化学学报 ›› 1988, Vol. 46 ›› Issue (1): 30-37. 上一篇    下一篇

研究论文

疏水作用对光化学和光物理过程的影响 I: 不良溶剂中长链β-萘甲酸烷基酯的簇集和激基缔合物的形成

佟振合;刘;徐承柏   

  1. 中国科学院感光化学研究所
  • 发布日期:1988-01-15

Hydrophobic effects on photophysical and photochemical processes I: Aggregation and excimer formation of long chain alkyl β-naphthoates in poor solvents

DONG ZHENHE;LIU;XU CHENGBAI   

  • Published:1988-01-15

研究了不同链长的β-萘甲酸烷基酯(An)在乙二醇-水(EG-H2O)和二甲基砜-水(DMSO-H2O)混合溶剂中的荧光光谱, 以及添加物(无机盐、长链饱和烷烃、糖淀粉)对An荧光的影响. 长链An在混合溶剂中很容易形成激基缔合物, 表明疏水作用促使长链分子相互簇集. 测定了不同链长的分子发生簇集的临界浓度和临界溶剂组成. 分别添加长链烷烃和糖淀粉都能引起激基缔合物的荧光强度减弱和单体荧光强度的增强, 表明An和长链烷烃共簇集, 与糖淀粉形成包结物. 研究了在簇集体中An形成激基缔合物的动力学和热力学, 测定了激基缔合物形成和解离速率常数、活化能和热焓的变化. 证明了簇集体中基态发色基团之间并不具有激基缔合物的构型, 在一定温度下, 簇集体会发生相变.

关键词: 光化学反应, 乙二醇, 羧酸酯, DMSO, 相变, 焓, 猝灭效应, 活化能, 反应速度常数, 疏水性质

The fluorescence spectra of alkyl b-naphthoates with various chain lengths (An) in DMSO-H2O and ethylene glycol-H2O mixtures were studied. The b-naphthoates with short chain show monomer fluorescence only in both solvent mixtures, while the fluorescence spectra of long chain alkyl b-naphthoates are dominated by excimer emission. The addition of long chain hydrocarbon and amylose resulted in the reduction of excimer emission and the enhancement of monomer fluorescence. All these experimental results support intermol. aggregation of long chain alkyl b-naphthoates in poor solvents. The kinetic parameters of formation and dissociation of excimer as well as fluorescence polarization in aggregates were measured.

Key words: PHOTOCHEMICAL REACTION, ETHANEDIOL, CARBOXYLIC ACID ESTER, DMSO, PHASE TRANSFORMATION, ENTHALPY, QUENCHING EFFECTS, ACTIVATION ENERGY, REACTION RATE CONSTANT, HYDROPHOBIC PROPERTIES

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