1
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Gousseva E, Towers Tompkins FK, Seymour JM, Parker LG, Clarke CJ, Palgrave RG, Bennett RA, Grau-Crespo R, Lovelock KRJ. Anion-Dependent Strength Scale of Interactions in Ionic Liquids from X-ray Photoelectron Spectroscopy, Ab Initio Molecular Dynamics, and Density Functional Theory. J Phys Chem B 2024; 128:5030-5043. [PMID: 38727250 PMCID: PMC11129296 DOI: 10.1021/acs.jpcb.4c00362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/24/2024]
Abstract
Using a combination of experiments and calculations, we have gained new insights into the nature of anion-cation interactions in ionic liquids (ILs). An X-ray photoelectron spectroscopy (XPS)-derived anion-dependent electrostatic interaction strength scale, determined using XPS core-level binding energies for IL cations, is presented here for 39 different anions, with at least 18 new anions included. Linear correlations of experimental XPS core-level binding energies for IL cations with (a) calculated core binding energies (ab initio molecular dynamics (AIMD) simulations were used to generate high-quality model IL structures followed by single-point density functional theory (DFT) to obtain calculated core binding energies), (b) experimental XPS core-level binding energies for IL anions, and (c) other anion-dependent interaction strength scales led to three main conclusions. First, the effect of different anions on the cation can be related to ground-state interactions. Second, the variations of anion-dependent interactions with the identity of the anion are best rationalized in terms of electrostatic interactions and not occupied valence state/unoccupied valence state interactions or polarizability-driven interactions. Therefore, the XPS-derived anion-dependent interaction strength scale can be explained using a simple electrostatic model based on electrostatic site potentials. Third, anion-probe interactions, irrespective of the identity of the probe, are primarily electrostatic, meaning that our electrostatic interaction strength scale captures some inherent, intrinsic property of anions independent of the probe used to measure the interaction strength scale.
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Affiliation(s)
| | | | - Jake M. Seymour
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
| | - Lewis G. Parker
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
| | - Coby J. Clarke
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Robert G. Palgrave
- Department
of Chemistry, University College London, London WC1H 0AJ, U.K.
| | - Roger A. Bennett
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
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2
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Li M, Zhu H, Adorinni S, Xue W, Heard A, Garcia AM, Kralj S, Nitschke JR, Marchesan S. Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages. Angew Chem Int Ed Engl 2024:e202406909. [PMID: 38701043 DOI: 10.1002/anie.202406909] [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: 04/11/2024] [Revised: 05/03/2024] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
We report a series of coordination cages that incorporate peptide chains at their vertices, prepared through subcomponent self-assembly. Three distinct heterochiral tripeptide subcomponents were incorporated, each exhibiting an L-D-L stereoconfiguration. Through this approach, we prepared and characterized three tetrahedral metal-peptide cages that incorporate thiol and methylthio groups. The gelation of these cages was probed through the binding of additional metal ions, with the metal-peptide cages acting as junctions, owing to the presence of sulfur atoms on the peripheral peptides. Gels were obtained with cages bearing cysteine at the C-terminus. Our strategy for developing functional metal-coordinated supramolecular gels with a modular design may result in the development of materials useful for chemical separations or drug delivery.
