US EPA

5366127 

Journal Article 

Effect of beta-cyclodextrin on the excited state proton transfer in 1-naphthol-2-sulfonate 

Abdel-Shafi, AA 

2001 

1 

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
ISSN: 1386-1425
EISSN: 1873-3557 

57 

9 

1819-1828 

English 

11506032 

10.1016/S1386-1425(01)00403-6 

WOS:000170065100011 

The photophysical properties of 1-naphthol-2-sulfonate (1-NOH-2-S) in various solvents and in aqueous beta-cyclodextrin (CD) solution have been investigated. The fluorescence quantum yields in non-aqueous solvents are approximately 0.5, while in water the fluorescence quantum yield is 0.1. The fluorescence quantum yield doubled on the addition of beta-CD. In aqueous solution, proton transfer to water takes place efficiently leading to the formation of the anion form with its longer wavelength emission broad band at about 460 nm. Any environmental changes have been found to affect the rate of deprotonation and subsequently the band intensity at 460 nm. In non-aqueous solution the anion emission band disappears completely. Upon the addition of beta-CD to the aqueous solution of 1-NOH-2-S, the anion emission decreases with an increase in the intensity of the neutral form at 362 nm. Fluorescence measurements show 1:1 inclusion of 1-NOH-2-S in the beta-CD cavity with an association constant of 1915 M(-1) using Benesi-Heldbrand treatment. 1H NMR studies are used to confirm the inclusion and to provide information on the orientation of 1-NOH-2-S inside the cavity of beta-CD. 

fluorescence; inclusion complexes; beta-cyclodextrin; naphthol derivatives; Benesi-Hildebrand; H-1 NMR