Effect of Cyclodextrin Nanocavity Confinement on the Photophysics of a -Carboline Analogue: A Spectroscopic Study

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• 作者：Paramita Das ; Alok Chakrabarty ; Basudeb Haldar ; Arabinda Mallick ; Nitin Chattopadhyay
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：June 28, 2007
• 年：2007
• 卷：111
• 期：25
• 页码：7401 - 7408
• 全文大小：169K
• 年卷期：v.111,no.25(June 28, 2007)
• ISSN：1520-5207

文摘

Interaction of a -carboline based biologically active molecule, 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ), with -, -, and -cyclodextrins (CDs) in aqueous solution has been studied usingsteady state and time-resolved fluorescence and steady-state fluorescence anisotropy techniques. Polaritydependent intramolecular charge transfer (ICT) process is responsible for the remarkable sensitivity of thisbiological fluorophore to the CD environments. Upon encapsulation, the CT fluorescence exhibits hypsochromicshift along with enhancements in the fluorescence yield, fluorescence anisotropy (r), and fluorescence lifetime.The reduction in the nonradiative deactivation rate of the fluorophore within the CD nanocavities leads to anincrease in both fluorescence yield and lifetime. Among the three CDs, -CD shows the most spectacularconfinement effect. The results establish the formation of 1:1 AODIQ:CD inclusion complexes in - and-CDs. In aqueous -CD solutions, however, depending on the concentration of the -CD, formation of both1:1 and 1:2 complexes have been revealed. Hydrodynamic radii of the 1:1 and 1:2 probe--CD supramolecularcomplexes have also been determined.