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Affiliation(s)
- Meng Li
- Department of Environmental Science and Engineering, North China Electric Power University, 689 Huadian Road, Baoding, 071003, P. R. China
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Chemical & Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127, Trieste, Italy
| | - Huangtianzhi Zhu
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Simone Adorinni
- Department of Chemical & Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127, Trieste, Italy
| | - Weichao Xue
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Andrew Heard
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Ana M Garcia
- Department of Chemical & Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127, Trieste, Italy
| | - Slavko Kralj
- Materials Synthesis Department, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
- Pharmaceutical Technology Department - Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Jonathan R Nitschke
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Silvia Marchesan
- Department of Chemical & Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127, Trieste, Italy
- INSTM, Unit of Trieste, 34127, Trieste, Italy
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3
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Siami H, Razmkhah M, Moosavi F. Cation functional group effect on SO 2 absorption in amino acid ionic liquids. Front Chem 2023; 11:1113394. [PMID: 36817168 PMCID: PMC9932779 DOI: 10.3389/fchem.2023.1113394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/19/2023] [Indexed: 02/05/2023] Open
Abstract
Introduction: The effect of the functional group of the cation on SO2 acidic gas absorption by some designed amino acid ionic liquids (AAILs) was studied. Methods: An isolated pair of glycinate anion and pristine imidazolium-based cation, as well as decorated cation functionalized by hydroxyl (OH), amine (NH2), carboxylic acid (COOH), methoxy (OCH3), and acetate (CH3COO) groups, were structurally optimized by density functional theory (DFT) using split-valence triple-zeta Pople basis set. Results and Discussion: The binding and Gibbs free energy (ΔGint) values of SO2 absorption show the AAIL functionalized by the COOH group is the most thermodynamically favorable green solvent and this functional group experiences the closest distance between anion and captured SO2 and vice versa in the case of cation … SO2 which may be the main reason for being the best absorbent; in addition, the highest net charge-transfer amount of SO2 is observed. Comparing the non-covalent interaction of the systems demonstrates that the strongest hydrogen bond between captured gas and anion, as well as π-hole, and van der Waals (vdW) interaction play critical roles in gas absorption; besides, the COOH functional group decreases the steric effect while the CH3COO functional group significantly increases steric effect after absorption that declines the hydrogen bond.
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Affiliation(s)
- Hasan Siami
- Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mohammad Razmkhah
- Salim Green Health R&D, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Fatemeh Moosavi
- Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, Iran,*Correspondence: Fatemeh Moosavi,
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4
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Gousseva E, Midgley SD, Seymour JM, Seidel R, Grau-Crespo R, Lovelock KRJ. Understanding X-ray Photoelectron Spectra of Ionic Liquids: Experiments and Simulations of 1-Butyl-3-methylimidazolium Thiocyanate. J Phys Chem B 2022; 126:10500-10509. [PMID: 36455069 PMCID: PMC9761679 DOI: 10.1021/acs.jpcb.2c06372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
We demonstrate a combined experimental and computational approach to probe the electronic structure and atomic environment of an ionic liquid, based on core level binding energies. The 1-butyl-3-methylimidazolium thiocyanate [C4C1Im][SCN] ionic liquid was studied using ab initio molecular dynamics, and results were compared against previously published and new experimental X-ray photoelectron spectroscopy (XPS) data. The long-held assumption that initial-state effects in XPS dominate the measured binding energies is proven correct, which validates the established premise that the ground state electronic structure of the ionic liquid can be inferred directly from XPS measurements. A regression model based upon site electrostatic potentials and intramolecular bond lengths is shown to account accurately for variations in core-level binding energies within the ionic liquid, demonstrating the important effect of long-range interactions on the core levels and throwing into question the validity of traditional single ion pair ionic liquid calculations for interpreting XPS data.
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Affiliation(s)
| | - Scott D. Midgley
- Department
of Chemistry, University of Reading, ReadingRG6 6DX, U.K.
| | - Jake M. Seymour
- Department
of Chemistry, University of Reading, ReadingRG6 6DX, U.K.
