Hydrophobic effects on photophysical and photochemical processes: excimer fluorescence and aggregate formation of long-chain alkyl 4-(N,N-dimethylamino) benzoate in water—organic binary mixtures
✍ Scribed by Zhen Zhen; Chen-Ho Tung
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 427 KB
- Volume
- 180
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Fluorescence probe techniques have been employed to investigate aggregate formation of long-chain molecules in water-organic binary mixtures. The very dilute solution (2x lo-' M) of hexadecyl4-(N,Ndimethylamino)benzoate (HDMAB) in ethylene glycol-water, dimethyl sulfoxide-water and dioxane-water mixtures exhibits excimer fluorescence, suggesting the formation of an aggregate which enhances the local concentration of the chromophore. Addition of a longchain hydrocarbon to the solution results in the enhancement of monomer fluorescence and reduction of excimer emission, due to formation of a coaggrwte between the hydrocarbon and HDMAB. Amylose forms a host-guest inclusion complex with HDMAB, thus destroying the aggregate.