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Hunger L, Al‐Sheakh L, Zaitsau DH, Verevkin SP, Appelhagen A, Villinger A, Ludwig R. Dissecting Noncovalent Interactions in Carboxyl‐Functionalized Ionic Liquids Exhibiting Double and Single Hydrogens Bonds Between Ions of Like Charge. Chemistry 2022; 28:e202200949. [PMID: 35785500 PMCID: PMC9543318 DOI: 10.1002/chem.202200949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Lasse Hunger
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Loai Al‐Sheakh
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Dzmitry H. Zaitsau
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
| | - Sergey P. Verevkin
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
| | - Andreas Appelhagen
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Alexander Villinger
- Institut für Chemie Abteilung für Anorganische Chemie Universität Rostock Albert-Einstein-Str. 3a 18059 Rostock Germany
| | - Ralf Ludwig
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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2
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Diclofenac Ion Hydration: Experimental and Theoretical Search for Anion Pairs. Molecules 2022; 27:molecules27103350. [PMID: 35630826 PMCID: PMC9146526 DOI: 10.3390/molecules27103350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/21/2022] Open
Abstract
Self-assembly of organic ions in aqueous solutions is a hot topic at the present time, and substances that are well-soluble in water are usually studied. In this work, aqueous solutions of sodium diclofenac are investigated, which, like most medicinal compounds, is poorly soluble in water. Classical MD modeling of an aqueous solution of diclofenac sodium showed equilibrium between the hydrated anion and the hydrated dimer of the diclofenac anion. The assignment and interpretation of the bands in the UV, NIR, and IR spectra are based on DFT calculations in the discrete-continuum approximation. It has been shown that the combined use of spectroscopic methods in various frequency ranges with classical MD simulations and DFT calculations provides valuable information on the association processes of medical compounds in aqueous solutions. Additionally, such a combined application of experimental and calculation methods allowed us to put forward a hypothesis about the mechanism of the effect of diclofenac sodium in high dilutions on a solution of diclofenac sodium.
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The Role of Hydrogen Bonds in Interactions between [PdCl 4] 2- Dianions in Crystal. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27072144. [PMID: 35408543 PMCID: PMC9000617 DOI: 10.3390/molecules27072144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/18/2022] [Accepted: 03/22/2022] [Indexed: 11/17/2022]
Abstract
[PdCl4]2- dianions are oriented within a crystal in such a way that a Cl of one unit approaches the Pd of another from directly above. Quantum calculations find this interaction to be highly repulsive with a large positive interaction energy. The placement of neutral ligands in their vicinity reduces the repulsion, but the interaction remains highly endothermic. When the ligands acquire a unit positive charge, the electrostatic component and the full interaction energy become quite negative, signalling an exothermic association. Raising the charge on these counterions to +2 has little further stabilizing effect, and in fact reduces the electrostatic attraction. The ability of the counterions to promote the interaction is attributed in part to the H-bonds which they form with both dianions, acting as a sort of glue.
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Weinhold F. Anti-Electrostatic Pi-Hole Bonding: How Covalency Conquers Coulombics. Molecules 2022; 27:377. [PMID: 35056689 PMCID: PMC8780338 DOI: 10.3390/molecules27020377] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 12/30/2021] [Accepted: 12/30/2021] [Indexed: 12/20/2022] Open
Abstract
Intermolecular bonding attraction at π-bonded centers is often described as "electrostatically driven" and given quasi-classical rationalization in terms of a "pi hole" depletion region in the electrostatic potential. However, we demonstrate here that such bonding attraction also occurs between closed-shell ions of like charge, thereby yielding locally stable complexes that sharply violate classical electrostatic expectations. Standard DFT and MP2 computational methods are employed to investigate complexation of simple pi-bonded diatomic anions (BO-, CN-) with simple atomic anions (H-, F-) or with one another. Such "anti-electrostatic" anion-anion attractions are shown to lead to robust metastable binding wells (ranging up to 20-30 kcal/mol at DFT level, or still deeper at dynamically correlated MP2 level) that are shielded by broad predissociation barriers (ranging up to 1.5 Å width) from long-range ionic dissociation. Like-charge attraction at pi-centers thereby provides additional evidence for the dominance of 3-center/4-electron (3c/4e) nD-π*AX interactions that are fully analogous to the nD-σ*AH interactions of H-bonding. Using standard keyword options of natural bond orbital (NBO) analysis, we demonstrate that both n-σ* (sigma hole) and n-π* (pi hole) interactions represent simple variants of the essential resonance-type donor-acceptor (Bürgi-Dunitz-type) attraction that apparently underlies all intermolecular association phenomena of chemical interest. We further demonstrate that "deletion" of such π*-based donor-acceptor interaction obliterates the characteristic Bürgi-Dunitz signatures of pi-hole interactions, thereby establishing the unique cause/effect relationship to short-range covalency ("charge transfer") rather than envisioned Coulombic properties of unperturbed monomers.
