1
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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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2
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Yan S, Wang B, Lin H. Tracking the Delocalized Proton in Concerted Proton Transfer in Bulk Water. J Chem Theory Comput 2023; 19:448-459. [PMID: 36630655 DOI: 10.1021/acs.jctc.2c01097] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A solvated proton in water is often characterized as a charge or structural defect, and it is important to track its evolution on-the-fly in certain dynamics simulations. Previously, we introduced the proton indicator, a pseudo-atom, whose position approximates the location of the excess proton modeled as a structural defect. The proton indicator generally yields a smooth trajectory of a hydrated proton diffusing in aqueous solutions, including in the events of stepwise proton transfer via the Grotthuss mechanism; however, the proton indicator did not perform well in the events of concerted proton transfer, for which it occasionally yielded large position displacements between two successive time steps. To overcome this hurdle, we develop a new algorithm of a proton indicator with greatly enhanced performance for concerted proton transfer in bulk water. A protocol is proposed to exhaustively explore the hydrogen-bonding network of the water wires over which the excess proton is delocalized and to properly account for the contributions of the water molecules in this network as the geometry evolves. The new proton indicator (called Indicator 2.0) is assessed in dynamics simulations of an excess proton in bulk water and in specially constructed model systems of more complex architectures. The results demonstrate that the new indicator yields a smooth trajectory in both stepwise and concerted proton transfers.
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Affiliation(s)
- Shengheng Yan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen360015P. R. China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen360015P. R. China
| | - Hai Lin
- Department of Chemistry, CB 194, University of Colorado Denver, P.O. Box 173364, Denver, Colorado80217, United States
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3
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Nachliel E, Gutman M. Reaction within the coulomb-cage; science in retrospect. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184071. [PMID: 36244436 DOI: 10.1016/j.bbamem.2022.184071] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 08/01/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
The Coulomb-cage is defined as the space where the electrostatic interaction between two bodies is more intensive than the thermal energy (kBT). For small molecule, the Coulomb-cage is a small sphere, extending only few water molecules towards the bulk and its radius is sensitive to the ionic strength of the solution. For charged proteins or membranal structures, the Coulomb-cage can engulf large fraction of the surface and provides a preferred pathway for ion propagation along the surface. Similarly, electrostatic potential at the inner space of a channel can form preferential trajectories passage for ions. The dynamics of ions inside the Coulomb-cage of ions was formulated by the studies of proton-anion recombination of excited photoacids. In the present article, we recount the study of intra- Coulomb-cage reaction taking place on the surface of macro-molecular bodies like micelles, membranes, proteins and intra-protein cavities. The study progressed stepwise, tracing the dynamics of a proton ejected from a photo-acid molecule located at defined sites (on membrane, inter-membrane space, active site of enzyme, inside Large Pore Channels etc.). Accumulation of experimental observations encouraged us to study of the reaction mechanism by molecular dynamics simulations of ions within the Coulomb-cage of proteins surface or inside large pores. The intra-Coulomb-cage proton transfer events follows closely the fine structure of the electrostatic field inside the cage and reflects the shape of nearby dielectric boundaries, the temporal ordering of the solvent molecules and the structural fluctuations of the charged side chains. The article sums some 40 years of research, which in retrospect clarifies the intra-Coulomb-cage reaction mechanism.
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Affiliation(s)
- E Nachliel
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel
| | - M Gutman
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel.
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4
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Ekimova M, Hoffmann F, Bekçioğlu-Neff G, Rafferty A, Kornilov O, Nibbering ETJ, Sebastiani D. Ultrafast Proton Transport between a Hydroxy Acid and a Nitrogen Base along Solvent Bridges Governed by the Hydroxide/Methoxide Transfer Mechanism. J Am Chem Soc 2019; 141:14581-14592. [PMID: 31446754 PMCID: PMC8168916 DOI: 10.1021/jacs.9b03471] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Aqueous
proton transport plays a key role in acid–base neutralization
and energy transport through biological membranes and hydrogen fuel
cells. Extensive experimental and theoretical studies have resulted
in a highly detailed elucidation of one of the underlying microscopic
mechanisms for aqueous excess proton transport, known as the von Grotthuss
mechanism, involving different hydrated proton configurations with
associated high fluxional structural dynamics. Hydroxide transport,
with approximately 2-fold-lower bulk diffusion rates compared to those
of excess protons, has received much less attention. We present femtosecond
UV/IR pump–probe experiments and ab initio molecular dynamics
simulations of different proton transport pathways of bifunctional
photoacid 7-hydroxyquinoline (7HQ) in water/methanol mixtures. For
7HQ solvent-dependent photoacidity, free-energy–reactivity
correlation behavior and quantum mechanics/molecular mechanics (QM/MM)
trajectories point to a dominant OH–/CH3O– transport pathway for all water/methanol mixing
ratios investigated. Our joint ultrafast infrared spectroscopic and
ab initio molecular dynamics study provides conclusive evidence for
the hydrolysis/methanolysis acid–base neutralization pathway,
as formulated by Manfred Eigen half a century ago. Our findings on
the distinctly different acid–base reactivities for aromatic
hydroxyl and aromatic nitrogen functionalities suggest the usefulness
of further exploration of these free-energy–reactivity correlations
as a function of solvent polarity. Ultimately the determination of
solvent-dependent acidities will contribute to a better understanding
of proton-transport mechanisms at weakly polar surfaces and near polar
or ionic regions in transmembrane proton pump proteins or hydrogen
fuel cell materials.
