Cation-calixarene derivatives: Solution complexation studies and solid-liquid cation extraction from aqueous medium.

The work presented in this thesis is focused on the removal of ions from saline water using macrocyclic ligands. Calixarene derivatives were synthesised to target metal cations found in saline water, followed by the attachment of the macrocycles onto solid supports such as silicates in order to work in aqueous media. A general introduction is given covering i) existing methods of desalination, ii) main aspects and development of Supramolecular Chemistry and previous work done in this area. This Thesis investigate the complexation properties of synthetic macrocyclic ligands such as calix[5]arene derivatives L1 and L2 towards metal cations in dipolar aprotic and protic media (MeCN and MeOH) at 298.15 K.1H NMR studies were used to investigate the interaction of the receptors 5, 11, 17,23,29p-tert-butyl-31, 32, 33, 34,35 penta-ethanoate calix[5]arene, L1 and 5, 11, 17,23,29p-tert-butyl-31, 32, 33, 34,35 penta-diethylacetamide, L2 with several metals cations. Conductance measurements clearly demonstrated that 1:1 and 2:1 metal cation: ligand stoichiometry are found with these metal cations in acetonitrile. The thermodynamic of complexation of Li and L2 with metal cations in acetonitrile and methanol at 298.15 K was derived from titration calorimetry and those derived by potentiometry. L1 and L2 behave in a similar fashion for alkaline-earth metal cations with a higher stability constant for Ba2+ cation relative to other metal cations in acetonitrile and methanol. The calix[4]arene acetamide was attached onto a modified silica as solid support. This was followed by the characterisation of the material and experimental work to establish the uptaking capacities under different conditions. Final conclusions and suggestions for further research in this area are given