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Affiliation(s)
- Frank Weinhold
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53705, USA
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5
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Al-Sheakh L, Fritsch S, Appelhagen A, Villinger A, Ludwig R. Thermodynamically Stable Cationic Dimers in Carboxyl-Functionalized Ionic Liquids: The Paradoxical Case of "Anti-Electrostatic" Hydrogen Bonding. Molecules 2022; 27:molecules27020366. [PMID: 35056680 PMCID: PMC8778807 DOI: 10.3390/molecules27020366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/28/2021] [Accepted: 01/03/2022] [Indexed: 11/18/2022] Open
Abstract
We show that carboxyl-functionalized ionic liquids (ILs) form doubly hydrogen-bonded cationic dimers (c+=c+) despite the repulsive forces between ions of like charge and competing hydrogen bonds between cation and anion (c+–a−). This structural motif as known for formic acid, the archetype of double hydrogen bridges, is present in the solid state of the IL 1−(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC−CH2−py][NTf2]. By means of quantum chemical calculations, we explored different hydrogen-bonded isomers of neutral (HOOC–(CH2)n–py+)2(NTf2−)2, single-charged (HOOC–(CH2)n–py+)2(NTf2−), and double-charged (HOOC– (CH2)n−py+)2 complexes for demonstrating the paradoxical case of “anti-electrostatic” hydrogen bonding (AEHB) between ions of like charge. For the pure doubly hydrogen-bonded cationic dimers (HOOC– (CH2)n−py+)2, we report robust kinetic stability for n = 1–4. At n = 5, hydrogen bonding and dispersion fully compensate for the repulsive Coulomb forces between the cations, allowing for the quantification of the two equivalent hydrogen bonds and dispersion interaction in the order of 58.5 and 11 kJmol−1, respectively. For n = 6–8, we calculated negative free energies for temperatures below 47, 80, and 114 K, respectively. Quantum cluster equilibrium (QCE) theory predicts the equilibria between cationic monomers and dimers by considering the intermolecular interaction between the species, leading to thermodynamic stability at even higher temperatures. We rationalize the H-bond characteristics of the cationic dimers by the natural bond orbital (NBO) approach, emphasizing the strong correlation between NBO-based and spectroscopic descriptors, such as NMR chemical shifts and vibrational frequencies.
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Affiliation(s)
- Loai Al-Sheakh
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Sebastian Fritsch
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Andreas Appelhagen
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Alexander Villinger
- Institut für Chemie, Abteilung für Anorganische Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany;
| | - Ralf Ludwig
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
- Department LL&M, University of Rostock, Albert-Einstein−Str. 25, 18059 Rostock, Germany
- Leibniz−Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein−Str. 29a, 18059 Rostock, Germany
- Correspondence:
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Sharma P, Dutta D, Gomila RM, Frontera A, Barcelo-Oliver M, Verma AK, Bhattacharyya MK. Benzoato bridged dinuclear Mn(II) and Cu(II) compounds involving guest chlorobenzoates and dimeric paddle wheel supramolecular assemblies: Antiproliferative evaluation and theoretical studies. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115409] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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7
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Canbulat Özdemir M, Aktan E, Şahin O. The association of like-charged ions in tunable protic pyrazolium salts. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Tarannam N, Shukla R, Kozuch S. Yet another perspective on hole interactions. Phys Chem Chem Phys 2021; 23:19948-19963. [PMID: 34514473 DOI: 10.1039/d1cp03533a] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hole interactions are known by different names depending on the key atom of the bond (halogen bond, chalcogen bond, hydrogen bond, etc.), and the geometry of the interaction (σ if in line, π if perpendicular to the Lewis acid plane). However, its origin starts with the creation of a Lewis acid by an underlying covalent bond, which forms an electrostatic depletion and a virtual antibonding orbital, which can create non-covalent interactions with Lewis bases. In this (maybe subjective) perspective, we will claim that hole interactions must be defined via the molecular orbital origin of the molecule. Under this premise we can better explore the richness of such bonding patterns. For that, we will study old, recent and new systems, trying to pinpoint some misinterpretations that are often associated with them. We will use as exemplars the triel bonds, a couple of metal complexes, a discussion on convergent σ-holes, and many cases of anti-electrostatic hole interactions.
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Affiliation(s)
- Naziha Tarannam
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel.
| | - Rahul Shukla
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel.
| | - Sebastian Kozuch
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel.
