International Conference on Basic Sciences and Technology (ICBAST), Antalya, Türkiye, 16 - 19 Kasım 2023, ss.9
Carbazole is an aromatic compound due to its conjugated double bond system.
Aromatic stability is achieved through the delocalization of π-electrons across the two
benzene rings and the nitrogen atom. It is noteworthy that electron-withdrawing
groups such as -F, -CN, -CF3 are commonly used to adjust the electronic properties of
carbazole derivatives. The fluorine atom, possessing high electronegativity and a small
atomic radius, has the capacity to modulate molecular energy levels and enhance
electron mobility when attached as a substituent to the molecule. Structures
containing C-F bonds are extensively employed in biomedical active systems and
electronic material design (such as OLEDs, DSSCs). Organic compounds containing
fluorine atoms gain high stability against oxidation due to their lower HOMO/LUMO
energy levels. Additionally, these compounds exhibit increased reduction potentials,
facilitating the electrochemical decomposition of fluorine compounds. In this study,
two carbazole-based compounds 3,6-bis(4-(trifluoromethyl)phenyl)-9-octyl-9Hcarbazole (IVa) and 3,6-bis(3,4,5-trifluorophenyl)-9-octyl-9H-carbazole (IVb) was
synthesized via the Suzuki-Miyaura cross-coupling reaction (Scheme 1). The
photophysical and thermal properties of this compound were determined by UV-Vis,
thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The
oxidation potentials of the molecules were determined on the gold electrode surface
in dichloromethane solution containing tetrabutylammonium hexafluorophosphate
using the cyclic voltammetry method. The HOMO and band gap (Eg,opt) energies were
calculated from oxidation potential and absorption bands. Similarities in the electronic
structures of compounds with similar structures containing CF3 and F were identified
using the obtained data.