Design and synthesis of new calix[6]arene-based molecular switches

Abstract

This PhD thesis describes the design, the synthesis and the characterization of calix[6]arene-based molecular machine prototypes, and the study of their dynamic properties triggered by external stimulation. Initially, the ability of a calix[6]arene wheel to increase the rate of a nucleophilic substitution reaction on a complexed guest was demonstrated, and by virtue of these results a new supramolecularly assisted strategy for the synthesis of oriented rotaxanes was set up. Then, the properties of new hydroxy- and bis(N-phenylureido)-calix[6]arene derivatives were steered, and the effects of the structural modification of the different macrocycle’s domains were evaluated. The ability of calix[6]arenes to form oriented complexes with dialkylviologen-based axles was then exploited for the synthesis of single and double station constitutionally isomeric rotaxanes, whose ability to behave as molecular level shuttles was proved. Moreover, the design, the synthesis and the characterization of an oriented calix[6]arene-based catenane, and the study of its electrochemical and dynamic properties were developed. As last part of this thesis, the study of possible synthetic pathways towards the synthesis of oriented calix[6]arene-based dimers and containers is reported.