Calix-macrocycles : from synthesis and physico-chemical studies to analytical and biological applications.

The thesis deals with an investigation on calix[4] based receptors, namely calix[4]pyrrole and calix[4]arene derivatives and their use in different environmental and medical applications. The work conducted throughout this study addresses three main topics. i) The first topic discusses the ability of meso-octamethylcalix[4]pyrrole, CP to remove arsenite and arsenate anions from natural waters. Sites and nature of interaction of the receptor with the investigated anions using 1H NMR and molecular simulation studies are identified. Optimal environmental conditions led to maximal uptake of the investigated anions by CP, uptake capacity of the receptor and the kinetics of the process for the investigated anions are determined. CP was used to remove arsenic species from real water samples and its efficiency is demonstrated. ii) The second topic is related to the synthesis and structural characterisation of two thioacetamide calix[4]pyrrole derivatives namely, meso-tetramethyl-tetrakis[(diethylthiocarbamoyl)phenoxy] calix[4]-pyrrole, CPIII, and 21,22,23-tri(N,N-diethyl-thioacetamide)octamethylcalix[4]pyrrole, CPII. The selectivity of these receptors towards mercury (II) cation relative to other cations was investigated through 1H NMR, conductance and thermodynamic complexation measurements in acetonitrile. Based on the outcome of fundamental studies, a CPIII based mercury (II) ion selective electrode was constructed and its optimal working conditions were determined. The role of thermodynamics in the selection of the electrode is discussed in relation to selectivity coefficients of the primary ion relative to other cations. Another work on Hg(II)-ion selective electrode using partially substituted calix[4]arene derivative with thioacetamide moiety, namely, 5,11,17,23-tetra-tert-butyl[25,27bis(diethylthiocarbamoyl)oxy]calix[4]arene, CAII, is discussed. iii) The third topic discusses the bioactivity of CAII against human adenocarcinoma Caco-2 cell line (colorectal cancer). Cytotoxicity and cell death mechanism using flow cytometry, 1H NMR and Raman Confocal spectroscopic techniques are reported. Conclusions and suggestions for further investigations are included