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Nowok A, Hellwig H, Dulski M, Książek M, Kusz J, Kuś P, Pawlus S. Revisiting Dynamic Processes and Relaxation Mechanisms in a Heterocyclic Glass-Former: Direct Observation of a Transient State. J Phys Chem B 2024; 128:1915-1926. [PMID: 38379513 PMCID: PMC10910497 DOI: 10.1021/acs.jpcb.3c06727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/10/2024] [Accepted: 02/07/2024] [Indexed: 02/22/2024]
Abstract
Despite decades of studies, a clear understanding of near-Tg phenomena remains challenging for glass-forming systems. This review delves into the intricate molecular dynamics of the small, heterocyclic thioether, 6-methyl-2,3-dihydro-1,4-benzodithiine (MeBzS2), with a particular focus on its near-Tg cold crystallization and relaxation mechanisms. Investigating isothermal crystallization kinetics at various temperatures reveals a significant interplay between its molecular dynamics and recrystallization from a supercooled liquid. We also identify two independent interconversion paths between energetically privileged conformers, characterized by strained transition states. We demonstrate that these spatial transformations induce substantial alterations in the dipole moment orientation and magnitude. Our investigation also extends to the complex salt PdCl2(MeBzS2), where we observe the transient conformers directly, revealing a direct relationship between their abundance and the local or macroscopic electric field. The initially energetically privileged isomers in an undisturbed system become less favored in the presence of an external electric field or ions, resulting even in an unexpected inversion of states. Consequently, we confirm the intramolecular character of secondary relaxation in MeBzS2 and its mechanism related to conformational changes within the heterocyclic ring. The research is based on the combination of broadband dielectric spectroscopy, X-ray diffraction, and quantum density functional theory calculations.
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Affiliation(s)
- Andrzej Nowok
- Department
of Experimental Physics, Wrocław University
of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław 50-370, Poland
- Laboratoire
National des Champs Magnétiques Intenses, EMFL, CNRS UPR 3228,
Université Toulouse, Université
Toulouse 3, INSA-T, Toulouse 31400, France
| | - Hubert Hellwig
- Center
for Integrated Technology and Organic Synthesis (CiTOS), MolSys Research
Unit, University of Liège, B6a, Room 3/19, Allée Du
Six Août 13, Liège, Sart Tilman 4000, Belgium
| | - Mateusz Dulski
- Faculty
of Science and Technology, Institute of Materials Engineering, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - Maria Książek
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Joachim Kusz
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Piotr Kuś
- Institute
of Chemistry, University of Silesia in Katowice, Szkolna 9, Katowice 40-003, Poland
| | - Sebastian Pawlus
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
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2
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Streu K, Hunsberger S, Patel J, Wan X, Daly CA. Development of a universal method for vibrational analysis of the terminal alkyne C≡C stretch. J Chem Phys 2024; 160:074106. [PMID: 38364010 DOI: 10.1063/5.0185580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/07/2024] [Indexed: 02/18/2024] Open
Abstract
The terminal alkyne C≡C stretch has a large Raman scattering cross section in the "silent" region for biomolecules. This has led to many Raman tag and probe studies using this moiety to study biomolecular systems. A computational investigation of these systems is vital to aid in the interpretation of these results. In this work, we develop a method for computing terminal alkyne vibrational frequencies and isotropic transition polarizabilities that can easily and accurately be applied to any terminal alkyne molecule. We apply the discrete variable representation method to a localized version of the C≡C stretch normal mode. The errors of (1) vibrational localization to the terminal alkyne moiety, (2) anharmonic normal mode isolation, and (3) discretization of the Born-Oppenheimer potential energy surface are quantified and found to be generally small and cancel each other. This results in a method with low error compared to other anharmonic vibrational methods like second-order vibrational perturbation theory and to experiments. Several density functionals are tested using the method, and TPSS-D3, an inexpensive nonempirical density functional with dispersion corrections, is found to perform surprisingly well. Diffuse basis functions are found to be important for the accuracy of computed frequencies. Finally, the computation of vibrational properties like isotropic transition polarizabilities and the universality of the localized normal mode for terminal alkynes are demonstrated.
