Cavity Size Specific Interaction of Cyclodextrins with Coumarin 6: Intriguing Photophysical Modulations

Bir, Ayon (2014) Cavity Size Specific Interaction of Cyclodextrins with Coumarin 6: Intriguing Photophysical Modulations. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Coumarin 6 (C6) is strongly fluorescent in solution and emits in the green. It is widely used as a laser dye and for various applications related to its optical properties. It is also fluorescent in the solid state. According to its hydrophobic structure, the dye can be expected to precipitate in water and tends to crystallize easily. Here we have demonstrated that different cavity sizes of cyclodextrins (CDs) allow differential interactions with C6 leading to interesting modifications in its photophysical properties. We have used fluorescence spectroscopy to show that the smallest of the CDs, α-CD, interacts with the microcrystals of C6 in aqueous medium to split them into smaller fragments. Whereas, the bigger ones, β- and γ-CDs encapsulate C6 molecules inside their cavities that modulates their fluorescence output based on the nature of guest-host complex formation. The studies show that the properties of the laser dye C6 can be modulated and tuned by using CDs having different cavity size.

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