1
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Firth AJ, Nakasu PYS, Hallett JP, Matthews RP. Exploiting Cation Structure and Water Content in Modulating the Acidity of Ammonium Hydrogen Sulfate Protic Ionic Liquids. J Phys Chem Lett 2024; 15:2311-2318. [PMID: 38386631 PMCID: PMC10926163 DOI: 10.1021/acs.jpclett.3c03583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/07/2024] [Accepted: 02/19/2024] [Indexed: 02/24/2024]
Abstract
In this paper, we investigated the effect of cation structure and water content on proton dissociation in alkylammonium [HSO4]- protic ionic liquids (ILs) doped with 20 wt % water and correlated this with experimental Hammett acidities. For pure systems, increased cation substitution resulted in a reduction in the number of direct anion-anion neighbors leading to larger numbers of small aggregates, which is further enhanced with addition of water. We also observed spontaneous proton dissociation from [HSO4]- to water only for primary amine-based protic ILs, preceded by the formation of an anion trimer motif. Investigation using DFT calculations revealed spontaneous proton dissociation from [HSO4]- to water can occur for each of the protic ILs investigated; however, this is dependent on the size of the anion aggregates. These findings are important in the fields of catalysis and lignocellulosic biomass, where solvent acidity is a crucial parameter in biomass fractionation and lignin chemistry.
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Affiliation(s)
- Anton
E. J. Firth
- Department
of Chemical Engineering, Imperial College
London, London SW7 2AZ, U.K.
| | - Pedro Y. S. Nakasu
- Department
of Chemical Engineering, Imperial College
London, London SW7 2AZ, U.K.
| | - Jason P. Hallett
- Department
of Chemical Engineering, Imperial College
London, London SW7 2AZ, U.K.
| | - Richard P. Matthews
- Department
of Chemical Engineering, Imperial College
London, London SW7 2AZ, U.K.
- Department
of Bioscience, School of Health, Sports and Bioscience, University of East London, Stratford, London E15 4LZ, U.K.
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2
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Das SK, Winghart MO, Han P, Rana D, Zhang ZY, Eckert S, Fondell M, Schnappinger T, Nibbering ETJ, Odelius M. Electronic Fingerprint of the Protonated Imidazole Dimer Probed by X-ray Absorption Spectroscopy. J Phys Chem Lett 2024; 15:1264-1272. [PMID: 38278137 PMCID: PMC10860131 DOI: 10.1021/acs.jpclett.3c03576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 01/28/2024]
Abstract
Protons in low-barrier superstrong hydrogen bonds are typically delocalized between two electronegative atoms. Conventional methods to characterize such superstrong hydrogen bonds are vibrational spectroscopy and diffraction techniques. We introduce soft X-ray spectroscopy to uncover the electronic fingerprints for proton sharing in the protonated imidazole dimer, a prototypical building block enabling effective proton transport in biology and high-temperature fuel cells. Using nitrogen core excitations as a sensitive probe for the protonation status, we identify the X-ray signature of a shared proton in the solvated imidazole dimer in a combined experimental and theoretical approach. The degree of proton sharing is examined as a function of structural variations that modify the shape of the low-barrier potential in the superstrong hydrogen bond. We conclude by showing how the sensitivity to the quantum distribution of proton motion in the double-well potential is reflected in the spectral signature of the shared proton.
