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Title: Water network-mediated, electron-induced proton transfer in [C 5H 5N • (H 2O) n] clusters

The role of proton-assisted charge accommodation in electron capture by a heterocyclic electron scavenger is investigated through theoretical analysis of the vibrational spectra of cold, gas phase [Py·(H 2O) n=3–5]– clusters. These radical anions are formed when an excess electron is attached to water clusters containing a single pyridine (Py) molecule in a supersonic jet ion source. Under these conditions, the cluster ion distribution starts promptly at n = 3, and the photoelectron spectra, combined with vibrational predissociation spectra of the Ar-tagged anions, establish that for n > 3, these species are best described as hydrated hydroxide ions with the neutral pyridinium radical, PyH (0), occupying one of the primary solvation sites of the OH . The n = 3 cluster appears to be a special case where charge localization on Py and hydroxide is nearly isoenergetic, and the nature of this species is explored with ab initio molecular dynamics calculations of the trajectories that start from metastable arrangements of the anion based on a diffuse, essentially dipole-bound electron. These calculations indicate that the reaction proceeds via a relatively slow rearrangement of the water network to create a favorable hydration configuration around the water molecule that eventually donates a protonmore » to the Py nitrogen atom to yield the product hydroxide ion. In conclusion, the correlation between the degree of excess charge localization and the evolving shape of the water network revealed by this approach thus provides a microscopic picture of the “solvent coordinate” at the heart of a prototypical proton-coupled electron transfer reaction« less
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  1. Yale Univ., New Haven, CT (United States)
  2. Yale Univ., New Haven, CT (United States); Fairfield Univ., Fairfield, CT (United States)
  3. Univ. of Pittsburgh, Pittsburgh, PA (United States)
  4. Univ. of Mississippi, University, MS (United States)
Publication Date:
Grant/Contract Number:
FG02-06ER15800; FG02-06ER15066
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 143; Journal Issue: 14; Journal ID: ISSN 0021-9606
American Institute of Physics (AIP)
Research Org:
Yale Univ., New Haven, CT (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1223330