Synthesis, photophysical and electrochemical properties of meso-substituted BODIPY compounds

BODIPY (4,4-Difloro-4-bora-3a,4a-diaza-s-indasen) dyes are highly colored compounds which show fluorescence properties and exhibit desirable very different properties such as high fluorescence quantum yield, low absorption-emission bandwidth and high stability. In addition, one of the important characteristics of these dyes is that the photophysical and electrochemical properties of the desired application area can be easily designed by introducing different substituents to the BODIPY core. In this thesis, firstly 4 different meso-BODIPY compounds were synthesized. In the second step, bromine was bound to C2 and C6 positions of these compounds. Finally, the effects on the photophysical and electrochemical properties of the substituents (phenyl, 4-bromophenyl, 4-methoxyphenyl, ethyl) and the bromine atom were investigated. In order to understand the effect of the substituents on photophysical properties, electron donor and acceptor groups bearing at meso position of the BODIPY core are chosen. All BODIPY derivatives were characterized by 1H NMR, 13C NMR, 19F NMR and FT-IR spectroscopy techniques. In addition, UV-Vis, fluorescence spectroscopy and cyclic voltammetry were used to investigate their spectral properties. The presence of an electron acceptor group at the meso position of the synthesized compounds was shown to decrease the molar absorption coefficient while increasing Stokes shift. Because of the electron acceptor nature of 4-bromophenyl group, compound 78 shows the red shift at absorption and emission spectra. Besides, the compound 81 with the electron donating group shows the absorption spectra at lower wavelenght. The addition of bromine to the structure did not cause a significant change in Stokes shifts, but increased the molar absorption coefficient and lead to a higher absorption wavelength shift.