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Affiliation(s)
- Sambit K. Das
- Department
of Physics, Stockholm University, AlbaNova
University Center, SE-106 91 Stockholm, Sweden
| | - Marc-Oliver Winghart
- Max
Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Peng Han
- Max
Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Debkumar Rana
- Max
Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Zhuang-Yan Zhang
- Max
Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Sebastian Eckert
- Institute
for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH, 12489 Berlin, Germany
| | - Mattis Fondell
- Institute
for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH, 12489 Berlin, Germany
| | - Thomas Schnappinger
- Department
of Physics, Stockholm University, AlbaNova
University Center, SE-106 91 Stockholm, Sweden
| | - Erik T. J. Nibbering
- Max
Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Michael Odelius
- Department
of Physics, Stockholm University, AlbaNova
University Center, SE-106 91 Stockholm, Sweden
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3
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Wylie L, Kéri M, Udvardy A, Hollóczki O, Kirchner B. On the Rich Chemistry of Pseudo-Protic Ionic Liquid Electrolytes. CHEMSUSCHEM 2023; 16:e202300535. [PMID: 37364035 DOI: 10.1002/cssc.202300535] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 06/25/2023] [Accepted: 06/26/2023] [Indexed: 06/28/2023]
Abstract
Mixing weak acids and bases can produce highly complicated binary mixtures, called pseudo-protic ionic liquids, in which a complex network of effects determines the physicochemical properties that are currently impossible to predict. In this joint computational-experimental study, we investigated 1-methylimidazole-acetic acid mixtures through the whole concentration range. Effects of the varying ionization and excess of either components on the properties, such as density, diffusion coefficients, and overall hydrogen bonding structure were uncovered. A special emphasis was put on understanding the multiple factors that govern the conductivity of the system. In the presence of an excess of acetic acid, the 1-methylimidazolium acetate ion pairs dissociate more efficiently, resulting in a higher concentration of independently moving, conducting ions. However, the conductivity measurements showed that higher concentrations of acetic acid improve the conductivity beyond this effect, suggesting in addition to standard dilution effects the occurrence of Grotthuss diffusion in high acid-to-base ratios. The results here will potentially help designing novel electrolytes and proton conducting systems, which can be exploited in a variety of applications.
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Affiliation(s)
- Luke Wylie
- University of Bonn, Clausius Institute of Physical and Theoretical Chemistry, Mulliken Center for Theoretical Chemistry, Beringstr. 4, 53115, Bonn, Germany
| | - Mónika Kéri
- University of Debrecen, Department of Physical Chemistry, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Antal Udvardy
- University of Debrecen, Department of Physical Chemistry, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Oldamur Hollóczki
- University of Debrecen, Department of Physical Chemistry, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Barbara Kirchner
- University of Bonn, Clausius Institute of Physical and Theoretical Chemistry, Mulliken Center for Theoretical Chemistry, Beringstr. 4, 53115, Bonn, Germany
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4
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Codescu MA, Kunze T, Weiß M, Brehm M, Kornilov O, Sebastiani D, Nibbering ETJ. Ultrafast Proton Transfer Pathways Mediated by Amphoteric Imidazole. J Phys Chem Lett 2023; 14:4775-4785. [PMID: 37186569 DOI: 10.1021/acs.jpclett.3c00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Imidazole, being an amphoteric molecule, can act both as an acid and as a base. This property enables imidazole, as an essential building block, to effectively facilitate proton transport in high-temperature proton exchange membrane fuel cells and in proton channel transmembrane proteins, enabling those systems to exhibit high energy conversion yields and optimal biological function. We explore the amphoteric properties of imidazole by following the proton transfer exchange reaction dynamics with the bifunctional photoacid 7-hydroxyquinoline (7HQ). We show with ultrafast ultraviolet-mid-infrared pump-probe spectroscopy how for imidazole, in contrast to expectations based on textbook knowledge of acid-base reactivity, the preferential reaction pathway is that of an initial proton transfer from 7HQ to imidazole, and only at a later stage a transfer from imidazole to 7HQ, completing the 7HQ tautomerization reaction. An assessment of the molecular distribution functions and first-principles calculations of proton transfer reaction barriers reveal the underlying reasons for our observations.