| | - Robert Seidel
- Helmholtz-Zentrum
Berlin für Materialien und Energie (HZB), Berlin14109, Germany
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5
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Massicot S, Sasaki T, Lexow M, Maier F, Kuwabata S, Steinrück H. On‐Surface Metathesis of an Ionic Liquid on Ag(111). Chemistry 2022; 28:e202200167. [PMID: 35363397 PMCID: PMC9321566 DOI: 10.1002/chem.202200167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 11/17/2022]
Abstract
We investigated the adsorption, surface enrichment, ion exchange, and on‐surface metathesis of ultrathin mixed IL films on Ag(111). We stepwise deposited 0.5 ML of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) and 1.0 ML of the aprotic IL 1‐methyl‐3‐octylimidazolium hexafluorophosphate ([C8C1Im][PF6]) at around 90 K. Thereafter, the resulting layered frozen film was heated to 550 K, and the thermally induced phenomena were monitored in situ by angle‐resolved X‐ray photoelectron spectroscopy. Between 135 and 200 K, [TfO]− anions at the Ag(111) surface are exchanged by [PF6]− anions and enriched together with [C8C1Im]+ cations at the IL/vacuum interface. Upon further heating, [dema][PF6] and [OMIm][PF6] desorb selectively at ∼235 and ∼380 K, respectively. Hereby, a wetting layer of pure [C8C1Im][TfO] is formed by on‐surface metathesis at the IL/metal interface, which completely desorbs at ∼480 K. For comparison, ion enrichment at the vacuum/IL interface was also studied in macroscopic IL mixtures, where no influence of the solid support is expected.
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Affiliation(s)
- Stephen Massicot
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Tomoya Sasaki
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamada-oka 2–1, Suita Osaka 565-0871 Japan
| | - Matthias Lexow
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Susumu Kuwabata
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamada-oka 2–1, Suita Osaka 565-0871 Japan
| | - Hans‐Peter Steinrück
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
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6
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Philippi F, Goloviznina K, Gong Z, Gehrke S, Kirchner B, Pádua AAH, Hunt PA. Charge transfer and polarisability in ionic liquids: a case study. Phys Chem Chem Phys 2022; 24:3144-3162. [PMID: 35040843 DOI: 10.1039/d1cp04592j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The practical use of ionic liquids (ILs) is benefiting from a growing understanding of the underpinning structural and dynamic properties, facilitated through classical molecular dynamics (MD) simulations. The predictive and explanatory power of a classical MD simulation is inextricably linked to the underlying force field. A key aspect of the forcefield for ILs is the ability to recover charge based interactions. Our focus in this paper is on the description and recovery of charge transfer and polarisability effects, demonstrated through MD simulations of the widely used 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4C1im][NTf2] IL. We study the charge distributions generated by a range of ab initio methods, and present an interpolation method for determining atom-wise scaled partial charges. Two novel methods for determining the mean field (total) charge transfer from anion to cation are presented. The impact of using different charge models and different partial charge scaling (unscaled, uniformly scaled, atom-wise scaled) are compared to fully polarisable simulations. We study a range of Drude particle explicitly polarisable potentials and shed light on the performance of current approaches to counter known problems. It is demonstrated that small changes in the charge description and MD methodology can have a significant impact; biasing some properties, while leaving others unaffected within the structural and dynamic domains.
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Affiliation(s)
- Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK
| | - Kateryna Goloviznina
- Laboratoire de Chimie, École Normale Supérieure de Lyon & CNRS, 69364 Lyon, France
| | - Zheng Gong
- Laboratoire de Chimie, École Normale Supérieure de Lyon & CNRS, 69364 Lyon, France
| | - Sascha Gehrke
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, D-53115 Bonn, Germany.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Agílio A H Pádua
- Laboratoire de Chimie, École Normale Supérieure de Lyon & CNRS, 69364 Lyon, France
| | - Patricia A Hunt
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.,School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand.
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7
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Massicot S, Sasaki T, Lexow M, Shin S, Maier F, Kuwabata S, Steinrück HP. Adsorption, Wetting, Growth, and Thermal Stability of the Protic Ionic Liquid Diethylmethylammonium Trifluoromethanesulfonate on Ag(111) and Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11552-11560. [PMID: 34569794 PMCID: PMC8495895 DOI: 10.1021/acs.langmuir.1c01823] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Indexed: 06/13/2023]
Abstract
We have studied the adsorption, wetting, growth, and thermal evolution of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) on Au(111) and Ag(111). Ultrathin films were deposited at room temperature (RT) and at 90 K, and were characterized in situ by angle-resolved X-ray photoelectron spectroscopy. For both surfaces, we observe that independent of temperature, initially, a closed 2D wetting layer forms. While the film thickness does not increase past this wetting layer at RT, at 200 K and below, "moderate" 3D island growth occurs on top of the wetting layer. Upon heating, on Au(111), the [dema][TfO] multilayers desorb at 292 K, leaving an intact [dema][TfO] wetting layer, which desorbs intact at 348 K. The behavior on Ag(111) is much more complex. Upon heating [dema][TfO] deposited at 90 K, the [dema]+ cations deprotonate in two steps at 185 and 305 K, yielding H[TfO] and volatile [dema]0. At 355 K, the formed H[TfO] wetting layer partly desorbs (∼50%) and partly decomposes to form an F-containing surface species, which is stable up to 570 K.
