Effect of inclusion complexation on the photophysical behavior of diphenylamine in β-cyclodextrin medium: A study by electronic spectra

Spectral characteristics of diphenylamine (DPA) have been investigated in β-cyclodextrin (β-CDx) solution. The formation of the complex was revealed by UV, steady state and time-resolved fluorescence spectroscopy. The stoichiometry of DPA:β-CDx complex, determined using Benesi–Hildebrand equation and Job's continuous variation method is 1:1. The binding constants calculated from various methods are reported. This inclusion complex formation from DPA and β-CDx was also confirmed by the FT-IR spectral study and SEM image analysis of solid complex prepared by co-precipitation method.

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► Enhancement of absorbance and fluorescence intensity occurs together with complex formation.
► Biexponential decay for DPA by the addition of β-CDx is due to the formation of inclusion complex.
► Binding constant and stoichiometry of DPA with β-CDx are calculated from BH plot.
► FT-IR and SEM images analysis confirm complex between DPA and β-CDx.