HOST-GUEST ASSOCIATION OF MORIN WITH ОІ-CD AND C-HEXYLPYROGALLOL[4]ARENE: STRUCTURE OF THE COMPLEXES AND THE EFFECT OF pH
S. Chandrasekaran1, I. V. Muthu1, V. Enoch1,2
1Department of Chemistry, Karunya University, Coimbatore, Tamil Nadu, India
drisraelenoch@gmail.com
2Department of Nanosciences and Technology, Karunya University, Coimbatore, Tamil Nadu, India
Keywords: host-guest complex, morin, b-cyclodextrin, C-hexylpyrogallol[4]arene, fluorescence spectroscopy
Abstract
The study of the host-guest association of Morin hydrate (MO) with b-cyclodextrin (b-CD) and C-hexylpyrogllol[4]arene (C-HPA) is reported in this paper. The iInclusion complexation of MO is studied by ultraviolet-visible, steady-state fluorescence, time-resolved fluorescence, 1H nuclear magnetic resonance (NMR), and two dimentional rotating-frame nuclear overhauser effect correlation (2D ROESY) spectroscopic techniques. The stoichiometry and the binding constant for the MO-b-CD complex are derived from the linearity of the Benesi-Hildebrand equation. The binding constant for the MO-C-HPA complex is calculated from the nonlinear curve fitting of fluorescence intensities. The effects of the acid strength on the absorption and fluorescence spectra of MO are studied in the absence and the presence of b-CD/C-HPA host molecules. The pKa values of the ground and the excited states are reported.
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