Photophysical Properties of 7-(diethylamino)coumarin-3-carboxylic Acid in the Nanocage of Cyclodextrins and in Different Solvents and Solvent Mixtures
The photophysical properties of 7-(diethylamino)coumarin-3-carboxylic acid (7-DCCA) were reported in three cyclodextrins ( -CDs) using steady state absorption, emission and time resolved fluorescence spectroscopy. It was observed that with gradual increase in concentration of -CD the fluorescence quantum yield and lifetime decreased in a regular pattern whereas with gradual increase in concentration of -CD the fluorescence quantum yield and lifetime gradually increased. With addition of urea, the fluorescence quantum yield and lifetime of 7-DCCA in CDs increased. Binding constant calculation shows that 7-DDCA forms 1:1 complex with -CD and with -CD it forms 1:1 and 1:2 (guest: host) inclusion complex. It was proposed that the dye molecule formed capping complex with -CD by means of hydrogen bonding and after addition of urea the hydrogen bonding network broke down and part of dye molecule entered inside the cavity of -CD.
The photophysics of 7-DCCA were studied in dioxane-water mixture and ethylene glycol-acetonitrile mixture to know the effect of polarity and viscosity of the media. The photophysics of 7-DCCA was also studied in different neat solvents. It was found that the photophysics of 7-DCCA depended on the structural feature of the solvents and solvent mixtures. This work has been published inPhotochemistry and Photobiology (DOI: 10.1111/php.12000).