Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants—Comparison with Salt Bridges and Molecular Systems

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Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants—Comparison with Salt Bridges and Molecular Systems. / Khudozhitkov, Alexander E.; Neumann, Jan; Niemann, Thomas et al.

In: Angewandte Chemie - International Edition, Vol. 58, No. 49, 02.12.2019, p. 17863-17871.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{e31edb1117114e94817020b4b885a999,

title = "Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants—Comparison with Salt Bridges and Molecular Systems",

abstract = "We present deuteron quadrupole coupling constants (DQCC) for hydroxyl-functionalized ionic liquids (ILs) in the crystalline or glassy states characterizing two types of hydrogen bonding: The regular Coulomb-enhanced hydrogen bonds between cation and anion (c–a), and the unusual hydrogen bonds between cation and cation (c–c), which are present despite repulsive Coulomb forces. We measure these sensitive probes of hydrogen bonding by means of solid-state NMR spectroscopy. The DQCCs of (c–a) ion pairs and (c–c) H-bonds are compared to those of salt bridges in supramolecular complexes and those present in molecular liquids. At low temperatures, the (c–c) species successfully compete with the (c–a) ion pairs and dominate the cluster populations. Equilibrium constants obtained from molecular-dynamics (MD) simulations show van't Hoff behavior with small transition enthalpies between the differently H-bonded species. We show that cationic-cluster formation prevents these ILs from crystallizing. With cooling, the (c–c) hydrogen bonds persist, resulting in supercooling and glass formation.",

keywords = "DFT calculations, hydrogen bonding, ionic liquids, molecular-dynamics simulations, solid-state NMR",

author = "Khudozhitkov, {Alexander E.} and Jan Neumann and Thomas Niemann and Dzmitry Zaitsau and Peter Stange and Dietmar Paschek and Stepanov, {Alexander G.} and Kolokolov, {Daniil I.} and Ralf Ludwig",

note = "{\textcopyright} 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.",

year = "2019",

month = dec,

day = "2",

doi = "10.1002/anie.201912476",

language = "English",

volume = "58",

pages = "17863--17871",

journal = "Angewandte Chemie - International Edition",

issn = "1433-7851",

publisher = "John Wiley and Sons Ltd",

number = "49",

}

RIS

TY - JOUR

T1 - Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants—Comparison with Salt Bridges and Molecular Systems

AU - Khudozhitkov, Alexander E.

AU - Neumann, Jan

AU - Niemann, Thomas

AU - Zaitsau, Dzmitry

AU - Stange, Peter

AU - Paschek, Dietmar

AU - Stepanov, Alexander G.

AU - Kolokolov, Daniil I.

AU - Ludwig, Ralf

PY - 2019/12/2

Y1 - 2019/12/2

N2 - We present deuteron quadrupole coupling constants (DQCC) for hydroxyl-functionalized ionic liquids (ILs) in the crystalline or glassy states characterizing two types of hydrogen bonding: The regular Coulomb-enhanced hydrogen bonds between cation and anion (c–a), and the unusual hydrogen bonds between cation and cation (c–c), which are present despite repulsive Coulomb forces. We measure these sensitive probes of hydrogen bonding by means of solid-state NMR spectroscopy. The DQCCs of (c–a) ion pairs and (c–c) H-bonds are compared to those of salt bridges in supramolecular complexes and those present in molecular liquids. At low temperatures, the (c–c) species successfully compete with the (c–a) ion pairs and dominate the cluster populations. Equilibrium constants obtained from molecular-dynamics (MD) simulations show van't Hoff behavior with small transition enthalpies between the differently H-bonded species. We show that cationic-cluster formation prevents these ILs from crystallizing. With cooling, the (c–c) hydrogen bonds persist, resulting in supercooling and glass formation.

AB - We present deuteron quadrupole coupling constants (DQCC) for hydroxyl-functionalized ionic liquids (ILs) in the crystalline or glassy states characterizing two types of hydrogen bonding: The regular Coulomb-enhanced hydrogen bonds between cation and anion (c–a), and the unusual hydrogen bonds between cation and cation (c–c), which are present despite repulsive Coulomb forces. We measure these sensitive probes of hydrogen bonding by means of solid-state NMR spectroscopy. The DQCCs of (c–a) ion pairs and (c–c) H-bonds are compared to those of salt bridges in supramolecular complexes and those present in molecular liquids. At low temperatures, the (c–c) species successfully compete with the (c–a) ion pairs and dominate the cluster populations. Equilibrium constants obtained from molecular-dynamics (MD) simulations show van't Hoff behavior with small transition enthalpies between the differently H-bonded species. We show that cationic-cluster formation prevents these ILs from crystallizing. With cooling, the (c–c) hydrogen bonds persist, resulting in supercooling and glass formation.

KW - DFT calculations

KW - hydrogen bonding

KW - ionic liquids

KW - molecular-dynamics simulations

KW - solid-state NMR

UR - http://www.scopus.com/inward/record.url?scp=85074818635&partnerID=8YFLogxK

U2 - 10.1002/anie.201912476

DO - 10.1002/anie.201912476

M3 - Article

C2 - 31588622

AN - SCOPUS:85074818635

VL - 58

SP - 17863

EP - 17871

JO - Angewandte Chemie - International Edition

JF - Angewandte Chemie - International Edition

SN - 1433-7851

IS - 49

ER -

ID: 22335610