A study of the interaction between rhodamine 6g and hydroxy propyl β-cyclodextrin by steady state fluorescence

The binding of rhodamine 6G and hydroxy propyl beta-cyclodextrin (H beta-CD) was investigated measuring fluorescence and absorption at pH 7.0. The solid inclusion complex of Rh6G and H beta-CD has been studied by Ultraviolet (UV) spectroscopy, Fluorimetry, Fourier Transform Infrared (FTIR), H-1 Nuclear Magnetic Resonance ((HNMR)-H-1) and in the Scanning Electron Microscope (SEM). Association constant K-g and K-e were determined by the enhancement of the fluorescence of rhodamine 6G in the presence of H beta-CD. Fluorescence of Rh6G is generally enhanced, in complexes of Rh6G and beta-Cyclodextrin in aqueous solutions. The free energy change for the ground state (Delta G(g)) and for the excited state (Delta G(e)) have also been determined. The experimental results indicated that the inclusion process is an exothermic and spontaneous. (C) 2011 Elsevier B.V. All rights reserved.