Dual fluorescence of dothiepin, doxepin drugs—effect of solvents and β-cyclodextrin

Abstract The absorption and fluorescence spectra of dothiepin and doxepin have been recorded in solvents of different polarities and β-cyclodextrin (β-CD). The inclusion complex of both drugs with β-CD is investigated by UV–visible, fluorimetry, DFT, FT-IR and scanning electron microscopy (SEM). In all solvents, the absorption and emission maxima of dothiepin are red shifted than doxepin. β-CD studies reveal that both drugs form a mixture inclusion complex with β-CD. The structured longer wavelength emission in β-CD aqueous solution suggests that viscosity plays major role in the β-CD. This study also confirms van der Waals forces and hydrophobic interactions are the driving forces for the inclusion complexes.