Spectroscopic studies on the inclusion complex of 2-naphthol-6-sulfonate with beta-cyclodextrin.
The photophysical properties of 2-naphthol-6-sulfonate (2-NOH-6-S) in various solvents and in aqueous beta-cyclodextrin solution have been investigated. The fluorescence quantum yields in non-aqueous solvents are approximately 0.20+/-0.02, while in water the yield is higher. The fluorescence quantum yield in water was found to depend on the pH value of the medium and increases as the pH increase up to a pH value of 4.0 where it comes to be constant. Absorption and fluorescence measurements show 1:1 inclusion of 2-NOH-6-S in the beta-cyclodextrin cavity. The association constant of 2-NOH-6-S-beta-cyclodextrin complex based on fluorescence measurements was calculated using Benesi-Hildbrand relationship and found to be 330+/-30M(-1). (1)H NMR studies are used to confirm the inclusion and to provide information on the geometry of 2-NOH-6-S inside the cavity of beta-cyclodextrin.
Abdel-Shafi
Ayman Ayoub
AA
Department of Chemistry, Faculty of Science, Ain Shams University, 11566 Abbassia, Cairo, Egypt. aaashafi@yahoo.com
D017666:Deuterium Oxide; D009682:Magnetic Resonance Spectroscopy; D009282:Naphthalenesulfonates / Q000737:chemistry*; D011522:Protons; D012996:Solutions / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D047392:beta-Cyclodextrins / Q000737:chemistry*
D009282:Naphthalenesulfonates; D011522:Protons; D012996:Solutions; D012997:Solvents; D047392:beta-Cyclodextrins; D017666:Deuterium Oxide; C031215:betadex