Single-Ion Reorganization Free Energy of Aqueous Ru(bpy) and Ru(HO) from Photoemission Spectroscopy and Density Functional Molecular Dynamics Simulation.
Photoelectron spectroscopy and density functional molecular dynamics simulations are combined to quantify and characterize the redox properties of Ru(bpy) and Ru(HO) in aqueous solution. We report the energy-resolved photoelectron spectrum of aqueous Ru(bpy) at 200 eV photon energy. From the peak po...
| Publicado en: | Journal of the American Chemical Society Vol. 131; no. 44; pp. 16127 - 16138 |
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| Autores principales: | , , , |
| Formato: | Artículo |
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American Chemical Society
11/11/2009
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=45585798&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 45585798 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 11/11/2009 vid: 131 iid: 44 pid: 997 pub: American Chemical Society artinfo: ui: 45585798 10.1021/ja9047834 ppf: 16127 ppct: 11 formats: tig: atl: Single-Ion Reorganization Free Energy of Aqueous Ru(bpy) and Ru(HO) from Photoemission Spectroscopy and Density Functional Molecular Dynamics Simulation. aug: au: Seidel, Robert Faubel, Manfred Winter, Bernd Blumberger, Jochen affil: Helmholtz-Zentrum Berlin für Materialien und Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany Max-Planck-Institut für Dynamik and Selbstorganisation, Bunsenstrasse 10, D-37073 Göttingen, Germany Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K. su: Linear free energy relationship Conditions & laws of chemical reaction Photoemission Spectrum analysis Molecular dynamics Chemical research sug: subj: Linear free energy relationship Conditions & laws of chemical reaction Photoemission Spectrum analysis Molecular dynamics Chemical research ab: Photoelectron spectroscopy and density functional molecular dynamics simulations are combined to quantify and characterize the redox properties of Ru(bpy) and Ru(HO) in aqueous solution. We report the energy-resolved photoelectron spectrum of aqueous Ru(bpy) 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) 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) and 1.92-2.42 eV for Ru(HO) 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)3 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) and Ru(HO) (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) 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. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2009 holdings: @attributes: islocal: N |
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