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Affiliation(s)
- Kristina Streu
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Sara Hunsberger
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Jeanette Patel
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Xiang Wan
- Department of Mathematics and Statistics, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, Illinois 60660, USA
| | - Clyde A Daly
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
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3
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Zhao Y, Bharadwaj S, Myers RL, Okur HI, Bui PT, Cao M, Welsh LK, Yang T, Cremer PS, van der Vegt NFA. Solvation Behavior of Elastin-like Polypeptides in Divalent Metal Salt Solutions. J Phys Chem Lett 2023; 14:10113-10118. [PMID: 37921693 DOI: 10.1021/acs.jpclett.3c02476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
The effects of CaCl2 and MgCl2 on the cloud point temperature of two different elastin-like polypeptides (ELPs) were studied using a combination of cloud point measurements, molecular dynamics simulations, and infrared spectroscopy. Changes in the cloud point for the ELPs in aqueous divalent metal cation solutions were primarily governed by two competing interactions: the cation-amide oxygen electrostatic interaction and the hydration of the cation. In particular, Ca2+ cations can more readily shed their hydration shells and directly contact two amide oxygens by the formation of ion bridges. By contrast, Mg2+ cations were more strongly hydrated and preferred to partition toward the amide oxygens along with their hydration shells. In fact, although hydrophilic ELP V5A2G3 was salted-out at low concentrations of MgCl2, it was salted-in at higher salt concentrations. By contrast, CaCl2 salted the ELP sharply out of solution at higher salt concentrations because of the bridging effect.
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Affiliation(s)
- Yani Zhao
- Department of Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Swaminath Bharadwaj
- Department of Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
- Department of Chemical Engineering, Shiv Nadar Institution of Eminence, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Ryan L Myers
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Halil I Okur
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Pho T Bui
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Mengrui Cao
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Lauren K Welsh
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Tinglu Yang
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Paul S Cremer
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802, United States
| | - Nico F A van der Vegt
- Department of Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
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4
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Mohamed A, Edington SC, Secor M, Breton JR, Hammes-Schiffer S, Johnson MA. Spectroscopic Characterization of the Divalent Metal Docking Motif to Isolated Cyanobenzoate: Direct Observation of Tridentate Binding to ortho-Cyanobenzoate and Implications for the CN Response. J Phys Chem A 2023; 127:1413-1421. [PMID: 36748882 DOI: 10.1021/acs.jpca.2c07658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cryogenic ion vibrational spectra of D2-tagged cyanobenzoate (CBA) derivatives are obtained and analyzed to characterize the intrinsic spectroscopic responses of the -CO2- headgroup to its location on the ring in both the isolated anions and the cationic complexes with divalent metal ions, M2+ (M = Mg, Ca, Sr). The benzonitrile functionality establishes the different ring isomers (para, meta, ortho) according to the location of the carboxylate and provides an additional reporter on the molecular response to the proximal charge center. The aromatic carboxylates display shifts slightly smaller than those observed for a related aliphatic system upon metal ion complexation. Although the CBA anions display very similar band patterns for all three ring positions, upon complexation with metal ions, the ortho isomer yields dramatically different spectral responses in both the -CO2- moiety and the CN group. This behavior is traced to the emergence of a tridentate binding motif unique to the ortho isomer in which the metal ions bind to both the oxygen atoms of the carboxylate group and the N atom of the cyano group. In that configuration, the -CO2- moiety is oriented perpendicular to the phenyl ring, and the CN stretching fundamental is both strong and red-shifted relative to its behavior in the isolated neutral. The behaviors of the metal-bound ortho complexes occur in contrast to the usual blue shifts associated with "Lewis" type binding of metal ions end-on to -CN. The origins of these spectroscopic features are analyzed with the aid of electronic structure calculations, which also explore differences expected for complexation of monovalent cations to the ortho carboxylate. The resulting insights have implications for understanding the balance between electrostatic and steric interactions at metal binding sites in chemical and biological systems.