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Affiliation(s)
- Maria Ekimova
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Felix Hoffmann
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
| | - Gül Bekçioğlu-Neff
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
| | - Aidan Rafferty
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Daniel Sebastiani
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
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5
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Zhao P, Cui H, Zhang Y, Zhang Y, Wang Y, Zhang Y, Xie Y, Yi W. Synergetic Effect of Brønsted/Lewis Acid Sites and Water on the Catalytic Dehydration of Glucose to 5-Hydroxymethylfurfural by Heteropolyacid-Based Ionic Hybrids. ChemistryOpen 2018; 7:824-832. [PMID: 30338206 PMCID: PMC6182251 DOI: 10.1002/open.201800138] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/14/2018] [Indexed: 11/11/2022] Open
Abstract
The effective dehydration of glucose to 5-hydroxymethylfurfural (HMF) has attracted increasing attention. Herein, a series of sulfonic-acid-functionalized ionic liquid (IL)-heteropolyacid (HPA) hybrid catalysts are proposed for the conversion of glucose to HMF. A maximum total yield of HMF and levoglucosan (LGA; ≈71 %) was achieved in the presence of pyrazine IL-HPA hybrid catalyst [PzS]H2PW in THF/H2O-NaCl (v/v 5:1). The mechanism of glucose dehydration was studied by tailoring the Brønsted/Lewis acid sites of the hybrid catalysts and altering the solvent composition. It was found that water and heteropolyanions have a significant effect on the reaction kinetics. Heteropolyanions are able to stabilize the intermediates and promote the direct dehydration of glucose and intermediate LGA to HMF. A small amount of water could facilitate the conversion of glucose to LGA and suppress the dehydration of LGA to levoglucosenone. In addition, the synergetic effect of Brønsted/Lewis acid sites and a little water was conducive to accelerated proton transfer, which improved the yield of HMF from glucose dehydration.
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Affiliation(s)
- Pingping Zhao
- College of Chemical and Environmental EngineeringShandong University of Science and TechnologyQingdao266590China
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Hongyou Cui
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Yunyun Zhang
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Yuan Zhang
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Yong Wang
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Yali Zhang
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Yujiao Xie
- School of Chemical EngineeringShandong University of TechnologyZibo255000China
| | - Weiming Yi
- School of Agricultural Engineering and Food ScienceShandong University of TechnologyZibo255000China
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6
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Hohenstein EG. Mechanism for the Enhanced Excited-State Lewis Acidity of Methyl Viologen. J Am Chem Soc 2016; 138:1868-76. [DOI: 10.1021/jacs.5b08177] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Edward G. Hohenstein
- Department
of Chemistry and Biochemistry, The City College of New York, New York, New York 10031, United States
- Ph.D.
Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
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7
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Solntsev KM, Popov AV, Solovyeva VA, Al-Ainain SA, Il’ichev YV, Hernandez R, Kuzmin MG. Kinetics of intra- and intermolecular excited-state proton transfer ofω-(2-hydroxynaphthyl-1)-decanoic acid in homogeneous and micellar solutions. Methods Appl Fluoresc 2015. [DOI: 10.1088/2050-6120/4/1/014001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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8
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Cuny J, Hassanali AA. Ab Initio Molecular Dynamics Study of the Mechanism of Proton Recombination with a Weak Base. J Phys Chem B 2014; 118:13903-12. [DOI: 10.1021/jp507246e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jérôme Cuny
- Laboratoire
de Chimie et Physique Quantiques (LCPQ), Université de Toulouse III [UPS] and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
- Department
of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich and Università della Svizzera Italiana, CH-6900 Lugano, Switzerland
| | - Ali A. Hassanali
- Condensed
Matter Physics Section, The Abdus Salaam International Center for Theoretical Physics, Strada Costiera 11, Trieste I-34151, Italy
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9
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Rivard U, Thomas V, Bruhacs A, Siwick B, Iftimie R. Donor-Bridge-Acceptor Proton Transfer in Aqueous Solution. J Phys Chem Lett 2014; 5:3200-3205. [PMID: 26276332 DOI: 10.1021/jz501378d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use ab initio molecular dynamics to study proton transfer in a donor-bridge-acceptor system in which the bridge is a single water molecule and the entire system is embedded in aqueous solution. The results, based on a large number of proton transfer trajectories, demonstrate that the dominant charge-transfer pathway is a subpicosecond "through bridge" event in which the bridge adopts an Eigen-like (hydronium) structure. We also identify another state in which the bridge forms a Zundel-like configuration with the acceptor that appears to be a dead end for the charge transfer. The reaction coordinate is inherently multidimensional and, as we demonstrate, cannot be given in terms of either local structural parameters of the donor-bridge-acceptor system or local solvent coordination numbers.
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Affiliation(s)
- Ugo Rivard
- †Département de Chimie, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal H3C3J7, Canada
| | - Vibin Thomas
- †Département de Chimie, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal H3C3J7, Canada
| | - Andrew Bruhacs
- ‡Departments of Chemistry and Physics, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montréal H3A2K6, Canada
| | - Bradley Siwick
- ‡Departments of Chemistry and Physics, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montréal H3A2K6, Canada
| | - Radu Iftimie
- †Département de Chimie, Université de Montréal, CP 6128, succursale Centre-Ville, Montréal H3C3J7, Canada
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10
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Nelson JG, Peng Y, Silverstein DW, Swanson JMJ. Multiscale Reactive Molecular Dynamics for Absolute p Ka Predictions and Amino Acid Deprotonation. J Chem Theory Comput 2014; 10:2729-2737. [PMID: 25061442 PMCID: PMC4095931 DOI: 10.1021/ct500250f] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Indexed: 01/16/2023]
Abstract
Accurately calculating a weak acid's pKa from simulations remains a challenging task. We report a multiscale theoretical approach to calculate the free energy profile for acid ionization, resulting in accurate absolute pKa values in addition to insights into the underlying mechanism. Importantly, our approach minimizes empiricism by mapping electronic structure data (QM/MM forces) into a reactive molecular dynamics model capable of extensive sampling. Consequently, the bulk property of interest (the absolute pKa) is the natural consequence of the model, not a parameter used to fit it. This approach is applied to create reactive models of aspartic and glutamic acids. We show that these models predict the correct pKa values and provide ample statistics to probe the molecular mechanism of dissociation. This analysis shows changes in the solvation structure and Zundel-dominated transitions between the protonated acid, contact ion pair, and bulk solvated excess proton.
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Affiliation(s)
- J Gard Nelson
- Department of Chemistry, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago , 5735 S. Ellis Ave., Chicago, Illinois 60637, United States
| | - Yuxing Peng
- Department of Chemistry, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago , 5735 S. Ellis Ave., Chicago, Illinois 60637, United States
| | - Daniel W Silverstein
- Department of Chemistry, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago , 5735 S. Ellis Ave., Chicago, Illinois 60637, United States
| | - Jessica M J Swanson
- Department of Chemistry, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago , 5735 S. Ellis Ave., Chicago, Illinois 60637, United States
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11
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Iftimie R, Tremblay MH, Thomas V, Hétu S, de Lasalle F, Rivard U. Moderately strong phenols dissociate by forming an ion-pair kinetic intermediate. J Phys Chem A 2013; 117:13976-87. [PMID: 24299203 DOI: 10.1021/jp410858d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We show computational evidence that ground-state moderately strong hydroxyarenes (Ar-OH, pKa ∼ 0) dissociate by forming an ion-pair intermediate that lives for 3-5 ps. The concentration of this intermediate is approximately 2 times smaller than that of the un-ionized acid at pH ∼ 0.6 and is characterized by average C-O bond lengths (1.30 Å) that are intermediate between those of un-ionized (1.29 Å) and fully dissociated (1.34 Å) species. During the lifetime of the ion-pair intermediate the excess proton fluctuates between the oxygen atom of the phenolic moiety and those of water molecules in the first and second solvation shells on a subpicosecond time scale (∼100-300 fs).
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Affiliation(s)
- Radu Iftimie
- Département de Chimie, Université de Montréal , CP 6128, succursale Centre-Ville, Montréal H3C3J7, Canada
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