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Literature DB >> 19831354

Single-ion reorganization free energy of aqueous Ru(bpy)32+/3+ and Ru(H2O)62+/3+ from photoemission spectroscopy and density functional molecular dynamics simulation.

Robert Seidel¹, Manfred Faubel, Bernd Winter, Jochen Blumberger.

Abstract

Photoelectron spectroscopy and density functional molecular dynamics simulations are combined to quantify and characterize the redox properties of Ru(bpy)32+/3+ and Ru(H2O)62+/3+ in aqueous solution. We report the energy-resolved photoelectron spectrum of aqueous Ru(bpy)32+ at 200 eV photon energy. From the peak position of the highest molecular orbital at 6.81 eV, an experimental value for the single-ion reorganization free energy of Ru(bpy)33+ is determined to be 1.21 +/- 0.04 eV. Density functional molecular dynamics calculations give a value of 0.84-1.20 eV for Ru(bpy)33+ and 1.92-2.42 eV for Ru(H2O)63+ depending on the method used to extrapolate the results to the infinite dilution limit. Since linear response is an excellent approximation for these systems, we report the same reorganization free energies for the divalent ions. The relatively small reorganization free energy of Ru(bpy)33+ is a consequence of the small changes in the Ru-N bond lengths upon reduction (0.04 eV inner sphere contribution) and of the large hydrophobic cavity formed by the bulky bipyridine ligands, which effectively reduces the dipolar response of the solvent in qualitative agreement with continuum theory. The large difference in redox potential between Ru(bpy)32+/3+ and Ru(H2O)62+/3+ (1 eV) is mainly associated with the difference in reorganization free energy rather than vertical ionization energy. Finally, the measured photoelectron spectrum of Ru(bpy)32+ is compared with the Kohn-Sham density of states for interpretation of occupied as well as computed virtual energy levels. This computational approach, in conjunction with first-ever photoelectron spectroscopy measurements of an aqueous transition metal ion, provides a quantitative benchmark for understanding the effect of water on metal redox potential and lays the groundwork for future studies of redox properties.

Entities: Chemical

Year: 2009 PMID： 19831354 DOI： 10.1021/ja9047834

Source DB: PubMed Journal: J Am Chem Soc ISSN： 0002-7863 Impact factor: 15.419

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Cited

6 in total

1. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)-cobalt(III) bimetallic complex.

Authors: Robert J Holbrook; David J Weinberg; Mark D Peterson; Emily A Weiss; Thomas J Meade
Journal: J Am Chem Soc Date: 2015-03-02 Impact factor: 15.419

2. First-principle protocol for calculating ionization energies and redox potentials of solvated molecules and ions: theory and application to aqueous phenol and phenolate.

Authors: Debashree Ghosh; Anirban Roy; Robert Seidel; Bernd Winter; Stephen Bradforth; Anna I Krylov
Journal: J Phys Chem B Date: 2012-05-04 Impact factor: 2.991

3. Fragment-based Quantum Mechanical/Molecular Mechanical Simulations of Thermodynamic and Kinetic Process of the Ru²⁺-Ru³⁺ Self-Exchange Electron Transfer.

Authors: Xiancheng Zeng; Xiangqian Hu; Weitao Yang
Journal: J Chem Theory Comput Date: 2012-12-11 Impact factor: 6.006

Single-ion reorganization free energy of aqueous Ru(bpy)32+/3+ and Ru(H2O)62+/3+ from photoemission spectroscopy and density functional molecular dynamics simulation.

1. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)-cobalt(III) bimetallic complex.

2. First-principle protocol for calculating ionization energies and redox potentials of solvated molecules and ions: theory and application to aqueous phenol and phenolate.

3. Fragment-based Quantum Mechanical/Molecular Mechanical Simulations of Thermodynamic and Kinetic Process of the Ru²⁺-Ru³⁺ Self-Exchange Electron Transfer.

4. Accurate Quantum Mechanical/Molecular Mechanical Calculations of Reduction Potentials in Azurin Variants.

Review 5. Multi-haem cytochromes in Shewanella oneidensis MR-1: structures, functions and opportunities.

6. Quantum localization and delocalization of charge carriers in organic semiconducting crystals.

Single-ion reorganization free energy of aqueous Ru(bpy)32+/3+ and Ru(H2O)62+/3+ from photoemission spectroscopy and density functional molecular dynamics simulation.

1. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)-cobalt(III) bimetallic complex.

2. First-principle protocol for calculating ionization energies and redox potentials of solvated molecules and ions: theory and application to aqueous phenol and phenolate.

3. Fragment-based Quantum Mechanical/Molecular Mechanical Simulations of Thermodynamic and Kinetic Process of the Ru2+-Ru3+ Self-Exchange Electron Transfer.

4. Accurate Quantum Mechanical/Molecular Mechanical Calculations of Reduction Potentials in Azurin Variants.

Review 5. Multi-haem cytochromes in Shewanella oneidensis MR-1: structures, functions and opportunities.

6. Quantum localization and delocalization of charge carriers in organic semiconducting crystals.

3. Fragment-based Quantum Mechanical/Molecular Mechanical Simulations of Thermodynamic and Kinetic Process of the Ru²⁺-Ru³⁺ Self-Exchange Electron Transfer.