Pre‐planarized triphenylamine based linear mixed valence charge transfer systems

Three linear dimers with two redox active planarized triphenylamines were synthesized and their structures verified by X-ray crystallography. Of great interest are their radical cations, which exhibit electron self-exchange between the two redox centers. This process was thoroughly investigated by means of electron paramagnetic resonance spectroscopy, absorption spectroscopy, and (time-dependent) density-functional-theory calculations. A comparison of the key parameters of electron transfer with non-planarized nitrogen-centered building blocks emphasizes the impact of using redox centers with low internal reorganization energies. However, the distance-dependence attenuation factor of the super-exchange mechanisms remains similar.