engleski

The solvent influence on the complexation of amphiphilic mannosides with β-cyclodextrin and cucurbit[7]uril

The solvent influence on the complexation of amphiphilic mannosides containing different non-polar moities with β-cyclodextrin and cucurbit[7]uril was explored in a wide range of temperatures by means of microcalorimetry and NMR spectroscopy. The stabilities of the complexes formed were higher in water than in other hydrogen-bonded solvents (ethylene glycol, formamide, N-methylformamide, and methanol), whereby all reactions were enthalpically controlled. The explored guest preffered cucurbit[7]uril as host. In the case of complexation reactions involving β- cyclodextrin and investigated guests in water notable temperature dependence of ΔrH° and ΔrS° was noticed. This resulted in almost perfect enthalpy-entropy compensation. The standard thermodynamic parameters for mannoside bindng with β-cyclodextrin in organic solvents exhibited relatively weak temperature dependence. The complex stability was strongly influenced by the compatibilty of guest and host cavity sizes, as well as the flexibility and the structure of the mannoside hydrophobic group. The carried out investigations clearly demonstrate that solvophobically driven formation of cyclodextrin and cucurbit[7]uril inclusion complexes is not a water limited phenomenon.

Complexation ; cyclodextrin ; cucurbituril ; hydrophobic effect ; solvation

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