A novel type of molecular assembly: aggregates formed by molecules with polar chains in nonpolar solvents
✍ Scribed by Chen-Ho Tung; Li-Zhu Wu
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 454 KB
- Volume
- 244
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The emission spectra and photodimerization of poly(ethylene glycol) oligomers with a naphthalene group as one terminal of each chain (N-P,) in nonpolar solvents were investigated. The fluorescence spectra of N-P, in isopentane at temperatures below -20°C are dominated by excimer emission. The addition of unlabeled poly(ethylene glycol) to the solutions results in a reduction in the excimer emission and an enhancement of monomer emission. Fluorescence depolarization measurements at 77 K suggest the existence of significant energy migration. The glassy solutions show a strong delayed excimer fluorescence and triplet excimer phosphorescence. The photoirradiation yields a 'cubane-like' photodimer of the naphthalene groups with high quantum yield. All these observations indicate that lipophobic interactions push N-P, chains together to form aggregates.