| Autor: |
Odella E; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Fetherolf JH; Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States., Secor M; Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States., DiPaola L; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Dominguez RE; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Gonzalez EJ; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Khmelnitskiy AY; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Kodis G; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Groy TL; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Moore TA; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States., Hammes-Schiffer S; Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States., Moore AL; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States. |
| Abstrakt: |
Bioinspired benzimidazole-phenol constructs with an intramolecular hydrogen bond connecting the phenol and the benzimidazole have been synthesized to study both proton-coupled electron transfer (PCET) and excited-state intramolecular proton transfer (ESIPT) processes. Strategic incorporation of a methyl group disrupts the coplanarity between the aromatic units, causing a pronounced twist, weakening the intramolecular hydrogen bond, decreasing the phenol redox potential, reducing the chemical reversibility, and quenching the fluorescence emission. Infrared spectroelectrochemistry and transient absorption spectroscopy confirm the formation of the oxidized product upon PCET and probe excited-state relaxation mechanisms, respectively. Density functional theory calculations of redox potentials corroborate the experimental findings. Additionally, time-dependent density functional theory calculations uncover the fluorescence quenching mechanism, showing that the nonradiative twisted intramolecular charge transfer state responsible for fluorescence quenching is more energetically favorable in the methyl-substituted system. Incorporating groups causing steric hindrance expands the design of biomimetic systems capable of performing both PCET and ESIPT. |
