1
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Yao JL, Zhang Z, Li Z. Scalable Transition-Metal-Free Synthesis of Aryl Amines from Aryl Chlorides through X@RONa-Catalyzed Benzyne Formation. J Am Chem Soc 2024; 146:8839-8846. [PMID: 38526012 DOI: 10.1021/jacs.4c00426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Aryl amines are highly useful organic chemicals, but large-scale, transition-metal-free syntheses of aryl amines are surprisingly underdeveloped. A mild and scalable (up to 500 mmol) aryl amine synthesis from benzyne chemistry was invented using easily accessible aryl chlorides as precursors, NaH as a stoichiometric base, and a new type of sodium alkoxide cluster, X@RONa, as a catalyst. The cluster catalyst X@RONa featured an externally hydrophobic dodecameric sodium alkoxide shell housing an encapsulated center anion. The cluster made from methoxy-tert-butanol was found to be the most effective. The intramolecular version of this reaction allowed the synthesis of indolines and indoles. Experimental and computational mechanistic studies revealed that the rate-determining step was likely the transport of solid NaH into the X@RONa cluster in the organic phase.
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Affiliation(s)
- Jia-Lin Yao
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong District, Shanghai 201210, P. R. China
| | - Zining Zhang
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong District, Shanghai 201210, P. R. China
| | - Zhi Li
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong District, Shanghai 201210, P. R. China
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2
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Schulke S, Nolten M, Schwaab G, Havenith M. Studying Local Electrostatics by Terahertz Spectroscopy Using Amines as a Probe. Chemphyschem 2024; 25:e202300389. [PMID: 37897334 DOI: 10.1002/cphc.202300389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/20/2023] [Accepted: 10/26/2023] [Indexed: 10/30/2023]
Abstract
In a previous study[1] we could show that a large amplitude mode of the zwitterion glycine can serve as a sensitive probe for protonation and allows to deduce local pKa values. Here we show that the underlying concept is more general: We present the results of a pH dependent measurement of Terahertz-FTIR (THz-FTIR) spectra of solvated amines, i. e. Diethylamine (DEA), Triethylamine (TEA), and Diisopropylamine (DiPA). We show that amines serve as a sensitive, label free probe for local protonation. Protonation of the amines yield intensity changes which can be quantified by precise THz spectroscopy (30 cm-1 -450 cm-1 ). A detailed analysis allows us to correlate the titration spectra of solvated amines in the THz range with pKa values. This demonstrates the potential of THz spectroscopy to probe the charge state of biomolecules in water in a label free manner.
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Affiliation(s)
- Simon Schulke
- Physical Chemistry 2, Ruhr-Univeristy Bochum, Universitaetsstraße 150, 44801, Bochum, Germany
| | - Melinda Nolten
- Physical Chemistry 2, Ruhr-Univeristy Bochum, Universitaetsstraße 150, 44801, Bochum, Germany
| | - Gerhard Schwaab
- Physical Chemistry 2, Ruhr-Univeristy Bochum, Universitaetsstraße 150, 44801, Bochum, Germany
| | - Martina Havenith
- Physical Chemistry 2, Ruhr-Univeristy Bochum, Universitaetsstraße 150, 44801, Bochum, Germany
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3
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Winterstein S, Privalov AF, Greve C, Siegel R, Pötzschner B, Bettermann M, Adolph L, Timm J, Marschall R, Rössler EA, Herzig EM, Vogel M, Senker J. Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework. J Am Chem Soc 2023; 145:27563-27575. [PMID: 38060438 PMCID: PMC10740000 DOI: 10.1021/jacs.3c09257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/12/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023]
Abstract
Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts. We report on the synthesis and postsynthetic sulfonation of an aromatic framework (SPAF-2) with a 3D-interconnected nanoporosity and varying sulfonation degrees. Water adsorption produces the system SPAF-2H20. It features proton exchange capacities up to 6 mequiv g-1 and exceptional proton conductivities of about 1 S cm-1. Two contributions are essential for the highly efficient transport. First, the nanometer-sized pores link the charge transport to the diffusion of adsorbed water molecules, which is almost as fast as bulk water. Second, continuous exchange between interface-bound and mobile species enhances the conductivities at elevated temperatures. SPAF-2H20 showcases how to tailor nanostructured electrolyte-host systems with liquid-like conductivities.
