Computational investigation of intramolecular reorganization energy in diketopyrrolopyrrole (DPP) derivatives

Abstract

Intramolecular reorganization energy (RE) of molecules derived from the diketopyrrolopyrrole (DPP) unithas been studied using B3LYP/6-31G(d,p) theory. It was found that the replacement of the oxygen atoms with sulfurin the DPP unit led to a smaller RE for both the hole and electron transfer processes. One disadvantage of the sulfurreplacement is the twist of the conjugated backbone, which might impair the π − π interactions in the solid state. TheRE calculated from the adiabatic potential energy surfaces and that derived from the normal mode analysis agreed wellfor both systems. Electronic structure data showed that the replacement of oxygen atoms with sulfur in the DPP unitmight lead to the development of ambipolar compounds with low RE.