Exploiting tunable functionalization of heterocycles for the future generation of organic lightning devices

Nowadays, one of the most efficient light-emitting devices are OLEDs (Organic Ligth-Emitting Diodes), however, only few of the excitons produced in the emitting layer are emissive. Therefore, fluorophores with Thermally-activated delayed fluorescence (TADF) arise as promising alternatives, since they are able to harvest the 75 % non-emissive excitons from the triplet state, increasing the OLED efficiency. N-heterocycles have been studied not only for their pharmacological properties but also for their luminescent ability, including as emitters in OLED devices. Therefore, the design and synthesis, as well as the photophysical properties of N-heterocycles were approached in this work. A family of azaindole derivatives was designed through DFT and td-DFT calculations, synthesized, and their photophysical properties were studied. These derivatives were designed to present a twisted charge-transfer structure with a donor-acceptor unit. DFT and td-DFT calculations demonstrated that some derivatives present promising characteristics necessary for TADF properties. Thus, the photophysical properties of these derivatives were studied further with the aim of verifying their TADF ability. Additionally, the photophysical properties of another family of azaindole derivatives was studied together with their cytotoxic action against cancer cells and their intracellular localization. The reactivity of acetanilides and pyridyl acetamides was evaluated in the Chan-Evans-Lam reaction with alkenylvinilboranes, as well as the reaction optimization, to obtain E-enamides as N-heterocycles intermediates. Different acetanilides and pyridyl-acetamides were tested and a wide range of 39 derivatives of E-enamides was obtained, in good yields. The reaction showed a good functional group tolerance as different donor and acceptor groups were compatible under the tested reaction conditions. To highlight the practical utility of the prepared E-enamides, a cyclization reaction was tested and 3 indole derivatives were obtained. Additionally, the reactivity of (hetero)aryl amines protected with a tosyl group ware evaluated in a N-alkynylation reaction with hypervalent iodine reagents. This study was performed using a synthetic strategy already described and 8 derivatives were obtained., A gold-catalyzed cyclization reaction was tested to obtain N-heterocycles. Finally, a family of 7 imidazo[1,2-a]pyridine derivatives was synthesized. Their photophysical properties in different solvents were evaluated and rationalized through DFT and td-DFT calculations. The derivatives obtained present a detectable fluorescence emission, however their emission quantum yields are inferior to 1 %. These derivatives are nevertheless promising to the design of novel fluorescent molecules based on this scaffold.