疏水作用对光化学和光物理过程的影响——Ⅷ.N-烷基吲哚在不良溶剂中的簇集及其荧光光谱

本文研究了链长不同的N-烷基吲哚和3-甲基-N-烷基吲哚在二甲基亚砜-水(DMSO-H_2O)混合溶剂中的稳态和时间分辩荧光光谱, 发现随混合溶剂中水的体积分数增大、短链吲哚衍生物的荧光峰位置红移。荧光寿命增长、而长链吲哚衍生物荧光峰位置明显兰移、荧光寿命变短。表明长链吲哚衍生物在混合溶剂中发生簇集,簇集体中微环境的极性和环己烷相似, 利用时间分辨荧光光谱计算出长链吲哚衍生物在溶液本体相和簇集体中的分布。

HYDROPHOBIC EFFECTS ON PHOTOPHYSICAL AND PHOTOCHEMICAL PROCESSES——Ⅷ. AGGREGATION AND FLUORESCENCE SPECTRA OF LONG CHAIN N-ALKYLINDOLES IN POOR SOLVENTS

The fluorescence spectra of N-alkylindoles and 3-methyl-N-alkylindoles with various chain lengths in dimethyl sulfoxide-water(DMSO-H_2O) were studied under stationary and nonstationary condition. As the fraction of water in solvent mixture (Φ) increases, the indoles with short chain display red shifts in fluorescence λ_(max) and increases in fluorescence lifetime. On the contrary, the fluorescence λ_(max) of long chain indoles shift to blue side and their fluorescence lifetimes decrease with increasing in Φ. This observation supports intermolecular aggregation of long chain indoles in poor solvents, The microscopic polarity in aggregates is similar to that in cyclohexane. The distribution of indoles between bulk solution and aggregates was determined by time resolved fluorescence technique.