1
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Ehrhard AA, Gunkel L, Jäger S, Sell AC, Nagata Y, Hunger J. Elucidating Conformation and Hydrogen-Bonding Motifs of Reactive Thiourea Intermediates. ACS Catal 2022; 12:12689-12700. [PMID: 36313523 PMCID: PMC9594049 DOI: 10.1021/acscatal.2c03382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/19/2022] [Indexed: 11/29/2022]
Abstract
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Substituted diphenylthioureas (DPTUs) are efficient hydrogen-bonding
organo-catalysts, and substitution of DPTUs has been shown to greatly
affect catalytic activity. Yet, both the conformation of DPTUs in
solution and the conformation and hydrogen-bonded motifs within catalytically
active intermediates, pertinent to their mode of activation, have
remained elusive. By combining linear and ultrafast vibrational spectroscopy
with spectroscopic simulations and calculations, we show that different
conformational states of thioureas give rise to distinctively different
N–H stretching bands in the infrared spectra. In the absence
of hydrogen-bond-accepting substrates, we show that vibrational structure
and dynamics are highly sensitive to the substitution of DPTUs with
CF3 groups and to the interaction with the solvent environment,
allowing for disentangling the different conformational states. In
contrast to bare diphenylthiourea (0CF-DPTU), we find the catalytically
superior CF3-substituted DPTU (4CF-DPTU) to favor the trans–trans conformation in solution,
allowing for donating two hydrogen bonds to the reactive substrate.
In the presence of a prototypical substrate, DPTUs in trans–trans conformation hydrogen bond to the
substrate’s C=O group, as evidenced by a red-shift of
the N–H vibration. Yet, our time-resolved infrared experiments
indicate that only one N–H group forms a strong hydrogen bond
to the carbonyl moiety, while thiourea’s second N–H
group only weakly interacts with the substrate. Our data indicate
that hydrogen-bond exchange between these N–H groups occurs
on the timescale of a few picoseconds for 0CF-DPTU and is significantly
accelerated upon CF3 substitution. Our results highlight
the subtle interplay between conformational equilibria, bonding states,
and bonding lifetimes in reactive intermediates in thiourea catalysis,
which help rationalize their catalytic activity.
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Affiliation(s)
- Amelie A. Ehrhard
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Lucas Gunkel
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Sebastian Jäger
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Arne C. Sell
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Johannes Hunger
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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2
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Reynolds JG, Graham TR, Pearce CI. Ion hydration controls self-diffusion in multicomponent aqueous electrolyte solutions of NaNO2-NaOH-H2O. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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Cota R, Woutersen S, Bakker HJ. Accelerated Vibrational Energy Relaxation of Water in Alkaline Environments. J Phys Chem B 2021; 125:11980-11986. [PMID: 34672577 PMCID: PMC8573739 DOI: 10.1021/acs.jpcb.1c02730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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We
observe that hydrated hydroxide ions introduce an additional
relaxation channel for the vibrational relaxation of the OD vibrations
of HDO molecules in aqueous NaOH solutions. This additional relaxation
path involves resonant (Förster) vibrational energy transfer
from the excited OD vibration to OH stretch vibrations of hydrated
OH– complexes. This energy transfer constitutes
an efficient mechanism for dissipation of the OD vibrational energy,
as the accepting OH stretch vibrations show an extremely rapid subsequent
relaxation with a time constant of <200 fs. We find that the Förster
energy transfer is characterized by a Förster radius of 2.8
± 0.2 Å.
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Affiliation(s)
- Roberto Cota
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands.,AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
| | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - Huib J Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
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4
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Cota R, van Dam EP, Woutersen S, Bakker HJ. Slowing Down of the Molecular Reorientation of Water in Concentrated Alkaline Solutions. J Phys Chem B 2020; 124:8309-8316. [PMID: 32841025 PMCID: PMC7520889 DOI: 10.1021/acs.jpcb.0c03614] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is generally accepted that the hydroxide ion (OH-) is a strong hydrogen bond acceptor and that its anomalously high diffusion constant in water results from a Grotthuss-like structural diffusion mechanism. However, the spatial extent over which OH- ions influence the dynamics of the hydrogen-bond network of water remained largely unclear. Here, we measure the ultrafast dynamics of OH groups of HDO molecules interacting with the deuterated hydroxide ion OD-. For solutions with OD- concentrations up to 4 M, we find that HDO molecules that are not directly interacting with the ions have a reorientation time constant of ∼2.7 ps, similar to that of pure liquid water. When the concentration of OD- ions is increased, the reorientation time constant increases, indicating a strong slowing down of the structural dynamics of the solution.
