scholarly journals Influence of a nearby substrate on the reorganization energy of hole exchange between dye molecules

2015 ◽  
Vol 17 (11) ◽  
pp. 7345-7354 ◽  
Author(s):  
Fabian Manke ◽  
Jarvist M. Frost ◽  
Valérie Vaissier ◽  
Jenny Nelson ◽  
Piers R. F. Barnes
Keyword(s):  
Reorganization Energy ◽  
Outer Sphere ◽  
Dye Molecules ◽  
Polar Solvents ◽  
Hole Transfer ◽  
Dielectric Substrates ◽  
Reorganisation Energy

The outer-sphere reorganisation energy for hole transfer between dye molecules in polar solvents is reduced by around 20% by dielectric substrates.

Evidences of Conformational Fluctuations of 2-methylaminofluorenone and 2-dimethylaminofluorenone in Polar Solvents

2004 ◽  
Vol 59 (3) ◽  
pp. 105-112 ◽  
Author(s):  
M. Józefowicza ◽  
J. R. Heldta ◽  
J. Heldta ◽  
J. Heldta
Keyword(s):  
Fluorescence Spectra ◽  
Polar Solvent ◽  
Reorganization Energy ◽  
Outer Sphere ◽  
Fluorescence Decay ◽  
Absorption And Fluorescence Spectra ◽  
Exponential Functions ◽  
Polar Solvents ◽  
Ground State Dipole Moment ◽  
Reorganization Energies

The absorption and fluorescence spectra of 2-methylaminofluorenone (2MAFl) and 2-dimethylaminofluorenone (2DMAFl) were determined at 293 K in a variety of solvents with different polarities. The spectral data were used, in combination with the 2MAFl and 2DMAFl ground state dipole moment (μg), to evaluate μe of the S1 state, to determine the outer-sphere solvent reorganization energy λouter, and the intramolecular reorganization energies: λ1 (associated with vibrations for which hv < kT) and λi(hv > kT). At 77 K the fluorescence spectra in a non-polar solvent are shifted to longer wavelengths. In polar solvents, for both molecules the behavior is opposite. The fluorescence decay data for 2MAFl and 2DMAFl in non-polar solvents are very well fitted by oneexponential functions, while in polar solvents by two-exponential functions. The spectroscopic data distinctly show that both studied molecules in polar solvents form an inhomogeneous emitting system.

scholarly journals Outer-sphere effects on ligand-field excited-state dynamics: solvent dependence of high-spin to low-spin conversion in [Fe(bpy)3]2+

2020 ◽  
Vol 11 (20) ◽  
pp. 5191-5204 ◽  
Author(s):  
Jennifer N. Miller ◽  
James K. McCusker
Keyword(s):  
Excited State ◽  
Reorganization Energy ◽  
Outer Sphere ◽  
Ligand Field ◽  
Spin Conversion ◽  
Energy Effect ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
State Recovery ◽  
Solvent Dependence

Time-resolved spectroscopic measurements of ground-state recovery for [Fe(bpy)3]2+ reveal that the solvent can induce an outer-sphere reorganization energy effect on excited-state dynamics involving metal-centered ligand-field electronic states.

Kinetics of N-substituted phenothiazines and N-substituted phenoxazines oxidation catalyzed by fungal laccases

2009 ◽  
Vol 4 (1) ◽  
pp. 62-67 ◽  
Author(s):  
Lidija Tetianec ◽  
Juozas Kulys
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Reorganization Energy ◽  
Outer Sphere ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Type I ◽  
Electron Transfer Mechanism ◽  
Recombinant Laccase ◽  
Kinetics Of

AbstractLaccase-catalyzed oxidation of N-substituted phenothiazines and N-substituted phenoxazines was investigated at pH 5.5 and 25°C. The recombinant laccase from Polyporus pinsitus (rPpL) and the laccase from Myceliophthora thermophila (rMtL) were used. The dependence of initial reaction rate on substrate concentration was analyzed by applying the laccase action scheme in which the laccase native intermediate (NI) reacts with a substrate forming reduced enzyme. The reduced laccase produces peroxide intermediate (PI) which in turn decays to the NI. The calculated constant (kox) values of the PI formation are (6.1±3.1)×105 M−1s−1 for rPpL and (2.5±0.9)×104 M−1s−1 for rMtL. The bimolecular constants of the reaction of the native intermediate with electron donor (kred) vary in the interval from 2.2×105 to 2.1×107 M−1s−1 for rPpL and from 1.3×102 to 1.8×105 M-1s−1 for rMtL. The larger reactivity of rPpL in comparison to rMtL is associated with the higher redox potential of type I Cu of rPpL. The variation of kred values for both laccases correlates with the change of the redox potential of substrates. Following outer sphere (Marcus) electron transfer mechanism the calculated activationless electron transfer rate and the apparent reorganization energy are 5.0×107 M−1s−1 and 0.29 eV, respectively.

scholarly journals Distal [FeS]-Cluster Coordination in [NiFe]-Hydrogenase Facilitates Intermolecular Electron Transfer

2017 ◽  
Author(s):  
Alexander Petrenko ◽  
Matthias Stein
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Electric Energy ◽  
Reorganization Energy ◽  
Outer Sphere ◽  
Intermolecular Electron Transfer ◽  
Sulfur Cluster ◽  
Donor And Acceptor ◽  
Marcus Equation ◽  
Hydrogenase Enzyme

Biohydrogen is a versatile energy carrier for the generation of electric energy from renewable sources. Hydrogenases can be used in enzymatic fuel cells to oxidize dihydrogen. The rate of electron transfer (ET) at the anodic side between the [NiFe]-hydrogenase enzyme distal iron&ndash;sulfur cluster and the electrode surface can be described by the Marcus equation. All parameters for the Marcus equation are accessible from Density Functional Theory (DFT) calculations. The distal cubane FeS-cluster has a three-cysteine and one-histidine coordination [Fe4S4](His)(Cys)3 first ligation sphere. The reorganization energy (inner- and outer-sphere) is almost unchanged upon a histidine-to-cysteine substitution. Differences in rates of electron transfer between the wild-type enzyme and an all-cysteine mutant can be rationalized by a diminished electronic coupling between the donor and acceptor molecules in the [Fe4S4](Cys)4 case. The fast and efficient electron transfer from the distal iron&ndash;sulfur cluster is realized by a fine-tuned protein environment, which facilitates the flow of electrons. This study enables the design and control of electron transfer rates and pathways by protein engineering.

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