engleski

Melting Down the Iceberg Model: Hydrophobic Cavities and (Sweetened) Alcohols

The temperature and solvent effect on the complexation of various guests with α-, β- and γ-cyclodextrin and cucurbit[7]uril was explored experimentally and by means of molecular dynamics simulations. The stability constants of all investigated complexes were by far the highest with cucurbit[7]uril in water. A pronounced temperature dependence of ΔrH° and ΔrS°, resulting in almost complete enthalpy- entropy compensation was observed solely in water. The complexation thermodynamics was in line with classical rationale of the hydrophobic effect at lower temperatures, and the non-classical explanation at higher ones. Unlike in water, the hosting in formamide and ethylene glycol could be attributed to non- classical solvophobic effect. The optimized inclusion complex structures corresponded to those deduced by means of NMR spectroscopy and the experimentally obtained and calculated ΔrG° were in very good agreement. The carried out research bridged the gap between the classical and non-classical rationale of hydrophobic effect and demonstrated that solvophobically driven formation of inclusion complexes is not a water-limited phenomenon. However, among explored structured solvents, water stood out as unique solvation and complexation medium.

Hydrophobic effect ; solvophobic effect ; inclusion complex ; complexation thermodynamics ; cyclodextrins ; cucurbit[7]uril ; mannoconjugates

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