tetraphenyl- and tetra-2-naphthyl-substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMRstudies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol−1. The redox and optical properties of these core-twisted PBIs have been characterized
A variety of perylenetetracarboxy-3,4:9,10-diimide derivatives have been synthesized. Particular attention was paid to substituents in positions 1, 6, 7 or 12. The energy differences between the frontier orbitals have been determined using optical spectroscopy (UV and fluorescence). The energy of the lowest unoccupied orbitals (LUMOs) were obtained by cyclic voltammetry. From both studies, the energies of the highest occupied orbitals (HOMOs) were also been calculated. A Hammett-type relationship was observed for the reduction potentials (Ered11/2) when correlated with the σ−ortho parameter. The energies of the frontier orbitals define the domains of application of these compounds. They significantly depend on the substitution in positions 1, 6, 7, or 12.