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Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
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When a Twist Makes a Difference: Exploring PCET and ESIPT on a Nonplanar Hydrogen-Bonded Donor-Acceptor System
Emmanuel Odella1, Jonathan H Fetherolf2, Maxim Secor2
1School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States.
The Journal of Physical Chemistry Letters
|October 22, 2024
Summary
Bioinspired benzimidazole-phenol molecules were synthesized to study proton-coupled electron transfer (PCET) and excited-state intramolecular proton transfer (ESIPT). Steric hindrance from methyl groups disrupts structure, altering electronic properties and quenching fluorescence.
Area of Science:
- Photochemistry
- Supramolecular Chemistry
- Organic Electronics
Background:
- Benzimidazole-phenol constructs are key in studying proton-coupled electron transfer (PCET) and excited-state intramolecular proton transfer (ESIPT).
- Understanding these processes is crucial for designing advanced functional materials.
Purpose of the Study:
- To synthesize bioinspired benzimidazole-phenol systems and investigate the impact of structural modifications on PCET and ESIPT.
- To explore how steric hindrance affects photophysical and electrochemical properties.
Main Methods:
- Synthesis of benzimidazole-phenol derivatives.
- Infrared spectroelectrochemistry to study oxidation products.
- Transient absorption spectroscopy to probe excited-state dynamics.
- Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations for redox potentials and fluorescence quenching mechanisms.
Main Results:
- Methyl group incorporation disrupted coplanarity, weakened intramolecular hydrogen bonds, and decreased redox potential.
- PCET was confirmed by spectroelectrochemistry, and excited-state relaxation mechanisms were elucidated.
- TD-DFT revealed that a nonradiative twisted intramolecular charge transfer state quenches fluorescence in methyl-substituted systems.
Conclusions:
- Steric hindrance in benzimidazole-phenol systems significantly influences PCET and ESIPT processes.
- These findings provide insights for designing biomimetic systems with tunable photophysical and electrochemical properties.
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