Diffusion coefficients of the ternary system (2-hydroxypropyl-β-cyclodextrin + caffeine + water) at T = 298.15 K

Ternary mutual diffusion coefficients measured by Taylor dispersion method (D11, D22, D12, and D21) are reported for aqueous solutions of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) + caffeine at T = 298.15 K at carrier concentrations from (0.000 to 0.010) mol · dm−3, for each solute, respectively. These diffusion coefficients have been measured having in mind a better understanding of the structure of these systems and thermodynamic behaviour of caffeine and 2-hydroxypropyl-β-cyclodextrin in solution. For example, from these data it will be possible to estimate some parameters, such as the fraction of associated species HP-β-CD (X1) and caffeine (X2) in this complex, the monomer and dimer fractions, X2M and X2D, respectively, and the limiting diffusion coefficients of the HP-β-CD, DHPBCD∘, of the dimers caffeine entities, DD∘, and of those complexes (1:1), Dcomplex∘.