Synthesis, characterization and investigation of photophysical and electrochemical properties of novel retinal

In this thesis, some organic molecules which are described as small molecules in the terms of OPV (organic photovoltaic) systems were synthesized and characterized. The retinal molecule, used as small molecule, was modified by attaching the newly synthesized benzimidazole derivatives. The target of the synthesis is the shifting of the optical absorption of the retinal into the visible region, and also reducing its band gap and LUMO energy levels to the suitable level. In the first part of thesis, synthesis part, benzothiadiazole derivatives were synthesized and their bisamine compounds were prepared. Then, the reaction between these bisamine groups and the retinal molecule, known as a natural dye, gave the target dyes such as 2-[(1E,3E,5E,7E)-2,6-dimethyl-8-(2,6,6-trimethylcyclohex-1-en-1-yl)octa-1,3,5,7-tetraen-1-yl]-4,7-bis(3-methoxyphenyl)-1H-benzimidazole (Ret-I), (3-{4-[3-(Dimethylamino)phenyl]-2-[(1E,3E,5E,7E)-2,6-dimethyl-8-(2,6,6-trimethylcyclohex-1-en-1-yl)octa-1,3,5,7-tetraen-1-yl]-1H-benzimidazole-7-yl}phenyl)dimethylamine (Ret-II), 2-[(1E,3E,5E,7E)-2,6-dimethyl-8-(2,6,6-trimethylcyclohex-1-en-1-yl)octa-1,3,5,7-tetraen-1-yl]-4,7-bis(3-fluorophenyl)-1H-benzimidazole (Ret-III) ve 2-[(1E,3E,5E,7E)-2,6-Dimethyl-8-(2,6,6-trimethylcyclohex-1-en-1-yl)octa-1,3,5,7-tetraen-1-yl]-4,7-bis[3-(trifluoromethyl)phenyl]-1H-benzimidazole (Ret-IV). All the synthesized dyes were characterized by UV-vis, FT-IR, 1H-NMR, 13C-NMR spectroscopy. In the second part of thesis, spectroscopy part, photophysical and emission properties of the dyes were studied by the fluorometer instrument. Electrochemical properties of the dyes were studied by the cyclic voltammetry method. HOMO-LUMO energy levels and band gap energy values of the dyes were calculated by this method. As a result, it is thought that Ret-I, Ret-II, Ret-III and Ret-IV dyes are porpmising structures for the OPV systems.