Abstract The properties of ionic liquids are described by a subtle balance between Coulomb interaction, hydrogen bonding, and dispersion forces. We show that lowering the attractive interaction choosing weakly coordinating anions leads to formation cationic clusters. These clusters like‐charged ions stabilized cooperative bonding controlled potential anion. IR NMR spectroscopy combined with computational methods used detect characterize these unusual, counter‐intuitively formed They can be...

In this contribution, we compute the 1H nuclear magnetic resonance (NMR) relaxation rate of liquid water at ambient conditions. We are using structural and dynamical information from Coupled Cluster Molecular Dynamics (CCMD) trajectories generated CCSD(T) electronic structure accuracy while also considering quantum effects in addition to consulting x-ray neutron scattering experiments. Our analysis is based on a recently presented computational framework for determining frequency-dependent...

We address the formation of hydrogen bonded domains among cationic constituents ionic liquid (IL) 1-(3-hydroxypropyl)pyridinium tetrafluoroborate [HPPy][BF4 ] by means cryogenic ion vibrational predissociation spectroscopy cold (ca. 35 K) gas-phase cluster ions and quantum chemistry. Specifically, analysis OH stretching bands reveals a chain-like OH⋅⋅⋅OH⋅⋅⋅OH⋅⋅⋅BF4- binding motif involving three cations in quinary (HPPy+ )3 (BF4- )2 . Calculations show that this cooperative H-bond attraction...

Abstract “Unlike charges attract, but like repel”. This conventional wisdom has been recently challenged for ionic liquids. It could be shown that like-charged ions attract each other despite the powerful opposing electrostatic forces. In principle, cooperative hydrogen bonding between of like-charge can overcome repulsive Coulomb interaction while pushing limits chemical bonding. The key challenge this solvation phenomenon is to establish design principles efficient formation clusters in...

We address the competition between intermolecular forces underlying recent observation that ionic liquids (ILs) with a hydroxyl-functionalized cation can form domains attractive interactions nominally repulsive positively charged constituents. Here we show this behavior is present even in isolated ternary (HEMIm+)2NTf2– complex (HEMIm+ = 1-(2-hydroxyethyl)-3-methylimidazolium) cooled to about 35 K photodissociation mass spectrometer. Of three isomers by double resonance techniques, one...

We provide comprehensive understanding of "like-likes-like" charge attraction in hydroxy-functionalized ionic liquids (ILs) by means infrared spectroscopy (IR), quantum chemistry and differential scanning calorimetry (DSC). show that hydrogen bonding between cation (c-c) is possible despite the repulsive forces ions like charge. Already at room temperature, bonds can compete with regular Coulomb-enhanced anion (c-a). For a large set well-selected ILs, we "like-charge attraction"...

We investigate the rotational and translational dynamics of ionic liquids (ILs) through a combined approach utilizing fast field cycling nuclear magnetic resonance (FFC NMR) relaxometry molecular (MD) simulations.

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 calculated robust local minima clear dissociation barriers preventing their "Coulomb explosion" into separated cations. 15 hydrogen bonding dispersion forces fully compensate for repulsive Coulomb between cations allowing quantification pure bond in order 20 kJ mol-1. The...

The combined experimental and theoretical approach for the gas liquid phases provides a quantitative understanding of competition between differently H-bonded charged constituents in liquids.

Abstract Quantum chemical calculations have been employed to study kinetically stable cationic clusters, wherein the monovalent cations are trapped by hydrogen bonding despite strongly repulsive electrostatic forces. We calculated linear and cyclic clusters of hydroxy‐functionalized cation N‐(3‐hydroxypropyl) pyridinium, commonly used as in ionic liquids. The largest cluster was a hexamer that very much resembles structural motifs molecular known for water alcohols. Surprisingly, strong...

We discuss the stability of cationic clusters when adding molecules or counterions, and predict their occurrence in gas phase experiments.

Ion pairing is one of the most fundamental atomic interactions in chemistry and biology. In contrast, between like-charged ions remains an elusive concept. So far, this phenomenon was observed only for large-scaled structures, assemblies, stabilizing frameworks, or aqueous solution wherein like-charge attraction supported by mediating water molecules. Recently, we reported formation cationic clusters pure ionic liquids (ILs) which all include hydroxyl groups (OH) possible hydrogen bonding....

Fast-field-cycling relaxometry is a nuclear magnetic resonance method growing in popularity; yet, theoretical interpretation limited to analytical models of uncertain accuracy. We present the first study calculating fast-field-cycling dipolar coupling directly from molecular dynamics simulation trajectory. In principle, frequency-resolved dispersion contains both rotational and translational diffusion information, among others. The joint experimental/molecular demonstrates that properties...

