Inclusion complexation of novel synthesis amino acid based ionic liquids with β-cyclodextrin

Inclusion complex formation between amino acid based ionic liquids (AAILs) i.e., 1-(2-(octylamino)-2-oxoethyl) pyridin-1-ium bromide and 44(hydroxyimino)methyl)-1-(2-(octylamino)-2-oxoethyl)pyridin-1-ium bromide into beta-cyclodextrin have been investigated in solution. The inclusion complexes (ICs) of AAILs with beta-CD were synthesized through the co-precipitation method. The solid IC formation is characterized by numerous analytical techniques, primarily by UV-vis spectroscopy and secondary by major techniques i.e., FT-IR and H-1 NMR. The binding constant and 1:1 stoichiometric of ICs nature of the complex between AAILs and beta-CD in solution were determined by Job's plot method using UV-vis spectroscopy. As results suggest, the binding constants of ICs are higher for OAOEPB-beta-CD as compared to HIMOAOEPB-beta-CD. The different thermodynamic parameters such as change in standard Gibbs free energy (Delta G(0)), standard enthalpy changes (Delta H-0) and standard entropy change (Delta S-0) have been estimated with the help of van't Hoff equation. Noteworthy changes of IR stretching frequency also support the IC formation. H-1 NMR results suggest that the tail part of AAILs is more suitably included inside the hydrophobic cavity of beta-CD and it shows 1:1 stoichiometric ICs formation. (C) 2019 Elsevier B.V. All rights reserved.