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Wysokiński R, Zierkiewicz W, Michalczyk M, Scheiner S. Crystallographic and Theoretical Evidences of Anion⋅⋅⋅Anion Interaction. Chemphyschem 2021; 22:818-821. [PMID: 33719162 DOI: 10.1002/cphc.202100132] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/08/2021] [Indexed: 11/10/2022]
Abstract
Planar (HgCl3 )- anions are stacked fairly closely together in a slipped parallel arrangement within several crystal structures. Quantum chemical analysis shows evidence of strong noncovalent spodium bonds between the Hg π-hole of one unit and the Cl atom of an adjacent unit. Anion⋅⋅⋅anion spodium bonds work in tandem with crystal packing forces.
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Affiliation(s)
- Rafał Wysokiński
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Wiktor Zierkiewicz
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Mariusz Michalczyk
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University Logan, Utah, 84322-0300, United States
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10
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Chen J, Dong K, Liu L, Zhang X, Zhang S. Anti-electrostatic hydrogen bonding between anions of ionic liquids: a density functional theory study. Phys Chem Chem Phys 2021; 23:7426-7433. [PMID: 33876102 DOI: 10.1039/d0cp06718k] [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
Hydrogen bonds (HBs) play a crucial role in the physicochemical properties of ionic liquids (ILs). To date, HBs between cations and anions (Ca-An) or between cations (Ca-Ca) in ILs have been reported extensively. Here, we provided DFT evidence for the existence of HBs between anions (An-An) in the IL 1-(2-hydroxyethyl)-3-methylimidazolium 4-(2-hydroxyethyl)imidazolide [HEMIm][HEIm]. The thermodynamic stabilities of anionic, cationic, and H2O dimers together with ionic pairs were studied using potential energy scans. The results show that the cation-anion pair is the most stable one, while the HB in the anionic dimer possesses similar thermodynamic stability to the water dimer. The further geometric, spectral and electronic structure analyses demonstrate that the inter-anionic HB meets the general theoretical criteria of traditional HBs. The strength order of four HBs in complexes is cation-anion pair > H2O dimer ≈ cationic dimer > anionic dimer. The energy decomposition analysis indicates that induction and dispersion interactions are the crucial factors to overcome strong Coulomb repulsions, forming inter-anionic HBs. Finally, the presence of inter-anionic HBs in the ionic cluster has been confirmed by a global minimum search for a system containing two ionic pairs. Even though hydroxyl-functionalized cations are more likely to form HBs with anions, there are still inter-anionic HBs between hydroxyl groups in the low-lying structures. Our studies broaden the understanding of HBs in ionic liquids and support the recently proposed concept of anti-electrostatic HBs.
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Affiliation(s)
- Junwu Chen
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China.
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11
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Wysokiński R, Zierkiewicz W, Michalczyk M, Scheiner S. Anionanion (MX 3-) 2 dimers (M = Zn, Cd, Hg; X = Cl, Br, I) in different environments. Phys Chem Chem Phys 2021; 23:13853-13861. [PMID: 34156052 DOI: 10.1039/d1cp01502h] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The possibility that MX3- anions can interact with one another is assessed via ab initio calculations in gas phase as well as in aqueous and ethanol solution. A pair of such anions can engage in two different dimer types. In the bridged configuration, two X atoms engage with two M atoms in a rhomboid structure with four equal M-X bond lengths. The two monomers retain their identity in the stacked geometry which contains a pair of noncovalent MX interactions. The relative stabilities of these two structures depend on the nature of the central M atom, the halogen substituent, and the presence of solvent. The interaction and binding energies are fairly small, generally no more than 10 kcal mol-1. The large electrostatic repulsion is balanced by a strong attractive polarization energy.
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Affiliation(s)
- Rafał Wysokiński
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
| | - Wiktor Zierkiewicz
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
| | - Mariusz Michalczyk
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University Logan, Utah 84322-0300, USA.
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Philipp JK, Fritsch S, Ludwig R. Cyclic Octamer of Hydroxyl-functionalized Cations with Net Charge Q=+8e Kinetically Stabilized by a 'Molecular Island' of Cooperative Hydrogen Bonds. Chemphyschem 2020; 21:2411-2416. [PMID: 32845043 PMCID: PMC7702028 DOI: 10.1002/cphc.202000681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/20/2020] [Indexed: 11/07/2022]
Abstract
Cyclic octamers are well-known structural motifs in chemistry, biology and physics. These include covalently bound cyclic octameric sulphur, cylic octa-alkanes, cyclo-octameric peptides as well as hydrogen-bonded ring clusters of alcohols. In this work, we show that even calculated cyclic octamers of hydroxy-functionalized pyridinium cations with a net charge Q=+8e are kinetically stable. Eight positively charged cations are kept together by hydrogen bonding despite the strong Coulomb repulsive forces. Sufficiently long hydroxy-octyl chains prevent "Coulomb explosion" by increasing the distance between the positive charges at the pyridinium rings, reducing the Coulomb repulsion and thus strengthen hydrogen bonds between the OH groups. The eightfold positively charged cyclic octamer shows spectroscopic properties similar to those obtained for hydrogen-bonded neutral cyclic octamers of methanol. Thus, the area of the hydrogen bonded OH ring represents a 'molecular island' within an overall cationic environment. Although not observable, the spectroscopic properties and the correlated NBO parameters of the calculated cationic octamer support the detection of smaller cationic clusters in ionic liquids, which we observed despite the competition with ion pairs wherein attractive Coulomb forces enhance hydrogen bonding between cation and anion.
