Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures
We present molecular dynamics simulation results describing proton/deuteron exchange equilibria along hydrogen bonds at the vicinity of HX acids (X = F, I) in aqueous clusters at low temperatures. To allow for an adequate description of proton transfer processes, our simulation scheme resorted on th...
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paper:paper_10895639_v120_n36_p7213_Litman2023-06-08T16:06:35Z Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures Videla, Pablo Ernesto Laria, Daniel Hector Isotopes Kinetic energy Molecular dynamics Molecules Quantum electronics Quantum theory Temperature Controlled experiment Exchange equilibria Molecular dynamics simulations Proton transfer process Quantum fluctuation Spatial confinement Thermodynamic stabilization Valence-bond state Hydrogen bonds We present molecular dynamics simulation results describing proton/deuteron exchange equilibria along hydrogen bonds at the vicinity of HX acids (X = F, I) in aqueous clusters at low temperatures. To allow for an adequate description of proton transfer processes, our simulation scheme resorted on the implementation of a multistate empirical valence bond hamiltonian coupled to a path integral scheme to account for effects derived from nuclear quantum fluctuations. We focused attention on clusters comprising a number of water molecules close to the threshold values necessary to stabilize contact-ion-pairs. For X = F, our results reveal a clear propensity of the heavy isotope to lie at the bond bridging the halide to the nearest water molecule. Contrasting, for X = I, the thermodynamic stability is reversed and the former connectivity is preferentially articulated via the light isotope. These trends remain valid for undissociated and ionic descriptions of the stable valence bond states. The preferences are rationalized in terms of differences in the quantum kinetic energies of the isotopes which, in turn, reflect the extent of the local spatial confinements prevailing along the different hydrogen bonds in the clusters. In most cases, these features are also clearly reflected in the characteristics of the corresponding stretching bands of the simulated infrared spectra. This opens interesting possibilities to gauge the extent of the isotopic thermodynamic stabilizations and the strengths of the different hydrogen bonds by following the magnitudes and shifts of the spectral signals in temperature-controlled experiments, performed on mixed clusters combining H2O and HOD. © 2016 American Chemical Society. Fil:Videla, P.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Laria, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2016 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v120_n36_p7213_Litman http://hdl.handle.net/20.500.12110/paper_10895639_v120_n36_p7213_Litman |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Isotopes Kinetic energy Molecular dynamics Molecules Quantum electronics Quantum theory Temperature Controlled experiment Exchange equilibria Molecular dynamics simulations Proton transfer process Quantum fluctuation Spatial confinement Thermodynamic stabilization Valence-bond state Hydrogen bonds |
| spellingShingle |
Isotopes Kinetic energy Molecular dynamics Molecules Quantum electronics Quantum theory Temperature Controlled experiment Exchange equilibria Molecular dynamics simulations Proton transfer process Quantum fluctuation Spatial confinement Thermodynamic stabilization Valence-bond state Hydrogen bonds Videla, Pablo Ernesto Laria, Daniel Hector Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| topic_facet |
Isotopes Kinetic energy Molecular dynamics Molecules Quantum electronics Quantum theory Temperature Controlled experiment Exchange equilibria Molecular dynamics simulations Proton transfer process Quantum fluctuation Spatial confinement Thermodynamic stabilization Valence-bond state Hydrogen bonds |
| description |
We present molecular dynamics simulation results describing proton/deuteron exchange equilibria along hydrogen bonds at the vicinity of HX acids (X = F, I) in aqueous clusters at low temperatures. To allow for an adequate description of proton transfer processes, our simulation scheme resorted on the implementation of a multistate empirical valence bond hamiltonian coupled to a path integral scheme to account for effects derived from nuclear quantum fluctuations. We focused attention on clusters comprising a number of water molecules close to the threshold values necessary to stabilize contact-ion-pairs. For X = F, our results reveal a clear propensity of the heavy isotope to lie at the bond bridging the halide to the nearest water molecule. Contrasting, for X = I, the thermodynamic stability is reversed and the former connectivity is preferentially articulated via the light isotope. These trends remain valid for undissociated and ionic descriptions of the stable valence bond states. The preferences are rationalized in terms of differences in the quantum kinetic energies of the isotopes which, in turn, reflect the extent of the local spatial confinements prevailing along the different hydrogen bonds in the clusters. In most cases, these features are also clearly reflected in the characteristics of the corresponding stretching bands of the simulated infrared spectra. This opens interesting possibilities to gauge the extent of the isotopic thermodynamic stabilizations and the strengths of the different hydrogen bonds by following the magnitudes and shifts of the spectral signals in temperature-controlled experiments, performed on mixed clusters combining H2O and HOD. © 2016 American Chemical Society. |
| author |
Videla, Pablo Ernesto Laria, Daniel Hector |
| author_facet |
Videla, Pablo Ernesto Laria, Daniel Hector |
| author_sort |
Videla, Pablo Ernesto |
| title |
Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| title_short |
Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| title_full |
Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| title_fullStr |
Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| title_full_unstemmed |
Positional Isotope Exchange in HX·(H2O)n (X = F, I) Clusters at Low Temperatures |
| title_sort |
positional isotope exchange in hx·(h2o)n (x = f, i) clusters at low temperatures |
| publishDate |
2016 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v120_n36_p7213_Litman http://hdl.handle.net/20.500.12110/paper_10895639_v120_n36_p7213_Litman |
| work_keys_str_mv |
AT videlapabloernesto positionalisotopeexchangeinhxh2onxficlustersatlowtemperatures AT lariadanielhector positionalisotopeexchangeinhxh2onxficlustersatlowtemperatures |
| _version_ |
1768544651563761664 |