scholarly journals Deciphering the incognito role of water in a light driven proton coupled electron transfer process

2018 ◽  
Vol 9 (4) ◽  
pp. 910-921 ◽  
Author(s):  
Senthil Kumar Thiyagarajan ◽  
Raghupathy Suresh ◽  
Vadivel Ramanan ◽  
Perumal Ramamurthy
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Transfer Process ◽  
Electron Transfer Process ◽  
Solvent Water ◽  
Proton Coupled Electron Transfer ◽  
Electron Proton Transfer ◽  
Role Of Solvent ◽  
Proton Transfer Process

The incognito role of solvent water as a proton transfer bridge in a multi-site electron proton transfer process was depicted.

scholarly journals Two-electron transfer stabilized by excited-state aromatization

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinseok Kim ◽  
Juwon Oh ◽  
Seongchul Park ◽  
Jose L. Zafra ◽  
Justin R. DeFrancisco ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Excited States ◽  
Transfer Process ◽  
Comprehensive Understanding ◽  
Electron Transfer Process ◽  
Photoactive Materials ◽  
Donor Acceptor ◽  
Scientific Significance

Abstract The scientific significance of excited-state aromaticity concerns with the elucidation of processes and properties in the excited states. Here, we focus on TMTQ, an oligomer composed of a central 1,6-methano[10]annulene and 5-dicyanomethyl-thiophene peripheries (acceptor-donor-acceptor system), and investigate a two-electron transfer process dominantly stabilized by an aromatization in the low-energy lying excited state. Our spectroscopic measurements quantitatively observe the shift of two π-electrons between donor and acceptors. It is revealed that this two-electron transfer process accompanies the excited-state aromatization, producing a Baird aromatic 8π core annulene in TMTQ. Biradical character on each terminal dicyanomethylene group of TMTQ allows a pseudo triplet-like configuration on the 8π core annulene with multiexcitonic nature, which stabilizes the energetically unfavorable two-charge separated state by the formation of Baird aromatic core annulene. This finding provides a comprehensive understanding of the role of excited-state aromaticity and insight to designing functional photoactive materials.

scholarly journals Visualizing the protons in a metalloenzyme electron proton transfer pathway

2020 ◽  
Vol 117 (12) ◽  
pp. 6484-6490 ◽  
Author(s):  
Hanna Kwon ◽  
Jaswir Basran ◽  
Juliette M. Devos ◽  
Reynier Suardíaz ◽  
Marc W. van der Kamp ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Transfer ◽  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Proton Donor ◽  
Biological Processes ◽  
Proton Coupled Electron Transfer ◽  
Neutron Structure ◽  
Bona Fide ◽  
Electron Proton Transfer

In redox metalloenzymes, the process of electron transfer often involves the concerted movement of a proton. These processes are referred to as proton-coupled electron transfer, and they underpin a wide variety of biological processes, including respiration, energy conversion, photosynthesis, and metalloenzyme catalysis. The mechanisms of proton delivery are incompletely understood, in part due to an absence of information on exact proton locations and hydrogen bonding structures in a bona fide metalloenzyme proton pathway. Here, we present a 2.1-Å neutron crystal structure of the complex formed between a redox metalloenzyme (ascorbate peroxidase) and its reducing substrate (ascorbate). In the neutron structure of the complex, the protonation states of the electron/proton donor (ascorbate) and all of the residues involved in the electron/proton transfer pathway are directly observed. This information sheds light on possible proton movements during heme-catalyzed oxygen activation, as well as on ascorbate oxidation.

scholarly journals Excited state structural dynamics of 4-cyano-4′-hydroxystilbene: deciphering the signatures of proton-coupled electron transfer using ultrafast Raman loss spectroscopy

2019 ◽  
Vol 21 (40) ◽  
pp. 22409-22419 ◽  
Author(s):  
Reshma Mathew ◽  
Surajit Kayal ◽  
Adithya Lakshmanna Yapamanu
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Structural Dynamics ◽  
Transfer Process ◽  
Electron Transfer Process ◽  
Proton Coupled Electron Transfer

The photo-initiated proton-coupled electron transfer process in the 4-cyano-4′-hydroxystilbene–tert-butylamine adduct strongly affects the excited-state structural dynamics of CHSB.

Efficient oxygen evolution on hematite at neutral pH enabled by proton-coupled electron transfer

2016 ◽  
Vol 52 (97) ◽  
pp. 14015-14018 ◽  
Author(s):  
Toshihiro Takashima ◽  
Koki Ishikawa ◽  
Hiroshi Irie
Keyword(s):  
Electron Transfer ◽  
Oxygen Evolution ◽  
Transfer Process ◽  
Electron Transfer Process ◽  
Neutral Ph ◽  
Proton Coupled Electron Transfer

The oxygen evolution activity of hematite at neutral pH was enhanced by inducing the concerted proton-coupled electron transfer process.

Surface photochemistry: Semiconductor mediated reactions of some saturated strained hydrocarbons

1988 ◽  
Vol 66 (7) ◽  
pp. 1579-1588 ◽  
Author(s):  
N. Colin Baird ◽  
Anthony M. Draper ◽  
Paul de Mayo
Keyword(s):  
Electron Transfer ◽  
Quantum Yield ◽  
Transfer Process ◽  
Radical Cations ◽  
Thermal Reaction ◽  
Electron Transfer Process ◽  
Electron Transfer Mechanism ◽  
Valence Isomerization ◽  
Back Electron Transfer

Quadricyclane (1) and 1,8-bishoniocubane (2) have been found to undergo valence isomerization to norborndiene and tricyclo[4.2.2.02,5]deca-3,7-diene, respectively, on illuminated CdS and ZnO. An electron transfer mechanism is proposed. Quantum yield, solvent effects, the role of oxygen, and the quenching of the reaction were investigated, and were consistent with this interpretation. The thermal reaction of 1 on CdS was also suggested to be an electron transfer process involving, in this case, defects or trapped holes on the surface of the semiconductor. An examination of a series of strained hydrocarbons structurally related to 1 (tetracyclo[3.3.0.02,8.04,6]octane 3, pentacyclo[4.3.0.02,4.03.805,7]nonane 4 and pentacyclo[4.4.0.02,4.03,8.05,7]decane 5) resulted, largely, in a demonstration of the resistance of their respective radical cations to rearrangement prior to back electron transfer. Calculations by MNDO, in combination with a modified version of MM2, were used to explore the differences in the reactivity of the radical cations of 1, 3, 4, 5, and an interpretation is presented.

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