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Affiliation(s)
- Simon
F. Winterstein
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Alexei F. Privalov
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Christopher Greve
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Renée Siegel
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Björn Pötzschner
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Bettermann
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Lea Adolph
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Jana Timm
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Roland Marschall
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Ernst A. Rössler
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Eva M. Herzig
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Vogel
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Jürgen Senker
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
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4
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Lin S, Cao LNY, Tang Z, Wang ZL. Size-dependent charge transfer between water microdroplets. Proc Natl Acad Sci U S A 2023; 120:e2307977120. [PMID: 37487062 PMCID: PMC10401017 DOI: 10.1073/pnas.2307977120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 06/26/2023] [Indexed: 07/26/2023] Open
Abstract
Contact electrification (CE) in water has attracted much attention, owing to its potential impacts on the chemical reactions, such as the recent discovery of spontaneous generation of hydrogen peroxide (H2O2) in water microdroplets. However, current studies focus on the CE of bulk water, the measurement of CE between micrometer-size water droplets is a challenge and its mechanism still remains ambiguous. Here, a method for quantifying the amount of charge carried by the water microdroplets produced by ultrasonic atomization is proposed. In the method, the motions of water microdroplets in a uniform electric field are observed and the electrostatic forces on the microdroplets are calculated based on the moving speed of the microdroplets. It is revealed that the charge transfer between water microdroplets is size-dependent. The large microdroplets tend to be positively charged while the small microdroplets tend to receive negative charges, implying that the negative charges transfer from large microdroplets to the small microdroplets during ultrasonic atomization. Further, a theoretical model for microdroplets charging is proposed, in which the curvature-induced surface potential/energy difference is suggested to be responsible for the charge transfer between microdroplets. The findings show that the electric field strength between two microdroplets with opposite charges during separation is strong enough to convert OH‒ to OH*, providing evidence for the CE-induced spontaneous generation of H2O2 in water microdroplets.
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Affiliation(s)
- Shiquan Lin
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing100083, People’s Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Leo N. Y. Cao
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing100083, People’s Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Zhen Tang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing100083, People’s Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Zhong Lin Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing100083, People’s Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA30332−0245
- Yonsei Frontier Lab, Yonsei University, Seoul03722, Republic of Korea
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5
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Sit I, Fashina BT, Baldo AP, Leung K, Grassian VH, Ilgen AG. Formic and acetic acid p Ka values increase under nanoconfinement. RSC Adv 2023; 13:23147-23157. [PMID: 37533784 PMCID: PMC10390803 DOI: 10.1039/d2ra07944e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 06/22/2023] [Indexed: 08/04/2023] Open
Abstract
Organic acids are prevalent in the environment and their acidity and the corresponding dissociation constants can change under varying environmental conditions. The impact of nanoconfinement (when acids are confined within nanometer-scale domains) on physicochemical properties of chemical species is poorly understood and is an emerging field of study. By combining infrared and Raman spectroscopies with molecular dynamics (MD) simulations, we quantified the effect of nanoconfinement in silica nanopores on one of the fundamental chemical reactions-the dissociation of organic acids. The pKa of formic and acetic acids confined within cylindrical silica nanopores with 4 nm diameters were measured. MD models were constructed to calculate the shifts in the pKa values of acetic acid nanoconfined within 1, 2, 3, and 4 nm silica slit pores. Both experiments and MD models indicate a decrease in the apparent acid dissociation constants (i.e., increase in the pKa values) when organic acids are nanoconfined. Therefore, nanoconfinement stabilizes the protonated species. We attribute this observation to (1) a decrease in the average dielectric response of nanoconfined aqueous solutions where charge screening may be decreased; or (2) an increase in proton concentration inside nanopores, which would shift the equilibrium towards the protonated form. Overall, the results of this study provide the first quantification of the pKa values for nanoconfined formic and acetic acids and pave the way for a unifying theory predicting the impact of nanoconfinement on acid-base chemistry.
