Synthesis and characterization of perylene tetracarboxylic bisester monoimide derivatives

The synthesis, optical properties, electrochemical properties and electronic structures of n-(1-butyl)perylene-3,4:9,10-tetracarboxylic-3,4-(bis-alkylester)-9,10-imide (C4–Cn) and 1,3-bis[(n-(1-butyl)perylene-3,4:9,10-tetracarboxylic-3-alkylester-9,10-imide)-4-ester] dioxypropane (C4–C3–C4) are reported. Molecular structures of the compounds were confirmed by FT-IR, 1H NMR spectroscopies and elemental analysis. Their optical and electrochemical properties were investigated by UV–vis absorption and fluorescence spectroscopy as well as cyclic voltammetry. C4–Cn exhibited strong green-yellow fluorescence (λmax = 523 nm) in dilute solution, while the dimer C4–C3–C4 exhibited orange with maximum emission at 568 nm. Both C4–Cn and C4–C3–C4 were soluble in common organic solvents such as chloroform and dichloromethane, which is due to the introduction of alkyl chains, compared to perylene. The HOMO and LUMO energy levels of the compounds studied are in the range of −3.76 to −3.79 eV and −5.96 to −6.10 eV. Calculations on the representative compounds by the Dmol3 package of MS Modeling 3.0 revealed that the increase of energy levels in both C4–Cn and C4–C3–C4, compared to that of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA), is due to the influence of the substituents on the energy band structures of the perylene derivatives, and they are excellent electron-transporting materials.