Analytical improvement in measuring formation constants of inclusion complexes between beta-cyclodextrin and phenolic compounds

Inclusion complex formation between sixteen para-substituted phenols and be ta-cyclodextrin have been investigated in order to establish Quantitative S tructure Affinity Relationships. An analytical methodology is proposed, in order to obtain reliable evaluation of binding affinities. Potentiometry an d circular dichroism have been applied to define experimental conditions an d to confirm postulated equilibriums. In addition, the use of algorithmic t reatments and concentration optimisation to determine formation constants l eads to coherent values between H-1 NMR, direct UV Spectroscopy and the spe ctral displacement method. The results emphasise the contribution of van de r Waals interactions, provided that no significant difference in the dipole of the molecule arises from the para-substituent.