engleski

The solvent effect on the host-guest complexation equilibria; the good and the bad

The lecture will cover the most important aspects of the solvent effect on thermodynamics of the complexation reactions involving calixarenes, cyclodextrins, and cucurbiturils as hosts and alkali-metal cations as well as non-polar species as guests. The rationalization of the medium influence on the binding properties of investigated macrocycles will rely on the thermodynamic data (complex stability constants, reaction and dissolution Gibbs energies, enthalpies and entropies) and the structural insights (NMR and computational methods). In addition, standard thermodynamic parameters of the reactants and the products transfer among the solvents will be discussed. A range of phenomena, from specific and selective solute-solvent interactions to the temperature-dependent hydration of hydrophobic guests in water will be presented. The trends regarding solvation of host and guest with respect to their size and structure will be revealed and their influence on the complexation thermodynamics pointed out. The potential for solvophobically driven hosting of non-polar species in organic solvents will be also addressed. The results of thermodynamic studies of host-guest reactions in different media clearly indicate how remarkable and complex the often underappreciated solvent influence on the binding ability of investigated macrocycles can be. They also provide a basis for targeted design of the efficient supramolecular receptors.

calix[4]arenes ; cyclodextrins ; complexation thermodynamics ; inclusion complex ; solvent effect

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