Fluorimetric and prototropic studies on the inclusion complexation of 3,3′-diaminodiphenylsulphone with β-cyclodextrin and its unusual behavior

The photophysical and photoprototropic properties of 3,3′-diaminodiphenylsulphone (3DADPS) in aqueous β-cyclodextrin (β-CDx) solution have been investigated using absorption and fluorescence spectral techniques. β-CDx forms 1:1 inclusion complex with 3DADPS as revealed by steady state and time-resolved fluorescence spectroscopy. This inclusion complex formation was also confirmed by the FT-IR and SEM image analysis of solid complex prepared by co-precipitation method. The existence of twisted intramolecular charge transfer state and the unusual red shift observed during inclusion complexation were analyzed and discussed. The ground and excited state acidity constants in β-CDx are reported. Based on the photophysical and photoprototropic characteristics of 3DADPS in β-CDx, the structure of the 1:1 inclusion complex is proposed.