Related Experiment Video
Updated: Oct 3, 2025
12:37
Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers
Published on: September 4, 2015
12.5K
High-Temperature Quantum Tunneling and Hydrogen Bonding Rearrangements Characterize the Solid-Solid Phase Transitions
Alexander E Khudozhitkov1,2, Masaki Donoshita3, Alexander G Stepanov1,2
1Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk, 630090, Russia.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|February 21, 2022
Summary
We uncovered complex phase behavior in a glass-forming protic ionic liquid (PIL). Deuteron NMR revealed tunneling-driven mobility in P-D bonds at high temperatures, offering new insights into PIL dynamics.
Area of Science:
- Materials Science
- Physical Chemistry
- Solid-State Physics
Background:
- Protic ionic liquids (PILs) exhibit complex phase behavior crucial for their applications.
- Understanding molecular dynamics in PILs is key to predicting their macroscopic properties.
- Solid-state NMR spectroscopy is a powerful tool for probing molecular motion in condensed phases.
Purpose of the Study:
- To investigate the complex phase behavior of d3-octylphosphonium bis(trifluoromethylsulfonyl)imide ([C8H17PD3][NTf2]) over a wide temperature range.
- To elucidate the molecular mechanisms governing the transitions between different dynamic states in the PIL.
- To provide evidence for tunneling-driven mobility in the glassy state of PILs.
Main Methods:
- Solid-state NMR spectroscopy was employed to study deuteron dynamics.
- Line shape analysis and spin relaxation studies were performed on the PD3 group.
- Temperature-dependent measurements were conducted from 71 K to 343 K.
Main Results:
- A static state was observed at 71 K, characterized by a unique deuteron quadrupole coupling constant.
- A transition from static to mobile state around 100 K, attributed to the breaking of hydrogen bonds, with an enthalpy of ~12 kJ/mol.
- Evidence for quantum tunneling driving mobility in P-D moieties up to 200 K.
- Above 250 K, a transition from anisotropic to isotropic motion indicates strong internal rotation of the PD3 group.
Conclusions:
- Solid-state NMR successfully mapped the phase behavior and molecular dynamics of the PIL.
- Tunneling-driven mobility of hydrogen-bonded P-D moieties occurs at surprisingly high temperatures in the glassy state.
- The study links molecular-level dynamics to macroscopic phase behavior, extending beyond DSC analysis.
Related Concept Videos
02:31Phase Transitions
20.6K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
20.6K
01:19Phase Changes
4.6K
Phase transitions play an important theoretical and practical role in the study of heat flow. In melting or fusion, a solid turns into a liquid; the opposite process is freezing. In evaporation, a liquid turns into a gas; the opposite process is condensation.
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
4.6K
02:33Phase Transitions: Sublimation and Deposition
18.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
18.3K
02:39Phase Transitions: Melting and Freezing
13.4K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
13.4K
02:39Phase Transitions: Vaporization and Condensation
19.1K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase...
19.1K
01:19Phase Diagram
6.2K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
6.2K