Photophysical and photoprototropic characteristics of phenothiazine in aqueous and β-cyclodextrin media

The photophysical and photoprototropic characteristics of phenothiazine (PTZ) in aqueous and β-cyclodextrin (β-CD) media have been investigated using absorption, steady state and time resolved fluorescence measurements. The absorbance and fluorescence intensities of the neutral and monocationic forms of PTZ are enhanced by the addition of β-cyclodextrin and it is due to the formation of 1:1 inclusion complex. The formation of complex is confirmed by the decay analysis and Job's continuous variation method in the liquid state while FT-IR spectral study and SEM image analysis in the solid state. The peak and pKa* values of PTZ in aqueous media are higher than in β-CD medium, which reveals that the >NH group of PTZ lies in the β-CD cavity.