Partially substituted calix[4]arene derivatives : Synthesis, characterisation and binding properties.

This thesis concerns the synthesis, characterisation and binding properties of partially substituted calix[4]arene amino derivatives in non-aqueous media. Thus, 5,11,17,23 - tetrakis - (1,1-dimethyl ethyl) - 25,27 - bis - [2 -(diethyl amino) ethoxy] calix[4]arene (L3) was structurally (1H NMR and X-ray crystallography) characterised and its interaction with metal cations and the proton has been investigated by several techniques. Information about the active sites of interaction of this ligand with ionic species was obtained from 1H NMR measurements. Conductance measurements were used to establish the composition of the metal-ion complexes in protic and dipolar aprotic solvents. Potentiometric measurements using two electrodes systems (mercury and glass electrodes) were carried out to determine quantitatively the strength of ligand-ion interactions in acetonitrile at 298.15 K. 2D NMR techniques were used to investigate the predominant processes (complexation or protonation) taking place in solution. The medium effect on the interaction of L3 with metal cations and the proton was assessed using a dipolar aprotic (acetonitrile) and a protic (methanol) solvent. In acetonitrile, L3 interacts with mercury (II), lead (II), cadmium (II), and magnesium (II) forming complexes of 1:1 stoichiometry while two protons are taking up per unit of ligand. No interaction was observed between L3 and alkali-metal cations in this solvent. In CD3OD the 1H NMR data show that the interaction is limited to mercury (II), lead (II) and magnesium (II) and protonation of L3 also occurs in methanol. In both solvents, the stoichiometry of the interaction of aluminium (III) and L3 was not clearly defined. It is concluded that both processes, complexation and protonation are taking place during the interaction of partially substituted calix[4]arene amino derivatives with metal cations in acetonitrile