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Affiliation(s)
- Izaac Sit
- Department of Nanoengineering, University of California San Diego La Jolla CA 92093 USA
| | - Bidemi T Fashina
- Geochemistry Department, Sandia National Laboratories Albuquerque NM 87123 USA
| | - Anthony P Baldo
- Geochemistry Department, Sandia National Laboratories Albuquerque NM 87123 USA
| | - Kevin Leung
- Geochemistry Department, Sandia National Laboratories Albuquerque NM 87123 USA
| | - Vicki H Grassian
- Department of Chemistry & Biochemistry, University of California San Diego La Jolla CA 92093 USA
| | - Anastasia G Ilgen
- Geochemistry Department, Sandia National Laboratories Albuquerque NM 87123 USA
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6
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Hao H, Adams EM, Funke S, Schwaab G, Havenith M, Head-Gordon T. Highly Altered State of Proton Transport in Acid Pools in Charged Reverse Micelles. J Am Chem Soc 2023; 145:1826-1834. [PMID: 36633459 PMCID: PMC9881006 DOI: 10.1021/jacs.2c11331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Indexed: 01/13/2023]
Abstract
Transport mechanisms of solvated protons of 1 M HCl acid pools, confined within reverse micelles (RMs) containing the negatively charged surfactant sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) or the positively charged cetyltrimethylammonium bromide (CTABr), are analyzed with reactive force field simulations to interpret dynamical signatures from TeraHertz absorption and dielectric relaxation spectroscopy. We find that the forward proton hopping events for NaAOT are further suppressed compared to a nonionic RM, while the Grotthuss mechanism ceases altogether for CTABr. We attribute the sluggish proton dynamics for both charged RMs as due to headgroup and counterion charges that expel hydronium and chloride ions from the interface and into the bulk interior, thereby increasing the pH of the acid pools relative to the nonionic RM. For charged NaAOT and CTABr RMs, the localization of hydronium near a counterion or conjugate base reduces the Eigen and Zundel configurations that enable forward hopping. Thus, localized oscillatory hopping dominates, an effect that is most extreme for CTABr in which the proton residence time increases dramatically such that even oscillatory hopping is slow.
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Affiliation(s)
- Hongxia Hao
- Kenneth
S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California94720, United States
| | - Ellen M. Adams
- Cluster
of Excellence Physics of Life, Technische
Universität Dresden, 01307Dresden, Germany
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Resource
Ecology, 01328Dresden, Germany
| | - Sarah Funke
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Gerhard Schwaab
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Martina Havenith
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Teresa Head-Gordon
- Kenneth
S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California94720, United States
- Department
of Bioengineering, Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
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7
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Crowder M, Tahiry F, Lizarraga I, Rodriguez S, Peña N, Sharma AK. Computatiaonal Analysis of Water Dynamics in AOT Reverse Micelles. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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8
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Heindel JP, Hao H, LaCour RA, Head-Gordon T. Spontaneous Formation of Hydrogen Peroxide in Water Microdroplets. J Phys Chem Lett 2022; 13:10035-10041. [PMID: 36264238 DOI: 10.1021/acs.jpclett.2c01721] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
There is accumulating evidence that many chemical reactions are accelerated by several orders of magnitude in micrometer-sized aqueous or organic liquid droplets compared to their corresponding bulk liquid phase. However, the molecular origin of the enhanced rates remains unclear as in the case of spontaneous appearance of 1 μM hydrogen peroxide in water microdroplets. In this Letter, we consider the range of ionization energies and whether interfacial electric fields of a microdroplet can feasibly overcome the high energy step from hydroxide ions (OH-) to hydroxyl radicals (OH•) in a primary H2O2 mechanism. We find that the vertical ionization energies (VIEs) of partially solvated OH- ions are greatly lowered relative to the average VIE in the bulk liquid, unlike the case of the Cl- anion which shows no reduction in the VIEs regardless of solvation environment. Overall reduced hydrogen-bonding and undercoordination of OH- are structural features that are more readily present at the air-water interface, where the energy scale for ionization can be matched by statistically probable electric field values.