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Affiliation(s)
- Marius-Andrei Codescu
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Thomas Kunze
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Moritz Weiß
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Daniel Sebastiani
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
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5
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Popov I, Zhu Z, Young-Gonzales AR, Sacci RL, Mamontov E, Gainaru C, Paddison SJ, Sokolov AP. Search for a Grotthuss mechanism through the observation of proton transfer. Commun Chem 2023; 6:77. [PMID: 37087505 PMCID: PMC10122652 DOI: 10.1038/s42004-023-00878-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023] Open
Abstract
The transport of protons is critical in a variety of bio- and electro-chemical processes and technologies. The Grotthuss mechanism is considered to be the most efficient proton transport mechanism, generally implying a transfer of protons between 'chains' of host molecules via elementary reactions within the hydrogen bonds. Although Grotthuss proposed this concept more than 200 years ago, only indirect experimental evidence of the mechanism has been observed. Here we report the first experimental observation of proton transfer between the molecules in pure and 85% aqueous phosphoric acid. Employing dielectric spectroscopy, quasielastic neutron, and light scattering, and ab initio molecular dynamic simulations we determined that protons move by surprisingly short jumps of only ~0.5-0.7 Å, much smaller than the typical ion jump length in ionic liquids. Our analysis confirms the existence of correlations in these proton jumps. However, these correlations actually reduce the conductivity, in contrast to a desirable enhancement, as is usually assumed by a Grotthuss mechanism. Furthermore, our analysis suggests that the expected Grotthuss-like enhancement of conductivity cannot be realized in bulk liquids where ionic correlations always decrease conductivity.
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Affiliation(s)
- Ivan Popov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA
| | - Zhenghao Zhu
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | | | - Robert L Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Catalin Gainaru
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Stephen J Paddison
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA.
| | - Alexei P Sokolov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA.
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6
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Zhang M, Hua H, Dai P, He Z, Han L, Tang P, Yang J, Lin P, Zhang Y, Zhan D, Chen J, Qiao Y, Li CC, Zhao J, Yang Y. Dynamically Interfacial pH-Buffering Effect Enabled by N-Methylimidazole Molecules as Spontaneous Proton Pumps toward Highly Reversible Zinc-Metal Anodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208630. [PMID: 36739482 DOI: 10.1002/adma.202208630] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/04/2022] [Indexed: 06/18/2023]
Abstract
Aqueous zinc-metal batteries have attracted extensive attention due to their outstanding merits of high safety and low cost. However, the intrinsic thermodynamic instability of zinc in aqueous electrolyte inevitably results in hydrogen evolution, and the consequent generation of OH- at the interface will dramatically exacerbate the formation of dead zinc and dendrites. Herein, a dynamically interfacial pH-buffering strategy implemented by N-methylimidazole (NMI) additive is proposed to remove the detrimental OH- at zinc/electrolyte interface in real-time, thus eliminating the accumulation of by-products fundamentally. Electrochemical quartz crystal microbalance and molecular dynamics simulation results reveal the existence of an interfacial absorption layer assembled by NMI and protonated NMI (NMIH+ ), which acts as an ion pump for replenishing the interface with protons constantly. Moreover, an in situ interfacial pH detection method with micro-sized spatial resolution based on the ultra-microelectrode technology is developed to probe the pH evolution in diffusion layer, confirming the stabilized interfacial chemical environment in NMI-containing electrolyte. Accordingly, with the existence of NMI, an excellent cumulative plating capacity of 4.2 Ah cm-2 and ultrahigh Coulombic efficiency of 99.74% are realized for zinc electrodes. Meanwhile, the NMI/NMIH+ buffer additive can accelerate the dissolution/deposition process of MnO2 /Mn2+ on the cathode, leading to enhanced cycling capacity.