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Affiliation(s)
- Jule Kristin Philipp
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Sebastian Fritsch
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Ralf Ludwig
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
- Universität RostockDepartment LL&MAlbert-Einstein-Str. 2518059RostockGermany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V.Albert-Einstein-Str. 29a18059RostockGermany
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13
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Philipp JK, Ludwig R. Clusters of Hydroxyl-Functionalized Cations Stabilized by Cooperative Hydrogen Bonds: The Role of Polarizability and Alkyl Chain Length. Molecules 2020; 25:molecules25214972. [PMID: 33121087 PMCID: PMC7662246 DOI: 10.3390/molecules25214972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 01/08/2023] Open
Abstract
We explore quantum chemical calculations for studying clusters of hydroxyl-functionalized cations kinetically stabilized by hydrogen bonding despite strongly repulsive electrostatic forces. In a comprehensive study, we calculate clusters of ammonium, piperidinium, pyrrolidinium, imidazolium, pyridinium, and imidazolium cations, which are prominent constituents of ionic liquids. All cations are decorated with hydroxy-alkyl chains allowing H-bond formation between ions of like charge. The cluster topologies comprise linear and cyclic clusters up to the size of hexamers. The ring structures exhibit cooperative hydrogen bonds opposing the repulsive Coulomb forces and leading to kinetic stability of the clusters. We discuss the importance of hydrogen bonding and dispersion forces for the stability of the differently sized clusters. We find the largest clusters when hydrogen bonding is maximized in cyclic topologies and dispersion interaction is properly taken into account. The kinetic stability of the clusters with short-chained cations is studied for the different types of cations ranging from hard to polarizable or exhibiting additional functional groups such as the acidic C(2)-H position in the imidazolium-based cation. Increasing the alkyl chain length, the cation effect diminishes and the kinetic stability is exclusively governed by the alkyl chain tether increasing the distance between the positively charged rings of the cations. With adding the counterion tetrafluoroborate (BF4−) to the cationic clusters, the binding energies immediately switch from strongly positive to strongly negative. In the neutral clusters, the OH functional groups of the cations can interact either with other cations or with the anions. The hexamer cluster with the cyclic H-bond motive and “released” anions is almost as stable as the hexamer built by H-bonded ion pairs exclusively, which is in accord with recent IR spectra of similar ionic liquids detecting both types of hydrogen bonding. For the cationic and neutral clusters, we discuss geometric and spectroscopic properties as sensitive probes of opposite- and like-charge interaction. Finally, we show that NMR proton chemical shifts and deuteron quadrupole coupling constants can be related to each other, allowing to predict properties which are not easily accessible by experiment.
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Affiliation(s)
- Jule K. Philipp
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, 18059 Rostock, Germany;
| | - Ralf Ludwig
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, 18059 Rostock, Germany;
- Department Life, Light & Matter, Universität Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
- Correspondence: ; Tel.: +49-381-498-6517
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14
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Holthoff JM, Engelage E, Weiss R, Huber SM. "Anti-Electrostatic" Halogen Bonding. Angew Chem Int Ed Engl 2020; 59:11150-11157. [PMID: 32227661 PMCID: PMC7317790 DOI: 10.1002/anie.202003083] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/30/2020] [Indexed: 01/03/2023]
Abstract
Halogen bonding is often described as being driven predominantly by electrostatics, and thus adducts between anionic halogen bond (XB) donors (halogen-based Lewis acids) and anions seem counterintuitive. Such "anti-electrostatic" XBs have been predicted theoretically but for organic XB donors, there are currently no experimental examples except for a few cases of self-association. Reported herein is the synthesis of two negatively charged organoiodine derivatives that form anti-electrostatic XBs with anions. Even though the electrostatic potential is universally negative across the surface of both compounds, DFT calculations indicate kinetic stabilization of their halide complexes in the gas phase and particularly in solution. Experimentally, self-association of the anionic XB donors was observed in solid-state structures, resulting in dimers, trimers, and infinite chains. In addition, co-crystals with halides were obtained, representing the first cases of halogen bonding between an organic anionic XB donor and a different anion. The bond lengths of all observed interactions are 14-21 % shorter than the sum of the van der Waals radii.