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Affiliation(s)
- Joseph P Heindel
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Hongxia Hao
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
| | - R Allen LaCour
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Teresa Head-Gordon
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
- Departments of Bioengineering and Chemical and Biomolecular EngineeringUniversity of California, Berkeley, California94720, United States
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9
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Wortmann S, Kutta RJ, Nuernberger P. Monitoring the photochemistry of a formazan over 15 orders of magnitude in time. Front Chem 2022; 10:983342. [PMID: 36247663 PMCID: PMC9554553 DOI: 10.3389/fchem.2022.983342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
2,3,5-triphenyltetrazolium chloride (TTC) may convert into phenyl-benzo[c]tetrazolocinnolium chloride (PTC) and 1,3,5-triphenylformazan (TPF) under irradiation with light. The latter reaction, albeit enzymatically rather than photochemically, is used in so-called TTC assays indicating cellular respiration and cell growth. In this paper, we address the photochemistry of TPF with time-resolved spectroscopy on various time scales. TPF is stabilized by an intramolecular hydrogen bond and switches photochemically via an E-Z isomerization around an N=N double bond into another TPF-stereoisomer, from which further isomerizations around the C=N double bond of the phenylhydrazone group are possible. We investigate the underlying processes by time-resolved spectroscopy in dependence on excitation wavelength and solvent environment, resolving several intermediates over a temporal range spanning 15 orders of magnitude (hundreds of femtoseconds to hundreds of seconds) along the reaction path. In a quantum-chemical analysis, we identify 16 stable ground-state isomers and discuss which ones are identified in the experimental data. We derive a detailed scheme how these species are thermally and photochemically interconnected and conclude that proton transfer processes are involved.
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10
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Konermann L, Kim S. Grotthuss Molecular Dynamics Simulations for Modeling Proton Hopping in Electrosprayed Water Droplets. J Chem Theory Comput 2022; 18:3781-3794. [PMID: 35544700 DOI: 10.1021/acs.jctc.2c00001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Excess protons in water exhibit unique transport properties because they can rapidly hop along H-bonded water wires. Considerable progress has been made in unraveling this Grotthuss diffusion mechanism using quantum mechanical-based computational techniques. Unfortunately, high computational cost tends to restrict those techniques to small systems and short times. Molecular dynamics (MD) simulations can be applied to much larger systems and longer time windows. However, standard MD methods do not permit the dissociation/formation of covalent bonds, such that Grotthuss diffusion cannot be captured. Here, we bridge this gap by combining atomistic MD simulations (using Gromacs and TIP4P/2005 water) with proton hopping. Excess protons are modeled as hydronium ions that undergo H3O+ + H2O → H2O + H3O+ transitions. In accordance with ab initio MD data, these Grotthuss hopping events are executed in "bursts" with quasi-instantaneous hopping across one or more waters. The bursts are separated by regular MD periods during which H3O+ ions undergo Brownian diffusion. The resulting proton diffusion coefficient agrees with the literature value. We apply this Grotthuss MD technique to highly charged water droplets that are in a size regime encountered during electrospray ionization (5 nm radius, ∼17,000 H2O). The droplets undergo rapid solvent evaporation and occasional H3O+ ejection, keeping them at ca. 81% of the Rayleigh limit. The simulated behavior is consistent with phase Doppler anemometry data. The Grotthuss MD technique developed here should be useful for modeling the behavior of various proton-containing systems that are too large for high-level computational approaches. In particular, we envision future applications related to electrospray processes, where earlier simulations used metal cations while in reality excess protons dominate.
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Affiliation(s)
- Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Scott Kim
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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