engleski

When hydrophobic cavities meet benzene derivatives

Macrocyclic receptors such as cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD) have found their use in various scientific fields and branches of industry as suitable receptors and solubilizers for hydrophobic compounds in aqueous solutions. This is attributed to favorable desolvation of the guest and the host cavity as well as their spatial compatibility. Benzene derivatives containing functionalities with different electron-donor properties were chosen as guests for investigation of substituent impact on the hydrophobically driven hosting. Their complexation with CB7 and β- CD in water was explored by means of isothermal titration microcalorimetry and NMR spectroscopy. The complexes with guests functionalized with electron-donor groups were more stable as a result of a more favorable reaction enthalpy. Most of the examined host-guest systems showed distinct temperature dependence of ΔrH° and ΔrS°, resulting in an almost complete temperature independence of reaction Gibbs energy. The complexation thermodynamics was in agreement with the classical interpretation of the hydrophobic effect at lower temperatures and the non-classical explanation at higher ones.

benzene derivatives ; β-cyclodextrin ; complexation thermodynamics ; cucurbit[7]uril ; hydrophobic effect ; inclusion complex

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