Inclusion complex of Alizarin Red S with β-cyclodextrin: Synthesis, spectral, electrochemical and computational studies

Inclusion complex formation of Alizarin Red S (ARS) with beta-cyclodextrin was studied by UV-visible, Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), cyclic voltammetry (CV) and molecular modeling methods. FTIR and NMR results had justified that ARS was partly included into the beta-CD cavity. The inclusion complex has 1:1 stoichiometry, where the apparent formation constant achieved was 4.137 x 10(3) L/mol using Benesi-Hildebrand equation. Cyclic voltammetry results shows the peak current decreased as the ARS molecule entered the hydrophobic cavity of beta-CD. Molecular modeling results showed that the aromatic ring of the ARS entered into the secondary hydroxyl rim of the CD cavity was more thermodynamically favorable. The lowest stabilization energy, Delta E was -17.80 kcal/mol, and dipole-dipole interaction is was one of the driving forces for the inclusion complex formation. (C) 2014 Elsevier B.V. All rights reserved.