Thesis presented November 29, 2022

Abstract:
During the last decade, the development of visible-light photocatalysts has revolutionized the synthetic organic chemistry field. Colloidal semiconductor nanocrystals, commonly known as Quantum Dots (QDs), have shown great promise as photocatalysts for various organic transformations, including oxidations, reductions, and, most recently, bond-forming reactions. QDs possess several encouraging properties for photocatalysis, including their size-tunable oxidation and reduction potentials and their high extinction coefficient values in the visible domain. In addition, due to their optical and size properties, QDs can interact with several substrates at once using very low catalytic loadings. In this Thesis, we have prepared different types and structures of QDs such as CdS, CdSe, and InP core-type QDs and different types of core-shell QDs such as CdSe-CdS, CdS-CdSe, CdSe-ZnS, and InP-ZnS. We also optimized the surface ligands layer to ensure better interaction between the QDs’ and the reaction substrates. After testing the photophysical properties and the possible charge transfer between the QDs and the desired reaction’s substrates, we used the prepared QDs as photocatalysts for newly developed reactions aiming to prepare value-added natural products (such as Tropane derivatives). Furthermore, we designed a new kind of semiconductor-metallic hybrid nanostructure by assembling CdSe-ZnS QDs with Gold nanoparticles (AuNP). The QD-AuNP nanostructures were chemically assembled using a click chemistry approach benefiting from the surface ligands functionalizing the QDs and the AuNP. The prepared hybrid structure enhanced the photocatalytic catalytic activity compared to the bare QDs-photocatalyzed reaction. The enhanced activity referred to the better charge separation and the new optical properties in the QD-AuNP hybrid nanostructure.

Keywords:
Redox photocatalysis, free radicals, quantum dots, gold nanoparticles