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Affiliation(s)
- Jana M. Holthoff
- Fakultät für Chemie und BiochemieRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
| | - Elric Engelage
- Fakultät für Chemie und BiochemieRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
| | - Robert Weiss
- Institut für Organische ChemieFriedrich-Alexander-Universität Erlangen-NürnbergHenkestraße 4291054ErlangenGermany
| | - Stefan M. Huber
- Fakultät für Chemie und BiochemieRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
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Theoretical Insights into the Structure of the Aminotris(Methylenephosphonic Acid) (ATMP) Anion: A Possible Partner for Conducting Ionic Media. Symmetry (Basel) 2020. [DOI: 10.3390/sym12060920] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We present a computational characterisation of Aminotris(methylenephosphonic acid) (ATMP) and its potential use as an anionic partner for conductive ionic liquids (ILs). We argue that for an IL to be a good candidate for a conducting medium, two conditions must be fulfilled: (i) the charge must be transported by light carriers; and (ii) the system must maintain a high degree of ionisation. The result trends presented herein show that there are molecular ion combinations that do comply with these two criteria, regardless of the specific system used. ATMP is a symmetric molecule with a total of six protons. In the bulk phase, breaking the symmetry of the fully protonated state and creating singly and doubly charged anions induces proton transfer mechanisms. To demonstrate this, we used molecular dynamics (MD) simulations employing a variable topology approach based on the reasonably reliable semiempirical density functional tight binding (DFTB) evaluation of the atomic forces. We show that, by choosing common and economical starting compounds, we can devise a viable prototype for a highly conductive medium where charge transfer is achieved by proton motion.
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Holthoff JM, Engelage E, Weiss R, Huber SM. “Anti‐elektrostatische” Halogenbrücken. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003083] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Jana M. Holthoff
- Fakultät für Chemie und BiochemieRuhr-Universität Bochum Universitätsstraße 150 44801 Bochum Deutschland
| | - Elric Engelage
- Fakultät für Chemie und BiochemieRuhr-Universität Bochum Universitätsstraße 150 44801 Bochum Deutschland
| | - Robert Weiss
- Institut für Organische ChemieFriedrich-Alexander-Universität Erlangen-Nürnberg Henkestraße 42 91054 Erlangen Deutschland
| | - Stefan M. Huber
- Fakultät für Chemie und BiochemieRuhr-Universität Bochum Universitätsstraße 150 44801 Bochum Deutschland
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17
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Structural Features of Triethylammonium Acetate through Molecular Dynamics. Molecules 2020; 25:molecules25061432. [PMID: 32245229 PMCID: PMC7146455 DOI: 10.3390/molecules25061432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/19/2020] [Indexed: 12/13/2022] Open
Abstract
I have explored the structural features and the dynamics of triethylammonium acetate by means of semi-empirical (density functional tight binding, DFTB) molecular dynamics. I find that the results from the present simulations agree with recent experimental determinations with only few minor differences in the structural interpretation. A mixture of triethylamine and acetic acid does not form an ionic liquid, but gives rise to a very complex system where ionization is only a partial process affecting only few molecules (1 over 4 experimentally). I have also found that the few ionic couples are stable and remain mainly embedded inside the AcOH neutral moiety.
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18
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Ender V, Weber J. The Maximum of Minimal Conductivity in Aqueous Electrolytes. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2018-1329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The present paper deals with the minima of conductivity in aqueous solutions, which occur due to the hydrolysis reaction with added bases. The minima show lower conductivities than the intrinsic conductivity of pure water. The minimum is a function of the molar conductivity of the added ions. There exists a limiting condition of <75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 for the occurrence of a minimum in the real (positive) concentration area. Values higher than 75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 lead to minimas in the virtual (negative) concentration area. Connecting all the minima, a curve with a maximum is observed. This point is given by 75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 and the intrinsic conductivity of pure water. The effect is independent of whether the added substances come from a strong or weak base. So far, the phenomenon should not influence measurements of conductivity under usual circumstances, but might be more of academic interest. Interestingly, we found that the effect for Rubidium and Cesium ions is different compared to other alkali metal ions. No minimum conductivity is predicted for these ions.