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Affiliation(s)
- Stephen Massicot
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Tomoya Sasaki
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan
| | - Matthias Lexow
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Sunghwan Shin
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Florian Maier
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Susumu Kuwabata
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan
| | - Hans-Peter Steinrück
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
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8
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Liu X, Turner CH. Computational study of the electrostatic potential and charges of multivalent ionic liquid molecules. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Seymour JM, Gousseva E, Large AI, Clarke CJ, Licence P, Fogarty RM, Duncan DA, Ferrer P, Venturini F, Bennett RA, Palgrave RG, Lovelock KRJ. Experimental measurement and prediction of ionic liquid ionisation energies. Phys Chem Chem Phys 2021; 23:20957-20973. [PMID: 34545382 DOI: 10.1039/d1cp02441h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquid (IL) valence electronic structure provides key descriptors for understanding and predicting IL properties. The ionisation energies of 60 ILs are measured and the most readily ionised valence state of each IL (the highest occupied molecular orbital, HOMO) is identified using a combination of X-ray photoelectron spectroscopy (XPS) and synchrotron resonant XPS. A structurally diverse range of cations and anions were studied. The cation gave rise to the HOMO for nine of the 60 ILs presented here, meaning it is energetically more favourable to remove an electron from the cation than the anion. The influence of the cation on the anion electronic structure (and vice versa) were established; the electrostatic effects are well understood and demonstrated to be consistently predictable. We used this knowledge to make predictions of both ionisation energy and HOMO identity for a further 516 ILs, providing a very valuable dataset for benchmarking electronic structure calculations and enabling the development of models linking experimental valence electronic structure descriptors to other IL properties, e.g. electrochemical stability. Furthermore, we provide design rules for the prediction of the electronic structure of ILs.
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Affiliation(s)
- Jake M Seymour
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK.
| | | | - Alexander I Large
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK. .,Diamond Light Source, Didcot, Oxfordshire, OX11 0DE, UK
| | - Coby J Clarke
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Peter Licence
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK
| | | | | | - Pilar Ferrer
- Diamond Light Source, Didcot, Oxfordshire, OX11 0DE, UK
| | | | - Roger A Bennett
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK.
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10
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Saranya V, Radhika R, Shankar R, Vijayakumar S. In silico studies of the inhibition mechanism of dengue with papain. J Biomol Struct Dyn 2020; 39:1912-1927. [PMID: 32249700 DOI: 10.1080/07391102.2020.1742205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Dengue virus is becoming a major global disease; the envelope protein is the major target for vaccine development against Dengue. Nowadays, the attention has focused on developing inhibitors based on Papain is a promising target for treating Dengue. In the present work, the theoretical studies of E-protein(Cys74-Glu79;Lys110)…Papain(Cys25, Asn175 and His159) complexes are analysed by Density Functional Theory (M06-2X/cc-pVDZ) method. Among the E-protein(Cys74-Glu79;Lys110)…Papain(Cys25, Asn175 and Hys159) complexes, E-protein(Glu76)…Papain(Cys25) complex has the highest interaction value of -352.22 kcal/mol. Moreover, the natural bond orbital analysis also supports the above results. The 100 ns Molecular Dynamics simulation reveals that, E-protein(Ala54-Ile129)…Papain(Cys25) complex had the lowest root mean square deviation value of 1 Å compared to the E-protein(Ala54-Ile129)… Papain(Asn175 & His159) complexes. The salt bridge formation between the Asp103 and Lys110 residues are the important stabilizing factor in E-protein(Ala54-Ile129)…Papain(Cys25) complex. This result can extend our knowledge of the functional behaviour of Papain and provides structural insight to target Envelope protein as forthcoming drug targets in Dengue.