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Affiliation(s)
- Minghao Zhang
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Haiming Hua
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Pengpeng Dai
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Zheng He
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Lianhuan Han
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Peiwen Tang
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jin Yang
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Pengxiang Lin
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yufei Zhang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Dongping Zhan
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jianken Chen
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yu Qiao
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Cheng Chao Li
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Jinbao Zhao
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yang Yang
- State Key Lab of Physical Chemistry of Solid Surfaces, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
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7
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Moses AA, Arntsen C. Ab initio molecular dynamics study of proton transport in imidazolium-based ionic liquids with added imidazole. Phys Chem Chem Phys 2023; 25:2142-2152. [PMID: 36562495 DOI: 10.1039/d2cp03262g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Development of efficient anhydrous proton-conducting materials would expand the operational temperature ranges of hydrogen fuels cells (HFCs) and eliminate their dependence on maintaining sufficient hydration levels to function efficiently. Protic ionic liquids (PILs), which have high ionic densities and low vapor pressures, have emerged as a potential material for proton conducting layers in HFCs. In this work, we investigate proton transport via the Grotthuss mechanism in 1-ethylimidazolium bis-(trifluoromethanesulfonyl)imide ([C2HIm][TFSI]) protic ionic liquids with added imidazole (Im0) using ab initio molecular dynamics. In particular, we vary the composition of the systems studied from pure [C2HIm][TFSI] to those where the mole fraction of Im0 is 0.67. Given the large difference in pKa between C2HIm+ and HTFSI, TFSI- does not accept acidic protons from C2HIm+; conversely, imidazolium (HIm+) and C2HIm+ have very similar pKa values, and thus Im0 can readily accept protons. We find that the unprotonated nitrogen on Im0 dominates solvation of the labile protons on C2HIm+ and other Im0 species, resulting in formation of robust imidazole wires. Given the amphoteric nature of Im0, i.e. its ability to accept and donate protons, these wires provide conduits along which protons can rapidly traverse via the Grotthuss mechanism, thereby greatly increasing the proton coefficient of self-diffusion. We find that the average length of the wires increases with added Im0, and thus as the mole fraction of Im0 increases so too does the proton diffusion constant. Lastly, we analyze our trajectories to determine the energy and time scales associated with proton transfer.
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Affiliation(s)
- Aurelia A Moses
- Department of Chemical and Biological Sciences, Youngstown State University, Youngstown, OH, 44555, USA.
| | - Christopher Arntsen
- Department of Chemical and Biological Sciences, Youngstown State University, Youngstown, OH, 44555, USA.
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8
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Bian J, Cruz A, López-Morales G, Kyrylenko A, McGregor D, López GE. Understanding Proton Transfer in Non-aqueous Biopolymers based on Helical Peptides: A Quantum Mechanical Study. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY 2022; 122:e26964. [PMID: 36213174 PMCID: PMC9543367 DOI: 10.1002/qua.26964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 06/07/2022] [Indexed: 06/16/2023]
Abstract
Histidine (an imidazole-based amino acid) is a promising building block for short aromatic peptides containing a proton donor/acceptor moiety. Previous studies have shown that polyalanine helical peptides substituted at regular intervals with histidine residues exhibit both structural stability as well as high proton affinity and high conductivity. Here, we present first-principle calculations of non-aqueous histidine-containing 310-, α- and π-helices and show that they are able to form hydrogen-bonded networks mimicking proton wires that have the ability to shuttle protons via the Grotthuss shuttling mechanism. The formation of these wires enhances the stability of the helices, and our structural characterizations confirm that the secondary structures are conserved despite distortions of the backbones. In all cases, the helices exhibit high proton affinity and proton transfer barriers on the order of 1~4 kcal/mol. Zero-point energy calculations suggest that for these systems, ground state vibrational energy can provide enough energy to cross the proton transport energy barrier. Additionally, ab initio molecular dynamics results suggests that the protons are transported unidirectionally through the wire at a rate of approximately 2 Å every 20 fs. These results demonstrate that efficient deprotonation-controlled proton wires can be formed using non-aqueous histidine-containing helical peptides.