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Affiliation(s)
- Volker Ender
- Department of Natural and Environmental Sciences , Hochschule Zittau/Goerlitz (University of Applied Sciences) , Theodor-Körner-Allee 18, D-02763 Zittau , Germany , Tel.: +49-(0)35836124705
| | - Jens Weber
- Department of Natural and Environmental Sciences , Hochschule Zittau/Goerlitz (University of Applied Sciences) , Theodor-Körner-Allee 18, D-02763 Zittau , Germany , Tel.: +49-(0)35836124705
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19
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Rabideau BD, Soltani M, Parker RA, Siu B, Salter EA, Wierzbicki A, West KN, Davis JH. Tuning the melting point of selected ionic liquids through adjustment of the cation's dipole moment. Phys Chem Chem Phys 2020; 22:12301-12311. [PMID: 32432261 DOI: 10.1039/d0cp01214a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In previous work with thermally robust salts [Cassity et al., Phys. Chem. Chem. Phys., 2017, 19, 31560] it was noted that an increase in the dipole moment of the cation generally led to a decrease in the melting point. Molecular dynamics simulations of the liquid state revealed that an increased dipole moment reduces cation-cation repulsions through dipole-dipole alignment. This was believed to reduce the liquid phase enthalpy, which would tend to lower the melting point of the IL. In this work we further test this principle by replacing hydrogen atoms with fluorine atoms at selected positions within the cation. This allows us to alter the electrostatics of the cation without substantially affecting the sterics. Furthermore, the strength of the dipole moment can be controlled by choosing different positions within the cation for replacement. We studied variants of four different parent cations paired with bistriflimide and determined their melting points, and enthalpies and entropies of fusion through DSC experiments. The decreases in the melting point were determined to be enthalpically driven. We found that the dipole moment of the cation, as determined by quantum chemical calculations, is inversely correlated with the melting point of the given compound. Molecular dynamics simulations of the crystalline and solid states of two isomers showed differences in their enthalpies of fusion that closely matched those seen experimentally. Moreover, this reduction in the enthalpy of fusion was determined to be caused by an increase in the enthalpy of the crystalline state. We provide evidence that dipole-dipole interactions between cations leads to the formation of cationic domains in the crystalline state. These cationic associations partially block favourable cation-anion interactions, which are recovered upon melting. If, however, the dipole-dipole interactions between cations is too strong they have a tendency to form glasses. This study provides a design rule for lowering the melting point of structurally similar ILs by altering their dipole moment.
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Affiliation(s)
- Brooks D Rabideau
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Mohammad Soltani
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Rome A Parker
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Benjamin Siu
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - E Alan Salter
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Andrzej Wierzbicki
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - Kevin N West
- Department of Chemical & Biomolecular Engineering, The University of South Alabama, Mobile, Alabama 36688, USA.
| | - James H Davis
- Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, USA.
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20
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Le Donne A, Adenusi H, Porcelli F, Bodo E. Structural Features of Cholinium Based Protic Ionic Liquids through Molecular Dynamics. J Phys Chem B 2019; 123:5568-5576. [PMID: 31185161 DOI: 10.1021/acs.jpcb.9b03314] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An analysis of the complex proton transfer processes in certain protic ionic liquids, based on amino acid anions, has been carried out through ab initio molecular dynamics in the view of finding naturally conductive and pure mediums. The systems analyzed here might serve as chemical prototypes for pure and dry ionic liquids where mobile protons can act as fast charge carriers. We have exploited the natural tendency of these liquids to form a complex network of hydrogen bonds. The presence of such a network allows the naturally repulsive interaction between like charge ions to be weakened to the point that a proton migration process inside the anionic component of the fluid becomes possible. We have also seen that the extent of these proton migrations is sizable for carboxylic based amino acid anions, while it is very limited for sulfur containing ones.
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Affiliation(s)
- Andrea Le Donne
- Chemistry Department , University of Rome "La Sapienza" , Piazzale Aldo Moro 5 , 00185 Rome , Italy
| | - Henry Adenusi
- Chemistry Department , University of Rome "La Sapienza" , Piazzale Aldo Moro 5 , 00185 Rome , Italy
| | - Francesco Porcelli
- Chemistry Department , University of Rome "La Sapienza" , Piazzale Aldo Moro 5 , 00185 Rome , Italy
| | - Enrico Bodo
- Chemistry Department , University of Rome "La Sapienza" , Piazzale Aldo Moro 5 , 00185 Rome , Italy
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21
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Ramondo F, Gontrani L, Campetella M. Coupled hydroxyl and ether functionalisation in EAN derivatives: the effect of hydrogen bond donor/acceptor groups on the structural heterogeneity studied with X-ray diffractions and fixed charge/polarizable simulations. Phys Chem Chem Phys 2019; 21:11464-11475. [PMID: 31112158 DOI: 10.1039/c9cp00571d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a study by energy-dispersive X-ray diffraction of liquid 2-(2-hydroxyethoxy)ethan-1-ammonium nitrate, NH3CH2CH2(OCH2CH2OH)+NO3- (22HHEAN). This ionic liquid is derived from the parent ethylammonium nitrate (EAN) with an ether link in the chain and a hydroxyl group in the terminal position. The absence of peaks at low-q values in the experimental diffraction curve indicates that the added polar groups and the high conformational isomerism of the cations alter strongly the nanosegregation of the parent EAN liquid. Aggregation between ionic species may involve hydrogen bonding between cations and anions and a variety of intermolecular hydrogen bonds between cations. Diffraction patterns are compared with the results of molecular dynamics simulations with two different force fields: the fixed point charge force field (GAFF) with different charge scaling protocols and the polarizable AMOEBA force field. Most point charge models lead to the appearance of a quite evident low q-peak which decreases gradually, when the percentage and type of the scaling (uniform vs. non-uniform) are increased. In the polarisable model and in the model where only anion charges are scaled to 20%, instead, the pre-peak is absent in agreement with our experiments.
