Synthesis and characterization of novel aza-BODIPY compounds

Aza-BODIPY compounds are one of the most important pyrrole derivatives with intriguing properties including fine photophysical behaviors and diverse biomedical and optical applications such as solar cells, organic light emitting diodes (OLEDs), logic gates, molecular sensors, biolabeling and drug delivery agents, and particularly as photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) agents. In this thesis, effect of incorporation of heavy atoms and dimerization on the photophysical properties of aza-BODIPY compounds was investigated. As a first, synthesis of aza-dipyrromethene and its BF2 chelated form was performed. In order to synthesize aza-dipyrromethene compound, 4-chlorobenzaldehyde was reacted with acetophenone and the resulting chalcone was then reacted with nitromethane. The precursor compound was refluxed in the presence of ammonium acetate to afford aza-dipyrromethene. Complexation of this compound with BF3.Et2O resulted in formation of aza-BODIPY molecule. In the following step, two ways were considered. The first of these involves the bromination of the aza-BODIPY compound to increase spin-orbit coupling with heavy atom effect. In the second route, to increase the penetration ability of the molecule to target cell, molecule was dimerized with iron (III) chloride through its β position. Consequently, fluorescence characteristics of the compounds were investigated. It was found that the brominated aza-BODIPY compound showed a decrease in its fluorescence quantum yields with heavy atom effect. It was also observed that halogens directly attached to the aza-BODIPY core displayed a higher spin-orbit coupling than those of attached to the benzene substituents of the molecule. Dimeric aza-BODIPY molecule has the highest florescence quantum yield among the synthesized compound in the context of the thesis, moreover, it showed an absorption maximum in the near-IR region as expected.