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Affiliation(s)
- Ahmed Mohamed
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
| | - Sean C Edington
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
| | - Maxim Secor
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
| | - James R Breton
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
| | - Sharon Hammes-Schiffer
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
| | - Mark A Johnson
- Sterling Chemistry Laboratory Department of Chemistry, Yale University, New Haven, Connecticut 06512, United States
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5
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Krevert CS, Gunkel L, Haese C, Hunger J. Ion-specific binding of cations to the carboxylate and of anions to the amide of alanylalanine. Commun Chem 2022; 5:173. [PMID: 36697920 PMCID: PMC9814750 DOI: 10.1038/s42004-022-00789-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 11/30/2022] [Indexed: 12/24/2022] Open
Abstract
Studies of ion-specific effects on oligopeptides have aided our understanding of Hofmeister effects on proteins, yet the use of different model peptides and different experimental sensitivities have led to conflicting conclusions. To resolve these controversies, we study a small model peptide, L-Alanyl-L-alanine (2Ala), carrying all fundamental chemical protein motifs: C-terminus, amide bond, and N-terminus. We elucidate the effect of GdmCl, LiCl, KCl, KI, and KSCN by combining dielectric relaxation, nuclear magnetic resonance (1H-NMR), and (two-dimensional) infrared spectroscopy. Our dielectric results show that all ions reduce the rotational mobility of 2Ala, yet the magnitude of the reduction is larger for denaturing cations than for anions. The NMR chemical shifts of the amide group are particularly sensitive to denaturing anions, indicative of anion-amide interactions. Infrared experiments reveal that LiCl alters the spectral homogeneity and dynamics of the carboxylate, but not the amide group. Interaction of LiCl with the negatively charged pole of 2Ala, the COO- group, can explain the marked cationic effect on dipolar rotation, while interaction of anions between the poles, at the amide, only weakly perturbs dipolar dynamics. As such, our results provide a unifying view on ions' preferential interaction sites at 2Ala and help rationalize Hofmeister effects on proteins.
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Affiliation(s)
- Carola Sophie Krevert
- grid.419547.a0000 0001 1010 1663Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Lucas Gunkel
- grid.419547.a0000 0001 1010 1663Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Constantin Haese
- grid.419547.a0000 0001 1010 1663Department of Molecular Electronics, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Johannes Hunger
- grid.419547.a0000 0001 1010 1663Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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6
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Zhu Q, Murphy CJ, Baker LR. Opportunities for Electrocatalytic CO 2 Reduction Enabled by Surface Ligands. J Am Chem Soc 2022; 144:2829-2840. [PMID: 35137579 DOI: 10.1021/jacs.1c11500] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To achieve high selectivity in enzyme catalysis, nature carefully controls both the catalyst active site and the pocket or environment that mediates access and the geometry of a reactant. Despite the many advantages of heterogeneous catalysis, active sites on a surface are rarely defined with atomic precision, making it difficult to control reaction selectivity with the molecular precision of homogeneous systems. In colloidal nanoparticle synthesis, structural control is accomplished using a surface ligand or capping layer that stabilizes a specific particle morphology and prevents nanoparticle aggregation. Usually, these surface ligands are considered detrimental for catalysis because they occupy otherwise active surface sites. However, a number of examples have shown that surface ligands can play a beneficial role in defining the catalytic environment and enhancing performance by a variety of mechanisms. This perspective summarizes recent advances and opportunities using surface ligands to enhance the performance of nanocatalysts for electrochemical CO2 reduction. Several mechanisms are discussed, including selective permeability, modulating interfacial solvation structure and electric fields, chemical activation, and templating active site selection. These examples inform strategies and point to emerging opportunities to design nanocatalysts toward molecular level control of electrochemical CO2 conversion.
