title: Effect of cyclodextrin nanocavity confinement on the photophysics of a beta-carboline analogue: a spectroscopic study.
abstract: Interaction of a beta-carboline based biologically active molecule, 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ), with alpha-, beta-, and gamma-cyclodextrins (CDs) in aqueous solution has been studied using steady state and time-resolved fluorescence and steady-state fluorescence anisotropy techniques. Polarity dependent intramolecular charge transfer (ICT) process is responsible for the remarkable sensitivity of this biological fluorophore to the CD environments. Upon encapsulation, the CT fluorescence exhibits hypsochromic shift 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 an increase in both fluorescence yield and lifetime. Among the three CDs, gamma-CD shows the most spectacular confinement effect. The results establish the formation of 1:1 AODIQ:CD inclusion complexes in alpha- and beta-CDs. In aqueous gamma-CD solutions, however, depending on the concentration of the gamma-CD, formation of both 1:1 and 1:2 complexes have been revealed. Hydrodynamic radii of the 1:1 and 1:2 probe-gamma-CD supramolecular complexes have also been determined.
authors.affiliation: Department of Chemistry, Jadavpur University, Calcutta, India.
authors.forename: Paramita
authors.initials: P
authors.lastname: Das
authors.forename: Alok
authors.initials: A
authors.lastname: Chakrabarty
authors.forename: Basudeb
authors.initials: B
authors.lastname: Haldar
authors.forename: Arabinda
authors.initials: A
authors.lastname: Mallick
authors.forename: Nitin
authors.initials: N
authors.lastname: Chattopadhyay
mesh_terms: D002243:Carbolines / Q000737:chemistry*; D003505:Cyclodextrins / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D010777:Photochemistry; D011807:Quinolizines / Q000737:chemistry; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: C510252:3-acetyl-4-oxo-6,7-dihydro-12H indolo(2,3-a)quinolizine; D002243:Carbolines; D003505:Cyclodextrins; D011807:Quinolizines