究了光诱导分子内电荷分离和电荷重组的低硫噻吩-甲基紫胶二偶体（Tn - MV2+·2X-, n = 4或8，X- = I-或PF6-）产生带正电荷的自由基对（Tn•+ - MV•+·2X-）。当T8−MV2+·2X-中的T8片段被激发后，由于T8−MV2+·2X-中的1T8*片段的荧光寿命比原始的1T8*短，通过T8 （1T8*）的激发单重态产生了自由基阳离子对（T8•+−MV•+·2X-）。T8•+−MV•+·2X-的寿命估计为720−980 ns，取决于反阴离子，I-或PF6-。另一方面，T4 - MV2+·2X-导致T4•+ - MV•+·2X-的寿命为210 ~ 240 ns，尽管电荷分离似乎是通过T4 （3T4*）的激发态发生的，因为没有观察到T4 - MV2+·2X-中1T4*部分的荧光猝灭。作为实现这些相对较长的寿命的因素…
Photoinduced intramolecular charge separation and charge recombination of oligothiophene−methyl viologen dyads (Tn−MV2+·2X-, n = 4 or 8, X- = I- or PF6-), which were designed to generate positively charged radical ion pairs (Tn•+−MV•+·2X-), have been investigated by the time-resolved fluorescence and transient absorption spectra in CH3CN. Upon excitation of the T8 moiety in T8−MV2+·2X-, the radical cation pair (T8•+−MV•+·2X-) was produced via the excited singlet state of T8 (1T8*), because the fluorescence lifetime of the 1T8* moiety in T8−MV2+·2X- becomes short compared with pristine 1T8*. The lifetimes of T8•+−MV•+·2X- were evaluated to be 720−980 ns depending on the counteranion, I- or PF6-. On the other hand, T4−MV2+·2X- leads to lifetimes of T4•+−MV•+·2X- of 210−240 ns, although the charge separation seems to occur via the excited triplet state of T4 (3T4*), because the fluorescence quenching of the 1T4* moiety in T4−MV2+·2X- was not observed. As factors to achieve these relatively long lifetimes of ...