Synthesis, characterization, and applications of dyes emitting in the uv-vis and near infrared regions

Abstract

In this thesis, synthesis, characterization and applications of synthetic organic dyes, especially Aza-BODIPY derivatives, which can absorb and emit light in a wide wavelength range are discussed. Aza-BODIPY dyes have remarkable applications in various fields such as biological imaging, photodynamic therapy and sensor technologies due to their light emitting properties in the near infrared (NIR) region (700–1700 nm). In this study, two different Aza-BODIPY derivatives were synthesized using the O'Shea method: one was unsubstituted and the other had a structure containing para-hydroxyl (p-OH) group. Then, the unsubstituted Aza BODIPY compound was converted to new derivatives containing bromine and formyl groups by bromination and formylation processes. These three different dye molecules were used in the detection of nitroaromatic compounds and the effects of different electron donating (EDG) and electron withdrawing (EWG) groups on the sensor performance were investigated. In the second application, a selective IDA (Indicator Displacement Assay) sensor system against halogen ions (especially fluoride ion) was designed by combining Aza BODIPY and calix[4]pyrrole molecules. There is no study in the literature where these two molecules are used together as sensors. In the third and last application, the Aza BODIPY derivative was integrated into the PGMA-b-OEGMA polymeric system synthesized by RAFT polymerization. This system was made compatible with biological environments and a potential structure was created for intracellular imaging applications. The results obtained revealed that different functional groups attached to the Aza BODIPY center directly affect the electronic structure of the system and determine the sensor performance. EDG groups increased the electron density of Aza-BODIPY and provided stronger interaction with nitro compounds, while EWG groups weakened the PET mechanism and decreased the sensitivity. However, exceptional cases such as the resonance effect of the formyl group showed that this limitation can be overcome. The Aza-BODIPY dye was incorporated into a polymeric framework and rendered suitable for biological environments in the second use. Studies using intracellular imaging may be possible with this structure. The third use was the creation of an IDA sensor system that was selective for halogen ions, particularly fluoride ions, by conjugating the Aza-BODIPY molecule with the calix[4]pyrrole structure. The study generally emphasized the advantages of Aza-BODIPY dyes such as high photostability, wide wavelength tunability and structural flexibility, while also evaluating some limitations such as selectivity and solubility. This thesis sheds light on the future applications by revealing the versatile usage potential of Aza-BODIPY based systems.