Dottorato in SCIENZE CHIMICHE

Titolo della tesi: A diversified Journey through typical and new Supramolecular scaffolds: Calixarenes, Cyclodextrins and Cryptands.

Herein I report the results of the research work I carried out during my PhD. I mainly focused on the study of supramolecular systems involving Host Guest interactions. My first aim was to control over time Supramolecular systems based on the interactions between basket shaped molecules, such as Calixarenes and alpha-Cyclodextrin and small molecules, by means of a chemical fuel (Chapters 1, 2 and 3). In the Chapters 1 and 2 the control over time of the supramolecular interactions was obtained modifying over time the conformations of the Calix[4]arene and Calix[6]arene scaffolds. These chemical scaffolds were properly functionalised in order to undergo through a conformational lock due to an acid stimulus. The transient acid stimulus provided by the 2-cyano-2-phenylpropanoic acid, and its para substituted derivatives allowed the control over time of the supramolecular properties of these two different Calixarene scaffold. In the Chapter 3, the Host Guest properties of the alpha-Cyclodextrin were controlled in aqueous media using the transient acid stimulus of the nitroacetic acid, which can be conveniently used to control the pH of aqueous solutions over time. Then I moved on to the use of a supramolecular capsule, obtained by the self assembly of six Calix[4]resorcinarene molecules in apolar solvent, in order to use the Host Guest interactions with smaller molecules to achieve ring closure reactions catalysis of large linear precursor, due to the nanoconfinement. The Chapter 4 reports the preliminary results of the Host Guest catalysis in a confined environment achieved with this kind of supramolecular cage. The Chapter 5 reports the preliminary results, that I obtained during my six months at Universität Ulm, under the supervision of the Prof. Max von Delius. In this project I used the dynamic combinatorial chemistry based on the dynamic boron oxygen bond to achieve the self-assembly of a new family of Cryptands. Thanks to the boron electron deficiency, for the first time was possible to achieve the self assembly of a negative charged Cryptand able to bind a bivalent cation.