Bioinspired supramolecular catalysis in nanoconfined space

Abstract

The nanoconfinement in Nature is the key for the selectivity of enzymatic reactions: when the substrates are confined in the enzyme pocket, overconcentration and proximity effects promote the reaction in very efficient and selective way. For this reason, several artificial enzymes have been designed in order to mimic the modus operandi of natural enzymes. Among them, the self-assembled resorcin[4]arene capsule is one of the most investigated system: its inner cavity looks like the enzyme active site, and like in an enzyme pocket, it can host the reagents in a selective way, can stabilize the intermediates and transition states of reactions by secondary interactions, and then, overconcentration and proximity effect leads to a reaction rate increasing. The most interesting aspect in conducting a reaction inside a cavity is that the reactivity of a substrate can be different from the classical one observed in bulk medium. At this regard, the main topic of the present PhD thesis is to extend the catalytic application of the hexameric resorcin[4]arene capsule. Firstly, the use of the capsule was implemented in a Michael type Friedel-Crafts reaction between heteroarenes and nitroalkenes and in the synthesis of bis(heteroaryl)methanes, interesting building blocks for the synthesis of natural and unnatural porphyrin derivatives. The results indicated that the capsule promotes the reactions in efficient and selective fashion thanks to its H-bonding ability and its intrinsic Brønsted acidity. In the second part of the thesis, the study was focused on the ability of the capsule to exert a supramolecular control over the composition of dynamic covalent libraries. ... [edited by Author]