Photoactive Molecules in Supramolecular Architectures and Photoredox Reactions

My PhD reasearch activity was mainly focused on two different fields: the study of the formation of supramolecular architectures and the investigation of the photophysical behaviour of different photocatalysts in organic reactions. The first supramolecular system shown in this thesis derives from a shapepersistent molecule, featuring four bipyridinium units, that upon reduction undergoes intermolecular pimerization because of the rigid architecture of the molecule. The same tetramer, with non-methylated bipyridium units, is able to form a supramolecular architecture upon complexation with four ruthenium porphyrins: the resulting multichromophoric system features a shape-persistent arrangement of the chromophores. During my PhD, I spent four months at the ETH, in Zurich, working in the group of Prof. Schlüter. Throughout my stay, I worked on the design, synthesis and characterization of a 2D polymer obtained at the air-water interface with Langmuir-Blodgett technique. In the field of photocatalysis, I studied four photoredox reactions, two of them photocatalyzed by a metal complex, and the other two by an organic chromophore. The first photoredox reaction studied provides an efficient access to indole 2- and 3-carboxylates in a single step (with good yields under mild reaction conditions), i.e. the direct photocatalytic carboxylation with CBr4/MeOH, visible light ad [Ru(bpy)3](PF6)2 as photocatalyst. In the second reaction, the complex [Fe(bpy)3]Br2 is involved in the enantioselective organocatalytic photoredox alkylation of aldehydes with various alpha-bromo carbonyl compounds, in presence of visible light. Then, we moved toward the use of organic dyes as photocatalysts. We found that a iodo-boron-dipyrromethene (iodo-BODIPY) dye derivate is able to promote the atom-transfer radical addition (ATRA) between bromoderivatives and alkenes, using ascorbate as sacrificial reductant. Finally, we investigated the mechanism of the reduction of aryl halides promoted by a two-photon mechanism by perylenediimide derivate.