Inclusion of tyrosine derivatives with α-cyclodextrin in aqueous medium of various pH conditions by surface tension, conductance, UV–Vis and NMR studies

Abstract

Abstract We investigated the 1:1 molecular inclusion of three bioenergetically important tyrosine derivatives, e.g., dopamine hydrochloride, tyramine hydrochloride and (±)-epinephrine hydrochloride with cyclic oligosaccharide (α-cyclodextrin) in aqueous medium of various pH conditions (e.g., at pH = 7.4 and at pH = 9.0). Surface tension and specific conductivity measurements were used to explain the molecular ratio of inclusion complexes. Using Benesi–Hildebrand method with the help of UV–Vis spectroscopic inspection, apparent formation constants (K) and thermodynamic parameters for the inclusion have been determined. 1 H NMR study of α-cyclodextrin confirms the inclusion phenomenon. Hydrophobicity, H-bonding and pH of the medium play a significant role to validate the stability of the inclusion complexes.