title: The enhancement of fluorescence quantum yields of anilino naphthalene sulfonic acids by inclusion of various cyclodextrins and cucurbit[7]uril.
abstract: The association constants (K) for the inclusion complexation of four kinds of cyclodextrins (CDs (β- and γ-), 2,6-di-O-methylated β-CD, and 2,3,6-tri-O-methylated β-CD) and cucurbit[7]uril (CB[7]) with 1,8- and 2,6-anilinonaphthalene sulfonic acids (ANSs) were determined from fluorescence spectra enhanced by inclusion. Various CDs and CB[7] form stable 1:1 inclusion complexes with 1,8- and 2,6-ANSs: K=80-11700 M(-1) for 2,6-ANS and 50-195 M(-1) for 1,8-ANS. The high stability of the inclusion complexes of 2,6-ANS with CB[7] and 2,6-di-O-methylated β-CD is shown. Further, we determined the fluorescence quantum yields (Φ values) for the inclusion complexes of ANSs by using a fluorescence spectrophotometer equipped with a half-moon unit. The Φ values of 1,8- and 2,6-ANSs were largely enhanced by the inclusion of methylated β-CDs and did not correlate with the degree of stability (K) of the inclusion complexes. We characterized the structures of the inclusion complexes by 2D ROESY-NMR measurements. In addition, the microenvironmental polarity inside the hydrophobic CD and CB[7] cavities was evaluated using the fluorescence probe 2,6-ANS. Based on the emission mechanism and the aspect of inclusion in a hydrophobic cavity, we have suggested that the microenvironmental polarity and viscosity for the excited state of ANS plays an important role for the Φ values of inclusion complexes.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, Kita-ku, Okayama, Japan. ysueishi@okayama-u.ac.jp
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sueishi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Fujita
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakatani
authors.forename: Naoya
authors.initials: N
authors.lastname: Inazumi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Osawa
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D003505:Cyclodextrins / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D000817:Anilino Naphthalenesulfonates; D001952:Bridged-Ring Compounds; D003505:Cyclodextrins; D005456:Fluorescent Dyes; D007093:Imidazoles; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C047136:2-anilinonaphthalene-6-sulfonic acid; C027132:1-anilino-8-naphthalenesulfonate
keywords: Anilinonaphthalene sulfonic acid; Cucurbit[7]uril; Cyclodextrin; Fluorescence quantum yields; Inclusion complex