Insights into cation–anion hydrogen bonding in mesogenic ionic liquids: an NMR study

Majhi, Debashis; Dai, Jing; Dvinskikh, Sergey V.

doi:10.1039/d2cp03188d

Cited by 3 publications

(5 citation statements)

References 56 publications

(129 reference statements)

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“…Here, several overlapping signals become visible for every resonance. It is possible that at this point, more than one phase of the IL exists inside the support, a hypothesis that has also been made by Majhi et al…”

Section: Resultsmentioning

confidence: 57%

“…have recently deposited [C 12 C 1 im][BF 4 ], [C 12 C 1 im]Br, and [C 12 C 1 im]Cl on MCM-41 and KIT-6. For the strong hydrogen bonding anions (Br – and Cl – ), indeed the same imidazolium shifts were observed, pointing toward the presence of completely isolated ions, which may occur when [C 2 C 1 im] is replaced by a much more apolar cation …”

Section: Resultsmentioning

confidence: 59%

“…For the strong hydrogen bonding anions (Br − and Cl − ), indeed the same imidazolium shifts were observed, pointing toward the presence of completely isolated ions, which may occur when [C 2 C 1 im] is replaced by a much more apolar cation. 20 With increasing IL loading, 1 H imidazolium chemical shifts increase again in the case of…”

Section: Resultsmentioning

confidence: 96%

“…Along the same lines, 11 B MAS NMR spectra of 1-butyl-3-methyl-1 H -imidazolium tetrafluoroborate [C 4 C 1 im][BF 4 ] showed a narrow and a broadened component, indicating two phases of different mobility . Two-dimensional (2D) heteronuclear correlation (HETCOR) spectra can indicate proximities between silica and individual groups of the IL. , Majhi et al used solid-state NMR spectroscopy under static conditions to investigate the order parameter of IL smectic phases and were able to trace the influence of water hydrogen bonding on these phases. , Using MAS NMR, the same group recently investigated hydrogen bonding and phase transition in a series of aprotic, long-chain (C 12 ) mesogenic ILs with halide and BF 4 – counter anions impregnated in KIT-6 and MCM-41 . In 2012, the groups of Haumann and Buntkowsky have investigated the IL 1-ethyl-3-methyl-1 H -imidazolium bis(trifluoromethylsulfonyl)imide [C 2 C 1 im][NTf 2 ] on a silica gel with different degrees of pore filling by MAS NMR.…”

Section: Introductionmentioning

confidence: 97%

“…18,19 Using MAS NMR, the same group recently investigated hydrogen bonding and phase transition in a series of aprotic, long-chain (C 12 ) mesogenic ILs with halide and BF 4 − counter anions impregnated in KIT-6 and MCM-41. 20 In 2012, the groups of Haumann and Buntkowsky have investigated the IL 1-ethyl-3-methyl-1Himidazolium bis(trifluoromethylsulfonyl)imide [C 2 C 1 im]-[NTf 2 ] on a silica gel with different degrees of pore filling by MAS NMR. They determined the point of full surface coverage by the complete disappearance of the 1 H resonance of isolated silanol groups.…”

Section: Introductionmentioning

confidence: 99%

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Wetting Behavior and Support Interactions in Imidazolium-Based Supported Ionic Liquid Phase Materials─A Systematic Study by Solid-State Nuclear Magnetic Resonance Spectroscopy

Frosch¹,

Mendez²,

Koch³

et al. 2023

J. Phys. Chem. C

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Supported ionic liquid phase (SILP) catalysts are an extremely promising class of materials that combine advantageous concepts from both homogeneous and heterogeneous catalysis. Optimized SILP catalysts should exhibit a thin, homogeneous, and continuous film of the ionic liquid (IL) to avoid pore blocking and to ensure a good accessibility of the catalyst. Yet, the interactions between the IL and the support, which determine the formation of such a film, are still poorly understood. We investigate here in a systematic way the deposition of three imidazolium-based ILs on silica supports with different surface areas and morphologies using 1 H magic angle spinning solidstate nuclear magnetic resonance spectroscopy. We demonstrate that the point of complete surface wetting can be determined by the disappearance of the 1 H resonance of isolated silanol groups and that this point depends both on the textural properties of the support material and the chemical properties of the IL. 1 H chemical shifts also provide valuable insight into hydrogen bonding interactions within the IL and between the IL and the support. They indicate cleavage of the anion−cation hydrogen bonds upon IL deposition and the formation of new hydrogen bonds with the silica surface.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 96%