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Affiliation(s)
- Roberto Cota
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands.,AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
| | | | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - Huib J Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
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5
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Sofronov OO, Bakker HJ. Vibrational Relaxation Dynamics of the Core and Outer Part of Proton-Hydration Clusters. J Phys Chem B 2019; 123:6222-6228. [PMID: 31265298 PMCID: PMC6661761 DOI: 10.1021/acs.jpcb.9b02067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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We study the ultrafast
relaxation dynamics of hydrated proton clusters
in acetonitrile using femtosecond mid-infrared pump-probe spectroscopy.
We observe a strong dependence of transient absorption dynamics on
the frequency of excitation. When we excite the OH vibrations with
frequencies ≤3100 cm–1, we observe an ultrafast
energy relaxation that leads to the heating of the local environment
of the proton. This response is assigned to the OH vibrations of the
water molecules in the core of the hydrated proton cluster. When we
excite with frequencies ≥3200 cm–1, we observe
a relatively slow vibrational relaxation with a T1 time constant ranging from 0.22 ± 0.04 ps at νex = 3200 cm–1 to 0.37 ± 0.02 ps at
νex = 3520 cm–1. We assign this
response to water molecules in the outer part of the hydrated proton
cluster.
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Affiliation(s)
| | - Huib J Bakker
- AMOLF , Science Park 104 , 1098 XG Amsterdam , The Netherlands
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6
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Sun CQ. Unprecedented O:⇔:O compression and H↔H fragilization in Lewis solutions. Phys Chem Chem Phys 2019; 21:2234-2250. [DOI: 10.1039/c8cp06910g] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Charge injection in terms of protons, lone pairs, cations and anions by acid and base solvation mediates the HB network and properties of Lewis solutions through H↔H fragilization, O:⇔:O compression and polarization, ionic polarization and hydrating H2O dipolar screen shielding, anion–anion repulsion, compressed solvent H–O bond elongation and undercoordinated solute H–O bond contraction.
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Affiliation(s)
- Chang Q. Sun
- EBEAM
- Yangtze Normal University
- Chongqing 408100
- China
- NOVITUS
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7
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Sun CQ. Aqueous charge injection: solvation bonding dynamics, molecular nonbond interactions, and extraordinary solute capabilities. INT REV PHYS CHEM 2018. [DOI: 10.1080/0144235x.2018.1544446] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Chang Q. Sun
- EBEAM, Yangtze Normal University, Chongqing, People's Republic of China
- NOVITAS, EEE, Nanyang Technological University, Singapore, Singapore
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8
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Silletta EV, Tuckerman ME, Jerschow A. Unusual Proton Transfer Kinetics in Water at the Temperature of Maximum Density. PHYSICAL REVIEW LETTERS 2018; 121:076001. [PMID: 30169046 DOI: 10.1103/physrevlett.121.076001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/26/2018] [Indexed: 06/08/2023]
Abstract
Water exhibits numerous anomalous properties, many of which remain poorly understood. One of its intriguing behaviors is that it exhibits a temperature of maximum density (TMD) at 4 °C. We provide here new experimental evidence for hitherto unknown abrupt changes in proton transfer kinetics at the TMD. In particular, we show that the lifetime of OH^{-} ions has a maximum at this temperature, in contrast to hydronium ions. Furthermore, base-catalyzed proton transfer shows a sharp local minimum at this temperature, and activation energies change abruptly as well. The measured lifetimes agree with earlier theoretical predictions as the temperature approaches the TMD. Similar results are also found for heavy water at its own TMD. These findings point to a high propensity of forming fourfold coordinated OH^{-} solvation complexes at the TMD, underlining the asymmetry between hydroxide and hydronium transport. These results could help to further elucidate the unusual properties of water and related liquids.
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Affiliation(s)
- Emilia V Silletta
- Department of Chemistry, New York University, New York, New York 10003, USA
| | - Mark E Tuckerman
- Department of Chemistry, New York University, New York, New York 10003, USA
- Courant Institute of Mathematical Science, New York University, New York, New York 10012, USA
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshan Road North, Shanghai 200062, China
| | - Alexej Jerschow
- Department of Chemistry, New York University, New York, New York 10003, USA
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9
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10
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Koga Y, Miki K, Nishikawa K. Effects of H + and OH − on H 2O as probed by the 1-propanol probing methodology: differential thermodynamic approach. Phys Chem Chem Phys 2017; 19:27413-27420. [DOI: 10.1039/c7cp05519f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-dimensional characterization map of H+ and OH−, together with other ions.