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Affiliation(s)
- Fabio Ramondo
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio I-67100, L'Aquila, Italy
| | - Lorenzo Gontrani
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via Selmi, 2, I-40126 Bologna, Italy. and Department of Chemistry, University "La Sapienza", Roma Piazzale Aldo Moro 5, I-00185, Roma, Italy
| | - Marco Campetella
- Department of Chemistry, University "La Sapienza", Roma Piazzale Aldo Moro 5, I-00185, Roma, Italy and Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris, F-75005 Paris, France
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22
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Panja SK, Haddad B, Debdab M, Kiefer J, Chaker Y, Bresson S, Paolone A. Cluster Formation through Hydrogen Bond Bridges across Chloride Anions in a Hydroxyl-Functionalized Ionic Liquid. Chemphyschem 2019; 20:936-940. [PMID: 30821876 DOI: 10.1002/cphc.201801206] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/01/2019] [Indexed: 11/10/2022]
Abstract
Several recent studies of hydroxyl-functionalized ionic liquids (ILs) have shown that cation-cation interactions can be dominating these materials at the molecular level when the anion involved is weakly interacting. The hydrogen bonds between the like ions led to the formation of interesting chain-like, ring-like, or distinct dimeric (i. e. two ion pairs) supermolecular clusters. In the present work, vibrational spectroscopy (ATR-IR and Raman) and density functional theory (DFT) calculations of the hydroxyl-functionalized imidazolium ionic liquid C2 OHmimCl indicate that anion-cation hydrogen bonding interactions are dominating, leading to the formation of distinct dimeric ion pair clusters. In this arrangement, the Cl- anions function as a bridge between the cations by establishing bifurcated hydrogen bonds with the OH group of one cation and the C(2)-H of another cation. Cation-cation interactions, on the other hand, do not play a significant role in the observed clusters.
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Affiliation(s)
- Sumit Kumar Panja
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, Karnataka, India
| | - Boumediene Haddad
- Department of Chemistry, Dr Moulay Tahar University of Saida, Algeria
| | - Mansour Debdab
- Laboratoire de Synthèse et Catalyse Tiaret LSCT, University of Tiaret, Algeria
| | - Johannes Kiefer
- Technische Thermodynamik, Universität Bremen, Badgasteiner Str. 1, 28359, Bremen, Germany
| | - Yassine Chaker
- Laboratoire de Synthèse et Catalyse Tiaret LSCT, University of Tiaret, Algeria
| | - Serge Bresson
- Laboratoire de Physique des Systèmes Complexes, Université Picardie Jules Verne, 33 rue St Leu, 80039, Amiens cedex, France
| | - Annalisa Paolone
- Consiglio Nazionale delle Ricerche Instituto dei Sistemi Complessi (CNR-ISC), University of Rome La Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy
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23
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Sahoo DK, Jena S, Dutta J, Rana A, Biswal HS. Nature and Strength of M-H···S and M-H···Se (M = Mn, Fe, & Co) Hydrogen Bond. J Phys Chem A 2019; 123:2227-2236. [PMID: 30802055 DOI: 10.1021/acs.jpca.8b12003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The significance of dispersion contribution in the formation of strong hydrogen bonds (H-bonds) can no more be ignored. It was illustrated that less electronegative and electropositive H-bond acceptors such as S, Se, and Te are also capable of forming strong N-H···Y H-bonds, mostly due to the high polarizabilities of H-bond acceptor atoms. Herein, for the first time, we report the evidence of formation of nonconventional M-H···Y H-bonds between metal hydrides (M-H, M = Mn, Fe, Co) and chalcogen H-bond acceptors (Y = O, S, or Se). The nature and the strength of unusual M-H···Y H-bonds were revealed by several quantum chemical calculations and H-bond descriptors. The structural parameters, electron density topology, donor-acceptor natural bond orbital (NBO) interaction energies, and spectroscopic observables such as M-H stretching frequencies and 1H chemical shifts are well-correlated to manifest the existence and strength of M-H···Y H-bonding. The M-H···Y H-bonds are dispersive in nature, and the computed H-bond energies are found to be in the range from ∼5 to 30 kJ/mol, which can be compared to those of the conventional H-bonds such as O-H···O, N-H···O, and N-H···O═C H-bonds, etc.
