TY - JOUR

T1 - Tributylphosphonium ionic liquids with anions of varying basicity: ion pair structure, hydrogen bonds and ion dynamics

AU - Khudozhitkov, Alexander E.

AU - Rauber, Daniel

AU - Philippi, Frederik

AU - Morgenstern, Bernd

AU - Schroeder, Daniel

AU - Gallei, Markus

AU - Kolokolov, Daniil I.

AU - Ludwig, Ralf

N1 - Alexander E. Khudozhitkov, Daniel Rauber, Frederik Philippi, Bernd Morgenstern, Daniel Schroeder, Markus Gallei, Daniil I. Kolokolov, Ralf Ludwig, Tributylphosphonium ionic liquids with anions of varying basicity: ion pair tructure, hydrogen bonds and ion dynamics, Journal of Molecular Structure, Volume 1378, 2026, 147300, ISSN 0022-2860, 10.1016/j.molstruc.2026.147300. This work has been supported by the Russian Science Foundation (grant N◦ 24-73-00032, https://rscf.ru/en/project/24-73-00032/). D.R. and M.G. would like to thank the state government of Saarland for partially supporting this study as part of the EnFoSaar project, which is funded by the Saarland Transformation Program for Research and Knowledge Transfer (Transformationsprogramm Forschung und Wissenstransfer Saar). Instrumentation and technical assistance for this work were provided by the Service Center X-ray Diffraction, with financial support from Saarland University and German Science Foundation (project number INST 256/506-1 (D8 Venture) and 256/582-1 (Synergy-S). R.L. is grateful to the Deutsche Forschungsgemeinschaft (DFG) for financing the projects LU 506/17-1, No. 470038970, and LU-506/18-1, No. 517661181.

PY - 2026/8/12

Y1 - 2026/8/12

N2 - We present the first deuteron quadrupole coupling constants (DQCCs) for tributylphosphonium ionic liquids (ILs) with anions of varying interaction basicity. The Pake spectra from solid-state NMR spectroscopy provide DQCC values between 103 kHz and 116 kHz for all studied ILs. No directional hydrogen bonds (H-bonds) between the P-H bonds and the respective anions are formed, which is in stark contrast to the trialkylammonium-based analogues, wherein the N–H bonds form strong, almost linear H-bonds to the anions. This finding is confirmed by the large H-bond distances and small H-bond angles obtained from X-ray crystallography. The nearly constant DQCCs allow for an evaluation of the deuterium T1 and T2 relaxation times to obtain valuable information about the temperature-dependent dynamics of the cations in the phosphonium-based ILs depending on the anion basicity.

AB - We present the first deuteron quadrupole coupling constants (DQCCs) for tributylphosphonium ionic liquids (ILs) with anions of varying interaction basicity. The Pake spectra from solid-state NMR spectroscopy provide DQCC values between 103 kHz and 116 kHz for all studied ILs. No directional hydrogen bonds (H-bonds) between the P-H bonds and the respective anions are formed, which is in stark contrast to the trialkylammonium-based analogues, wherein the N–H bonds form strong, almost linear H-bonds to the anions. This finding is confirmed by the large H-bond distances and small H-bond angles obtained from X-ray crystallography. The nearly constant DQCCs allow for an evaluation of the deuterium T1 and T2 relaxation times to obtain valuable information about the temperature-dependent dynamics of the cations in the phosphonium-based ILs depending on the anion basicity.

KW - твердотельный ядерный магнитный резонанс

KW - ионные жидкости

KW - водородная связь

KW - расчеты DFT

KW - времена корреляции

KW - константы квадрупольного взаимодействия дейтрона

KW - Solid-state nuclear magnetic resonance

KW - Ionic liquids

KW - Hydrogen bonding

KW - DFT calculations

KW - Deuteron quadrupole coupling constants

KW - Correlation times

UR - https://www.mendeley.com/catalogue/45ce8795-0bb3-38b1-b587-75259db57c37/

UR - https://www.scopus.com/pages/publications/105047051356

U2 - 10.1016/j.molstruc.2026.147300

DO - 10.1016/j.molstruc.2026.147300

M3 - Article

VL - 1378

JO - Journal of Molecular Structure

JF - Journal of Molecular Structure

SN - 0022-2860

ER -