Photophysical Properties of 7‐(diethylamino)Coumarin‐3‐carboxylic Acid in the Nanocage of Cyclodextrins and in Different Solvents and Solvent Mixtures

Abstract

The photophysical properties of 7-(diethylamino) coumarin-3-carboxylic acid (7-DCCA) were studied in cyclodextrins (α, β, γ,-CDs), different neat solvents and solvent mixtures by using steady state absorption, emission and time-resolved fluorescence spectroscopy. We have observed that with gradual increase in concentration of β-CD the fluorescence quantum yield and lifetime decreased in a regular pattern whereas with gradual increase in concentration of γ-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 β-CD and with γ-CD it forms 1:1 and 1:2 (guest:host) inclusion complex. We proposed that the dye molecule formed capping complex with β-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 β-CD. The photophysics of 7-DCCA was 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.

Photophysics of a Coumarin in Different Solvents: Use of Different Solvatochromic Models

“…Cigan and co‐workers have also found similar type of behavior in the case of 7‑(Dimethylamino)coumarin‐3‐carbaldehyde in the presence of CHCl 3 . The same type of behavior was found in our previous study . Halogenated solvents often show variable effects of solvatochromism on the fluorophore with high ICT character .…”

“…The fluorescence emission peak of 7‐DCCAE in n‐heptane is 422 nm, whereas in presence of water, the emission peak appeared at 477 nm. The emission peak of 7‐DCCAE is quite different from its analogue 7‐DCCA . The significant difference of emission peak position of 7‐DCCAE with our previous results may be due to the deprotonated form of 7‐DCCA.…”

“…The emission peak of 7‐DCCAE is quite different from its analogue 7‐DCCA . The significant difference of emission peak position of 7‐DCCAE with our previous results may be due to the deprotonated form of 7‐DCCA. The emission peak position of 7‐DCCAE in the presence of different neat solvents is found to be strongly dependent on solvent polarity like 7‐DCCA .…”

“…The significant difference of emission peak position of 7‐DCCAE with our previous results may be due to the deprotonated form of 7‐DCCA. The emission peak position of 7‐DCCAE in the presence of different neat solvents is found to be strongly dependent on solvent polarity like 7‐DCCA . The absorption and emission peak position of 7‐DCCAE in DMSO is slightly redshifted compared to methanol.…”

“…S1a. In our previous study, we have observed that in water 7‐DCCA showed absorption peak at 408 nm . The absorption peak positions of 7‐DCCAE in other neat solvents are also quite different compared to the absorption peak of 7‐DCCA.…”