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Affiliation(s)
- Jiang Bian
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
- Ph. D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, 10016, USA
| | - Anthony Cruz
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
- Ph. D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, 10016, USA
| | - Gabriel López-Morales
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
- Ph. D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, 10016, USA
| | - Anton Kyrylenko
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
| | - Donna McGregor
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
- Ph. D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, 10016, USA
| | - Gustavo E. López
- Department of Chemistry, Lehman College of the City University of New York, Bronx, New York, 10468, USA
- Ph. D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, 10016, USA
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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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Evolution of microscopic heterogeneity and dynamics in choline chloride-based deep eutectic solvents. Nat Commun 2022; 13:219. [PMID: 35017478 PMCID: PMC8752670 DOI: 10.1038/s41467-021-27842-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/17/2021] [Indexed: 01/29/2023] Open
Abstract
Deep eutectic solvents (DESs) are an emerging class of non-aqueous solvents that are potentially scalable, easy to prepare and functionalize for many applications ranging from biomass processing to energy storage technologies. Predictive understanding of the fundamental correlations between local structure and macroscopic properties is needed to exploit the large design space and tunability of DESs for specific applications. Here, we employ a range of computational and experimental techniques that span length-scales from molecular to macroscopic and timescales from picoseconds to seconds to study the evolution of structure and dynamics in model DESs, namely Glyceline and Ethaline, starting from the parent compounds. We show that systematic addition of choline chloride leads to microscopic heterogeneities that alter the primary structural relaxation in glycerol and ethylene glycol and result in new dynamic modes that are strongly correlated to the macroscopic properties of the DES formed. Tailoring the macroscopic properties of deep eutectic solvents requires knowing how these depend on the local structure and microscopic dynamics. The authors, with computational and experimental tools spanning a wide range of space- and timescales, shed light into the relationship between micro and macroscopic properties in glyceline and ethaline.
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11
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Zhang X, Zhou S, Leonik FM, Wang L, Kuroda DG. Quantum mechanical effects in acid–base chemistry. Chem Sci 2022; 13:6998-7006. [PMID: 35774178 PMCID: PMC9200130 DOI: 10.1039/d2sc01784a] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/17/2022] [Indexed: 01/04/2023] Open
Abstract
Acid–base chemistry has immense importance for explaining and predicting the chemical products formed by an acid and a base when mixed together. However, the traditional chemistry theories used to describe acid–base reactions do not take into account the effect arising from the quantum mechanical nature of the acidic hydrogen shuttling potential and its dependence on the acid base distance. Here, infrared and NMR spectroscopies, in combination with first principles simulations, are performed to demonstrate that quantum mechanical effects, including electronic and nuclear quantum effects, play an essential role in defining the acid–base chemistry when 1-methylimidazole and acetic acid are mixed together. In particular, it is observed that the acid and the base interact to form a complex containing a strong hydrogen bond, in which the acidic hydrogen atom is neither close to the acid nor to the base, but delocalized between them. In addition, the delocalization of the acidic hydrogen atom in the complex leads to characteristic IR and NMR signatures. The presence of a hydrogen delocalized state in this simple system challenges the conventional knowledge of acid–base chemistry and opens up new avenues for designing materials in which specific properties produced by the hydrogen delocalized state can be harvested. Acid-based theories do not consider the quantum mechanical nature of the acidic hydrogen shuttling potential. Here, it is demonstrated that this particularity is needed to explain the formation acid-base complex with a delocalized acidic hydrogen.![]()
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Affiliation(s)
- Xiaoliu Zhang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Shengmin Zhou
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Fedra M. Leonik
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Lu Wang
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Daniel G. Kuroda
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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12
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Atsango AO, Tuckerman ME, Markland TE. Characterizing and Contrasting Structural Proton Transport Mechanisms in Azole Hydrogen Bond Networks Using Ab Initio Molecular Dynamics. J Phys Chem Lett 2021; 12:8749-8756. [PMID: 34478302 DOI: 10.1021/acs.jpclett.1c02266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Imidazole and 1,2,3-triazole are promising hydrogen-bonded heterocycles that conduct protons via a structural mechanism and whose derivatives are present in systems ranging from biological proton channels to proton exchange membrane fuel cells. Here, we leverage multiple time-stepping to perform ab initio molecular dynamics of imidazole and 1,2,3-triazole at the nanosecond time scale. We show that despite the close structural similarities of these compounds, their proton diffusion constants vary by over an order of magnitude. Our simulations reveal the reasons for these differences in diffusion constants, which range from the degree of hydrogen-bonded chain linearity to the effect of the central nitrogen atom in 1,2,3-triazole on proton transport. In particular, we uncover evidence of two "blocking" mechanisms in 1,2,3-triazole, where covalent and hydrogen bonds formed by the central nitrogen atom limit the mobility of protons. Our simulations thus provide insights into the origins of the experimentally observed 10-fold difference in proton conductivity.
