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Hydrophobic Acceleration of Electron Transfer Processes
Ji-Liang Shi1, Xin Chen, Xi-Kui Jiang
1Shanghai Institute of Organic Chemistry, 354 Fenglin Lu, Shanghai 200032, China.
The Journal of Organic Chemistry
|July 12, 1996
Summary
Electron transfer between naphthylalkanes and benzoquinones, driven by hydrophobic-lipophilic interactions (HLI), was studied. Static quenching indicates preassociation, allowing assessment of HLI-driven coaggregation using Stern-Volmer slopes.
Area of Science:
- Supramolecular Chemistry
- Photochemistry
- Physical Organic Chemistry
Background:
- Hydrophobic-lipophilic interactions (HLI) play a crucial role in molecular recognition and self-assembly.
- Electron transfer reactions are fundamental processes in chemistry and biology, influenced by molecular structure and environment.
- Fluorescence spectroscopy is a powerful tool for studying molecular interactions and electron transfer dynamics.
Purpose of the Study:
- To investigate electron transfer processes between specific naphthylalkane donors and benzoquinone acceptors.
- To elucidate the role of hydrophobic-lipophilic interactions (HLI) in facilitating these electron transfer events.
- To assess the impact of solvent composition and molecular structure on preassociation and electron transfer.
Main Methods:
- Fluorescence spectroscopy was employed in dioxane-water mixtures with varying solvent compositions (psi values).
- Electron paramagnetic resonance (EPR) and UV-visible (UV-vis) spectroscopy were used to confirm electron transfer.
- Stern-Volmer analysis was applied to quantify the extent of preassociation and HLI-driven coaggregation.
Main Results:
- Evidence from EPR, UV-vis, and fluorescence quenching confirmed electron transfer between 1-12 and 2-12.
- UV-vis data and fluorescence lifetime measurements indicated that electron transfer is preceded by static preassociation.
- Stern-Volmer slopes (Ksv) were used to assess HLI-driven coaggregation, revealing chain-length effects and solvent aggregating power (SAgP) influences.
Conclusions:
- HLI significantly facilitates electron transfer between the studied molecules.
- The quenching process is static, driven by preassociation of donor and acceptor molecules.
- Solvent composition and molecular structure, including chain length, critically influence the observed electron transfer and coaggregation phenomena.