Excited-state dynamics of thiophene substituted betaine pyridinium compounds.
Excited-state dynamics of thiophene substituted betaine pyridinium compounds.
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DOI：
10.1039/c3cp53614a
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
S. Aloïse;Zuzanna Pawlowska;O. Poizat;G. Buntinx;A. Perrier;F. Maurel;Kazuhiro Ohkawa;Atsushi Kimoto;J. Abe
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文献类型：
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作者：
S. Aloïse;Zuzanna Pawlowska;O. Poizat;G. Buntinx;A. Perrier;F. Maurel;Kazuhiro Ohkawa;Atsushi Kimoto;J. Abe
本文研究了单(Th2SBpa)和双噻吩链(Th4SBpa)对称取代2-吡啶-1-基-1H-苯并咪唑(SbpA)的新型吡啶甜菜碱的光物理性质。这项研究是基于PCM-(TD)DFT计算支持的稳态、飞秒瞬时吸收光谱测量的组合。研究发现，母体分子发生的两步ICT过程(S0→S2激发，S2(CT)→S1(CT)内转化)对Th2SBpa没有影响，而Th4SBpa的情况则不太清楚。实际上，对于这两个分子，一条新的衰变路径涉及到π-电子系统中的噻吩基，这是导致三重态产生的原因。人们强烈怀疑这条新路线参与了S1(CT)的平行生产。
This work deals with the photophysics of novel pyridinium betaine based on 2-pyridin-1-yl-1H-benzimidazole (SBPa) substituted symmetrically by mono- (Th2SBPa) and bi-thiophene fragments (Th4SBPa). The study is based on a combination of steady-state, femtosecond transient absorption spectroscopic measurements supported by PCM-(TD)DFT calculations. It is found that the two step ICT process (S0 → S2 excitation followed by S2(CT) → S1(CT) internal conversion) occurring for the parent molecule remains unaffected for Th2SBPa while the situation is less clear for Th4SBPa. Actually, for both molecules, a new decay route involving the π-electron system localized in thiophenic groups is responsible for the production of triplet states. Involvement of this new route in the parallel production of S1(CT) is strongly suspected.