Development and investigation of the photophysical process of photo-energy harvesting and transfer using σ-π and π-π interactions.

研究了α，ω-二芳基低聚硅烷（1-萘基）-（SiMe_2）_n-（1-萘基）（1-5）和（9-蒽基）-（SiMe_2）_n-（9-蒽基）（6-10），（9-蒽基）-（SiMe_2）_n-（1-萘基）（11- 1 - 5）（n= 1，2，3，4，6）的物理化学性质。在这些化合物中，观察到三种类型的相互作用，即链单元中的硅原子之间的σ-σ相互作用、两个芳香基团之间的π-π相互作用以及芳香族化合物与硅链单元之间的σ-π相互作用。结果，观察到分子内激基复合物/激基复合物发射和电荷转移（CT）发射。当n ≥ 2时，在环己烷中观察到分子内激基缔合物发射。最强的激基缔合物发射2和7是相反的平山规则（n=3）提出的碳类似物，也表明，分子内环加成是轻微的。蒽基系列的时间分辨荧光（TR-FL）光谱表明，激基缔合物形成的时间常数随链长的变化而变化（82-152 ps）。在4、5和10的情况下，在乙腈或THF中观察到电荷转移（CT）发射。10的CT状态形成的时间常数相对较慢（45 ps），这可能表明构象变化。从局部激发态的单体发射观察到1和6在环己烷和乙腈。对于12-15，在环己烷中观察到分子内激基复合物发射。对于固定和TR-FL测量，萘基部分的激发显示出非常有效的分子内能量转移到蒽基部分，因此仅观察到来自蒽基部分的荧光。在14和15的情况下，在乙腈中观察到电荷转移（CT）发射。然后TR-FL的15揭示了从萘基到蒽基部分的分子内能量转移比电荷转移快。

The photophysical properties of α, ω-diaryloligosilanes : (1-naphthyl)-(SiMe_2)_n-(1-naphthyl) (1-5) and (9-anthryl)-(SiMe_2)_n-(9-anthryl) (6-10), (9-anthryl)-(SiMe_2)_n-(1-naphthyl) (11-15), n=1,2,3,4 and 6 were investigated. In these compounds, three types of interactions, a σ-σ interaction between silicon atoms in the chain unit, a π-π interaction between two aromatic groups, and a σ-π interaction between aromatics and a silicon chain unit were observed. As a result, intramolecular excimer/exciplex emissions and charge-transfer (CT) emission were observed. Intramolecular excimer emission was observed in cyclohexane when n【greater than or equal】2. The strongest excimer emission of 2 and 7 is in contrast to the Hirayama-rule (n=3) proposed for carbon analogues and also shows that intramolecular cycloaddition is minor. The time resolved fluorescence (TR-FL) spectra of an anthryl series revealed that the time constant of the excimer formation varied depending on the chain length (82-152 ps). In the cases of 4,5,and 10,charge-transfer (CT) emission was observed in acetonitrile or THF. The time constant of the CT state formation for 10 was relatively slow (45 ps), which may indicate a conformational change. A monomer emission from the locally excited state was observed for 1 and 6 in both cyclohexane and acetonitrile. For 12-15,the intramolecular exciplex emission was observed in cyclohexane. For the stationary and the TR-FL measurements, the excitation of the naphthyl moiety showed a very efficient intramolecular energy transfer to the anthryl moiety, thus only fluorescence from the anthryl moiety was observed. In the case of 14 and 15,a charge-transfer (CT) emission was observed in acetonitrile. Then TR-FL of 15 revealed that the intramolecular-energy transfer from the naphthyl to anthryl moieties is faster than the charge transfer.