Excimer formation in inclusion complexes of β-cyclodextrin with salbutamol, sotalol and atenolol: Spectral and molecular modeling studies

The inclusion complexation behavior of salbutamol, sotalol and atenolol drugs with beta-cyclodextrin (beta-CD) were investigated by UV-visible, fluorometry, time resolved fluorescence, FT-IR, 1H NMR, SEM and PM3 methods. The above drugs gave a single emission maximum in water where as dual emission in beta-CD. In beta-CD solutions the shorter wavelength fluorescence intensity was regularly decreased and longer wavelength fluorescence intensity increased. Addition of beta-CD to aqueous solutions of drugs resulted into excimer emission. The excimer emission is concluded to be due to a 1:2 inclusion complex between beta-CD and drug. Nanosecond time-resolved studies indicated that all drugs exhibited biexponential decay in solvents and triexponential decay in CD. Investigations of thermodynamic and electronic properties confirmed the stability of the inclusion complex. (C) 2012 Elsevier B.V. All rights reserved.