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11
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Fogarty RM, Palgrave RG, Bourne RA, Handrup K, Villar-Garcia IJ, Payne DJ, Hunt PA, Lovelock KRJ. Electron spectroscopy of ionic liquids: experimental identification of atomic orbital contributions to valence electronic structure. Phys Chem Chem Phys 2019; 21:18893-18910. [PMID: 31441923 DOI: 10.1039/c9cp02200g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The atomic contributions to valence electronic structure for 37 ionic liquids (ILs) are identified using a combination of variable photon energy XPS, resonant Auger electron spectroscopy (RAES) and a subtraction method. The ILs studied include a diverse range of cationic and anionic structural moieties. We introduce a new parameter for ILs, the energy difference between the energies of the cationic and anionic highest occupied fragment orbitals (HOFOs), which we use to identify the highest occupied molecular orbital (HOMO). The anion gave rise to the HOMO for 25 of the 37 ILs studied here. For 10 of the ILs, the energies of the cationic and anionic HOFOs were the same (within experimental error); therefore, it could not be determined whether the HOMO was from the cation or the anion. For two of the ILs, the HOMO was from the cation and not from the anion; consequently it is energetically more favourable to remove an electron from the cation than the anion for these two ILs. In addition, we used a combination of area normalisation and subtraction of XP spectra to produce what are effectively XP spectra for individual ions; this was achieved for 10 cations and 14 anions.
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Affiliation(s)
| | | | - Richard A Bourne
- Institute of Process Research and Development, Schools of Chemistry and Chemical and Process Engineering, University of Leeds, UK
| | | | | | - David J Payne
- Department of Materials, Imperial College London, UK
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12
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Liu KY, Carter-Fenk K, Herbert JM. Self-consistent charge embedding at very low cost, with application to symmetry-adapted perturbation theory. J Chem Phys 2019; 151:031102. [DOI: 10.1063/1.5111869] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Kuan-Yu Liu
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
| | - Kevin Carter-Fenk
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
| | - John M. Herbert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
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13
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How cationic and anionic portions of an imidazolium-based ionic liquid interact with molecular liquids: Insights from density functional theory calculations. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Clarke CJ, Maxwell-Hogg S, Smith EF, Hawker RR, Harper JB, Licence P. Resolving X-ray photoelectron spectra of ionic liquids with difference spectroscopy. Phys Chem Chem Phys 2018; 21:114-123. [PMID: 30519695 DOI: 10.1039/c8cp06701e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
X-ray photoelectron spectroscopy (XPS) is a powerful element-specific technique to determine the composition and chemical state of all elements in an involatile sample. However, for elements such as carbon, the wide variety of chemical states produce complex spectra that are difficult to interpret, consequently concealing important information due to the uncertainty in signal identity. Here we report a process whereby chemical modification of carbon structures with electron withdrawing groups can reveal this information, providing accurate, highly refined fitting models far more complex than previously possible. This method is demonstrated with functionalised ionic liquids bearing chlorine or trifluoromethane groups that shift electron density from targeted locations. By comparing the C 1s spectra of non-functional ionic liquids to their functional analogues, a series of difference spectra can be produced to identify exact binding energies of carbon photoemissions, which can be used to improve the C 1s peak fitting of both samples. Importantly, ionic liquids possess ideal chemical and physical properties, which enhance this methodology to enable significant progress in XPS peak fitting and data interpretation.
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Affiliation(s)
- Coby J Clarke
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK.
