2004年6月
Thermodynamics and fluorescence spectra of 1,10-phenanthroline in micelles of poly (ethylene oxide)-type nonionic surfactant
JOURNAL OF SOLUTION CHEMISTRY
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- 巻
- 33
- 号
- 6-7
- 開始ページ
- 699
- 終了ページ
- 709
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- 出版者・発行元
- KLUWER ACADEMIC/PLENUM PUBL
The distribution of 1,10-phenanthroline (phen) in micellar solutions of the nonionic surfactants Triton X and C12En with varying poly (ethylene oxide) chain lengths has been studied by potentiometry, calorimetry, and fluorometry at 298 K. Micelles accommodate 1,10-phenanthroline according to the reaction, phen + Y-m = Y-m(phen), where Ym denotes a surfactant molecule aggregated in micelles. The constant Km for the reaction of Triton X increases as a linear function of n*, the number of ethylene oxide (EO) groups, as K-m = K(EO)n* + K-c. Nonzero K-EO and K-c values suggest a heterogeneous inner structure of the micelle, i.e., the hydrophobic core surrounded by a hydrophilic poly (ethylene oxide) (PEO) shell. On the basis of molar volumes, the intrinsic thermodynamic parameters of transfer of 1,10-phenantholine were extracted. The enthalpy and entropy of transfer of 1,10-phenanthroline from the PEO shell to the core are found to be small and negative. By using KEO and Kc values for C12En obtained by fluorometry, individual fluorescence spectra of 1,10-phenanthroline in the PEO shell and core were extracted. The fluorescence intensity of 1,10-phenathroline accommodated in the core, like in organic solvents, is significantly reduced relative to that in water. These facts indicate that the aromatic rings of 1,10-phenanthroline penetrate into the hydrophobic core, while its hydrophilic N site is still hydrated in the PEO shell.
- リンク情報
- ID情報
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- ISSN : 0095-9782
- Web of Science ID : WOS:000224268200008