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Affiliation(s)
- Quansong Zhu
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Catherine J Murphy
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - L Robert Baker
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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7
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Bredt AJ, Kim Y, Mendes de Oliveira D, Urbina AS, Slipchenko LV, Ben-Amotz D. Expulsion of Hydroxide Ions from Methyl Hydration Shells. J Phys Chem B 2022; 126:869-877. [PMID: 35077175 DOI: 10.1021/acs.jpcb.1c08420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The affinity of hydroxide ions for methyl hydration shells is assessed using a combined experimental and theoretical analysis of tert-butyl alcohol (TBA) dissolved in pure water and aqueous NaOH and NaI. The experimental results are obtained using Raman multivariate curve resolution (Raman-MCR) and a new three-component total least squares (Raman-TLS) spectral decomposition strategy used to highlight vibrational perturbations resulting from interactions between TBA and aqueous ions. The experiments are interpreted and extended with the aid of effective fragment potential molecular dynamics (EFP-MD) simulations, as well as Kirkwood-Buff calculations and octanol/water partition measurements, to relate TBA-ion distribution functions to TBA solubility changes. The combined experimental and simulation results reveal that methyl group hydration shells more strongly expel hydroxide than iodide anions, whose populations near the methyl groups of TBA are predicted to be correlated with sodium counterion localization near the TBA hydroxyl group.
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Affiliation(s)
- Aria J Bredt
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yongbin Kim
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | | | - Andres S Urbina
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lyudmila V Slipchenko
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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8
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Bofill JM, Quapp W, Albareda G, Moreira IDPR, Ribas-Ariño J. Controlling Chemical Reactivity with Optimally Oriented Electric Fields: A Generalization of the Newton Trajectory Method. J Chem Theory Comput 2022; 18:935-952. [PMID: 35044173 DOI: 10.1021/acs.jctc.1c00943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of oriented external electric fields (OEEF) as a tool to accelerate chemical reactions has recently attracted much interest. A new model to calculate the optimal OEEF of the least intensity to induce a barrierless chemical reaction path is presented. A suitable ansatz is provided by defining an effective potential energy surface (PES), which considers the unperturbed or original PES of the molecular reactive system and the action of a constant OEEF on the overall dipole moment of system. Based on a generalization of the Newton Trajectories (NT) method, it is demonstrated that the optimal OEEF can be determined upon locating a special point of the potential energy surface (PES), the so-called "optimal bond-breaking point" (optimal BBP), for which two different algorithms are proposed. At this point, the gradient of the original or unperturbed PES is an eigenvector of zero eigenvalue of the Hessian matrix of the effective PES. A thorough discussion of the geometrical aspects of the optimal BBP and the optimal OEEF is provided using a two-dimensional model, and numerical calculations of the optimal OEEF for a SN2 reaction and the 1,3-dipolar retrocycloaddition of isoxazole to fulminic acid plus acetylene reaction serve as a proof of concept. The knowledge of the orientation of optimal OEEF provides a practical way to reduce the effective barrier of a given chemical process.
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Affiliation(s)
- Josep Maria Bofill
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.,Institut de Química Teòrica i Computacional, (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
| | - Wolfgang Quapp
- Mathematisches Institut, Universität Leipzig, PF 100920, D-04009 Leipzig, Germany
| | - Guillermo Albareda
- Institut de Química Teòrica i Computacional, (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.,Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Ibério de P R Moreira
- Institut de Química Teòrica i Computacional, (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.,Departament de Ciència de Materials i Química Física, Secció de Química Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
| | - Jordi Ribas-Ariño
- Institut de Química Teòrica i Computacional, (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.,Departament de Ciència de Materials i Química Física, Secció de Química Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
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