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Affiliation(s)
- Austin O Atsango
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mark E Tuckerman
- Department of Chemistry, New York University, New York, New York 10003, United States
- Courant Institute of Mathematical Science, New York University, New York, New York 10012, United States
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshan Road North, Shanghai 200062, China
| | - Thomas E Markland
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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Batista PR, Penna TC, Ducati LC, Correra TC. p-Aminobenzoic acid protonation dynamics in an evaporating droplet by ab initio molecular dynamics. Phys Chem Chem Phys 2021; 23:19659-19672. [PMID: 34524295 DOI: 10.1039/d1cp01495a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protonation equilibria are known to vary from the bulk to microdroplet conditions, which could induce many chemical and physical phenomena. Protonated p-aminobenzoic acid (PABA + H+) can be considered a model for probing the protonation dynamics in an evaporating droplet, as its protonation equilibrium is highly dependent on the formation conditions from solution via atmospheric pressure ionization sources. Experiments using diverse experimental techniques have shown that protic solvents allow formation of the O-protomer (PABA protonated in the carboxylic acid group) stable in the gas phase, while aprotic solvents yield the N-protomer (protonated in the amino group) that is the most stable protomer in solution. In this work, we explore the protonation equilibrium of PABA solvated by different numbers of water molecules (n = 0 to 32) using ab initio molecular dynamics. For n = 8-32, the protonation is either at the NH2 group or in the solvent network. The solvent network interacts with the carboxylic acid group, but there is no complete proton transfer to form the O-protomer. For smaller clusters, however, solvent-mediated proton transfers to the carboxylic acid were observed, both via the Grotthuss mechanism and the vehicle or shuttle mechanism (for n = 1 and 2). Thermodynamic considerations allowed a description of the origins of the kinetic trapping effect, which explains the observation of the solution structure in the gas phase. This effect likely occurs in the final evaporation steps, which are outside the droplet size range covered by previous classical molecular dynamics simulations of charged droplets. These results may be considered relevant in determining the nature of the species observed in the ubiquitous ESI based mass spectrometry analysis, and in general for droplet chemistry, explaining how protonation equilibria are drastically changed from bulk to microdroplet conditions.
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Affiliation(s)
- Patrick R Batista
- Department of Fundamental Chemistry, Institute of Chemistry - University of São Paulo, Av. Prof. Lineu Prestes, 748, Cidade Universitária, São Paulo, SP, Brazil.
| | - Tatiana C Penna
- Department of Fundamental Chemistry, Institute of Chemistry - University of São Paulo, Av. Prof. Lineu Prestes, 748, Cidade Universitária, São Paulo, SP, Brazil.
| | - Lucas C Ducati
- Department of Fundamental Chemistry, Institute of Chemistry - University of São Paulo, Av. Prof. Lineu Prestes, 748, Cidade Universitária, São Paulo, SP, Brazil.
| | - Thiago C Correra
- Department of Fundamental Chemistry, Institute of Chemistry - University of São Paulo, Av. Prof. Lineu Prestes, 748, Cidade Universitária, São Paulo, SP, Brazil.
