Effect of. gamma. -cyclodextrin on the intramolecular charge transfer processes in aminocoumarin laser dyes
- Indian Association for the cultivation of Science, Calcutta (India)
Steady-state and time-resolved studies on the emission properties of three 7-(diethylamino)coumarin laser dyes (I-III) in aqueous {gamma}-cyclodextrin ({gamma}-CD) solutions are reported. On addition of {gamma}-CD, fluorescence maxima of all the three dyes shift to higher energy, with a huge enhancement of the yield of intramolecular charge transfer (ICT) emission for the flexible ones (I and II) and a very slight enhancement for the rigid analogue III. The results are explained in terms of the concept of polarity-dependent twisted ICT rates. It is proposed that twisted ICT, the main nonradiative process in the excited ICT states of these dyes, is severely restricted inside the {gamma}-cyclodextrin cavity because of the reduced polarity. This is responsible for the enhancement of fluorescence from the ICT state.
- OSTI ID:
- 6378460
- Journal Information:
- Journal of Physical Chemistry; (USA), Vol. 94:10; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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