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Title: Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H{sub 2}O){sub n≤5}]H{sup +}: Evidence for ground-state proton transfer to solvent for n ≥ 3

Abstract

Vibrational and electronic photodissociation spectra of mass-selected protonated benzaldehyde-(water){sub n} clusters, [BZ-(H{sub 2}O){sub n}]H{sup +} with n ≤ 5, are analyzed by quantum chemical calculations to determine the protonation site in the ground electronic state (S{sub 0}) and ππ{sup *} excited state (S{sub 1}) as a function of microhydration. IR spectra of [BZ-(H{sub 2}O){sub n}]H{sup +} with n ≤ 2 are consistent with BZH{sup +}-(H{sub 2}O){sub n} type structures, in which the excess proton is localized on benzaldehyde. IR spectra of clusters with n ≥ 3 are assigned to structures, in which the excess proton is located on the (H{sub 2}O){sub n} solvent moiety, BZ-(H{sub 2}O){sub n}H{sup +}. Quantum chemical calculations at the B3LYP, MP2, and ri-CC2 levels support the conclusion of proton transfer from BZH{sup +} to the solvent moiety in the S{sub 0} state for hydration sizes larger than the critical value n{sub c} = 3. The vibronic spectrum of the S{sub 1} ← S{sub 0} transition (ππ{sup *}) of the n = 1 cluster is consistent with a cis-BZH{sup +}-H{sub 2}O structure in both electronic states. The large blueshift of the S{sub 1} origin by 2106 cm{sup −1} upon hydration with a single H{sub 2}O ligand indicatesmore » that the proton affinity of BZ is substantially increased upon S{sub 1} excitation, thus strongly destabilizing the hydrogen bond to the solvent. The adiabatic S{sub 1} excitation energy and vibronic structure calculated at the ri-CC2/aug-cc-pVDZ level agrees well with the measured spectrum, supporting the notion of a cis-BZH{sup +}-H{sub 2}O geometry. The doubly hydrated species, cis-BZH{sup +}-(H{sub 2}O){sub 2}, does not absorb in the spectral range of 23 000–27 400 cm{sup −1}, because of the additional large blueshift of the ππ{sup *} transition upon attachment of the second H{sub 2}O molecule. Calculations predict roughly linear and large incremental blueshifts for the ππ{sup *} transition in [BZ-(H{sub 2}O){sub n}]H{sup +} as a function of n. In the size range n ≥ 3, the calculations predict a proton transfer from the (H{sub 2}O){sub n}H{sup +} solvent back to the BZ solute upon electronic ππ{sup *} excitation.« less

Authors:
; ;  [1]; ; ;  [2]; ;  [3]
  1. Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)
  2. Institut des Sciences Moleculaires d’Orsay, UMR-CNRS 8214, and Centre Laser de l’Université Paris Sud/LUMAT FR 2764, Batiment 106, l’Université Paris Sud 11, 91405 Orsay Cedex (France)
  3. Physique des Interactions Ioniques et Moléculaires, UMR-CNRS 7345 Aix Marseille Université, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20 (France)
Publication Date:
OSTI Identifier:
22254182
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 140; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BENZALDEHYDE; DISSOCIATION; EXCITATION; EXCITED STATES; GROUND STATES; HYDRATION; INFRARED SPECTRA; LIGANDS; PHOTOLYSIS; PROTONS; SOLUTES; SOLVENTS; WATER

Citation Formats

Dopfer, Otto, Patzer, Alexander, Chakraborty, Shamik, Alata, Ivan, Omidyan, Reza, Broquier, Michel, Dedonder, Claude, and Jouvet, Christophe. Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H{sub 2}O){sub n≤5}]H{sup +}: Evidence for ground-state proton transfer to solvent for n ≥ 3. United States: N. p., 2014. Web. doi:10.1063/1.4869341.
Dopfer, Otto, Patzer, Alexander, Chakraborty, Shamik, Alata, Ivan, Omidyan, Reza, Broquier, Michel, Dedonder, Claude, & Jouvet, Christophe. Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H{sub 2}O){sub n≤5}]H{sup +}: Evidence for ground-state proton transfer to solvent for n ≥ 3. United States. https://doi.org/10.1063/1.4869341
Dopfer, Otto, Patzer, Alexander, Chakraborty, Shamik, Alata, Ivan, Omidyan, Reza, Broquier, Michel, Dedonder, Claude, and Jouvet, Christophe. 2014. "Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H{sub 2}O){sub n≤5}]H{sup +}: Evidence for ground-state proton transfer to solvent for n ≥ 3". United States. https://doi.org/10.1063/1.4869341.
@article{osti_22254182,
title = {Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H{sub 2}O){sub n≤5}]H{sup +}: Evidence for ground-state proton transfer to solvent for n ≥ 3},
author = {Dopfer, Otto and Patzer, Alexander and Chakraborty, Shamik and Alata, Ivan and Omidyan, Reza and Broquier, Michel and Dedonder, Claude and Jouvet, Christophe},
abstractNote = {Vibrational and electronic photodissociation spectra of mass-selected protonated benzaldehyde-(water){sub n} clusters, [BZ-(H{sub 2}O){sub n}]H{sup +} with n ≤ 5, are analyzed by quantum chemical calculations to determine the protonation site in the ground electronic state (S{sub 0}) and ππ{sup *} excited state (S{sub 1}) as a function of microhydration. IR spectra of [BZ-(H{sub 2}O){sub n}]H{sup +} with n ≤ 2 are consistent with BZH{sup +}-(H{sub 2}O){sub n} type structures, in which the excess proton is localized on benzaldehyde. IR spectra of clusters with n ≥ 3 are assigned to structures, in which the excess proton is located on the (H{sub 2}O){sub n} solvent moiety, BZ-(H{sub 2}O){sub n}H{sup +}. Quantum chemical calculations at the B3LYP, MP2, and ri-CC2 levels support the conclusion of proton transfer from BZH{sup +} to the solvent moiety in the S{sub 0} state for hydration sizes larger than the critical value n{sub c} = 3. The vibronic spectrum of the S{sub 1} ← S{sub 0} transition (ππ{sup *}) of the n = 1 cluster is consistent with a cis-BZH{sup +}-H{sub 2}O structure in both electronic states. The large blueshift of the S{sub 1} origin by 2106 cm{sup −1} upon hydration with a single H{sub 2}O ligand indicates that the proton affinity of BZ is substantially increased upon S{sub 1} excitation, thus strongly destabilizing the hydrogen bond to the solvent. The adiabatic S{sub 1} excitation energy and vibronic structure calculated at the ri-CC2/aug-cc-pVDZ level agrees well with the measured spectrum, supporting the notion of a cis-BZH{sup +}-H{sub 2}O geometry. The doubly hydrated species, cis-BZH{sup +}-(H{sub 2}O){sub 2}, does not absorb in the spectral range of 23 000–27 400 cm{sup −1}, because of the additional large blueshift of the ππ{sup *} transition upon attachment of the second H{sub 2}O molecule. Calculations predict roughly linear and large incremental blueshifts for the ππ{sup *} transition in [BZ-(H{sub 2}O){sub n}]H{sup +} as a function of n. In the size range n ≥ 3, the calculations predict a proton transfer from the (H{sub 2}O){sub n}H{sup +} solvent back to the BZ solute upon electronic ππ{sup *} excitation.},
doi = {10.1063/1.4869341},
url = {https://www.osti.gov/biblio/22254182}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 12,
volume = 140,
place = {United States},
year = {Fri Mar 28 00:00:00 EDT 2014},
month = {Fri Mar 28 00:00:00 EDT 2014}
}