chapter  6
30 Pages

Supramolecular Chromatography

The chromatographic retention factor k is deˆned as the ratio of the time a component B spends in the stationary phase t′ = t – to (t = total retention time) to the time it spends in the mobile phase to, that is, k = t′/to = (t – to)/to. The retention factor k is equal to the product of the distribution (partition) constant Kc (the ratio of the stationary to mobile phase concentrations of B) and the phase ratio φ (the ratio of the stationary to mobile phase volumes), that is, k = Kcφ (universal equation of chromatography).5 The temperature dependence of k is derived from the Gibbs-Helmholtz equation: RT ln Kc = –ΔG° = –ΔH° + TΔS°. It follows that ln k = ln Kc + ln φ = –ΔH°/RT + ΔS°/R + ln φ. The plot of ln k vs. 1/T (van’t Hoff plot) is linear, yielding the standard enthalpy ΔH° and the standard entropy ΔS° of the transfer of the

Introduction ............................................................................................................ 129 Link between Supramolecular Chemistry and Separation Science ....................... 131 Supramolecular Chromatographic Separations of Fullerenes on Various Stationary Phases ................................................................................................... 135 Chromatographic Fullerene-Containing Stationary Phases ................................... 140 Carbon Nanotubes .................................................................................................. 147 Synthetic Supramolecular Cn-Symmetric Receptors ............................................. 149 Challenges .............................................................................................................. 151 References .............................................................................................................. 153

component B from the mobile to the stationary phase when ideal conditions prevail (T = absolute temperature in Kelvin, R = gas constant).