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Affiliation(s)
- Yoshikata Koga
- Department of Chemistry
- The University of British Columbia
- Vancouver, BC
- V6T 1Z1, Canada, and Suitekijuku
- Vancouver
| | - Kumiko Miki
- Department of Liberal Arts and Basic Sciences
- College of Industrial Technology
- Nihon University
- Narashino
- Japan
| | - Keiko Nishikawa
- Graduate School of Advanced Integration Science, Chiba University
- Chiba 263-8522
- Japan
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11
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Crespo Y, Hassanali A. Characterizing the local solvation environment of OH(-) in water clusters with AIMD. J Chem Phys 2016; 144:074304. [PMID: 26896983 DOI: 10.1063/1.4941107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In this work, we use ab initio molecular dynamics coupled with metadynamics to explore and characterize the glassy potential energy landscape of the OH(-) in a 20 and 48 water cluster. The structural, energetic, and topological properties of OH(-) are characterized for both clusters and the molecular origins of the IR signatures are examined. We find that in both the small and large clusters, the OH(-) can donate or accept a varying number of hydrogen bonds confirming that the amphiphilic character does not depend on cluster size. However, we highlight some important differences found between the energetic and topological properties of both families of clusters which may have implications on understanding the changes in the solvation structure of OH(-) between bulk and interfacial environments. By studying the IR spectra of smaller subsets of molecules within the 20 water molecule cluster, we find that the IR spectrum of the bare OH(-) as well as the water molecule donating a strong hydrogen bond to it exhibits characteristic absorption along the amphiphilic band between 1500 and 3000 cm(-1) at positions very similar to those found for the entire hydroxide cluster. The results presented here will be useful in the calibration and improvement of both ab initio and semi-empirical methods to model this complex anion.
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Affiliation(s)
- Yanier Crespo
- International Institute of Physics (IIP), Av. Odilon Gomes de Lima, 1722-Capim Macio, 59078-400 Natal-RN, Brazil
| | - Ali Hassanali
- The Abdus Salam ICTP, Strada Costiera 11, I-34151 Trieste, Italy
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12
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MORITA M, TAKAHASHI K. Ionic Hydrogen Bonding Vibration in OH<sup>−</sup>(H<sub>2</sub>O)<sub>2-4</sub>. JOURNAL OF COMPUTER CHEMISTRY-JAPAN 2016. [DOI: 10.2477/jccj.2016-0012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Masato MORITA
- Department of Physics, University of Nevada, Reno, 1664 N. Virginia St, Reno, NV 89557
| | - Kaito TAKAHASHI
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1, Roosevelt Rd., Sec. 4, Taipei, 10617, Taiwan
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13
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van der Post ST, Hsieh CS, Okuno M, Nagata Y, Bakker HJ, Bonn M, Hunger J. Strong frequency dependence of vibrational relaxation in bulk and surface water reveals sub-picosecond structural heterogeneity. Nat Commun 2015; 6:8384. [PMID: 26382651 PMCID: PMC4595750 DOI: 10.1038/ncomms9384] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/17/2015] [Indexed: 02/07/2023] Open
Abstract
Because of strong hydrogen bonding in liquid water, intermolecular interactions between water molecules are highly delocalized. Previous two-dimensional infrared spectroscopy experiments have indicated that this delocalization smears out the structural heterogeneity of neat H2O. Here we report on a systematic investigation of the ultrafast vibrational relaxation of bulk and interfacial water using time-resolved infrared and sum-frequency generation spectroscopies. These experiments reveal a remarkably strong dependence of the vibrational relaxation time on the frequency of the OH stretching vibration of liquid water in the bulk and at the air/water interface. For bulk water, the vibrational relaxation time increases continuously from 250 to 550 fs when the frequency is increased from 3,100 to 3,700 cm(-1). For hydrogen-bonded water at the air/water interface, the frequency dependence is even stronger. These results directly demonstrate that liquid water possesses substantial structural heterogeneity, both in the bulk and at the surface.
