Pre-Planarized Triphenylamine-Based Linear Mixed-Valence Charge-Transfer Systems

Area of Science:

• Molecular Chemistry
• Supramolecular Chemistry
• Electrochemistry

Background:

• Triphenylamines are versatile redox-active building blocks.
• Planarization of redox centers can influence electron transfer properties.
• Understanding electron self-exchange is key for designing functional molecular materials.

Purpose of the Study:

• To synthesize and characterize linear dimers of planarized triphenylamines.
• To investigate the electron self-exchange process in their radical cations.
• To evaluate the impact of low internal reorganization energy on electron transfer.

Main Methods:

• X-ray crystallography for structural verification.
• Electron paramagnetic resonance (EPR) spectroscopy.
• Absorption spectroscopy.
• (Time-dependent) density functional theory (TD-DFT) calculations.

Main Results:

• Successful synthesis and structural confirmation of three linear dimers.
• Observation of electron self-exchange between the two redox centers in radical cations.
• Demonstration that low internal reorganization energies significantly impact electron transfer parameters.
• Similar distance-dependence attenuation factors for super-exchange mechanisms compared to non-planarized systems.

Conclusions:

• Planarized triphenylamine units facilitate efficient electron self-exchange.
• Low reorganization energy is a critical factor for optimizing electron transfer in molecular systems.
• These findings contribute to the design of advanced materials for molecular electronics and energy storage.