Stoichiometrically different inclusion complexes of 2-aminofluorene and 2-amino-9-hydroxyfluorene in beta-cyclodextrin: a spectrofluorimetric study.
Beta-cyclodextrin (beta-CDx) forms inclusion complexes with 2-aminofluorene (2AF) and 2-amino-9-hydroxyfluorene (2AHF) in different stoichiometries (Guest-host ratio 1:1 and 1:2 respectively) which is discussed on the basis of study by absorption and fluorescence spectroscopy. The ground and the excited state acidity constants for the neutral-monocation equilibrium of the two fluorophores in aqueous beta-CDx medium are determined by spectrophotometric and fluorimetric titration methods respectively. The dual fluorescence observed for 2AHF monocation in aqueous solution is due to the formation of monocation-water exciplex. This monocation-water exciplex formation is hindered in beta-CDx solution by the inclusion complexation. Based on the results obtained, the structures of the inclusion complexes are proposed.
Enoch
I V Muthu Vijayan
IV
Department of Chemistry, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India.
Swaminathan
M
M
D005449:Fluorenes / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D047392:beta-Cyclodextrins / Q000737:chemistry*
D005449:Fluorenes; D047392:beta-Cyclodextrins; C012177:2-aminofluorene; C031215:betadex