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Affiliation(s)
| | - Cho-Shuen Hsieh
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.,Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Masanari Okuno
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Huib J Bakker
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Mischa Bonn
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Johannes Hunger
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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14
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Mandal A, Ramasesha K, De Marco L, Tokmakoff A. Collective vibrations of water-solvated hydroxide ions investigated with broadband 2DIR spectroscopy. J Chem Phys 2015; 140:204508. [PMID: 24880302 DOI: 10.1063/1.4878490] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The infrared spectra of aqueous solutions of NaOH and other strong bases exhibit a broad continuum absorption for frequencies between 800 and 3500 cm(-1), which is attributed to the strong interactions of the OH(-) ion with its solvating water molecules. To provide molecular insight into the origin of the broad continuum absorption feature, we have performed ultrafast transient absorption and 2DIR experiments on aqueous NaOH by exciting the O-H stretch vibrations and probing the response from 1350 to 3800 cm(-1) using a newly developed sub-70 fs broadband mid-infrared source. These experiments, in conjunction with harmonic vibrational analysis of OH(-)(H2O)n (n = 17) clusters, reveal that O-H stretch vibrations of aqueous hydroxides arise from coupled vibrations of multiple water molecules solvating the ion. We classify the vibrations of the hydroxide complex by symmetry defined by the relative phase of vibrations of the O-H bonds hydrogen bonded to the ion. Although broad and overlapping spectral features are observed for 3- and 4-coordinate ion complexes, we find a resolvable splitting between asymmetric and symmetric stretch vibrations, and assign the 2850 cm(-1) peak infrared spectra of aqueous hydroxides to asymmetric stretch vibrations.
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Affiliation(s)
- Aritra Mandal
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Krupa Ramasesha
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Luigi De Marco
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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15
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Giammanco CH, Kramer PL, Fayer MD. Dynamics of Dihydrogen Bonding in Aqueous Solutions of Sodium Borohydride. J Phys Chem B 2015; 119:3546-59. [DOI: 10.1021/jp512426y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chiara H. Giammanco
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Patrick L. Kramer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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16
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Mazur K, Bonn M, Hunger J. Hydrogen bond dynamics in primary alcohols: a femtosecond infrared study. J Phys Chem B 2015; 119:1558-66. [PMID: 25531023 DOI: 10.1021/jp509816q] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrogen-bonded liquids are excellent solvents, in part due to the highly dynamic character of the directional interaction associated with the hydrogen bond. Here we study the vibrational and reorientational dynamics of deuterated hydroxyl groups in various primary alcohols using polarization-resolved femtosecond infrared spectroscopy. We show that the relaxation of the OD stretch vibration is similar for ethanol and its higher homologues (∼0.9 ps), while it is appreciably faster for methanol (∼0.75 ps). The fast relaxation for methanol is attributed to strong coupling of the OD stretch vibration to the overtone of the CH3 rocking mode. Subsequent to excited state relaxation, the dissipation of the excess energy leads to structural relaxation of the alcohol liquid structure. We show that this relaxation of the H-bonded network depends on the alkyl chain length. We find that the anisotropy of the excitation decays by both thermal diffusion from excited OD groups to nonexcited molecules and reorientational motion. The reorientation is described well by a model employing two relaxation times that increase linearly with increasing alcohol size. The short reorientation time is assigned to the partial reorientation of molecules within the alcohol cluster, while the long reorientation times can be attributed to breaking and reforming of hydrogen bonds.
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Affiliation(s)
- Kamila Mazur
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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17
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Morita M, Takahashi H, Yabushita S, Takahashi K. Why does the IR spectrum of hydroxide stretching vibration weaken with increase in hydration? Phys Chem Chem Phys 2014; 16:23143-9. [DOI: 10.1039/c4cp03623a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Mazur K, Buchner R, Bonn M, Hunger J. Hydration of Sodium Alginate in Aqueous Solution. Macromolecules 2014. [DOI: 10.1021/ma4023873] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kamila Mazur
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Richard Buchner
- Institut
für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Johannes Hunger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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19
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Chen C, Huang C, Waluyo I, Nordlund D, Weng TC, Sokaras D, Weiss T, Bergmann U, Pettersson LGM, Nilsson A. Solvation structures of protons and hydroxide ions in water. J Chem Phys 2013; 138:154506. [PMID: 23614429 DOI: 10.1063/1.4801512] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
X-ray Raman spectroscopy (XRS) combined with small-angle x-ray scattering (SAXS) were used to study aqueous solutions of HCl and NaOH. Hydrated structures of H(+) and OH(-) are not simple mirror images of each other. While both ions have been shown to strengthen local hydrogen bonds in the hydration shell as indicated by XRS, SAXS suggests that H(+) and OH(-) have qualitatively different long-range effects. The SAXS structure factor of HCl (aq) closely resembles that of pure water, while NaOH (aq) behaves similar to NaF (aq). We propose that protons only locally enhance hydrogen bonds while hydroxide ions induce tetrahedrality in the overall hydrogen bond network of water.
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Affiliation(s)
- Chen Chen
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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20
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Morita M, Takahashi K. Multidimensional local mode calculations for the vibrational spectra of OH−(H2O)2 and OH−(H2O)2·Ar. Phys Chem Chem Phys 2013; 15:14973-85. [DOI: 10.1039/c3cp51903a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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