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Hori Y, Dekura S, Sunairi Y, Ida T, Mizuno M, Mori H, Shigeta Y. Proton Conduction Mechanism for Anhydrous Imidazolium Hydrogen Succinate Based on Local Structures and Molecular Dynamics. J Phys Chem Lett 2021; 12:5390-5394. [PMID: 34080418 DOI: 10.1021/acs.jpclett.1c01280] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Anhydrous organic crystalline materials incorporating imidazolium hydrogen succinate (Im-Suc), which exhibit high proton conduction even at temperatures above 100 °C, are attractive for elucidating proton conduction mechanisms toward the development of solid electrolytes for fuel cells. Herein, quantum chemical calculations were used to investigate the proton conduction mechanism in terms of hydrogen-bonding (H-bonding) changes and restricted molecular rotation in Im-Suc. The local H-bond structures for proton conduction were characterized by vibrational frequency analysis and compared with corresponding experimental data. The calculated potential energy surface involving proton transfer (PT) and imidazole (Im) rotational motion showed that PT between Im and succinic acid was a rate-limiting step for proton transport in Im-Suc and that proton conduction proceeded via the successive coupling of PT and Im rotational motion based on a Grotthuss-type mechanism. These findings provide molecular-level insights into proton conduction mechanisms for Im-based (or -incorporated) H-bonding organic proton conductors.
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Affiliation(s)
- Yuta Hori
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Shun Dekura
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yoshiya Sunairi
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tomonori Ida
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
| | - Motohiro Mizuno
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
- NanoMaterials Research Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Hatsumi Mori
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
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Cendagorta JR, Shen H, Bačić Z, Tuckerman ME. Enhanced Sampling Path Integral Methods Using Neural Network Potential Energy Surfaces with Application to Diffusion in Hydrogen Hydrates. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000258] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - Hengyuan Shen
- Department of Chemistry New York University Shanghai 1555 Century Avenue Pudong Shanghai 200122 China
| | - Zlatko Bačić
- Department of Chemistry New York University New York NY 10003 USA
- NYU‐ECNU Center for Computational Chemistry at NYU Shanghai 3663 Zhongshan Road, North Shanghai 200062 China
| | - Mark E. Tuckerman
- Department of Chemistry New York University New York NY 10003 USA
- NYU‐ECNU Center for Computational Chemistry at NYU Shanghai 3663 Zhongshan Road, North Shanghai 200062 China
- Courant Institute of Mathematical Sciences New York University New York NY 10012 USA
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Mukherji S, Avula NVS, Kumar R, Balasubramanian S. Hopping in High Concentration Electrolytes - Long Time Bulk and Single-Particle Signatures, Free Energy Barriers, and Structural Insights. J Phys Chem Lett 2020; 11:9613-9620. [PMID: 33125248 DOI: 10.1021/acs.jpclett.0c02995] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although ion-hopping is believed to be a significant mode of transport for small ions in liquid high concentration electrolytes (HCE), its bulk signatures over sufficiently long time intervals are yet to be shown. We computationally establish the long and short time imprints of hopping in HCEs using LiBF4-in-sulfolane mixtures as models. The high viscosity of this electrolyte leads to significant dynamic heterogeneity in Li-ion transport. Li-ions exhibit a preference to transit to previously occupied Li-ion-sites, bridged through anion or solvent molecules. Hopping in the liquid matrix was found to be an activated process, whose free energy barrier and transition state structure have been determined. Evidence for nanoscale compositional heterogeneity at high salt concentrations is also presented. The simulations shed light on the composition, stiffness, and lifetime of the solvation shell of Li ions. The understanding of HCEs gleaned from this study will spearhead the choice, engineering and applicability of this class of electrolytes.
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Affiliation(s)
- Srimayee Mukherji
- Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Nikhil V S Avula
- Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Rahul Kumar
- Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sundaram Balasubramanian
- Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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