Supramolecular materials for sensing

Abstract

In this thesis the design, synthesis and characterization of cavitand based receptors for chemical sensing and environmental analyses is discussed. The thesis is organised in three main topics: (1) Design and synthesis of novel Qx-BOX receptors for Benzene detection in air (Chapter 1) The development of a cavitand-based selective pre-concentrator unit for benzene detection in air. The cavitands developed for this propose are quinoxaline-based cavitands blocked in rigid vase configuration, obtained blocking the four quinoxaline walls with aliphatic linkers. The performances of these quinoxaline cavitands in detecting benzene at sub ppb level has been confirmed by SPME analyses. This new class of cavitands resulted fluorescent and the studies confirmed the increase of the fluorescent intensity upon BTEX complexation. (2) Water soluble Phosphonate cavitands (Chapter 4) The synthesis of a water-soluble tetraphosphonate cavitands to be used in human fluids for the detection of monometylated species as potential cancer marker is reported. Different synthetic approaches have been tested to synthesise a water soluble tetraphosphonate cavitand The best strategy resulted to functionalize the cavitand at the upper rim with four ethylphosphonate bridging units and at the lower rim with four pendant amino groups. (3) Lanthanides inclusion in molecular containers (Chapter 5) The aim of this study was the self-assembly of supramolecular cages incorporating luminescent lanthanide complexes. The ability of different molecular cavities to coordinate luminescent Lanthanide complexes has been studied both in solution and in the solid state. Different approaches were undertaken to encapsulate Lanthanide complexes in different cages like: solvent free assembly, hydrophobic effect using water soluble molecular container and multiples interactions with metal ions.