We present a computational framework for reliably determining the frequency-dependent intermolecular and intramolecular nuclear magnetic resonance (NMR) dipole-dipole relaxation rates of spin 1/2 nuclei from Molecular Dynamics (MD) simulations. This approach avoids alterations caused by well-known finite-size effects translational diffusion. Moreover, procedure is derived to control correct fixed distance-sampling cutoffs periodic boundary conditions. By construction, this capable accurately...

We report a concerted theoretical and experimental effort to determine the reorientational dynamics as well hydrogen bond lifetimes for doubly ionic +OH⋯O− in liquid (2-hydroxyethyl)trimethylammonium bis(trifluoromethylsulfonyl)imide [Ch][NTf2] by using combination of NMR relaxation time experiments, density functional theory (DFT) calculations, molecular (MD) simulations. Due fast proton exchange, determination rotational correlation times is challenging. For liquids, 17O-enhanced...

Hydrogen-bonded structures and their lifetimes in ionic liquids (ILs) are governed by the subtle balance between Coulomb interactions, hydrogen bonding, dispersion forces. Despite dominant interaction, local directional bonds (HBs) can play an important role behavior of ILs. Compared to water, archetype hydrogen-bonded liquids, ILs have larger constituents higher viscosities but typically lacking a three-dimensional HB network. Hydroxyl-functionalized even more special: regular HBs cations...

NMR field cycling relaxometry is a powerful method for determining the rotational and translational dynamics of ions, molecules, dissolved particles. This in particular true ionic liquids (ILs) which both ions carry sensitive nuclei. In IL triethylammonium bis(trifluoromethanesulfonyl)imide ([TEA][NTf2]), there are 1H nuclei at [TEA]+ cations 19F [NTf2]− anions. Moreover, high viscosity this leads to frequency-dependent relaxation rates, leaving so-called extreme narrowing regime. Both...

Abstract Die Eigenschaften ionischer Flüssigkeiten werden durch ein Gleichgewicht von Coulomb‐Wechselwirkung, Wasserstoffbrücken und Dispersionskräften beschrieben. Eine Verringerung der attraktiven Coulomb‐Wechselwirkung die Verwendung schwach koordinierender Anionen führt zur Bildung kationischer Cluster. Diese kooperative stabilisiert, ihre wird Wechselwirkungsstärke kontrolliert. Zum Nachweis dieser Cluster kamen IR‐ NMR‐Spektroskopie in Kombination mit Quantenchemie zum Einsatz. können...

Hydroxy functionalization of cations in ionic liquids (ILs) can lead to formation contacts between their OH groups [so-called (c–c) interactions]. One class these linkages involves cooperatively enhanced hydrogen bonds anionic partners that are sufficiently strong overcome the repulsion two positively charged centers. Herein, we clarify how propensity for depends on alkyl chain length cationic rings and by analyzing temperature-dependent IR spectra bulk ILs as well vibrational...

Sensitive probe of like-charge attraction: analyzing infrared spectra allows counting the number cations involved in clusters opposite (c–a) and like-charged (c–c) ions ionic liquids. This approach is also applicable to molecular

Hydrogen bonding in hydroxyl-functionalized ionic liquids (right) prevents favourable dispersion interaction between cation and anion (left). We analyze this subtle balance of interactions by combining calorimetry, IR spectroscopy MD simulations.

Abstract Wir untersuchen die Bildung von wasserstoffverbrückten Domänen zwischen den kationischen Bestandteilen der ionischen Flüssigkeit (IL) 1‐(3‐Hydroxypropyl)‐pyridinium‐tetrafluoroborat [HPPy][BF 4 ] mithilfe kryogenen Ionenschwingungs‐Prädissoziationsspektroskopie kalten (≈35 K) Gasphasenclustern und quantenchemischen Berechnungen. Eine Analyse OH‐Streckschwingungen zeigt ein kettenförmiges OH⋅⋅⋅OH⋅⋅⋅OH⋅⋅⋅BF − ‐Strukturmotiv, an dem drei Kationen in einem quinären Cluster (HPPy + ) 3...

We show that deuteron quadrupole coupling constants (DQCCs), and reorientational correlation times of molecular bonds N-D are involved in hydrogen bonding, can be determined from NMR T1 relaxation time experiments simultaneously. For this purpose, we used trialkylammonium-based protic ionic liquids (PILs) as model compounds. They exhibit high viscosities wide liquid ranges allow measurements far beyond the extreme narrowing region (ω0τc ≪ 1). The minima already occur at temperatures...