engleski

Coordination chemistry of calix[4]arenes: thermodynamic and structural points of view

Calixarenes are macrocyclic oligomers which consist of four or more phenolic residues linked by methylene group in the ortho position. Many calixarene derivatives are known to be very efficient, and, in some cases, selective binders of ions and neutral molecules. In this lecture the comprehensive investigation of several calix[4]arene complexation reactions will be described. The thermodynamic data (complex stability constants and derived reaction Gibbs energies, reaction enthalpies and entropies) determined by means of UV and NMR spectroscopies, fluorimetry, potentiometry, conductometry, and microcalorimetry will be correlated with structural results obtained by X- ray crystallography, NMR, and computational methods (DFT and molecular dynamics). The intra- and intermolecular hydrogen-bonding and solvent effects (especially specific solvent-solute interactions) on the equilibria of binding reactions will be particularly addressed. The results of the above-mentioned studies have clearly indicated how remarkable and complex the influence of the solvent on the ion-hosting abilities of the calixarene derivatives, and macrocycles in general, can be. They have also suggested that integrated and comprehensive experimental and computational investigations can provide a rather detailed insight into the ligand properties and reactivities, i.e. the factors governing the complexation processes. This can serve as a basis for targeted design of efficient and selective supramolecular receptors.

calixarenes ; complexation ; solvation ; hydrogen bonding ; thermodynamics

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