Charge-Transfer Chromatographic Study on the Interaction of Nonhomologous Series of Nonionic Surfactants with Heptakis(2,6-di-O-methyl)-β-cyclodextrin

A spectral displacement study of cyclodextrin/naphthenic acids inclusion complexes

The spectral displacement technique has been used to obtain 1:1 β-cyclodextrin (β-CD)/carboxylate anion equilibrium binding constants (K2) for some complex mixtures of naphthenic acids (NAs) and some examples of single-component NAs in aqueous solution. Three specific examples of single-component NAs were chosen with variable Z values as follows: 2-hexyldecanoic acid (Z = 0; S1), trans-4-pentylcyclohexanecarboxylic acid (Z = –2; S2), and dicyclohexylacetic acid (Z = –4; S3). The estimated K2 values for S1, S2, and S3 are as follows: 1.42 × 103 M–1, 52.2 × 104 M–1, and 13.1 × 104 M–1, respectively. The corresponding K2 values are 2.34 × 104 M–1 and 1.27 × 104 M–1 for commercial (Fluka) and industrial (Syncrude) sourced NAs, respectively. The magnitude of K2 for 1:1 complexes formed between β-CD and S1, S2, or S3 did not correlate with the degree of hydrogen deficiency (Z-series) but there was a correlation with the size of the guest molecules (n) examined in this study. The correlation between complex stability and the relative size of the lipophilic fragments of the guest molecule are related to the importance of the hydrophobic effect for inclusion of such carboxylic acid guest molecules within β-CD.

Use of liquid chromatography for the determination of interactions between bioactive compounds

Molecular interactions can be easily determined both by thin-layer and high performance liquid chromatography. The theory and practice of the determination of molecular interactions and the various methods for the calculation of complex stability are presented. Examples of the application of liquid chromatographic methods for the measurements of molecular interactions are also discussed.

Interaction of some anti-hypoxia drugs with hydroxypropyl-beta-cyclodextrin studied by means of charge transfer chromatography

The interaction of 12 anti-hypoxia drugs with hydroxypropyl-beta-cyclodextrin (HPBCD) and the influence of LiCl, NaCl and KCl on the strength of interaction was studied by charge transfer chromatography. Most of the drugs form inclusion complexes with HPBCD and the relative strength of interaction varies markedly according to the structure of the drugs. Salts exert a considerable influence on the inclusion complex formation and the effect depends on the radii of the cation. The significant correlations between the lipophilicity of drugs and their capacity to form inclusion complexes with HPBCD indicate the involvement of hydrophobic forces in the interaction.