Synthesis and photophysical properties of N,N′-bis(4-cyanophenyl)-3,4,9,10-perylenebis(dicarboximide) and N,N′-bis(4-cyanophenyl)-1,4,5,8-naphthalenediimide

Abstract

N,N′-Bis(4-cyanophenyl)-1,4,5,8-naphthalenediimide (CN-NDI) and N,N′-bis(4-cyanophenyl)-3,4,9,10-perylenebis(dicarboximide) (CN-PDI) have been synthesized under special conditions in high yield. The compounds are characterized by UV-Vis, IR, NMR, MS, DSC, TGA and CV measurements. The fluorescence lifetimes, quantum yields and singlet-state energies are presented. CN groups at the phenyl moieties improve the thermal stability of the compounds. The LUMO energy values, −3.91 eV (CN-NDI in solution) and −3.96 eV (CN-NDI and CN-PDI at solid state), are determined by cyclic voltammetry. Whereas CN-NDI shows two reversible (−0.89 and −1.34 V) reduction steps (vs. Fc) in solution, CN-NDI and CN-PDI exhibit only one reversible wave at −0.48 V vs. Ag/AgCl at solid state, assigned to the one-electron reduction. Formation of aggregates shifts the UV absorption spectrum of CN-PDI to shorter wavelengths and its lifetime is measured as 4.6 ns at 580 nm. CN-PDI may be a promising dye for organic solar cells.