HARNESSING CLICK CHEMISTRY AND LIGHT: FROM NANOMATERIAL FUNCTIONALIZATION AND BIOMEDICAL APPLICATIONS TO PHOTO-INDUCED METAL CATALYSIS

During my three years of doctoral studies, I had the opportunity to develop three research projects focused on the preparation of organic compounds for specific applications. Although these projects covered completely different areas of organic chemistry, they were unified by a common goal: employing key enabling techniques to address recurring challenges, simplify synthetic procedures to make them easily reproducible in any setting, reduce waste, and prioritize greener methodologies over classical approaches. At the same time, each project aimed to fill gaps in the literature and tailor the synthesized products to their intended applications. Across all three projects, click chemistry and photochemistry played a central role, and in one project these two techniques were even combined. In chapter 2 is reported the synthesis of organic custom-made ligands that can be covalently bound to the surface of NPs, using photo-click-chemistry. The goal of the project was to drastically change the surface properties of NPs for the preparation of magnetorheological electrolytes (MRE) to be applied in the REMAP (Reusable Mask Patterning) project. REMAP is a project funded by the European Union that wants to revolutionize the microfabrication sector (e.g. for advanced photovoltaic applications) by developing a greener surface patterning technique. The crafted MRE properties are exploited to form infinitely reusable masks that would represent a huge step forward in the field of microfabrication with respect to standard lithography, in a period in which, more than ever, the interest in the reduction of pollution and waste, and in the displacement of fossil fuels is high. The use of photochemistry continues in Chapter 3, focusing in detail on the novel field of light-induced transition-metal catalysis. A new type of isocyanide-insertion reaction was developed to prepare amides in a single step from alkyl iodides, isocyanides, and water through a multicomponent light-activated palladium-catalysed coupling reaction. Despite being among the most used tools in the hand of synthetic chemist, palladium catalysed reactions have some limitations. The most relevant is its incompatibility with alkyl electrophiles. Visible light-induced transition metal catalysis has emerged as an innovative approach to overcome those constraints. In these transformations a transition metal complex plays a dual role by harvesting photon energy and enabling bond forming/breaking reactions. Lastly, chapter 4 reports the design and characterization of amphiphilic dendrimers as potential building blocks for self-assembled nanostructures (micelles or vesicles) suitable for drug delivery and nanomedical applications. Dendrimers are highly branched, tree-like macromolecules whose structure and surface chemistry can be precisely controlled. Their unique architecture allows them to mimic biological polymers such as proteins, making them attractive candidates for biomedical use. The project involved the stepwise synthesis of a second-generation dendrimer using a convergent approach, combining a hydrophilic polyamide dendron with a hydrophobic D-mannitol-based core through a Cu-catalysed azide–alkyne cycloaddition (“click”) reaction.