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Affiliation(s)
- Dipak Kumar Sahoo
- School of Chemical Sciences , National Institute of Science Education and Research , 752050 Bhubaneswar , India.,Homi Bhabha National Institute , Training School Complex , Anushakti Nagar, Mumbai 400094 , India
| | - Subhrakant Jena
- School of Chemical Sciences , National Institute of Science Education and Research , 752050 Bhubaneswar , India.,Homi Bhabha National Institute , Training School Complex , Anushakti Nagar, Mumbai 400094 , India
| | - Juhi Dutta
- School of Chemical Sciences , National Institute of Science Education and Research , 752050 Bhubaneswar , India.,Homi Bhabha National Institute , Training School Complex , Anushakti Nagar, Mumbai 400094 , India
| | - Abhijit Rana
- School of Chemical Sciences , National Institute of Science Education and Research , 752050 Bhubaneswar , India.,Homi Bhabha National Institute , Training School Complex , Anushakti Nagar, Mumbai 400094 , India
| | - Himansu S Biswal
- School of Chemical Sciences , National Institute of Science Education and Research , 752050 Bhubaneswar , India.,Homi Bhabha National Institute , Training School Complex , Anushakti Nagar, Mumbai 400094 , India
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24
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Niemann T, Stange P, Strate A, Ludwig R. When hydrogen bonding overcomes Coulomb repulsion: from kinetic to thermodynamic stability of cationic dimers. Phys Chem Chem Phys 2019; 21:8215-8220. [PMID: 30672530 DOI: 10.1039/c8cp06417b] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Quantum chemical calculations have been employed to study the kinetic and thermodynamic stability of hydroxy-functionalized 1-(3-hydroxyalkyl)pyridinium cationic dimers. For [Py-(CH2)n-OH+]2 structures with n = 2-17 we have calculated the robust local minima with clear dissociation barriers preventing their "Coulomb explosion" into separated cations. For n = 15 hydrogen bonding and dispersion forces fully compensate for the repulsive Coulomb forces between the cations allowing for the quantification of the pure hydrogen bond in the order of 20 kJ mol-1. The increasing kinetic stability even turns to thermodynamic stability with further elongated hydroxyalkyl chains. Now, quantum-type short-range attraction wins over classical long-range electrostatic repulsion resulting in negative binding energies and providing the first thermodynamically stable cationic dimers. The electronic, structural and spectroscopic signatures of the cationic dimers could be correlated to NBO parameters, supporting the existence of anti-electrostatic hydrogen bonds (AEHB) as recently suggested by Weinhold. In principle, these pure cationic dimers should be detectable in gas-phase experiments at low temperatures without the need of mediating molecules or counteranions.
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Affiliation(s)
- T Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany.
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25
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Tan X, Liu X, Yao X, Zhang Y, Jiang K. Theoretical Study of Ionic Liquid Clusters Catalytic Effect on the Fixation of CO2. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b03947] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xin Tan
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Xiaomin Liu
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, Shandong, China
| | - Xiaoqian Yao
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
| | - Yaqin Zhang
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
| | - Kun Jiang
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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26
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Le Donne A, Adenusi H, Porcelli F, Bodo E. Hydrogen Bonding as a Clustering Agent in Protic Ionic Liquids: Like-Charge vs Opposite-Charge Dimer Formation. ACS OMEGA 2018; 3:10589-10600. [PMID: 31459182 PMCID: PMC6645488 DOI: 10.1021/acsomega.8b01615] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/22/2018] [Indexed: 06/10/2023]
Abstract
The local structure of a series of homologous protic ionic liquids (PILs) is investigated using ab initio computations and ab initio-based molecular dynamics. The purpose of this work is to show that in PILs the network of hydrogen bonds may promote like-charge clustering between anionic species. We correlate the theoretical evidence of this possibility with viscosity experimental data. The homologous series of liquids is obtained by coupling choline with amino acid anions and varying the side chain. We find that the frictional properties of the liquids are clearly connected to the ability of the side chain to establish additional hydrogen bonds (other than the trivial cation-anion interaction). We also show that the large variation of bulk properties along the series of compounds can be explained by assuming that one of the sources of friction in the bulk liquid is the like-charge interaction between anions.
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