Synthesis, characterization and physicochemical properties of novel derivatives of calix(n)arenes (n=4,6,8).

Following an overview on the progress so far made in the general area of calixarene chemistry, this thesis reports investigations related to i) the acid-base properties of p-tert-butycalix[n]arenes (n=4,6,8) and amines (trimethylamine, tert-butylamine, atropine, 1-aminoadmantane, morpholine, R-(+)-alpha-methylbenzylamine, piperazine, cryptands 22 and 222) in benzonitrile at 298.15 K and their implications on the proton transfer reaction from the calixarene to the amine. Fom experimental data, the individual processes which contribute to the overall extraction of tert-butylamine from water by p-tert-butylcalix[8]arene in benzonitrile were quantitatively assessed. ii) the use of phase transfer catalysis for the synthesis of ethy p-tert-butycalix[n]arene (n=4,6,8) ethanoates. Advantages with respect to current preparative methods are outlined. The stability constant of sodium and ethyl p-tert-butylcalix[4]arene tetraethanoate in acetonitrile at 298.15 K was determined by direct potentiometry using an ion-selective electrode. The result obtained, is in good agreement with that recently reported from a double competitive potentiometric method. Extraction data in the water-benzonitrile solvent system at 298.15 K were used to quantitatively evaluate for the first time the individual processes involved in the overall extraction of alkali-metal picrates by ethy p-tert-butycalix[4]arene tetraethanoate. iii) the synthesis and characterization of new calixarene derivatives obtained by the lower rim functionalization of p-tert-butycalixarense by the introduction of a) N,N-dimethylcarbamoyl and N-acetylglycine groups using phase transfer catalysts (18-crown-6,4- dimethylaminopyridine and 1,3-dicyclohexylcarbodiimide). In both cases, disubstituted calixarene derivatives were obtained in distorted cone conformations, b) aliphatic (methyl, ethyl, isopropyl), alicyclic (piperidine, pyrrolidine, morpholine) and aromatic (quinoline, pyridine) amino groups. These were characterized by elemental analysis, 1H and 13C NMR spectroscopy. The acid-base properties of these derivatives were investigated in methanol. The ability of these ligands in their neutral and protonated forms to interact with cations and anions; respectively, is discussed. Final conclusions of these investigations are summarized and suggestions for further work are given