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15
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Welz E, Böhnke J, Dewhurst RD, Braunschweig H, Engels B. Unravelling the Dramatic Electrostructural Differences Between N-Heterocyclic Carbene- and Cyclic (Alkyl)(amino)carbene-Stabilized Low-Valent Main Group Species. J Am Chem Soc 2018; 140:12580-12591. [DOI: 10.1021/jacs.8b07644] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Eileen Welz
- Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Julian Böhnke
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rian D. Dewhurst
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Bernd Engels
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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16
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Configurational effect on ion-pair interaction energies and intermolecular potential energy functions in imidazolium-based ionic liquids: A theoretical study. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.04.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Saielli G. Computational Spectroscopy of Ionic Liquids for Bulk Structure Elucidation. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800084] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Giacomo Saielli
- CNR Institute on Membrane Technology; Unit of Padova; Via Marzolo 1-35131 Padova Italy
- Department of Chemical Sciences; University of Padova; Via Marzolo 1-35131 Padova Italy
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18
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Heller BSJ, Kolbeck C, Niedermaier I, Dommer S, Schatz J, Hunt P, Maier F, Steinrück HP. Surface Enrichment in Equimolar Mixtures of Non-Functionalized and Functionalized Imidazolium-Based Ionic Liquids. Chemphyschem 2018; 19:1733-1745. [PMID: 29645340 PMCID: PMC6175172 DOI: 10.1002/cphc.201800216] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Indexed: 11/30/2022]
Abstract
For equimolar mixtures of ionic liquids with imidazolium‐based cations of very different electronic structure, we observe very pronounced surface enrichment effects by angle‐resolved X‐ray photoelectron spectroscopy (XPS). For a mixture with the same anion, that is, 1‐methyl‐3‐octylimidazolium hexafluorophosphate+1,3‐di(methoxy)imidazolium hexafluorophosphate ([C8C1Im][PF6]+[(MeO)2Im][PF6]), we find a strong enrichment of the octyl chain‐containing [C8C1Im]+ cation and a corresponding depletion of the [(MeO)2Im]+ cation in the topmost layer. For a mixture with different cations and anions, that is, [C8C1Im][Tf2N]+[(MeO)2Im][PF6], we find both surface enrichment of the [C8C1Im]+ cation and the [Tf2N]− (bis[(trifluoromethyl)sulfonyl]imide) anion, while [(MeO)2Im]+ and [PF6]− are depleted from the surface. We propose that the observed behavior in these mixtures is due to a lowering of the surface tension by the enriched components. Interestingly, we observe pronounced differences in the chemical shifts of the imidazolium ring signals of the [(MeO)2Im]+ cations as compared to the non‐functionalized cations. Calculations of the electronic structure and the intramolecular partial charge distribution of the cations contribute to interpreting these shifts for the two different cations.
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Affiliation(s)
- Bettina S J Heller
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Claudia Kolbeck
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Inga Niedermaier
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Sabine Dommer
- Lehrstuhl für Organische Chemie I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91058, Erlangen, Germany
| | - Jürgen Schatz
- Lehrstuhl für Organische Chemie I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91058, Erlangen, Germany
| | - Patricia Hunt
- Chemistry Department, Imperial College London, SW72AZ, London, United Kingdom
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
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19
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Fogarty RM, Matthews RP, Ashworth CR, Brandt-Talbot A, Palgrave RG, Bourne RA, Vander Hoogerstraete T, Hunt PA, Lovelock KRJ. Experimental validation of calculated atomic charges in ionic liquids. J Chem Phys 2018; 148:193817. [DOI: 10.1063/1.5011662] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Richard M. Fogarty
- Department of Chemistry, Imperial College London, London, United Kingdom
| | | | - Claire R. Ashworth
- Department of Chemistry, Imperial College London, London, United Kingdom
| | | | - Robert G. Palgrave
- Department of Chemistry, University College London, London, United Kingdom
| | - Richard A. Bourne
- School of Chemical and Process Engineering and Institute of Process Research and Development, School of Chemistry, University of Leeds, Leeds, United Kingdom
| | | | - Patricia A. Hunt
- Department of Chemistry, Imperial College London, London, United Kingdom
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