Synthesis and optoelectronic properties of Imidic peri- xanthenoxanthene derivatives

Nowadays polycyclic aromatic hydrocarbons (PAHs) have been the object of study in the search for novel semiconductor materials. Synthetic research in this field is ongoing since the beginning of the century, but it was only in recent years that technological development caused an increased interest for the optoelectronic properties of such systems. As a result, spectroscopic studies revealed interesting properties of peri-xanthenoxanthene (PXX) and its derivatives that will be extensively presented and discussed in this thesis. Concerning the tuning and tailoring of the optoelectronic properties of PAHs, many strategies can be applied in the quest for novel and better performing materials. One of the most common and efficient techniques is the atom doping that consists of a replacement of a carbon atom with a heavier one, such as oxygen or sulphur. In Chapter 1, before addressing the detailed investigation of this thesis work, a brief introduction on the nature and applications of organic semiconductor materials is given. Optoelectronic properties of well-known perylene diimides (PDIs) are compared and the discussion eventually moves to PXX derivatives that are the core of this thesis. In Chapter 2, a variety of synthetic pathways is explored in order to prepare PXX imide derivatives bearing electron-withdrawing groups in the peri position. The bottom-up approach is used to afford novel PXX systems. The synthesis of the desired systems is shown and discussed exploiting the key hydroxynaphthalene anhydride substrate. As a conclusion of this thesis, Chapter 3 deals with the characterisation of the optoelectronic properties of PXX imide derivatives. Furthermore, PXX substrates have been screened as photoredox systems to perform dehalogenation reactions and the mechanism of the photo-triggered chemical transformation has been investigated.